Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (6): 1501-1510.doi: 10.3866/PKU.WHXB201603171

• ARTICLE • Previous Articles     Next Articles

Morphological Effects of Manganese Dioxide on Catalytic Reactions for Low-Temperature NH3-SCR

Meng-Ting SUN1,Bi-Chun HUANG1,2,*(),Jie-Wen MA1,Shi-Hui LI1,Li-Fu DONG1   

  1. 1 College of Environment and Energy, South China University of Technology, Guangzhou 510006, P. R. China
    2 Key Laboratory of the Ministry of Education for Pollution Control and Ecosystem Restoration in Industry Clusters,South China University of Technology, Guangzhou 510006, P. R. China
  • Received:2015-12-23 Published:2016-06-03
  • Contact: Bi-Chun HUANG E-mail:cebhuang@scut.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(51478191);Guangdong Provincial Science and Technology Project, China(2014A020216003)

Abstract:

α-MnO2 nanorods,γ-MnO2 nanosheets,and δ-MnO2 nanofilm-assembled microspheres wereprepared using a hydrothermal method and evaluated as catalysts for the selective catalytic reduction(SCR)of nitrogen oxides(NOx).They were also structurally characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),N2 adsorption- desorption,temperatureprogrammedreduction with hydrogen(H2-TPR),temperature-programmed desorption of ammonia(NH3-TPD),X-ray photoelectron spectroscopy(XPS),and Raman spectroscopy.The γ-MnO2 nanosheets performed thebest for the reduction of NOx and selectivity of N2,while the α-MnO2 nanorods performed the worst.Structuralanalysis indicated that the main factor determining the catalytic activities of the nanomaterials was not thespecific surface area but the crystal structure and the exposed active crystals.The γ-MnO2 nanosheets performedbest because their exposed(131)planes contained multiple Mn cations in coordinatively unsaturatedenvironments,which formed numerous strongly acidic sites.They also benefited from active oxygen species.The active sites allowed the activation of NH3 and NOx at lower temperatures.Moreover,high concentrationsof liquid oxygen and Mn cations at high oxidation states facilitated the redox reactions.

Key words: Selective catalytic reduction, Nitrogen oxide, MnO2 nanomaterial, Hydrothermal synthesis, Morphology effect

MSC2000: 

  • O643