Porous ZnO nanorods that displayed excellent photocatalytic degradation of organic pollutants (RhB and phenol) were prepared via a solvent thermal method followed by surface modification with carbon dots (C-dots) using a deposition method. The photocatalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-Vis) spectroscopy. The degradation of the organic pollutants using the nanorods was tested under Xe-light illumination and was enhanced following C-dot modification. Nanorods that were modified by the C-dots at a mass fraction of 1.2% (CZn1.2) exhibited the highest photocatalytic activity for the degradation of RhB, which was 2.5 times of the pure porous ZnO nanorods. Additionally, the modified nanorods with strangely oxidation ability could catalyze the degradation of phenol by open-rings reaction under Xe-light illumination. The improved photocatalytic activity was attributed to the effective separation of the photogenerated electrons and holes, in which the C-dots served as the receptor of the photogenerated electrons.

P25-reduced graphene oxide nanocomposites (RGO-P25) are prepared by using a facile one-step hydrothermal method. Their structure and photoelectrical properties are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The degradation effect of different addition ratios of the RGO-P25 nanocomposite on the photocatalytic degradation of methylene blue (MB) is investigated under UV and visible illumination. Results show that graphene oxide can be reduced during the hydrothermal reaction and thus, a mixed high defect P25 particles and RGO sheet composite is formed by electrostatic attraction. Band gaps of nanocomposites decreased from 3.00 to 2.27 eV with an increase in the amount of the RGO content. The electrical conductivities of the nanocomposites enhanced with an increased RGO amount. Over 80% of the initial methylene blue dye is decomposed by 1% (w, mass fraction) RGO-P25 after 30 min under either visible light or ultraviolet light. Under UV light illumination, 63% (molar fraction) of the N3 dye, cis-Ru(H₂dcbpy)₂(NCS)₂ (H₂dcbpy = 4, 4'-dicarboxy-2, 2'-bipyridyl), is decomposed by the 1% RGO-P25 nanocomposite. Compared with the bare P25 (75% anatase; 25% rutile), the continual addition of RGO enhances the photocatalytic activity and gives rise to the more effective separation of photogenerated electron-hole pairs.

A series of MnSAPO-34 molecular sieves were synthesized by a hydrothermal method for selective catalytic reduction (SCR) of NO with NH₃ and characterized using X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature-programmed desorption (TPD). Three factors were studied, including Mn-loading, calcination temperature, and synthesis time. The MnSAPO-34, which was synthesized in 6 h and calcined at 550 ℃ with the Mn-loading (n_(MnO)/n_(P2O5)= 0.1), exhibits the highest activity among all the samples, with NO_x conversion of almost 100% and N₂ selectivity higher than 80%. The results show that the porous and crystalline structures of MnSAPO-34 are greatly affected by addition of manganese, and excessive Mn-loading could result in lower crystallinity and the generation of nonframework manganese oxides. Meanwhile, a decrease in specific surface area and pore volume are observed in MnSAPO-34 with higher Mn-loading; however, the opposite characteristics are observed with a decreasing calcination temperature and shorter synthesis time. Manganese species of high oxidation state, mostly Mn⁴⁺, are shown to be on the catalysts surface after high temperature calcination, and the increase ratio of Mn³⁺ could help to improve the catalytic activity. Under proper synthesis conditions, the incorporation of manganese could improve the adsorption of nitric oxide and ammonia, and the interaction between the strongly adsorbed NO and strongly adsorbed NH₃ might be the reason for the enhancement in their catalytic efficiency.

The conversion of CO₂ into organic compounds is a promising method to mitigate global warming and assist in sustaining energy resources. A series of plasmonic photocatalysts, comprised of Ag supported on Ag₂WO₄ (Ag/Ag₂WO₄) with different crystalline phases, are fabricated by a facile ion-exchange method and subsequent reduction with hydrazine hydrate. The catalysts are characterized using X-ray diffraction (XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), UV-Vis absorption spectroscopy, and Brunauer-Emmett-Teller analyses. Compared with Ag₂WO₄, the Ag/Ag₂WO₄ exhibits a markedly improved quantum yield (QY), energy returned on energy invested (EROEI), and turnover number (TON) for CO₂ reduction to CH₄ under visible-light irradiation. Among Ag/α-Ag₂WO₄, Ag/β-Ag₂WO₄, and Ag/γ-Ag₂WO₄ catalysts, the highest activity for CO₂ photoreduction to CH₄ is obtained for Ag/β-Ag₂WO₄ with an actual molar composition of 4% Ag and 96% Ag₂WO₄. Correspondingly the QY, EROEI, TON, and pseudo first-order rate constant are 0.145%, 0.067%, 9.61, and 1.96×10^-6 min^-1, respectively. Moreover, the plasmonic Ag/Ag₂WO₄ photocatalysts are stable after repeated reaction cycles under visible-light irradiation. It is proposed that the localized surface plasma resonance effect of surfacedeposited Ag contributed to the enhanced activities and stabilities of the Ag/Ag₂WO₄ photocatalysts.

A Cu₃(BTC)₂ (copper(Ⅱ) benzene 1, 3, 5-tricarboxylate) metal organic framework (MOF) catalyst was successfully prepared through an electrochemical route and used for selective catalytic reduction of nitrogen oxide (NO_x) with NH₃ for the first time. After systematically optimizing the reaction conditions such as solvents, voltage, electrolyte concentration, and reaction time, pure Cu₃(BTC)₂ with high crystallinity was obtained in 97.2% yield. The physicochemical properties of the catalyst were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy, in situ Fourier transform infrared (FTIR) spectroscopy, temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). TGA results indicated that the framework was stable up to 310℃. The catalytic activity of Cu₃(BTC)₂ was evaluated using NO conversion as a model reaction. The Cu₃(BTC)₂ activation temperature significantly affected the catalytic activity. The Cu₃(BTC)₂ sample activated at 240℃ had the best catalytic activity and gave NO conversion of 90% at 220-280℃. A reaction mechanism was proposed based on the in situ FTIR spectroscopy results.

CeO₂-ZrO₂ and CeO₂-ZrO₂-La₂O₃ catalysts with mass ratios of 60:40 and 60:30:10 were prepared by co-precipitation method, respectively. The catalytic activity in oxidation of the soluble organic fraction (SOF) in diesel exhausts was studied using thermogravimetric-differential thermal analysis (TGDTA). The results indicate that the catalytic activity of the La-modified CeO₂-ZrO₂ catalyst is better than that of the CeO₂-ZrO₂ catalyst; the light-off temperature of SOF is 164 ℃, and the weightlessness fastest point temperature is 212 ℃, whereas for CeO₂-ZrO₂, these temperatures are 168 and 221 ℃, respectively. X-ray diffraction (XRD) shows that modification with La is beneficial to decrease the growth rate of the crystallite size relative to that of CeO₂-ZrO₂ after high-temperature ageing. N₂ adsorption-desorption results suggest that the addition of La enlarges the surface area. O₂-temperature-programmed desorption (O₂-TPD) and X-ray photoelectron spectroscopy (XPS) show that modification with La increases the amount of chemisorbed oxygen on the CeO₂-ZrO₂ catalyst. The CeO₂-ZrO₂-La₂O₃ catalyst shows better activity and ageing resistance than the CeO₂-ZrO₂ catalyst.

CeO₂ promoted CuCl/activated carbon (AC) adsorbents were prepared using an incipient wetness impregnation method, and characterized using N₂ adsorption/desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The Cu(II) on the AC surface was reduced to Cu(I) when calcination was performed in a nitrogen flow. The effects of Ce on the C₂H₄/C₂H₆ adsorptive separation performance were investigated. The adsorption isotherms showed that the addition of CeO₂ improved the separation performance by decreasing the C₂H₆ adsorption capacity compared with that of the nonpromoted sample. The XRD and XPS results indicated that the active crystal particles on the AC surface became smaller, leading to higher dispersion and a higher degree of Cu(II) reduction. The best adsorption selectivity was obtained using the 5Ce50Cu [CeO₂ and CuCl2 mass fractions (w) 5% and 50%, respectively] sample, i.e., with CeO₂ in the adsorbent; the adsorption selectivity increased from 4.2 to 8.7 at 660 kPa compared with that of the 50Cu sample.

The growth mode, electronic structure, and thermal stability of Ni nanoparticles on thin ZrO₂(111) film surfaces were investigated using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. Stoichiometric ZrO₂(111) thin films with thickness of 3 nm were epitaxially grown on a Pt(111) single-crystal surface. The results indicate that the growth of Ni vapor deposited on thin ZrO₂(111) films follows two-dimensional growth up to 0.5 ML (monolayer), followed by threedimensional growth (i.e., the Stranski-Krastanov growth mode). The Ni 2p_3/2 binding energy (BE) increases with decreasing Ni coverage. We used the Auger parameter method to differentiate the contributions to this BE shift from the initial-state and final-state effects. The main contribution to the Ni 2p core level BE shift is made by the final-state effect. However, at low Ni coverages, the initial-state effect also contributes. This suggests that at the initial stage of Ni growth on the ZrO₂(111) surface, Ni and ZrO₂ interact strongly, leading to charge transfer from Ni to the ZrO₂ substrate, with the appearance of partially positively charged Ni_δ+. Thermal stability studies of Ni/ZrO₂(111) model catalysts with two different coverages (0.05 and 0.5 ML) indicate further oxidation of Ni to Ni₂₊ and concurrent diffusion of Ni into the ZrO₂ substrate at elevated temperatures. These findings provide an atomic-level fundamental understanding of the interactions between Ni with ZrO₂, which is essential for identifying the structures of real ZrO₂-supported Ni catalysts.

ZSM-5 zeolites with different pore structures were synthesized using different templates (tetrapropyl ammonium hydroxide (TPAOH), cetyltrimethylammonium bromide (CTAB) and C_18-6-6Br₂). The obtained nanosized (NZ), mesoporous (MZ), and nanosheets (NSZ) ZSM-5 samples were compared with conventional microporous ZSM-5 zeolite (CZ). The physicochemical properties of these samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂ adsorption-desorption, and temperature-programmed desorption of ammonia (NH₃-TPD). The results showed that the mesopore volumes and surface areas of the four samples increased in the order NSZ > MZ > NZ > CZ, and the ratio of strong/weak acidity increased in the order CZ > MZ > NZ > NSZ. In the methanol to propylene (MTP) reaction, the catalyst porosity played an important role on the product selectivity and catalytic stability. The selectivities for propylene and total olefins improved with increasing mesoporosity; NSZ, with the largest mesopore volume, gave the highest propylene selectivity, i.e., 47.5%, and 78.4% total olefins. Meanwhile, the introduction of mesopores into the ZSM-5 zeolite extended the catalytic lifetime. The NZ sample displayed reliable MTP catalytic activity for 200 h, which was predominately attributed to its optimal combination of acidity and porosity.

Cu-SSZ-13 catalysts had been prepared by using a microwave irradiation (MW) method and a conventional hydrothermal (CH) method, which were applied to removal of NO_x from diesel vehicles by NH₃. The physical and chemical properties of the samples were characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, H₂ temperature-programmed reduction (H₂-TPR), electron paramagnetic resonance (EPR), NH₃ temperature-programmed desorption (NH₃-TPD), inductively coupled plasma-mass spectroscopy (ICP-MS), and X-ray photoelectron spectroscopy (XPS). The MW had some significant advantages, greatly shortening the crystallization time of SSZ-13 and improving its physical and chemical properties. The sample synthesized using MW with a crystallization time of 9 h had similar crystallinity to that synthesized by the CH with a crystallization time of 72 h. The sample synthesized by the MW had improved pore structure and amounts of Lewis (L) acid and Brönsted (B) acid. The great increase in Cu load as an active component indicated that the MW enhanced the ability of SSZ-13 to perform Cu exchange. The Cu-SSZ-13 synthesized by MW had improved low-temperature activity and anti-aging ability.

By using pulse-microwave assisted chemical reduction, we prepared a Pt-Ni alloy supported on a cobalt-polypyrrole-carbon (Co-PPy-C) catalyst. The catalyst microstructure and morphology were characterized by using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrocatalytic performance and durability of the catalysts were measured with cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The metal particles were well dispersed on the carbon support, and the particle size of PtNi/Co-PPy-C was about 1.77 nm. XRD showed that the Pt(111) diffraction peak was strongest, so the most of the Pt in the catalysts was in a face-centered cubic lattice. The electrochemical surface area (ECSA) of PtNi/Co-PPy-C (72.5 m²·g^-1) was higher than that of Pt/C(JM) (56.9 m²·g^-1). After an accelerated durability test for 5000 cycles, the particle size of PtNi/Co-PPy-C obviously increased. The degradation rate of ECSA and the mass activity (MA) of PtNi/Co-PPY-C were 38.2% and 63.9%, respectively. We applied the PtNi/Co-PPy-C catalyst after optimizing the membrane electrode assembly (MEA) with an area of 50 cm². The fuel cell could be suitably operated at 70 ℃ with a back pressure of 50 kPa. At these conditions, the maximum power density of MEA by PtNi/Co-PPy-C was 523 mW·cm^-2. The excellent performance of PtNi/Co-PPy-C makes it a promising catalyst for proton exchange membrane fuel cells (PEMFCs).

Three types of hierarchical, flower-like CuS particles were prepared by a hydrothermal method and samples were formulated as thin nanosheets. The aggregation density of the sheets could be readily controlled with the aid of polyvinylpyrrolidone (PVP) or 1, 3, 5-benzenetricarboxylic acid (BTC) organic molecules. The three substrates were then used for the growth of nickel nanocatalysts and the structures of the composites characterized by environment scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Ultraviolet-visible absorption spectrometry was applied to study the catalytic reduction of 4-nitrophenol. Results show that a sample of Ni nanoparticles (Ni NPs, ~5 nm in diameter) grown on CuS micro-flowers, composed of the sparsest nanosheets (Ni@SUB2) with an ultralow loading of 0.469% (w), showed the best catalytic properties amongst the three Ni@SUB composites. During reduction of 4-nitrophenol with initial 4-nitrophenol concentrations of 0.2 mmol·L^-1, the Ni@SUB2 showed almost 100% transformation within 4 min, while the same quantity of pure Ni NPs showed a transformation of only ~43%. The enhanced catalytic properties for 4-nitrophenol degradation could be ascribed to well-dispersed Ni NPs supported on the CuS substrate providing greater numbers of catalytic active sites. Furthermore, because of CuS is insoluble, it can be easily collected by centrifugation, which can be environmentally beneficial.

Graphene oxide (GO) was fabricated from graphite powder by Hummers oxidation method and then, under ultrasonic irradiation, a series of GO/Ag₃PO₄ composite photocatalysts (4% (w, mass fraction) GO/Ag₃PO₄, 8% GO/Ag₃PO₄, 16% GO/Ag₃PO₄, 32% GO/Ag₃PO₄) were synthesized by a facile liquid deposition process. The products were characterized by N₂-physical adsorption, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, Fourier transform infrared (FT-IR) spectroscopg, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The effect of GO content on the photocatalytic activity of Ag₃PO₄ was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results show that GO can be easily dispersed into Ag₃PO₄, producing a well-connected GO/Ag₃PO₄ composite. Coupling of GO largely enhanced the surface area of the catalyst and the adsorption of MO. At the optimal GO content (16%), the degradation rate of MO over GO/Ag₃PO₄ was 83% after 120 min of light irradiation, exhibiting 7.5 times higher activity than that of pure Ag₃PO₄. The increase in photocatalytic activity and stability can be mainly attributed to the coupling of GO, which increased the surface area and suppressed the recombination rate of electron-hole (e^-/h⁺) pairs and generated greater numbers of active free radicals.

Membranes with both good permeation and selectivity are highly desired for gas separations. We synthesized a polyimide (PI) asymmetric membrane using the phase-inversion method, and then modified the surface with a mixture of porous fillers and poly(amic acid) (PAA). The porous fillers included the metal organic framework (MOF) of Cu₃(BTC)₂ (copper benzene-1, 3, 5-tricarboxylate), the zeolite imidazole framework (ZIF) of ZIF-8, and the porous hydrotalcite of MgAl-LDH. A series of asymmetric mixed-matrix membranes (MMMs) were obtained after surface coating and thermal amidation. The MMM structure, CO₂, CH₄, and N₂ permeance, and the ideal gas selectivity were investigated. With the surface modification, the morphology of the surface separation layers of the asymmetric PI/ZIF-8, PI/LDH, and PI/Cu₃(BTC)₂ MMMs significantly changed, and the gas separation performance changed accordingly. The PI/ZIF-8 asymmetric MMM with 5% (w) ZIF-8 doping exhibited both enhanced ideal gas selectivity and permeance; the CO₂/N₂ and CO₂/CH₄ selectivity were as high as 24 and 83, respectively. Thus, this surface modification provides improved MMM gas separation performance.

Ag₃PO₄ polyhedrons were synthesized by a facile hydrothermal route using polyethylene glycol-6000 (PEG-6000). The effects of hydrothermal temperature, reaction time, and PEG-6000 dosage on the morphologies and structures of the products were systematically investigated. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), and photoluminescence (PL) spectra. The hydrothermal temperature and the PEG dosage are key factors in the production of Ag₃PO₄ polyhedrons with oriented {110} facets. The Ag₃PO₄ polyhedrons evolve via Ostwald ripening, and exhibit superior visible-light photocatalytic degradation of Rhodamine B (RhB) relative to Ag₃PO₄ samples without oriented {110} facets and Ag₃PO₄ nanoparticles prepared by anion-exchange. The reaction rate constant of the Ag₃PO₄ polyhedrons was 8.3 times that of the Ag₃PO₄ nanoparticles. Total organic carbon (TOC) analysis and cycling experiments revealed that the polyhedrons have better mineralization efficiency and exhibit good circulation runs. Holes (h+) and hydroxyl radicals (·OH) are confirmed to be the dominant active species in the presence of radical scavengers and in N₂-saturated solution. Given the redox potential of the active species and the band structure of Ag₃PO₄ polyhedron, the separation and migration mechanism of photogenerated electron-hole (e^--h⁺) pairs at the photocatalytic interface was proposed.

Pb(II) adsorption by three activated carbons (ACs) with similar surface chemistry but different pore distributions was investigated by isothermal adsorption experiments. The ACs were characterized by scanning electron microscopy (SEM) and N₂ adsorption at 77 K, while the micropore and mesopore size distributions were obtained from the density functional theory (DFT) and the Barrett-Joyner-Halenda (BJH) method, respectively. The specific surface area and total volume were ranked in order of AC1, AC2, and AC3. The AC2 sample had a uniform distribution of open pores on the surface and the highest saturating adsorption capacity, while the capacity of AC3, which had more aggregated pores, was similar to that of AC1, which had a concentrated distribution of open pores on the surface. A correlation analysis of pore structure and adsorption capacity indicated that pores with diameters in the range of 0.4-0.6 nm were favorable for Pb(II) adsorption, whereas pores with diameters in the ranges of 10.5-20.6 nm, 20.6-55.6 nm, and 5.2-10.5 nm had an adverse effect.

Microwave hydrogen plasma was used to introduce hydrogen termination on the diamond surface. Optical emission spectroscopy (OES) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to characterize the active radicals in the plasma and the concentration of H-termination on the diamond surface, respectively. Thermal hydrogenation treatment carried out by hot filament heat in a hydrogen atmosphere was also proposed for incorporation of H-termination on the diamond surface. The results showed that the CH radical content in the microwave plasma and the H-termination concentration on the diamond surface after microwave plasma treatment were both facilitated by increasing the substrate temperature, plasma density, and input power. Interestingly, thermal hydrogenation treatment can produce Htermination on the diamond surface compared with to a similar extent to microwave plasma treatment. These observations show that the crucial factor for forming the H-terminated diamond surface is the surface chemical reaction controlled by temperature, rather than the plasma etching effect. When the temperature is above 500 ℃, C=O bonds on the O-terminated diamond surface decompose to CO and leave dangling bonds, which then connect with atomic or molecular hydrogen.

A series of non-platinic lean NO_x trap (LNT) CuO-K₂CO₃/TiO₂ catalysts with different Cu loadings were prepared by sequential impregnation, and they showed relatively good performance for lean NO_x storage and reduction. The catalyst containing 8% (w) CuO showed not only the largest NO_x storage capacity of 1.559 mmol·g^-1 under lean conditions, but also the highest NO_x reduction percentage of 99% in cyclic lean/rich atmospheres. Additionally, zero selectivity of NO_x to N₂O was achieved over this catalyst during NO_x reduction. Multiple techniques, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), temperature-programmed desorption of CO₂ (CO₂-TPD), extended X-ray absorption fine structure (EXAFS), temperature-programmed reduction of H₂ (H₂-TPR), and in-situ diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS), were used for catalyst characterization. The results indicate that highly dispersed CuO is the main active phase for oxidation of NO to NO₂ and reduction of NO_x to N₂. The strong interaction between K₂CO₃ and CuO was clearly revealed, which favors NO_x adsorption and storage. The appearance of negative bands at around 1436 and 1563 cm^-1, corresponding to CO₂ asymmetric stretching in bicarbonates and -C=O stretching in bidentate carbonates, showed the involvement of carbonates in NO_x storage. After using the catalysts for 15 cycles of NO_x storage and reduction in alternative lean/rich atmospheres, the CuO species in the catalysts showed little change, indicating high catalytic stability. Based on the results of in-situ DRIFTS and the other characterizations, a model describing the NO_x storage processes and the distribution of CuO and K₂CO₃ species is proposed.

The catalytic activity, hydrothermal aging resistance, and sulfur tolerance of a Pd-Pt-based methane oxidation catalyst were evaluated in a fixed fluidized bed reactor containing simulated lean-burn natural gas vehicle exhaust gases. Zirconium-doped Pd-Pt/Al₂O₃ (Pd-Pt/Zr_xAl_(1-x)O_(3+x)/2) was found to significantly improve the catalytic activity, hydrothermal aging resistance, and sulfur tolerance. Zr-modified alumina supports were prepared by co-precipitation with molar ratios of Zr to Al of 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0. The Pd-Pt bimetallic catalysts containing 1.5% (w, mass fraction) Pd and 0.3% (w) Pt supported on the above-modified composite supports were prepared by the co-impregnating method. The catalysts were characterized by N₂ adsorption/desorption, X-ray diffraction(XRD), H₂ temperatureprogrammed reduction (H₂-TPR), O₂ temperature-programmed desorption, and X-ray photoelectron spectroscopy (XPS). The results show that the crystallinity of the samples, dispersion of the active component, number of Pd²⁺ species, and electron density around Pd2+ species increase after addition of ZrO₂ to Al₂O₃ supports. Compared with the activity results of Pd-Pt/Al₂O₃ and Pd-Pt/ZrO₂ catalysts after different pretreatment conditions, the performance of the catalyst is greatly enhanced by adding ZrO₂ in the Al₂O₃ supports, and Pd-Pt/Zr_0.5Al_0.5O_1.75 shows the best catalytic activity, strongest hydrothermal aging resistance, and highest sulfur tolerance among the investigated catalysts.

Supports have a significant effect on the dispersion and stability of Au nanoparticles because of the support-metal interaction. In the present work, TiO_x/SiO₂ composite supports were prepared by the surface sol-gel (SSG) method to enhance the binding strength between the metal and the support. The samples were characterized by low-energy ion scattering (LEIS) spectroscopy, X-ray photoelectron spectroscopy (XPS), Xray diffraction (XRD), transmission electron microscopy (TEM), and N₂ physisorption (BET). The results showed that the TiO_x species in TiO_x/SiO₂ were highly dispersed on SiO2 with the formation of Ti―O―Si linkages. The catalytic activity and stability for CO oxidation on Au/TiO_x/SiO₂ were significantly enhanced, because of the better dispersion of Au nanoparticles compared with Au/TiO₂.

Perfluorosulfonic acid functionalized carbon-based solid acid catalysts were prepared by liquid deposition of perfluorosulfonic acid-polytetrafluoroethylene (PTFE) copolymer using carbon nanotubes, mesoporous carbon molecular sieves, and nitrogen-doped mesoporous carbon as precursors. The obtained catalysts were characterized by N₂ adsorption, thermogravimetric analysis (TG), transmission electron microscope (TEM), Fourier transform Infrared (FTIR) spectrometer, and potentiometric titration. Their catalytic behavior in the Friedel-Crafts (F-C) alkylation of anisole was also investigated. It was found that the surface area of the precursor and its interaction with perfluorosulfonic acid play important roles in the preparation of highly active catalysts. The highest activity as well as the best stability was observed over perfluorosulfonic acid functionalized nitrogen-doped mesoporous carbon.

MnO_x nanoparticles obtained by the emulsion method were loaded on a microporous tubular titanium membrane to prepare a functional MnO_x/Ti electrocatalytic membrane. The effects of calcination temperature on the crystal structure of MnO_x as well as the electrochemical properties and catalytic performance to oxidize benzyl alcohol of MnO_x/Ti membrane were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), cyclic voltammetry (CV), chronoamperometry (CA), and other characterization methods. The results indicated that the crystal structure of MnO_x was gradually transformed from Birnessite-MnO₂ to K_0.27MnO₂, and finally to α-MnO₂ from Mn3O4 with increasing calcination temperature. The α-MnO₂ particles in the MnO_x/Ti electrocatalytic membrane showed high crystallinity and uniform particle size (less than 30 nm). The superior electrochemical properties and catalytic performance of α-MnO₂/Ti membrane obtained at a calcination temperature of 450 ℃ could be attributed to the binding effects between unsaturated coordination atoms of Mn and oxygen vacancies with the Ti substrate. The α-MnO₂/Ti membrane obtained at 450 ℃ was used as the anode to assemble an electrocatalytic membrane reactor to oxidize benzyl alcohol. 64% conversion of benzyl alcohol and 79% selectivity to benzaldehyde was achieved under the operating conditions: reaction temperature 25 ℃, aqueous benzyl alcohol solution of 50 mmol·L^-1, current density 2 mA·cm^-2, and residence time 15 min.

NiMo/TiO₂-Al₂O₃ slurry catalysts with fluorine as an additive were prepared by complete liquidphase technology for hydrodesulfurization. The effect of different fluorine addition methods on the properties of the catalysts for 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) hydrodesulfurization were investigated. The catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction of H₂ (H₂-TPR), N₂ adsorption-desorption isotherms (BET), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). The results reveal that in the absence of nitric acid, adding fluoride into the catalyst before the introduce of molybdenum and nickel ions can significantly increase the surface area and average pore size, improve the dispersion of metallic nickel on the surface of catalyst, and weaken the interaction between the metal and the support. This effectively increases the sulfidation degree of Mo, MoS₂ slab stacking, and the content of the highly active Ni-Mo-S(II) phase, which can promote the hydrogenation of the aromatic ring and the hydrogenolysis of the C-S bond, and thus increase the hydrodesulfurization activity for 4, 6-DMDBT.

The core-shell type poly(styrene-N-isopropylacrylamide)/poly(N-isopropylacrylamide-co-3-methacryloxypropyltrimethoxysilane) (P(St-NIPAM)/P(NIPAM-co-MPTMS)) composite microgels with thermosensitivity were synthesized by two-step polymerization methods. Using P(St-NIPAM)/P(NIPAM-co-MPTMS) composite microgels modified by (3-mercaptopropyl) trimethoxysilane (MPS) as support material, Ag nanoparticles (AgNPs) were in-situ controllably synthesized using ethanol as a reducing regent. The structure, composition and properties of the prepared P(St-NIPAM)/P(NIPAM-co-MPTMS)-(SH)Ag composite materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fouriertransform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and UV-visible spectroscopy (UV-Vis). Additionally, the catalytic activity of the composite microgels was investigated using the reduction of 4-nitrophenol (4-NP) by NaBH₄ as a model reaction. The results showed that the dispersity of the in situ formed AgNPs was greatly improved because of the confining effect of the organic-inorganic microgel network with mercapto groups. Although the thermosensitivity of the composite microgels decreased because of the PNIPAM segments separated by the inorganic networks formed by MPTMS, the composite microgels still showed excellent catalytic performance and thermosensitivity in modulating the catalytic activity of AgNPs. These findings are related to the following aspects. The separated PNIPAM segments are favorable for mass transfer, and the networks with mercapto groups allow control of the size and local distribution of the in situ formed AgNPs. The present results are significant for construction of functional nanoscale metal catalytic materials.

Carbon nanotubes (CNTs) pretreated with concentrated HNO3 and tetrabutyl titanate were used as raw materials to prepare CNTs-TiO₂ composite supports by the sol-gel method. Vanadium was then dipped into the CNTs-TiO₂ composite support to synthesize the V₂O₅/CNTs-TiO₂ catalyst. The influence of calcination temperature on the active species of the catalyst and the catalytic oxidation performance for degradation of hexachlorobenzene (HCB) were investigated. The synthesized catalysts were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet-visible (UV-Vis) spectroscopy. The surface chemical properties were analyzed by X-ray photoelectron spectroscopy (XPS). The results indicated that the modified carbon nanotubes have high purity and graphitization degree. The effect of calcination temperature on the active components and the activity of the catalyst were investigated. The results showed that calcination at 450 ℃ favored the dispersion of the active species of the catalyst and the formation of catalytic oxidation valences of V⁵⁺ and Ti⁴⁺ in the V₂O₅/CNTs-TiO₂ catalyst. The presence of V⁵⁺ and Ti⁴⁺ increased the concentration of the surface oxygen of the catalyst, resulting in a higher catalytic activity because of promotion of the electron mobility and oxygen transfer: 94.78% of HCB can be conversed with a loading of 0.2 g of the catalyst in an atmosphere of N₂ (80%) + O₂ (20%) at 250 ℃. The conversion of HCB remained above 90% during a 24 h batch test, which showed a stable catalytic performance.

A sequential modification by sodium hydroxide (NaOH) and ammonium hexafluorosilicate ((NH₄)₂SiF₆) solution was used for preparing MTP (methanol to propylene reaction) catalyst for the first time. The parent and modified samples were characterized by diverse techniques including powder X-ray diffraction (XRD), X-ray fluorescence (XRF) spectroscopy, N₂ adsorption-desorption, transmission electron microscopy (TEM), and NH₃ temperature-programmed desorption (NH₃-TPD). The effect of modification on the physicochemical properties, such as framework, chemical composition, texture, and acidity, were investigated in detail. The results showed that the mesopore volume of the zeolite catalyst increased significantly following sequential NaOH and (NH₄)₂SiF₆ modification. The acidity was also modulated effectively. The composite modification method successfully overcame the disadvantages associated with individual simple alkali and (NH₄)₂SiF₆ treatments. For instance, using a simple alkali treatment would destroy the framework of the zeolite easily, whereas using a simple (NH₄)₂SiF₆ treatment would only modify the external surface of the zeolite owing to the limited diffusion of the ammonium hexafluorosilicate molecule. When used in MTP reaction, the induction period of the composite modified sample was greatly shortened, and the initial selectivity for propylene increased to 43% under the following operating conditions: T=470 ℃, p=0.1 MPa (p_MeOH=50 kPa), and weight hourly space velocity (WHSV)=2 h^-1. Moreover, the composite modified zeolite catalyst exhibited significantly improved stability, and the catalytic lifespan was triple that of the parent sample.

Graphene oxide (GO) was synthesized using an improved Hummers method. Subsequently, catalysts of manganese oxides (at varying loadings) supported on graphene (MnO_x/GR) were prepared by hydrothermal reaction for application in the selective catalytic reduction (SCR) of NO_x with NH₃ at low temperatures. The structural properties and catalytic performance were evaluated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption-desorption, X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR). The characterization results indicated that abundant functional groups existed on the surface of the prepared GO that could combine with manganese during preparation of the catalysts. Manganese oxide entities, with different crystallinities (MnO, Mn₃O₄, or MnO₂), were dispersed on the surface of graphene. The results of the catalytic studies showed that the MnO_x/GR catalysts prepared with different MnO_x loadings all exhibited excellent low-temperature SCR activities. The catalyst with 20%(w) MnO_x displayed the best activity, which was attributed to the high content of high-valent manganese and oxygen adsorbed onto the catalyst surface, as well as to the enhancement in redox abilities and the addition of active sites at low temperatures.

Tin-promoted Ru/H-CMK-3 catalysts were prepared by a novel reductant-impregnation method for application in the hydrogenation of cinnamaldehyde. The catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface areas, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The effects of the synthesis reaction conditions on the selective hydrogenation of cinnamaldehyde were examined in detail. The results showed that the mesoporous CMK-3 carbon material could disperse the catalytically active species better. Using appropriate amounts of Sn(IV) provided electron-rich Ru sites, which are one of the main catalytically active species. The interaction between Ru and Sn promoted the activation of C＝O in cinnamaldehyde. Furthermore, changes in other reaction conditions, such as temperature and pressure, greatly influenced the selective hydrogenation of cinnamaldehyde.

Sr/TiO₂ catalysts with different Sr/Ti molar ratios (n(Sr)/n(Ti)) were synthesized by fractional precipitation. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrometry, and ultraviolet-visible diffuse reflectance spectrophotometry (UV-Vis RDS). The photocatalytic activity of the samples under visible light was determined using the photocatalytic degradation of methylene blue. The photocatalytic activities and structures of the catalysts changed with n(Sr)/n(Ti) molar ratio. When n(Sr)/n(Ti)≤3/2, the catalysts, which were composed of TiO₂ and SrTiO₃, showed a globular structure. When n(Sr)/n(Ti) was between 3/2 and 4/1, the catalysts had a flaky structure. As the n(Sr)/n(Ti) increased, the composition of the catalysts changed from SrTiO₃ and Sr₂₄ to Sr₂₄ and Sr(OH)₂·H₂O. When the n(Sr)/n(Ti) ratio was 9/1, the catalyst mainly consisted of Sr(OH)₂ ·H₂O and exhibited an acicular structure. The sample with n(Sr)/n(Ti)=4/1 exhibited the highest photocatalytic activity; its first-order reaction rate constant was 5.0 times as high as that of the perovskite catalyst SrTiO₃ and 86.7 times as high as that of the commercial Ti photocatalyst P25.

Cu/SiO₂ catalysts for the hydrogenation of methyl acetate (MA) to ethanol were prepared using the urea hydrolysis method. The catalysts were characterized using N₂-physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The effects of the copper loading and reduction temperature on the catalyst structure and catalytic performance were investigated. Experimental studies of the influence of the copper loading showed that a 20% (mass fraction, w) Cu/SiO₂ catalyst had uniformly dispersed copper particles and a large number of active centers, and therefore gave the best hydrogenation performances among the three catalysts with the copper loadings of 10%, 20%, and 30%, respectively. Then 20% (w) Cu/SiO₂ was reduced at different temperatures (270, 350, and 450 ℃). The results showed that 20% (w) Cu/SiO₂ reduced at 350 ℃ had the best catalytic activity. This was attributed to the homogeneous distribution of copper nanoparticles, and appropriate Cu⁰/(Cu⁰+Cu⁺) molar ratio, which achieved simultaneous dissociation of hydrogen and MA activation. Under the optimum reaction conditions, the MA conversion and ethanol selectivity reached 97.8% and 64.9% (theoretical maximum value: 66.6%), respectively.

We used skeletal Co as the core to prepare a skeletal Co@HZSM-5 core-shell catalyst by growing an HZSM-5 membrane on skeletal Co via hydrothermal synthesis. The physicochemical properties of the catalyst were determined using elemental analysis, N₂ physisorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and NH₃ desorption. In gas-phase Fischer-Tropsch synthesis (FTS), the skeletal Co@HZSM-5 core-shell catalyst was more efficient than a physically mixed skeletal Co-HZSM-5 catalyst in cracking long-chain hydrocarbons, giving higher selectivity for C₅-C₁₁ gasoline products. The thickness of the zeolite shell on the skeletal Co@HZSM-5 core-shell catalyst was easily tuned by adjusting the hydrothermal time. At a suitable zeolite shell thickness, the long-chain hydrocarbons were cracked completely, with high FTS activity, leading to high selectivity for the gasoline fraction. Increasing the reaction temperature resulted in higher FTS and cracking activities, but the product distribution shifted to short-chain hydrocarbons. For the optimum skeletal Co@HZSM-5 core-shell catalyst, which was subjected to hydrothermal treatment for 4 d, selectivity for the gasoline fraction reached 79% at 250 ℃, which shows an excellent synergistic effect between the FTS active sites and the acidic sites on this catalyst.

A visible-light-active graphitic-like carbon nitride (g-C₃N₄)/BiVO₄ nanocomposite photocatalyst was synthesized using a facile ultrasonic dispersion method. The nanocomposite was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence (PL) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and photocurrent response measurements. The photocatalytic activity in the photoreduction of CO₂ under visible-light irradiation (λ>420 nm) was determined. The g-C₃N₄/BiVO₄ catalyst containing 40% (w) g-C₃N₄ showed the highest photocatalytic activity; it was almost twice that of g-C₃N₄ nanosheets and four times that of BiVO₄. The enhanced photocatalytic activity is attributed to the formation of heterostructures at the g-C₃N₄/BiVO₄ interface and appropriate alignment of the energy levels between them, which can facilitate separation of photogenerated electrons and holes.

CuO-CeO₂-SiO₂ and rare-earth-doped CuO-Ce_0.9M_0.1O₂-SiO₂ (M=La, Pr, Nd) catalysts for recycling Cl₂ from HCl oxidation were prepared by a template method, using activated carbon as a hard template. The catalyst structures were determined using X-ray diffraction (XRD), N₂ adsorption-desorption, transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and H₂ temperatureprogrammed reduction (H₂-TPR). The catalytic performances were also investigated. The results showed that La, Pr, and Nd cations were incorporated into the CeO₂ lattice and formed nanosized solid solutions; this greatly reduced the catalyst grain sizes, leading to higher surface areas. In addition, the oxygen vacancy concentrations were significantly improved. The changes in the structures and surface properties of the solid solutions significantly affected the HCl catalytic oxidation performances. The order of the activities of various catalysts was CuO-Ce_0.9La_0.1O₂-SiO₂>CuO-Ce_0.9Nd_0.1O₂-SiO₂>CuO-Ce_0.9Pr_0.1O₂-SiO₂>CuO-CeO₂-SiO₂. The oxygen vacancy concentrations of the solid solutions were strongly related to their catalytic activities. However, the structures and performances of the Ce_0.9M_0.1O₂-SiO₂ catalysts showed that an increase in the number of oxygen vacancies resulted in decreased catalytic activities of the solid solutions. Kinetic studies showed that oxygen adsorption could be the rate-determining step for rare-earth-doped catalysts; a higher oxygen vacancy concentration in the solid solution led to a slower reaction rate when the volumetric flow ratio of O₂ to HCl was 1. For the CuOCe_0.9M_0.1O₂-SiO₂ catalysts, spillover of oxygen species in the solid solution into the highly dispersed CuO interfaces was enhanced, which increased the overall reaction rate and gave high activity.

Poly(lactic acid) (PLA) has attracted considerable interest as an environmentally friendly and biodegradable polymer. The properties of poly(L-lactic acid) (PLLA) at an air/water interface were studied based on the Langmuir-Blodgett (LB) film balance and atomic force microscopy (AFM). The surface pressure-area (π-A) isotherm indicated that the surface pressure of PLLA initially increased as the interfacial film was compressed; at π=9.0 mN·m^-1, a plateau was observed in the π-A isotherm, in which the area of the repeat unit was in the approximate range 0.11-0.17 nm². The AFM results showed that there is a clear structural transition in the PLLA film during the compression: (i) at the beginning of the plateau, a number of fibrils are present at the air/water interface and (ii) multilayer structures (at least bilayer, i.e., the underlying layer and top layer consisting of fibrils) is formed in the plateau region. In particular, when π=20.0 mN·m^-1, a thin film of PLLA of thickness about 6.0 nm was fabricated. Our findings suggest that the plateau in the PLLA π-A isotherm is closely related to a change in the film structure from monolayer to multilayer at the air/water interface. This is significantly different from the behavior of conventional amphiphiles, because the plateau in amphiphiles π-A isotherm is equivalent to a phase transition of monolayers derived from amphiphiles in a two-dimensional plane.

A series of W/SiO₂/Al₂O₃ catalysts with various tungsten loadings were synthesized via the impregnation method. The as-synthesized catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, H2 temperature-programmed reduction (H₂-TPR), and NH₃ temperature-programmed desorption (NH₃-TPD). The results reveal that the tungsten loadings were crucial to the dispersion and reducibility of the tungsten oxide species and the acidity of catalysts. The catalytic performances were also investigated during the metathesis of 1-butene to propene. Amongst these catalysts, W/SiO₂/Al₂O₃ with a tungsten mass fraction of 6.0% gave the highest activity and stability during the 1-butene metathesis reaction. The excellent catalytic performance of the catalyst containing a tungsten mass fraction of 6.0% is attributed to its moderate dispersion, suitable reducibility of the WO_x species and suitable acidity. We speculate that these factors are favorable for the formation of active centers for olefin metathesis.

Nickel catalysts supported on TiO₂ were prepared using an impregnation method. Changes in the reduction temperature from 200 to 400 ℃ resulted in dispersion of nickel with different oxidation states on TiO₂. The gas-phase hydrogenation of acetonitrile was found to be influenced by the nickel oxidation state. Nickel reduced at 300 ℃ gave the highest acetonitrile conversion ratio, i.e., about 100%, when the reaction temperature was 100 ℃. The product yields depend on the amount of acidic sites on Ni/TiO₂ catalysts; this can be influenced not only by the TiO₂ support, but also by the properties of the supported nickel nanoparticles. The triethylamine yield increased to a maximum (from 34% to about 48%) with increasing reduction temperature; this corresponded to the gradual appearance of Ni⁰ in Ni/TiO₂ and a decrease in the intrinsic acidity of the Ni/TiO₂ catalyst. Triethylamine was the initial product in the hydrogenation of acetonitrile with Ni/TiO₂. The oxidation state of nickel influenced not only the conversion of acetonitrile but also desorption of the final products. Amechanism for the first step in this reaction is proposed.

A series of novel catalysts derived from Ni-Mg-Al-LDHs (LDHs: layered double hydroxides) were synthesized in-situ on γ-Al₂O₃ and evaluated in CO₂ reforming of CH₄ (dry reforming of methane, DRM) reaction system. The catalytic precursors were decomposed and reduced by calcination and an atmospheric plasma technique, respectively. Activity and stability tests showed that the catalytic properties were greatly affected by the pretreatment method. The best catalytic performance was obtained with the catalyst that was directly reduced and decomposed using an atmospheric H₂/Ar plasma jet. Compared with the pure LDH precursor, Ni- Mg-Al-LDHs/γ-Al₂O₃ had much greater mechanical strength, because of the γ-Al₂O₃ support. This feature extends the long lifetime of catalyst at high temperatures. X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂-adsorption-desorption, and thermogravimetry-differential thermal analysis (TG-DTA) results showed that the excellent catalytic performance was based on the small particle size and uniform dispersion of active Ni crystals, as well as the high mechanical strength and large specific surface area of the catalyst.

A novel visible-light-responsive photoanode (Ta/Al-Fe₂O₃) was fabricated by co-doping Ta and Al into iron oxide. The properties of the prepared electrodes were examined using X- ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy. XPS analysis suggested that the surface chemical environments of Al and O were significantly affected by Ta doping. Photoelectrochemical (PEC), electrocatalytic (EC), and photocatalytic (PC) degradations of methylene blue (MB) were performed using Ta/Al-Fe₂O₃ and Al-Fe₂O₃ electrodes as the photoanodes. The results indicated that synergetic effects in PEC enhanced the MB degradation efficiency compared with the individual PC or EC processes. The estimated rate constant for MB degradation on Ta/Al-Fe₂O₃ was about twice that on Al-Fe₂O₃ under visible-light irradiation in the PEC process. The greatly improved visible-light activity and film stability indicated that Ta doping was an efficient way to improve the PEC activity of Ta/Al-Fe₂O₃ films.

Pore structure and acidity of ZSM-5 catalysts were successfully regulated by alkali treatment. ZSM- 5 was etched in 0.2 mol·L- 1 NaOH solution at 65 and 85 ℃. Micro-mesoporous ZSM-5 catalysts were successfully prepared with a high density of acidic sites. The activity and stability were significantly enhanced with alkali-treated ZSM-5, giving a conversion of glycerol above 95%, with selectivity for acrolein of 78% after 10 h compared with a ZSM-5-at85 (alkali-treated at 85 ℃) catalyst. Characterization of N₂ adsorption and desorption isotherms, X-ray diffraction (XRD), ²⁷Al mass atomic spectroscopy-nuclear magnetic resonance (²⁷Al MAS-NMR), and transmission electron microscopy (TEM) were performed to interpret the morphology and surface properties. The results reveal that the Si in the framework of ZSM-5 was leached out by alkali treatment, and many mesopores were formed on the ZSM-5 surface. However, the MFI topology did not change and Al was mainly integrated within the framework. X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), and NH₃-temperature-programed desorption (NH₃-TPD) experiments demonstrated that the molar ratio of Si/ Al on the external surface was lower than that in the framework, indicating that more Si on the external surface of ZSM-5 was leached by alkali treatment, while the acidic density increased because of the lower molar ratio of Si/Al near newly formed mesopores. ZSM-5 catalysts with mesopores and higher acidic density enhance reactant diffusion and coking tolerance, which improves the activity and stability during glycerol dehydration.

Butyl levulinate (BL) is one of the most important biochemicals derived from cellulose, and it is of particular interest in industrial applications. Efficient synthesis of BL from cellulose in bio-butanol (bio-BuOH) medium has been investigated in the presence of acidic SO₃H-functionalized ionic liquid (SFIL) catalysts. The results showed that the acid strength of the SFILs, catalyst dosage, reaction temperature, reaction time, and solvent composition significantly affected the conversion of cellulose and the yield of the target products. Using the strongest acidic SFIL 1- (4-sulfobutyl)-3-methylimidazolium hydrosulfate ([C₄H₈SO₃Hmim]HSO₄) as the catalyst, 98.4% of cellulose could be converted into 31.1% of BL accompanied with 33.4%, 20.6%, and 23.8% of butyl formate (BF), water soluble products (WSPs), and biofuel (Biof), respectively, under the optimized conditions. This catalytic system was water-tolerant, and the addition of 0.2 mL water did not significantly decrease its ability for conversion of cellulose. Furthermore, this acidic SFIL catalyst could be recycled up to six consecutive times without loss of catalytic activity.

A series of bimetallic PdAu catalysts with different structures were prepared by changing the loading sequence of Pd and Au for the hydrogenation of 2-ethylanthraquinone. Pd/Au/Al₂O₃ was obtained by loading Pd onto Au particles deposited onto an Al₂O₃ support with a hydrogenation efficiency up to 14.27 g·L^-1. According to X-ray diffraction, transmission electron microscopy, hydrogen temperature program reduction, and X-ray photoelectron spectroscopy measurements, the popcorn structure and unique electronic properties of the Pd species in the Pd/Au/Al₂O₃ catalyst resulted in the highest content of surface metallic Pd, which was the most active component for the reaction. What is more, the addition of Au can effectively reduce the amount of degradation products by suppressing side reactions.

Using silica as a support, 2-(diphenylphosphino)ethyltriethoxysilane (DPPES) was anchored on silica surface by a grafting method to produce a bonded phosphine (denoted as SiO₂(PPh₂)), which displays excellent performance. The supported SiO₂(PPh₂)/Rh catalyst was formed in situ in 1-octene hydroformylation with SiO₂(PPh₂) as ligand and Rh(acac)(CO)₂ as precursor (acac: acetylacetone). SiO₂(PPh₂) and SiO₂(PPh₂)/ Rh were characterized by Fourier transform infrared (FTIR) spectroscopy. The effects of the ratio of phosphine to rhodium ([P]/[Rh]) and reaction temperature on 1-octene hydroformylation were investigated. Results show that an increase of the ratio of phosphine to rhodium can greatly improve the selectivity for aldehydes and decrease the rhodium leaching in organic phase. Under the moderate conditions: [P]/[Rh]=12, 363 K, 2 MPa, and 1.5 h, the conversion of 1-octene and the selectivity for aldehydes were 98.4% and 95.3%, respectively. The catalytic activity could compare with homogeneous catalysis with DPPES or triphenylphosphine (TPP) as ligand. The reaction activity was clearly unchanged after the SiO₂(PPh₂)/Rh catalyst was reused four times, with the conversion of 1-octene remaining at 97.0%, the rhodium content leaching in organic phase detected by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was less than 0.1%.

Polymethyl methacrylate (PMMA) microspheres were synthesized using an emulsifier-free emulsion polymerization method. A three-dimensionally ordered macroporous (3DOM) MgFe_0.1Al_1.9O₄ spinel-type oxide catalyst was prepared using the synthesized colloidal crystal templates and evaluated for oxidative dehydrogenation of ethylbenzene with CO₂. Several techniques, such as powder X-ray diffraction, scanning electron microscopy, temperature-programed reduction, and ⁵⁷Fe-Mössbauer spectra, were used to characterize the physicochemical properties of the catalyst. The results indicate that 3DOM MgFe_0.1Al_1.9O₄ has a hexagonal ordered arrangement, with a pore diameter of 230 nm and a shell thickness of 60 nm, and that most of its Fe species are incorporated into the spinel lattice. Compared with a nano MgFe_0.1Al_1.9O₄, the 3DOM MgFe_0.1Al_1.9O₄ catalyst exhibited a much higher catalytic stability and less carbon deposition. A possible explanation for the enhanced catalytic stability of 3DOM MgFe_0.1Al_1.9O₄ catalyst is discussed. The three-dimensionally ordered macroporous structure has a large effect on the diffusion of coke precursors and the stability of the catalyst.

Composite support CeZrYLa + LaAl was prepared by co-precipitation, and platinum catalyst supported on the composite support was prepared by impregnation. The behavior of the Pt catalyst for the reaction of NO reduction by CH₄ from the exhausts of natural gas vehicles (NGVs) was studied under stoichiometric conditions. Additionally, the effects of 10% (volume fraction, φ) H₂O and stoichiometric O₂ on the reaction in the presence of CO₂ were also investigated. Results show that N₂ and CO₂ were the main products for the different reactions, CO was detected under high temperature, and NO_x was detected under low temperature (in the presence of O₂, the NO_x was NO₂, whereas the NO_x was N₂O when no O₂ was present). In the presence of 10% (φ) H₂O, the conversion of CH₄ noticeably decreased and NO conversion remained unchanged, possibly because the presence of H₂O weakens the reforming reaction of CH₄ with CO₂, but does not affect the activity of NO reduction by CH₄. In the presence of stoichiometric O₂, there was an obvious increase of CH₄ conversion and a decrease of NO conversion. These could be explained by the competition between NO and O₂, where the oxidation of methane by O₂ is the main reaction, limiting the reaction of NO reduction by CH₄. Moreover, in the presence of 10% (φ) H₂O and stoichiometric O₂, CO₂ reforming of CH₄ was negligible. Numerous reactions were detected simultaneously, such as the oxidation of CH₄ by NO, steam reforming of CH₄, and the reduction of NO by CH₄, thus improving the conversions of CH₄ and NO.

The water-gas shift reaction (WGSR) has been carried out over CuO/Fe₂O₃ catalysts modified by different loadings of Al₂O₃ (0%-15% (w)), prepared by a stepwise co-precipitation method. Composite mixture CuFe₂O₄ was produced, and the crystalline size, redox property, and surface metallic Cu dispersion were manipulated. The appropriate introduction of Al₂O₃ can promote the phase transition of spinel CuFe₂O₄ from tetragonal to cubic, inhibit aggregation of Cu-crystallite, improve Cu dispersion, and increase the amount of weak basic sites, as confirmed using powder X-ray diffraction (XRD), Raman spectroscopy, N₂ physisorption, N₂O decomposition, and temperature-programmed desorption of carbon dioxide (CO₂-TPD) techniques. In addition, a temperature-programmed reduction of hydrogen (H₂-TPR) technique was used to investigate the reducibility of the modified CuO/Fe₂O₃ catalysts. It was found that the Al₂O₃-doping plays an important role in increasing the hydrogen consumption of the copper species, and decreasing reduction temperature. This means that the Al₂O₃ can promote a synergistic interaction between the copper and iron species in the CuO/Fe₂O₃ catalysts. Overall, the Al₂O₃-modified catalyst (10%(w)) has a smaller Cu particle size, better Cu dispersion, greater reducibility, and larger amount of weak basic sites, resulting in a much higher initial catalytic activity and better thermal stability.

Polyaniline (PANI) nanorods grown on layered graphitic carbon nitride (g-C₃N₄) sheets are synthesized by interfacial polymerization. The structure, morphology, and properties of the photocatalysts are characterized by Fourier transform infrared (FTIR), X- ray diffraction (XRD), and UV-visible (UV-Vis) spectroscopies, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and electrochemical analysis. Photocatalytic degradation of methylene blue is investigated to determine the photoactivity of the catalyst. The results suggest that g-C₃N₄ possesses good dispersion with an intercalated nanostructure and interfacial adhesion with PANI. In addition, the PANI/g-C₃N₄ composites retain the advantage of high thermal stability resident with g-C₃N₄. This is ascribed to a physical barrier effect on the emanation of degradation products and inhibited polymer motion. The resulting composites also show more intensive photocatalytic activity than does g-C₃N₄.

An Fe-loaded mesoporous silica SBA-15, Fe/SBA-15, was prepared by incipient wetness impregnation, characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques and used for heterogeneous Fenton oxidation of dye Rhodamine B (RhB) in aqueous solution. The characterization showed that the Fe/SBA-15 retained a mesoporous structure with a long-range ordered arrangement, reduced pore diameter and surface area, and existed as agglomerates of rod-like crystallites with a mean diameter of 0.6 μm. The Fe species occurred both inside and outside the support pores in the form of α-Fe₂O₃ crystallites. The removal of RhB in the presence of Fe/SBA-15 and H₂O₂ was shown to be caused by the synergistic effects of adsorption and catalytic oxidative degradation, and was closely related to Fe/SBA-15 dosage. Removal was almost independent of initial solution pH, with approximately 93% achieved at an Fe/SBA-15 dosage of 0.15 g·L^-1, initial RhB concentration of 10.0 mg·L^-1, H₂O₂/Fe³⁺ molar ratio of 2000:1; initial solution pH of 5.4 and 21 ℃. The Langmuir monolayer adsorption capacity of the Fe/SBA-15 was 99.11 mg·g^-1. In addition, Fe/SBA-15 can be easily regenerated by soaking in H₂O₂ then reused for up to six runs, with RhB removal greater than 80% and Fe leaching below 0.1 mg·L^-1 (or 0.6% (mass fraction)) for each run. A removal mechanism for RhB by Fe/SBA-15 and H₂O₂ was proposed based on the quenching tests, UV-Vis spectra, and gas chromatography-mass spectrometry (GC-MS) analysis. The heterogeneous Fenton catalyst Fe/SBA-15 can be applied to remove nonbiodegradable organics such as dye RhB.

A low-temperature hydrothermal route was applied to fabricate ZnO nano-arrays on fluorinated tin oxide (FTO)-coated glass substrates. The effects of the molar ratios of the precursor concentrations on the ZnO nano-arrays were studied with respect to morphology, optical properties, and growth mechanism. The results show that the length reduced with the increased molar ratios of precursor concentrations, and the diameter first increased then decreased. In general, the change of optical band gap followed the same trend as that for the change in diameter. When the molar ratio of precursor concentrations is 5:5, the optical band gap is 3.2 eV, which is similar to the theoretical value at room temperature. We propose that the optimal molar ratio of zinc nitrate (Zn(NO₃)₂) to hexamethylenetetramine (HMT, C₆H₁₂N₄) is 5:5 for the preparation of ZnO nano-arrays. Spike-shaped CuO/ZnO nano-arrays were also successfully synthesized using a two-step solution-system method. Field emission scanning electron microscope (FE-SEM) results show that there were a large number of copper oxide (CuO) nano-particles (NPs) deposited onto the ZnO nano-array surfaces to form spike-shaped structures. The covered CuO NPs exhibited improved photocatalytic properties over pure ZnO nano-arrays under UV irradiation, and the possible photocatalytic mechanism of the CuO/ZnO nano-heterojunction was discussed in detail.

Zeolite membranes, especially the MFI-type zeolite membranes, have attracted significant attention for decades because of their special properties. While organic templates such as tetrapropylammonium hydroxide (TPAOH) have typically been used for the synthesis of ZSM-5 zeolite and zeolite membranes, the templates remain trapped in the as-synthesized zeolite crystals. A common method for removing organic templates and generating porous frameworks is calcination; however, during this process, the channel structure may be affected. In particular, for ZSM-5 membranes, membrane defects may be produced and the separation efficiency therefore may decrease to some extent. In this study, the low-temperature hydrocracking of TPAOH in ZSM-5 zeolite crystals was studied under H₂/N₂, while N₂ adsorption, thermogravimetric (TG) analysis, Fourier transform infrared (FTIR) spectroscopy, temperature-programmed desorption of ammonia (NH₃-TPD), and Raman spectroscopy were used to characterize zeolite samples. The results show that the organic template in the pores of ZSM-5 can be effectively removed below 350 ℃ by low-temperature hydrocracking. Characterization analyses by BET specific surface area, TG, FTIR, and Raman spectroscopy demonstrated that a reducing atmosphere containing H₂ was more conducive to template removal at low temperature than atmospheres of air or N₂. The degree of template removal increased with temperature increasing. The BET surface area of the crystal after hydrocracking at 280 ℃ reached 252 m²·g^-1, although a small amount of organic residue remained. Furthermore, after hydrocracking at 350 ℃, the BET surface area reached 399m2·g^-1, and only trace amount of inorganic carbon residue remained. In addition, the introduction of hydrogen at low temperatures could prevent coke deposits on acid sites and thus ZSM-5 zeolite crystals had greater numbers of acidic sites after low-temperature hydrocracking.

HNO₃-modified activated carbon (AC) was prepared to determine its mercury removal ability on a fixed-bed reactor. In this study, the HNO₃-modified AC was found to be effective for mercury removal in simulated flue gas. The original sample, the HNO₃-modified sample and the production sample were characterized by elemental analysis, Brunauer-Emmett-Teller (BET) specific surface area measurements, scanning electron microscopy (SEM), Raman spectra, Boehm titrations, temperature programmed desorption (TPD) technique, and X-ray photoelectron spectroscopy (XPS). The results show that HNO₃ treatment increases the content of oxygen and nitrogen on the AC. Compared with the physical characteristics of HNO₃-modified AC, the effects of its chemical characteristics on mercury removal are more significant. The Hg⁰ is mainly oxidized to HgO by the HNO₃-modified AC. The oxygen functional groups, possibly carbonyls, esters or anhydrides were found to be the adsorption sites for mercury removal, and these groups were reduced to hydroxyl groups or ether groups. The N-functional groups, possibly pyrrolic tautomers, were found to be the active catalytic sites. The mechanism for Hg⁰ removal by HNO₃-modified activated carbon is proposed based on the characterization results.

A series of composites consisting of anatase-rutile TiO₂ and graphene (TrG) were synthesized by a hydrothermal route. The influence of the amount of graphene oxide on the photocatalytic activity during the degradation of methyl blue was studied. The photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) specific surface area measurements. The results show that as-prepared TiO₂ formed in the anatase and rutile phase with a bar structure and it dispersed uniformly over the surface of the graphene sheets. The composites possess higher catalytic activity because of the strong absorption capacity of graphene, the establishment of heterojunctions between rutile and anatase TiO₂, the remarkable electrical transport between TiO₂ and graphene and the high specific surface areas. The photodegradation performance of methyl blue by the TrG composites under UV light was studied. Our results indicate that the photocatalytic activities of titanium dioxide-graphene composites were higher than those of pure TiO₂. We also found that the TrG composites prepared with a loading of 0.8%(mass fraction, w) graphene oxide had the best photocatalytic activity.

Supported cobalt amorphous catalysts Co-B/γ-Al₂O₃ were prepared using an impregnation-chemical reduction method for liquid phase hydrogenation of ethyl lactate to 1,2-propanediol (1,2-PDO). The Co-B/γ-Al₂O₃ catalysts were characterized using inductively coupled plasma (ICP) optical emission spectrometry, X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and X-ray photoelectron spectroscopy (XPS). The effects of the catalyst preparation conditions on the hydrogenation of ethyl lactate were investigated. All the fresh catalysts showed an amorphous structure and Co-B particles were dispersed uniformly on the γ-Al₂O₃ support. The thermal stability of the amorphous catalyst and the Co/B atomic ratio of surface composition increased with increasing the Co content. The Co-B/γ-Al₂O₃ amorphous catalyst showed the highest catalytic activity when the theoretical loading of metal Co was 30% (mass fraction, w). The ethyl lactate turnover frequency (TOF), conversion, and selectivity to 1,2-PDO reached 1.41 h^-1, 93.63%, and 96.10%, respectively at a reaction temperature of 160 ℃ and hydrogen pressure of 6.0 MPa for 9 h. The higher catalytic performance of the 30%(w) Co-B/γ-Al₂O₃ supported amorphous catalyst is attributed to its highly dispersing Co-B particles, higher Co/B atomic ratio of surface composition, and electron transfer effect between Co and B.

A series of Mo-Ni₂P/SBA-15 catalysts with various Mo loadings were prepared by impregnating nickel nitrate, diammonium hydrogen phosphate, and ammonium molybdate onto an SBA-15 support, followed by temperature-programmed reduction (TPR) under H₂. The structure of the catalysts was characterized by Xray diffraction (XRD), N₂ adsorption-desorption, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalytic performance was evaluated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The results indicate that the mesoporous structure was maintained and the Ni₂P phase was present in all of the catalysts. The chemical states of Ni were Ni^δ+ and Ni²⁺, the chemical states of P were P^δ- and P⁵⁺, and the chemical states of Mo were Mo^δ+ and Mo⁶⁺. Mo was shown to promote the HDS catalytic performance of Ni₂P/SBA-15 catalysts. The Mo-Ni₂P/SBA-15 catalysts with 1% (w, mass fraction) Mo loading exhibited the highest HDS activity. The conversion of the DBT reached 99.03%under reaction conditions of 380 ℃ and 3.0 MPa. The HDS of DBT proceeded mainly via the direct desulfurization (DDS) pathway over all of the tested Mo-Ni₂P/SBA-15 catalysts.

In this study, a series of Bi₂O₃-containing Bi₂WO₆ catalysts were prepared by a simple mixing method. We used the oxidation of phenol in water under UV light as a model reaction, and found that as the amount of Bi₂O₃ in the mixture increased, its photocatalytic activity increased, and then started to decrease. A maximum activity was observed with the catalyst containing 12.5% (mass fraction, w) of Bi₂O₃, about 4 times that of Bi₂WO₆. Solid characterization revealed that the composite was a mixture of β-Bi₂O₃ and Bi₂WO₆. The water oxidation photocurrent over the β-Bi₂O₃/Bi₂WO₆ thin film electrode was much larger than the sum of the photocurrents of the β-Bi₂O₃ and Bi₂WO₆ thin film electrodes. It is proposed that there is a valence hole transfer from Bi₂WO₆ to β-Bi₂O₃, which improves the charge separation efficiency, and consequently increases the rate of phenol degradation.

The activities of 25% (mass fraction, w) MoO₃/Al₂O₃ and 5% (w) CoO-25%MoO₃/Al₂O₃ catalysts in a sulfur-resistant methanation process were examined as the concentration of H₂S was varied from 0 to 12 mL· L^-1 (volume fraction φ=0.00%-1.20%). The results showed that the catalytic activity of 5%CoO-25%MoO₃/Al₂O₃ catalyst increased steadily as the concentration of H₂S increased. However, the catalytic performance of the 25%MoO₃/Al₂O₃ catalyst was insensitive to the H₂S concentration. Co was found to benefit the 25%MoO₃/Al₂O₃ catalyst when H₂S concentration was greater than 0.40%(φ). Below this threshold, addition of Co to the catalyst matrix inhibited the activity of the 25%MoO₃/Al₂O₃ catalyst. N₂-physisorption (BET) and X-ray diffraction (XRD) analyses were used to characterize the fresh and used catalysts. The results indicated that exposure to H₂S at various concentrations did not significantly affect the physical structure of the catalysts, but it will affect the active phase through metal sulfides. The results provide the appropriate range of H₂S concentration to add Co as promoter for 25%MoO₃/Al₂O₃ catalyst, which is likely to be useful for industrial catalyst selection.

SSZ-13 molecular sieves were synthesized in situ on the surface of a honeycomb-shaped cordierite support using a hydrothermal method, and the resulting material was characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The process for preparing SSZ-13/cordierite was optimized in detail. Furthermore, the ion exchange levels of the 50% Cu-SSZ-13/cordierite and Cu-SSZ-13 catalysts were tested in the ammonia-selective catalytic reduction (NH₃-SCR) of NO both before and after the hydrothermal treatment process using a fixed-bed reactor. The results of these experiments showed that the Cu-SSZ-13/cordierite prepared in situ by hydrothermal synthesis had good catalytic activity, and gave an NO conversion of more than 80% at temperatures in the range of 200-500 ℃, with the highest NO conversion of 96.4%being reached at 300 ℃. After being aged hydrothermally at 850 ℃ for 12 h, the SCR activity of the Cu- SSZ-13 catalyst was significantly reduced, whereas that of Cu-SSZ-13/cordierite remained largely unchanged with an NO conversion of 91% at 300 ℃. Analysis of the catalysts framework both before and after the hydrothermal treatment by X-ray diffraction and solid state ²⁷Al NMR revealed a significant reduction in the intensities of the X-ray diffraction and tetrahedral aluminumpeaks for Cu-SSZ-13, whereas those of the Cu-SSZ- 13/cordierite material remained unchanged. These results indicated that the Cu-SSZ-13/cordierite prepared by in situ hydrothermal synthesis was less prone to deactivation by hydrothermal aging.

Ionic liquid (IL) catalyst attracts increasing attention during last few decades due to its excellent advantages of both homogeneous and heterogeneous catalyst. Here, a novel and efficient strategy for the production of trimethylolpropane (TMP) is proposed with basic IL catalysts. The catalytic activities of the IL catalysts are investigated. The effects of catalyst dosage, reaction temperature, time, and the molar ratio of the reactants are also studied. The results show that the basicity of the IL catalyst has a significant effect on the catalytic activity, where stronger basicity indicates higher catalytic activity. The IL 1-butyl-3-methyl imidazolium hydroxyl ([bmim]OH) is proven to be the most efficient catalyst where more than 84% isolated yield of TMP was obtained under optimized conditions. Furthermore, both the IL catalyst and butyraldehyde show excellent recyclability. Moreover, this IL catalytic system avoids the inevitable desalination encountered by current processes utilizing inorganic alkali catalysts.

Y-type zeolites with different cerium ion content were prepared by liquid phase ion exchange (LPIE) and their structural properties were characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), N₂ adsorption isotherm, and temperature-programmed desorption of ammonia (NH₃-TPD). The influence of cerium ion modification of the Y-type zeolites on the acidity and catalytic behavior was studied by in situ Fourier transform infrared spectroscopy (in situ FTIR) techniques with pyridine and thiophene as probe molecules. The results indicate that the original crystal structures of the zeolites remain unchanged after modification with cerium ions. During the modification process the Ce species tend to be located in sodalite (SOD) cages after calcination and remain in the supercages upon a gradual increase in Ce cation content. The amount and strength of the Brönsted (B) acid sites in the zeolites generated by the modification increases initially and then stabilizes with an increase in Ce ion content. The strong and weak Lewis (L) acid sites related to the non-framework aluminum and the rare earth species increase continuously during the modification process. Thiophene adsorption FTIR spectra indicate that the adsorbed thiophene molecules protonate at the strong Brönsted acid sites of the zeolites. The protonated products then oligomerize. The synergy between Ce species and B acid sites is favorable for the thiophene oligomerization reaction.

α-MnO₂, β-MnO₂, γ-MnO₂, and δ-MnO₂ catalysts were synthesized by hydrothermal methods, and their catalytic performances towards the oxidation of ethanol were evaluated in detail. The as-synthesized MnO₂ catalysts were characterized by N₂ adsorption- desorption measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR). The α-MnO₂ catalyst showed the best activity of the catalysts tested for the combustion of ethanol and the trend in the activity of different MnO₂ catalysts towards the oxidation of ethanol was of the order α-MnO₂>δ-MnO₂>γ-MnO₂>β-MnO₂. The effect of the crystal phase structure on the activity of the MnO₂ catalysts was investigated. The XRD results showed that there were differences in the crystallinities of the α-, β-, γ-, δ-MnO₂ catalysts, but these differences did not have a significant effect on their catalytic performances towards the oxidation of ethanol. The BET surface areas of the α-, β-, γ-, δ-MnO₂ catalysts exhibited similar tendencies to their ethanol oxidation activities, although the results of standardization calculations showed that the surface area was not the main factor affecting their catalytical activities. The XPS results showed that the lattice oxygen concentration played an important role in defining the catalytic performance of the MnO₂. The α-MnO₂ catalyst showed the best reducibility of all of the MnO₂ catalysts tested, as determined by H₂-TPR. The excellent performance of α-MnO₂ was attributed to its higher lattice oxygen concentration and reducibility, which were identified as the main factors affecting the activity of the MnO₂ towards the complete oxidation of ethanol.

Core/shell nanostructured monolithic TiO₂/SiO₂ composite aerogels were prepared by the anilineacetone in situ water formation sol-gel method. Titanium(IV) n-butoxide was used as a precursor followed by supercritical modification with partially hydrolyzed titanium alkoxide and tetraethoxysilane during ethanol supercritical fluid drying. The obtained composite aerogel showed excellent mechanical strength with a Young's modulus of 4.5 MPa. The composite aerogel exhibited excellent heat resistance. After heat treatment at 1000 ℃ its linear shrinkage decreased from 31% for the TiO₂ aerogel to 10% for the composite aerogel. The specific surface area increased from 31 m² ·g^-1 for the TiO₂ aerogel to 143 m² ·g^-1 for the composite aerogel. The composite aerogel exhibited excellent photocatalytic performance during the degradation of methylene blue after heat treatment at 1000 ℃. Its excellent photocatalytic property is attributed to its high specific surface area and the small particle size of the composite aerogel after heat treatment at 1000 ℃. The enhanced heat resistance, mechanical strength, and photocatalytic performance makes the obtained core/shell nanostructured TiO₂/SiO₂ composite aerogel a promising candidate for photocatalytic applications.

Two-dimensional Ti₂C and Ti₃C₂ structures are highly stable and have high specific surface areas, and therefore represent promising materials with potential applications as carriers in transition metal catalysis, Li-ion batteries, and hydrogen storage devices. It was envisaged that investigating the surface adsorption activities of Ti₂C and Ti₃C₂ would provide useful information about their surface properties. The results of a firstprinciples study showed that the adsorption energies of OH, O, and F on Ti₂C and Ti₃C₂ surfaces were quite high. By comparing the electronic properties of Ti₂C, Ti₃C₂, Ti(001), and TiC(001), we found that the un-polarized Ti- 3d orbitals were responsible for the high surface adsorption activities of these materials. The high surface adsorption activities of the Ti₂C and Ti₃C₂ materials caused them to be terminated with O, F, and OH surface groups. The surface adsorption energies of the Au particles on the Ti₂CO_2-2x(OH)_2x and Ti₃C₂O_2-2x(OH)_2x) surfaces increase as the ratio of OH increased.

The metal-organic frameworks (MOFs), MIL-53(Al), MIL-96(Al), and MIL-120(Al) (MIL: Material Institute of Lavorisier) were synthesized and used as supports, to incorporate low-cost Ni nanoparticles (NPs) by wet impregnation. The samples were used as catalysts in the hydrogenation of nitrobenzene to aniline. The catalyst prepared with MIL- 53(Al) as a support exhibited excellent catalytic performance. Ni/MIL- 53(Al) heterogeneous catalysts were prepared using nickel nitrate, nickel acetate, and nickel ethanediamine as precursors. Characterization by powder X-ray diffraction, Fourier-transforminfrared spectroscopy, inductively coupled plasma spectroscopy, N₂ sorption measurements, H₂-temperature programmed reduction, and transmission electron microscopy showed that the Ni precursor affected the metal-support interaction, Ni particle size and particle distribution. The catalyst prepared using nickel ethanediamine possessed moderate metalsupport interactions, smaller Ni nanoparticles (4-5 nm), and a high Ni distribution. This resulted in its superior catalytic activity, with 100% conversion of nitrobenzene in the hydrogenation. The Ni/MIL-53(Al) catalyst retained its catalytic activity after five cycles, and exhibited a nitrobenzene conversion of ~92%.

Reported here is a facile route for the synthesis of polyvinyl pyrrolidone (PVP)-stabilized Pd/Co bimetallic nanoparticles via a chemical co-reduction process. The effects of molar ratio of PVP and reducing reagent (NaBH₄) to the total metal ions, and metal ion concentration and composition on the catalytic activity for hydrogen generation from NaBH₄ over Pd/Co bimetallic nanoparticles (BNPs) were studied. The transmission electron microscopy (TEM) results indicated that the prepared Pd/Co bimetallic nanoparticles, which had an average size of 1.5-2.8 nm, showed much higher catalytic activity than Pd and Co monometallic nanoparticles (MNPs). The highest catalytic activity of all the prepared bimetallic nanoparticles was 15570 mol·mol^-1·h^-1 (the activity was normalized by the content of Pd in the BNPs), which was achieved with Pd/Co theoretical atomratio of 1/9. The higher catalytic activity of the Pd/Co BNPs compared with the corresponding MNPs was ascribed to electronic charge transfer effects; this hypothesis was validated using density functional theory (DFT) calculations, which showed that the Pd atoms were indeed negatively charged, while the Co atoms were positively charged because of electron donation fromthe Co atoms to the Pd atoms. The positively charged Co atoms and negatively charged Pd atoms acted as catalytic active sites for the hydrolysis reaction of the alkaline NaBH₄ solution. Good catalytic stability was observed with the existing high catalytic activity, even after five runs of evaluating the catalytic activity. Moreover, no clear agglomeration was observed in the nanoparticle catalyst used. The corresponding apparent activation energy was determined as 54 kJ·mol^-1, based on the kinetic study of the hydrogen generation achieved via the NaBH₄ hydrolysis over the PVP-protected Pd₁₀Co₉₀ bimetallic nanoparticles.

NiS-modified Cd_1-xZn_xS has been prepared using a simple hydrothermal method. Notably, the H₂ evolution rate of 0.5% (y, molar fraction) NiS/Cd_0.3Zn_0.7S(1840 μmol·h^-1) was found to be 2.1- and 1.3-fold greater than those of Cd_0.3Zn_0.7S(884 μmol·h^-1) and 0.5% (w, mass fraction) Pt (1390 μmol·h^-1), respectively, when 0.35 mol·L^-1 Na₂SO₃ and 0.25 mol·L^-1 Na₂Swere used as sacrificial agents. The apparent quantumefficiency of 0.5% (y) NiS/Cd_0.3Zn_0.7S at 420 nm was 36.8%. The characterization of this material by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) showed that the NiS particles provided the active sites required for H₂ evolution and transferring the photo generated electrons, and therefore enhanced the photocatalytic activity of the catalyst towards H₂ production.

Aseries of band gap-tunable K⁺ doped graphitic carbon nitride (g-C₃N₄) photocatalysts have been prepared using potassiumhydrate and melamine as precursors, and fully characterized by X-ray diffraction (XRD), UV-Vis spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FTIR) spectroscopy, N₂ adsorption, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). The results of these analyses indicated that the positions of the valence and conduction bands were obviously changed as the concentration of K⁺ increased. The K⁺ ions were found to be embedded in the structural units of the g-C₃N₄, which inhibited the growth of the graphitic carbon nitride crystals, enhanced the surface area, and increased the separation rate of the photogenerated electrons and holes. The activity of K⁺ doped g-C₃N₄ catalysts was tested towards the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. The result indicated that the activity improved significantly after K⁺ doping. Furthermore, the K⁺ doped g-C₃N₄ catalysts exhibited outstanding structural and catalytic stability.

The K-LaZrO₂ and K-CuLaZrO₂ catalysts used for the synthesis of isobutanol fromsyngas have been characterized by X-ray diffraction (XRD), temperature programmed desorption (TPD), X-ray photoelectron spectrometry (XPS), Fourier transforminfrared (FTIR) spectroscopy, and chemical enrichment methods. The results of these analyses indicated that a solid solution of Cu-Zr was formed after the addition of Cu, and that the CuO was well dispersed. Furthermore, the addition of Cu inhibited the formation of t-ZrO₂. CO-TPD showed that the addition of Cu led to an increase in the amount of COadsorbed by the catalyst. Furthermore, H₂-TPD showed that the addition of Cu led to an increase in the amount of H₂ adsorbed at lowtemperatures, which was related to the activity of catalyst. The results of FTIR and chemical enrichment analyses also revealed that the level of CO adsorption increased following the addition of Cu, as well as amount of C₁ intermediates. Taken together, these results indicated that the activity of catalyst was significantly enhanced by the addition of Cu and that the selectivity towards isobutanol increased up to 48.5% when the reaction was conducted at p=10.0 MPa, gas hourly space velocity (GHSV) = 3000 h^-1, T=360℃, and V(H₂)/V(CO)=1:1.

Pt/γ-Al₂O₃ catalyst nanoparticles were prepared by self-assembly (AS) and wetness impregnation (WI) methods, and evaluated for the oxidation of volatile organic compounds including toluene, isopropanol, acetone, and ethyl acetate. The morphology, structure, and surface properties of the catalyst particles were correlated to their oxidation activity. Toluene, isopropanol, acetone, and ethyl acetate (1000×10^-6, volume fraction) in the feed stream (gas hourly space velocity of 18000 mL·g^-1·h^-1) were completely oxidized and removed by Pt/γ-Al₂O₃-AS at below 130, 135, 145, and 215℃, respectively. Pt/γ-Al₂O₃-AS exhibited outstanding activity and stability at high concentrations and space velocities. The high catalytic activity of Pt/γ-Al₂O₃-AS was attributed to its high surface area, small size, finely dispersed Pt nanoparticles, better reproducible activity at lowtemperature, and a higher number of hydroxyl groups.

Diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) were used as single templates to synthesize mesoporous zeolite ZSM-5 microspheres. The obtained 10-15 μm hierarchical aggregates had a uniformspherical morphology, which was spontaneously assembled by primary zeolite nanocrystals of 50 nmin size during the hydrothermal synthesis. The ZSM-5 aggregates had a tunable textual porosity, large mesopore volume, and high catalytic activity in the Friedel-Crafts alkylation. Diamine templates only acted as structure directing agents in our previous work. The current alkyl-polyamine templates acted as structure directing agents and space fillers in the synthesis of the hierarchical zeolites.

Iron and copper bimetallic catalysts with fixed total contents of copper and iron were prepared by a co-impregnation method, and then used for selective catalytic oxidation of ammonia to nitrogen. The properties of the catalysts were characterized by N₂ adsorption-desorption, H₂ temperature-programmed reduction (H₂- TPR), NH₃ temperature-programmed desorption (NH₃-TPD), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The iron and copper bimetallic catalysts exhibited good activity and high selectivity of N₂ at the gas hourly space velocity (GHSV) of 100000 h^-1. The activity and N₂ selectivity in the low temperature range increased with increasing Cu loading, whereas in the high temperature range (above 400 ℃) the selectivity of N₂ was directly related to the content of iron. The highest NH₃ conversion was achieved at about 350℃ for Fe_0.25Cu_0.75/ZSM-5, and the N₂ selectivity was up to 97% at 300 ℃. On the other hand, the extremely high N₂ selectivity about 98% was obtained over Fe_0.75Cu_0.25/ZSM-5 at 500 ℃. In addition, N₂O as the by-product and greenhouse gas was obtained in very low amounts for all the catalysts. The characterization results showed that the activity was influenced by the acid content and the amounts of copper species. Moreover, the highly reducing capacity could improve the N₂ selectivity.

Ordered mesoporous silica materials SBA-15, MCM-41, SBA-16, KIT-6 with different pore sizes and properties were prepared. Several SBA-15 materials were synthesized with different pore diameters by changing the hydrothermal temperature. The materials produced were characterized using small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption. The adsorption isotherms of organic aldehyde were measured, using butyraldehyde as a model molecule. The results were compared with those for the adsorption capacity of Y-zeolite; they showed that the specific surface area originating from the mesopores was proportional to the amount of butyraldehyde adsorption. The adsorption isotherms agreed with Langmuir mode for monolayer adsorption. Mesoporous silica MCM-41 with the highest mesopore specific surface area showed the highest adsorbed amount of butyraldehyde (484 mg·g^-1). The SBA-15 sample was selected for the fabrication of cigarette filters, and the results showed that SBA-15 significantly reduced the amount of Croton aldehyde released in cigarette smoke.

A two-step method combining colloid synthesis and incipient wetness impregnation was developed for the preparation of bimetallic Pd-Cu/γ-Al₂O₃ catalysts, with the aim of increasing the selectivity to styrene in the selective hydrogenation of phenylacetylene. The structural properties of the catalysts were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), CO-pulse chemisorption, N₂ physisorption, and inductively coupled plasma atomic emission spectrometry (ICPAES). The effects of changing the Cu/Pd molar ratio, the Pd loading, and the order in which the Pd and Cu were introduced into the catalysts on the catalytic activity and selectivity were investigated. The results showed that Pd-Cu/γ-Al₂O₃ exhibited much higher selectivity toward styrene than Pd/γ-Al₂O₃. In particular, Pd-Cu/γ-Al₂O₃ with a Pd loading of 0.3%(w) and a Cu/Pd molar ratio of 0.6 displayed excellent performance at 40℃under 0.1 MPa H₂, with a high selectivity of 95% at a conversion of 90%, and a selectivity of approximately 82%, even at conversions of higher than 99%. The increased selectivity of Pd-Cu/γ- Al₂O₃ was ascribed mainly to the geometrical effects of the Pd-Cu bimetallic alloys, rather than the electronic effects, since no electron transfer occurred between Pd and Cu.

With the aim of decreasing the dehydriding temperature and improving the hydriding/dehydriding kinetic properties of MgH₂, we prepared MgH₂+20%(w) MgTiO₃ composite via ball-milling, and investigated the hydrogen storage properties of the composite. X- ray diffraction (XRD) results showed that the MgTiO₃ decomposed into Mg₂TiO₄ and TiO₂ during the ball-milling. These two resulting compounds remained stable during the hydriding/dehydriding processes, working as catalysts for the hydriding/dehydriding. Temperatureprogrammed- desorption (TPD) and hydriding/dehydriding kinetics tests showed that doping MgH₂ with MgTiO₃ lowered the onset dehydrogenation temperature of MgH₂ from 389 to 249 ℃, as well as increasing the hydrogen absorption amount from 0.977%(w) to 2.902%(w) at 150 ℃, and increasing the desorption amount from 2.319% (w) to 3.653%(w) at 350 ℃. The MgTiO₃ additive decreased the dehydriding activation energy of MgH₂ from 116 to 95.7 kJ·mol^-1. The thermodynamic and kinetic performance of the MgH₂+20%(w) MgTiO₃ composite was significantly improved compared with pristine MgH₂, which was attributed to the high catalytic activity of the (insitu formed) TiO₂ and Mg₂TiO₄ during the ball-milling and dehydriding processes.

Photocatalytic overall water splitting under a two-step photocatalytic (Z scheme) system was studied with layered perovskite H_1.9K_0.3La_0.5Bi_0.1Ta₂O₇ (HKLBT) and Pt/WO₃ used as the hydrogen and oxygen evolution photocatalysts, respectively. The influence of the redox mediator species and the concentration of the redox mediator was investigated. The results showed that overall water splitting (H₂/O₂ volume ratio: 2:1) was achieved using Fe²⁺/Fe³⁺ as the redox mediator, where the hydrogen and oxygen evolution rates reached 66.8 and 31.8 μmol·h^-1 (H₂/O₂ volume ratio: 2.1:1), respectively. A very high concentration of the redox mediator is unable to improve the photocatalytic activity because it is blocked by the carrier mediator redox rate based on the activity of the photocatalysts.

Silver phosphate/bismuth vanadate (Ag₃PO₄/BiVO₄) composite photocatalysts were successfully synthesized by coupling a reflux method with an in situ precipitation route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy were used to characterize the as-prepared products. The XRD and FESEM results showed that Ag₃PO₄/BiVO₄ composite photocatalysts were successfully obtained. An energy-efficient light emitting diode lamp was used as the visible light source, and the photocatalytic performances of the as-synthesized products were evaluated for dye degradation in a low-cost photocatalytic system. The Ag₃PO₄/BiVO₄ composite with a Ag₃PO₄:BiVO₄ molar ratio of 1:3 exhibited much higher photocatalytic activity than pure Ag₃PO₄ catalyst, resulting in decreased use of Ag₃PO₄. The Ag₃PO₄/BiVO₄ composite photocatalyst showed the best photoactivity in neutral solution and had a higher photodegradation rate for cationic dyes than anionic dyes. The superoxide radicals (O₂^-·) and holes (h+) were considered to be the main active species in the Ag₃PO₄/BiVO₄ system. The photocatalytic activity of the Ag₃PO₄/BiVO₄ composite photocatalyst decreased to different degrees after three cycles because of the production of metallic silver.

A Bi₂MoO₆/BiVO₄ photocatalyst with a heterojunction structure was synthesized by a one-pot hydrothermal method. Its crystal structure and microstructure were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The FESEM and HRTEM images indicated that Bi₂MoO₆ nanoparticles were loaded on the surface of BiVO₄ nanoplates to form a heterojunction. The ultraviolet visible (UV-Vis) diffuse reflection spectra (DRS) showed that the resulting Bi₂MoO₆/BiVO₄ heterojunction possessed more intensive absorption within the visible light range compared with pure Bi₂MoO₆ and BiVO₄. These excellent structural and spectral properties endowed the Bi₂MoO₆/BiVO₄ heterojunction with enhanced photocatalytic activity. It was found that the Rhodamine B (RhB) degradation rate with Bi₂MoO₆/BiVO₄ was higher than that with pure BiVO₄ and Bi₂MoO₆ under visible light (λ>420 nm) by photocatalytic measurements. The enhanced photocatalytic performance of the Bi₂MoO₆/BiVO₄ sample can be attributed to the improved separation efficiency of photogenerated hole-electron pairs generated by the heterojunction between Bi₂MoO₆ and BiVO₄, intensive absorption within the visible light range, and high specific surface area.

Nano-sized Ag₂CO₃ and carbon nanotube (CNT) composites were fabricated by a facile chemical precipitation approach in N,N-dimethylformamide (DMF) solvent. The as-prepared Ag₂CO₃/CNT samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and ultra violet-visible (UV-Vis) diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the nano-sizedAg₂CO₃ particles and CNTs were well combined. The Ag₂CO₃/CNT composite with CNT content of 1.5%(w) exhibited optimal photocatalytic activity under visible light. Ninetythree percent of the MO was removed by the Ag₂CO₃/CNT composite within 60 min. For the Ag₂CO₃/CNT composites, we found that the incorporation of CNT improved the structural stability of Ag₂CO₃ compared with Ag₂CO₃. After three cycles, 81% of the MO was decomposed by the Ag₂CO₃/CNT composite with CNT content of 1.5% (w), but only 59.5% of the MO could be removed by Ag₂CO₃. The improvements in the activity and stability are attributed to the conductive structure supported by CNTs, which favors electron-hole separation and the removal of photogenerated electrons from the decorated Ag₂CO₃.

A series of Ce-Cu-Co/carbon nanotubes (CNTs) catalysts with different Ce contents were prepared by co-impregnation, and the catalytic performance was investigated for the synthesis of higher alcohols from syngas. The catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction of H₂ (H₂-TPR), N₂ adsorption-desorption isotherms (BET), transmission electron microscopy (TEM), and temperature-programmed desorption of CO (CO-TPD). The results showed that at a Ce content of 3% the catalyst had the highest catalytic activity. The formation rate and selectivity of alcohol reached 696.4 mg·g^-1· h^-1 and 59.7%, where the mass fraction of ethanol was 46.8% of the total amount of alcohols. The addition of an appropriate amount of Ce facilitated the dispersion of Cu and promoted reduction of the catalysts. It also markedly increased the adsorption capacity for CO, and significantly improved the formation of active sites for alcohols, which is favorable for the catalytic activity and to improve the selectivity of alcohols. Research showed that combining the CuCo-based catalyst, which has high activity and a high ability of carbon chain growth, with the confinement effect of CNTs can result in a narrow distribution of alcohols and significantly improve the selectivity of ethanol.

A series of ZrO₂/MWCNTs were prepared, using ZrO(NO₃)₂·2H₂O as a precursor, by the surface modification of multiwalled carbon nanotubes (MWCNTs). Manganese oxides were supported on the ZrO₂/ MWCNTs to prepare MnO_x/ZrO₂/MWCNTs catalysts. The effect of zirconium on the selective catalytic reduction (SCR) activity of the catalysts was investigated. Furthermore, the structural properties of the catalysts were comprehensively characterized by a suite of analytical methods. The results show that the addition of zirconium improved the SCR activity of the MnO_x/MWCNTs significantly and the catalyst with 30% Zr loading was found to have the highest activity. X- ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), and N₂ adsorption-desorption results revealed that the modification of zirconium could enhance the dispersion of MnO_x on the support as well as enhance the interaction between the metal oxides and the MWCNTs. Additionally, zirconium could also increase the specific surface area, the total pore volume, and the average pore size of the catalysts. Moreover, from the results of X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR), and temperature-programmed desorption of NH₃ (NH₃- TPD), zirconium increased the atomic concentration of the chemisorbed oxygen on the catalysts surface and promoted the conversion of Mn³⁺ to Mn⁴⁺. Therefore, the surface-active sites increased and the redox ability of the catalysts improved. Additionally, the amount and strength of acid on catalyst surface increased. These factors are the main reason for the MnO_x/ZrO₂/MWCNTs catalysts having better low-temperature SCR activity.

TiO₂ rutile nanorods were successfully synthesized by a hydrochloric acid-modified hydrothermal process, using butyl titanate as the titanium source, followed by hydrogenation treatment. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis near infrared (NIR) diffuse reflection spectroscopy (UV- Vis- NIR DRS), electron paramagnetic resonance (EPR), surface photovoltage spectroscopy (SPS), and the photodegradation of gas-phase acetaldehyde and liquid-phase phenol to evaluate the photocatalytic activity of the catalysts. The results show that the photoresponse of TiO₂ gradually expands from the ultraviolet region to the visible and near-infrared regions upon increasing the hydrogenation time at high temperature. Its color changed from white to gray, and this is attributed to the introduction of Ti³⁺ defects and oxygen vacancies. Based on surface photovoltage spectroscopy responses and the amount of hydroxyl radicals produced, hydrogenation treatment promoted the photogenerated charge separation significantly. This is responsible for the improved photocatalytic degradation activity toward gasphase acetaldehyde and liquid-phase phenol under visible or ultraviolet irradiation. Therefore, a specific amount of defects and/or vacancies can induce new and appropriate surface states below the conduction band of the TiO₂ samples. However, if the amount of introduced defects or vacancies is too high, low-level surface states are produced and this is not favorable for photogenerated charge separation, and detrimental to photocatalytic reactions.

In this study, Ag₃PO₄ nanoparticles (NPs), cobalt phosphate (Co₃(PO₄)₂, CoP) nanosheets (NSs), and their composites (CoP/Ag₃PO₄) were synthesized via a facile chemical precipitation method. Their visiblelight photocatalytic activities were compared and investigated. The structural, morphological, optical, and visiblelight photocatalytic properties of the prepared samples were characterized by X-ray diffraction (XRD), fieldemission scanning electron microscopy (FESEM), ultraviolet- visible (UV- Vis) diffuse absorbance and photoluminescence (PL) spectroscopies. We found that both the degradation rate and cyclical stability of the CoP/Ag₃PO₄ hybrids increased significantly under visible-light irradiation when methyl orange (MO) was used as the target with reference to single-phase Ag₃PO₄ NPs or CoP NSs. This suggests that CoP might play a cocatalyst role, which suppresses carrier recombination and provides a large number of photogenerated holes. Additionally, we also observed that the CoP/Ag₃PO₄ hybrids hardly degraded Rhodamine B (RhB), a cationic dye. This behavior might be attributed to the lower amount of dye molecule absorption because of a change in surface polarity. We thus present a new approach for the development of low-cost and visible-light responsive photocatalysts.

The surface-enhanced Raman scattering (SERS) spectrum and pre-resonance Raman spectra of Aflatoxin B₂ (AFB₂) adsorbed on silver cluster were calculated by density functional theory (DFT) methods with the B3LYP/6-311G (d,p)(C, H, O)/LanL2DZ(Ag) basis set. The results show that the SERS enhancement factors were 10², and this belongs to the C=O stretching vibration of the pyrane ring because of the larger static polarizability of the complex. The pre-resonance Raman spectra of the AFB₂-Ag₂ complex were explored at 1144 and 544 nm, which corresponds to charge transfer excitation energy, and its enhancement factor was 10². The pre-resonance enhancement factor was 10⁴ when incident light charge transfer pre-resonant wavelengths of 432 and 410 nm were selected. These come from a charge transfer resonance enhancement between the silver cluster and the AFB₂ molecule. Therefore, changing the wavelength of the incident light is more conducive to the trace detection of the strong carcinogen AFB₂.

⁹⁰Sr is an important radionuclide that needs to be removed from radioactive waste water (RWW) in nuclear power plants (NPP) prior to its discharge into the environment. Hydrous antimony oxide is a type of selective adsorbent for Sr(Ⅱ) ions, especially in acid solution. In this paper, a series of self-doped hydrous antimony oxides Sb(Ⅲ)/Sb₂O₅ were prepared by a two-step process in an absolute alcohol solvent, using antimony trichloride as a stable and low-toxic antimony source and H₂O2 solution as an oxidant. UV radiation was used to enhance the oxidation rate of Sb(Ⅲ). The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy analyses, and the effect of the preparation conditions on the composition and structure of the products are discussed. Batch adsorption experiments were performed to study the relationship between the Sb(Ⅲ)/Sb(total) ratio in the oxide adsorbent and the Sr(Ⅱ) adsorption activity. Moreover, the influence of the initial pH of the waste water was investigated. The results showed that Sb(Ⅲ) ions can coexist with Sb(V) and form the solid solution of Sb(Ⅲ)/Sb₂O₅ with cubic pyrochlore structure. Materials with different Sb(Ⅲ)/Sb(total) ratios can be obtained by choosing different alcohols as the solvent and a suitable mixing method of the reactants, as well as by changing the reaction temperature during the oxidation process. Among the as- prepared Sb(Ⅲ)/Sb₂O₅ adsorbents, the sample with a Sb(Ⅲ)/Sb(total) ratio of 49.8% showed the best Sr(Ⅱ) adsorption performance, and the distribution coefficients of Sr(Ⅱ) was about 6.6×107 mL·g^-1. This hydrous antimony oxide showed favorable performance in the wide pH value of pH=3-13. In addition, Sr(Ⅱ) adsorption on the as-prepared material fitted the Langmuir model very well under the conditions studied.

The influence of sodium and potassium promoters on the structure and reaction behavior of an FeMn catalyst toward light olefin synthesis from syngas was investigated by N₂ adsorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), H₂ temperature-programmed reduction (H₂-TPR), CO/CO₂ temperature-programmed desorption (CO/CO₂-TPD), Mössbauer spectroscopy (MES) and CO+H₂ reaction. We found that an increase in manganese improves the dispersion of the active Fe component and light olefin selectivity; however, excessive enrichment with the Mn promoter on the catalyst surface suppresses CO conversion. Potassium and sodium inhibit the reduction of the catalyst in H₂ and improve the adsorption of CO₂ and CO because of the enhanced surface basicity of the catalysts. After reduction with syngas (n_H2/n_CO=20) and reaction with syngas (n_H2/n_CO=3.5), the analysis of the bulk structure was compared with those of the FeMn, FeMnNa, and FeMnK catalysts. The results show that FeC_x is found in relatively high levels in the FeMnK catalysts because of the stronger alkalinity and adsorbability of CO. However, Fischer-Tropsch synthesis (FTS) results indicate that sodium and potassium improved the selectivity toward light olefins. The best catalytic performance was achieved by the FeMnNa catalyst. Its CO conversion and light olefins selectivity were 96.2% and 30.5% (molar fraction), respectively.

We used Zr_0.5Ce_0.5O₂ solid solution modified high specific surface area SiC as the catalyst support and synthesized Ni/Ce_0.5Zr_0.5O₂/SiC, Fe/Ce_0.5Zr_0.5O₂/SiC, and Co/Ce_0.5Zr_0.5O₂/SiC catalysts by a two-step impregnation method. The catalytic activity and stability were investigated in the catalytic combustion deoxidation of coal-bed gas. The as-prepared catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma- mass spectroscopy (ICP- MS), high- resolution transmission electron microscope (HRTEM), Brunner-Emmet-Teller (BET) measurements, thermal gravimetric analysis (TGA), and temperature-programmed reduction of H₂ (H₂-TPR). The results suggest that partial diffusion of Ni, Fe, and Co to the Ce_0.5Zr_0.5O₂ lattice leads to the formation of defects in the catalyst bulk phase. Ce_0.5Zr_0.5O₂ increased the redox process between metals and their oxides, improving the oxygen storage, mobility capacity, and the activation of CH₄. In addition, the excellent resistance of both SiC and Ce_0.5Zr_0.5O₂ solid solution to carbon deposition effectively inhibited coke formation on the catalysts during the combustion of rich methane atmosphere. Hence, these catalysts have good catalytic combustion deoxidation activity and stability. Co/ Ce_0.5Zr_0.5O₂/SiC catalyst had the best activity among the three catalysts: CH₄ was activated at 320 ℃ and O2 was completely removed at 410 ℃.

The nickel atoms in a metal ferrite lattice inhibit photocatalytic activity with hydrogen peroxide. However, activated carbon bonded on nickel ferrite (AC-NiFe₂O₄) induces photocatalytic activity of nickel ferrite with hydrogen peroxide, enabling photo-Fenton catalytic oxidation of ammonia under visible-light irradiation in the presence of hydrogen peroxide. The AC-NiFe₂O₄ catalyst was characterized using X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, and a vibrating sample magnetometer at room temperature. The photocatalytic tests showed that the ammonia degradation efficiency approached 91.0% in the presence of the AC-NiFe₂O₄ catalyst, whereas the efficiency was only 24.0% without the catalyst under similar conditions over 10 h. Another test showed that the single NiFe₂O₄ catalyst achieved a degradation efficiency of only 30.0% under similar conditions, indicating that activated carbon can accelerate the rate of ammonia oxidation. Exploration of the oxidation mechanism showed that the oxidation pathway involves an HONH₂ intermediate, forming nitrite ions. Kinetic studies showed that the oxidation of ammonia follows a pseudo-first order kinetic law, with a rate constant of 3.538×10^-3 min^-1. The catalyst was used in eight runs, and shown to be stable, recoverable, separable, and reusable, suggesting that it has potential applications in the disposal of ammonia.

A series of Fe-doped graphitic carbon nitride (g-C₃N₄) photocatalysts were prepared using ferric nitrate and melamine as precursors. X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, Fouriertransform infrared (FT-IR) spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), photoluminescence (PL) spectrum, and X-ray photoelectron spectroscopy (XPS) were used to identify changes in the characteristics caused by coordination of N atoms in the structural units of g-C₃N₄. The results indicate that embedded Fe³⁺ changed the optical properties, affected the energy band structure, and increased the electron/hole separation rate. The activities of the Fe³⁺-doped g-C₃N₄ catalysts were tested in the photocatalytic degradation of rhodamine B (RhB) under visible light. The degradation rate of RhB over Fe³⁺-doped g-C₃N₄ was 99.7% in 120 min. The rate constant for Fe³⁺-doped g-C₃N₄ was 3.2 times as high as that of pure g-C₃N₄. Disodium ethylenediamine tetraacetate, tert-butyl alcohol, and 1,4-benzoquinone were used as hole (h_VB⁺), hydroxyl radical (·OH), and superoxide radical (O₂^-·) scavengers, respectively, to investigate the possible mechanism.

Single-crystalline Cu₃B₂O₆/CuB₂O₄ was successfully prepared by a sol-gel method fromcupric nitrate/ cupric acetate and boric acid, using citric acid as a foaming agent. The obtained materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and thermogravimetry-differential thermal analysis (TG-DTA). The photodegradation of methylene blue (MB) solution was used to evaluate the photocatalytic activity of Cu₃B₂O₆/CuB₂O₄ under visiblelight irradiation (400 nm<λ<1100 nm). The results indicated that both Cu₃B₂O₆ and CuB₂O₄ displayed good photocatalytic activity. Under visible-light irradiation for 6 h, the photocatalytic activities of CuB₂O₄ and Cu₃B₂O₆ reached 63.36% and 99.52%, respectively, in MB aqueous solution (50 mg·L^-1) containing 1 g·L^-1 catalyst. Ultraviolet-visible analysis showed that the width of the midgap state for Cu₃B₂O₆ is 1.78 eV, which is much narrower than that of CuB₂O₄ (1.95 eV), and the band gap of Cu₃B₂O₆ is narrow (E_g=2.34 eV). These results indicated that electron transitions can occur in both the midgap state and forbidden band for Cu₃B₂O₆; this is why Cu₃B₂O₆ has higher visible-light photocatalytic activity than CuB₂O₄.

In this study, a cobalt hydroxide-reduced graphene oxide (Co(OH)₂/rGO) composite was synthesized by one-step self-assembly, and used as a catalyst in dye degradation. The catalyst was characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive Xray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The catalyst had well-distributed Co(OH)₂ nanoparticles on the reduced graphene oxide surface. The catalytic performance of this hybrid material was investigated for the activation of peroxymonosulfate (PMS), and used to degrade acid orange 7 (AO7) dye in aqueous solution. The experimental results showed that the composite had high catalytic activity in the degradation of AO7, and 100% decomposition was achieved in less than 12 min. Total organic carbon (TOC) experiments indicated a high degree of mineralization, suggesting excellent catalytic activity. Stability tests showed that the catalyst was stable in the degradation of AO7 over several runs. AO7 was completely degraded in 16 min in the third run.

Hierarchical micro-sized zeolite aggregates with the MEL structure were prepared hydrothermally froma tetrabutylammoniumhydroxide (TBAOH)-tetraethyl orthosilicate (TEOS)-H₂O system. The obtained microsized silicalite-2 microspheres had sizes larger than 10 μm, high BET surface area (460 m²·g^-1), and large pore volume (0.74 cm³·g^-1). The formation of micro-sized spheres alleviates preparation and application difficulties. The presence of inter-crystalline mesopores originating from the spontaneous assembly of nano-sized primary particles during hydrothermal synthesis gives the advantages of nanoparticles, reducing diffusion limitations. The introduction of titanium does not strongly affect the morphology and textural properties of the MEL-type zeolite, which are quite similar to those of silicalite-2 aggregates. The micro-sized titanium silicalite-2 (TS-2) microspheres showed comparable catalytic activity in phenol hydroxylation to that of titanium silicalite-1 (TS-1) of size 100-200 nm, and were easily recovered by traditional filtration, simplifying the separation and recovery compared with nano-sized TS-1.

Potassium-modified SBA-15-supported molybdenum oxide catalysts were prepared using a twostep impregnation method. The physical and chemical properties of the catalysts were characterized using N2- adsorption-desorption, X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible (UV-Vis) spectroscopy, Raman spectroscopy, NH₃ temperature-programmed desorption (NH₃-TPD), CO₂ temperatureprogrammed desorption (CO₂-TPD), and H₂ temperature-programmed reduction (H₂-TPR). The results showed that potassium addition resulted in the formation of new potassium molybdates, and the states of molybdenum species varied with changes in the K/Mo molar ratio. The addition of potassium to Mo_0.75/SBA-15 effectively improved the activity of catalysts and the selectivity to the total aldehydes (formaldehyde, acetaldehyde, and acrolein), especially for acetaldehyde in the selective oxidation of ethane. The turn-over frequency (TOF) and product selectivity depended strongly on the potassium content. The maximum selectivity and yield of aldehydes were obtained by varying the K/Mo molar ratio. At 575 ℃, the maximum yield of aldehydes reached 8.5%(molar fraction) over K_0.25-Mo_0.75/SBA-15 catalyst. The formation of new potassium-molybdates promoted the activities and selectivities of the catalysts.

15Co_xLi/AC catalysts promoted by different trace amounts of Li doping were prepared by incipientwetness impregnation. The catalysts were investigated by means of CO hydrogenation and characterized by X-ray diffraction (XRD), temperature-programmed reduction (H₂-TPR), and temperature-programmed surface reaction (TPSR) techniques. The results show that CO conversion, selectivity towards C₅₊ hydrocarbons, selectivity towards mixed linear α-alcohols and the distribution of higher alcohols (C₆₊OH) in the alcohol products were improved by adding trace amounts of Li to the 15Co/AC catalysts. XRD, H₂-TPR, and TPSR results indicate that the existence of trace amounts of Li promotes weak interaction between Li and Co species, disperses the Co species of the catalysts, decreases the size of metallic Co particles, and promotes the formation of Co₂C species.

A microspherical ZSM-5 zeolite aggregated from nanosized zeolite crystals with intra- and intercrystalline mesoporous structures (MMZ- 5) was prepared using presilanized silica as silica source. The acidic properties of this mesoporous zeolite were characterized via Fourier transform infrared spectroscopy (FTIR) in combination with pyridine (Py) and 2,6-di-tert-butylpyridine (DTBPy). Compared with conventional microporous ZSM- 5, the MMZ- 5 zeolite possessed more Lewis acid sites and many more accessible Brönsted acid sites for bulky DTBPy molecule (1.05 nm in diameter). This mesoporous zeolite thus afforded both effective active sites and reaction voids allowing the reaction of larger molecules, resulting in enhanced catalytic activity and stability of the MMZ-5 zeolite during the benzylation of naphthalene with benzyl chloride (BC) to form bulky monobenzylnaphthalenes and dibenzylnaphthalenes, during which the selectivity for monobenzylnaphthalenes was estimated to be about 79%. Moreover, the selectivity for dibenzylnaphthalenes was enhanced with increasing reaction time, owing to the consecutive reactions between monobenzylnaphthalenes and BC occurring at the effective reaction voids of the MMZ-5 zeolite. The distribution of the monobenzylnaphthalene isomers (α-BN and β-BN) was found to be independent of both reaction temperature and extent of BC conversion, the α-BN/β-BN molar ratio being about 83:17.

A series of tungsten-based catalysts were synthesized via a traditional impregnation method using SBA-15, hexagonal mesoporous silica (HMS), and SnO₂ as the support. The supported catalysts were characterized by X-ray powder diffraction (XRD), transmission electron microscopy/field-emission transmission electron microscopy (TEM/FETEM), UV-Vis diffuse reflection spectroscopy (UV-Vis DRS), Raman spectrometry, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It was found that the support was crucial to the dispersion and nature of the tungsten species on the catalyst. In this study, the catalytic performances of catalysts with different supports were investigated for the synthesis of adipic acid (AA) from the selective oxidation of cyclohexene oxide. The excellent catalytic performance of the catalyst was obtained over WO₃/SnO₂, followed by WO₃/HMS and WO₃/SBA-15. The XRD results indicate that the degree of crystallinity of the tungsten species of WO₃/SnO₂ catalyst was low and the particle size of WO₃ was small (~2 nm). TEM and XPS results imply a high dispersion of tungsten species on the SnO₂ support. The UV-Vis DRS spectra demonstrate the existence of [WO₄] and low-polymeric tungsten species. In addition, the W-based catalyst with SnO₂ as the support could retain high activity, even after being reused six times, suggesting that there is strong interaction between tungsten species and the SnO₂-support that enhanced the stability of the catalyst. This shows the potential of the WO₃/SnO₂ as a catalyst for the synthesis of adipic acid.

Highly ordered TiO₂ nanotube arrays (TNAs) were fabricated by an electrochemical anodization process and Cu₂O nanoparticles were subsequently deposited onto these TNAs via pulse deposition to form Cu₂O/TiO₂ nanotube heterojunction composite materials. Samples were characterized by field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffusion reflection spectroscopy (DRS). The photocatalytic performances of the Cu₂O/TiO₂ composites were investigated by following the visible-light induced photocatalytic decomposition of methyl orange (MO). The results indicated that the inner surfaces and interfaces of the TNAs had been successfully modified with uniformly distributed Cu₂O nanoparticles, and that these composites could effectively improve the visible light photocatalytic performance. The Cu₂O/TiO₂ nanotube composite obtained using 0.01 mol·L^-1 CuSO₄ solution exhibited the best photocurrent and photocatalytic performance. Based on the results obtained, a possible photocatalytic mechanism is also discussed.

In-Si co-modified TiO₂ photocatalysts were synthesized via a microwave-assisted solvothermal method. The obtained materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, N₂ addesorption (BET), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and UVVis diffuse reflectance spectroscopy (UV-Vis DRS). The photocatalysts all exist in an anatase phase, despite the fact that the crystallinity slightly decreased upon modification of the TiO₂ photocatalysts. Si-modification resulted in smaller nanoparticles and larger specific surface areas. In-modification led to the formation of In₂O₃ on the surface of TiO₂, such that In cannot enter the TiO₂ lattice, contributing to efficient charge transfer between the coupled semiconductors In₂O₃ and TiO₂. Degradation of Rhodamine B (RhB) showed that In-Si co-modified TiO₂ photocatalysts can exhibit high photocatalytic activity under both ultraviolet and visible light. The highest activity was obtained for In-Si co-modified TiO₂ with an Si:In:Ti molar ratio of 0.03:0.02:1 (IST-2), with which RhB was completely degraded within 3 min under ultraviolet light and where 97% of RhB was degraded after 120 min under visible light. The improved photocatalytic activity of In- Si co-modified TiO₂ may be ascribed to synergistic effects between large surface area, efficient electron transmission at the In₂O₃-TiO₂ interface, and the dye sensation effect of RhB. Photodegradation for colorless phenol occurred at a much slower rate than that for RhB, and the phenol did not completely degrade within 700 min.

A BaFeO_3-x+Cu-ZSM-5 coupled catalyst was designed and synthesized to eliminate the NO_x emitted from lean-burn exhausts, providing an alternative to the traditional noble-metal-based NO_x storage reduction (NSR) catalysts. During the lean-burn period, the NO oxidation and storage processes mainly occurred over the BaFeO_3-x catalyst. During the fuel-rich period, the released NO_x from the BaFeO_3-x catalyst was further reduced over the Cu-ZSM-5 catalyst. Our results show that, compared with the BaFeO_3-x and Cu-ZSM-5 catalyst alone, the operating temperature window of the coupled BaFeO_3-x+Cu-ZSM-5 catalyst is extended from 250 to 400 ℃, and its NO_x elimination performance is significantly improved. The maximum NO_x conversion of the coupled catalyst was 98%, while the N₂ selectivity was close to 100%.

The present work investigated the effects of two types of CeO₂ materials on the lean NO_x trap (LNT) performance over NO_x storage reduction (NSR) catalysts below 300 ℃. These materials were obtained by mechanical mixing of 2% (w) Pt/Al₂O₃ (PA) with CeO₂-X (X=S, I). X-ray diffraction (XRD), BET surface area measurements, and scanning electron microscopy (SEM) were used to characterize the physical structures of the catalysts, while X-ray photoelectron spectroscopy (XPS) and H₂ temperature-programmed reduction (H₂-TPR) were employed to identify and quantify the surface Ce³⁺ concentrations and the amounts of surface-active oxygen. In-situ diffuse reflectance infrared Fourier transform spectroscopy (In-situ DRIFTS) was applied to analyze the surface adsorbed NO_x species. Compared with CeO₂-I, CeO₂-S presented superior physico-chemical properties, including higher surface area, richer porous texture, stronger aging-resistance, and higher surface Ce³⁺ concentration. As a result, the PA+CeO₂-S sample also exhibited outstanding NO_x trapping capacity. Furthermore, interaction between Pt and CeO₂ was observed in the PA+CeO₂-X mixtures, which facilitates NO oxidation and the NO_x trapping process owing to the accompanying increase in the activity of surface active oxygen on the CeO₂. This interaction was stronger in the case of the PA+CeO₂-S sample as compared with the PA+CeO₂-I. The Ce³⁺ content and presence of active oxygen species on the CeO₂ surface both play critical roles in the NO_x trapping process and hydrothermal treatment of the CeO₂ significantly decreased the NO_x trapping capacity of both PA+CeO₂ samples. It was also determined that the interaction between Pt and aged CeO₂ is weakened and that the NO_x trapping capacity of aged CeO₂ is enhanced after loading a small amount of Pt, which is attributed to the promotion of nitrate formation by increased surface oxygen activity.

This study investigated the effects of NO₂ on the selective catalytic reduction (SCR) of NO by NH₃ over Cu/SAPO-34 catalyst at temperatures ranging from 100 to 500 ℃. The Cu/SAPO- 34 sample was hydrothermally treated at 750 ℃ for 4 h to obtain a de-greened sample and X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structure of the catalyst. SCR activity test, kinetic analysis, and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ-DRIFTS) were all applied to evaluate the changes in catalytic activity in the presence of various NO/NO₂ ratios. The SCR results for different NO/NO₂ molar ratios demonstrated that NO₂ inhibited the NO_x removal efficiency over the Cu/SAPO- 34 catalyst at low temperatures (100-280 ℃), but enhanced the efficiency at high temperatures (above 280 ℃). The amount of N₂O was observed to increase with decreasing NO/NO₂ ratios, owing to the decomposition of NH₄NO₃. The kinetic results showed that the fast SCR reaction exhibited a higher apparent activation energy (E_a=64.02 kJ·mol^-1) than that of the standard SCR reaction (E_a=48.00 kJ·mol^-1) over Cu/SAPO-34 catalyst. The results of in situ-DRIFTS showed that NO₂ did not efficiently generate nitrate species on Cu2+ sites compared with NO, and that some nitrate species combined with NH₄₊ on Brønsted acid sites to generate NH₄NO₃. The inhibitory effect of NO₂ at low temperatures is evidently caused by deposited NH₄NO₃ covering the active sites of Cu/SAPO-34 catalyst, while these NH₄NO₃ species can be reduced by NO or thermally decomposed as the temperature increases.

MnO_x/CeO₂/SiO₂ catalysts were prepared by the adsorption phase reaction technique and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. HRTEM showed that MnO_x and CeO₂ particles were uniformly coated on the surface of SiO₂. The XRD spectra showed that the intensity of the Mn₃O₄ diffraction peaks gradually decreased and then completely disappeared with the increasment of the CeO₂ content, which indicated that CeO₂ reduced the crystallinity of MnO_x and improved the dispersibility of MnO_x. Raman spectroscopy indicated that Mn ions on the surface of catalysts could enter into the lattice of CeO₂, replace oxygen ions, and form oxygen vacancies. With the increasment of CeO₂ content, the density of oxygen vacancies initially increased and then decreased. We used the catalysts for selective catalytic reduction (SCR) of NO_x with NH₃. The catalytic activity initially increased and then decreased with the increasment of CeO₂ content, similar to the change in the density of oxygen vacancies. Thus, the catalytic activity of the MnO_x/CeO₂/SiO₂ catalysts increases with increasing the density of oxygen vacancies.

TiO₂-Al₂O₃ composite supports were prepared by in situ sol-gel and co-precipitation methods, and the supported nickel phosphide catalysts were prepared by incipient wetness impregnation and the in situ H₂ reduction method. The catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption (BET), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and inductive couple plasma atomic emission spectrometry techniques (ICP-AES). The hydrodenitrogenation (HDN) activity of the supported nickel phosphide catalysts were evaluated on a continuousflow fixed-bed reactor using quinoline as the model molecule. The results showed that the composite support prepared by the in situ sol-gel method basically retained the original pore properties of γ-Al₂O₃ but with a larger surface area and decentralized pore size distribution, and TiO₂ was enriched on the tubular γ-Al₂O₃ surface. The composite support prepared by the co-precipitation method had a smaller surface area and a centralized pore size distribution, and TiO₂ was evenly dispersed on the massive γ-Al₂O₃ surface. The main active phases after reduction were Ni₂P and Ni₁₂P₅ for the catalyst supported on sol-gel prepared TiO₂-Al₂O₃, but only Ni₂P for the catalyst supported on co-precipitated TiO₂-Al₂O₃. Different TiO₂-Al₂O₃ preparation techniques and different Ti/Al atomic ratios had a great effect on the HDN activity of the catalysts. The catalyst supported on co-precipitated TiO₂-Al₂O₃ exhibited better reducibility and HDN activity than the catalyst supported on in situ sol-gel prepared TiO₂-Al₂O₃. The optimal HDN activity occurred for the catalyst supported on co-precipitated TiO₂-Al₂O₃ with an initial Ti/Al atomic ratio of 1:8. At a reaction temperature of 340 ℃, pressure of 3 MPa, hydrogen/oil volume ratio of 500, and liquid hourly space velocity of 3 h^-1, the HDN conversion of quinoline was 91.3%.