物理化学学报 >> 2021, Vol. 37 >> Issue (8): 2010001.doi: 10.3866/PKU.WHXB202010001

所属专题: 二维光催化材料

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磷酸根修饰的Mn掺杂介孔TiO2在VUV-PCO体系高效催化氧化甲苯性能

舒亚婕1, 梁诗敏1, 肖家勇2, 涂志凌3, 黄海保1,*()   

  1. 1 中山大学环境科学与工程学院,广州 510274
    2 珠海市金湾区联港基础投资有限公司,广东 珠海 519000
    3 湖南建工集团有限公司,广东 珠海 519000
  • 收稿日期:2020-10-01 录用日期:2020-11-30 发布日期:2020-12-04
  • 通讯作者: 黄海保 E-mail:seabao8@gmail.com
  • 基金资助:
    国家重点研发项目(2016YFC0204800)

Phosphate- and Mn-Modified Mesoporous TiO2 for Efficient Catalytic Oxidation of Toluene in VUV-PCO System

Yajie Shu1, Shimin Liang1, Jiayong Xiao2, Zhiling Tu3, Haibao Huang1,*()   

  1. 1 School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
    2 Zhuhai Jinwan District Liangang Infrastructure Investment Co., Ltd., Zhuhai 519000, Guangdong Province, China
    3 Hunan Construction Engineering Group Co., Ltd., Zhuhai 519000, Guangdong Province, China
  • Received:2020-10-01 Accepted:2020-11-30 Published:2020-12-04
  • Contact: Haibao Huang E-mail:seabao8@gmail.com
  • About author:Haibao Huang, Email: seabao8@gmail.com; Tel. & Fax: +86-20-39336475
  • Supported by:
    the National Key Research and Development Program of China(2016YFC0204800)

摘要:

真空紫外光解协同催化氧化(VUV-PCO)工艺作为常温下的一种高效目标物消除方式,具有真空紫外光解(VUV)、光催化(PCO)以及臭氧催化氧化(OZCO)三重功效。由于甲苯毒性强,存在广泛,本文选取甲苯作为雾霾重要前驱体的挥发性有机污染物(VOCs)的目标污染物,采用自制固定床连续流反应器(VUV光解和PCO工艺),通过浸渍法成功制备了介孔P-Mn-TiO2催化剂,考察其在VUV-PCO体系降解甲苯性能。本文通过扫描电镜(SEM)、透射电镜(TEM)、紫外可见吸收光谱(UV-Vis)、X射线衍射光谱(XRD)等表征手段分析催化剂结构特征与活性的构效关系,探究Mn和磷酸改性对复合催化剂的光催化、臭氧催化活性以及吸附性能的影响机制。实验结果表明,磷酸修饰和Mn掺杂改性协同作用能有效提高催化剂臭氧催化活性及光催化性能,实现了臭氧的完全消除的同时,促进甲苯的高效降解。Mn3+掺杂进Ti的晶格提高了TiO2的吸光性能,同时可以在催化剂表面产生氧空位,增强催化剂对氧气、臭氧等的吸附和转化。适量磷酸修饰则能进一步提高催化剂对O2、O3等物种的吸附性能和表面光生电子-空穴分离效率,进一步增强催化剂光催化活性及臭氧催化活性。催化剂优异的性能归因于催化剂介孔结构对污染物的有效吸附、表面氧空位上催化分解O3生成O(1D),O(3P),·OH及高效光催化反应产生的活性氧物种共同作用。甲苯首先被VUV光解打断,生成大量中间产物后,经光催化和臭氧催化氧化使最终生成的中间产物和剩余甲苯被系统中的活性氧物种进一步氧化降解为CO2和H2O。与此同时,出口臭氧彻底消除。

关键词: 磷酸, Mn掺杂, VUV-PCO, 甲苯, 臭氧催化氧化

Abstract:

Vacuum ultraviolet irradiation coupled with photocatalytic oxidation (VUV-PCO) is an efficient and promising method for eliminating pollutants at room temperature; it involves three processes: vacuum ultraviolet (VUV) photolysis, photocatalytic oxidation (PCO), and ozone catalytic oxidation. Herein, toluene was chosen as the representative volatile organic compound (VOC), which is one of the most important precursors to form fine particulate matter and photochemical smog, because of its high toxicity and extensive existence in industries. All experiments were performed in a fixed-bed continuous-flow reactor that contained units for VUV photolysis and PCO. Mesoporous P-Mn-TiO2 was prepared by one-step hydrolysis and used as a catalyst for the oxidation of gaseous toluene under VUV irradiation through the VUV-PCO process. The as-prepared P-Mn-TiO2 samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet-visible light (UV-Vis) spectroscopy, and X-ray diffraction (XRD) analysis to determine the physicochemical properties of the catalysts and to determine the mechanisms of Mn doping and phosphoric acid modification and the effects of these processes on photocatalytic activity, ozone catalytic activity, and adsorption performance. The results indicated that the synergistic effect of phosphoric acid modification and Mn doping can improve the ozone catalytic activity and photocatalytic performance by increasing the number of oxygen active sites, completely eliminating the outlet ozone, and simultaneously promoting the efficient degradation of toluene. Moreover, doping TiO2 with Mn3+ significantly enhanced light harvesting, and numerous oxygen vacancies can be generated on the catalyst surface because of the presence of doped Mn3+ in the lattice, which adsorbs and transforms the oxygen species for toluene degradation. In addition, modification with an appropriate amount of phosphate groups can facilitate O2 and O3 adsorption on the TiO2 surface that can favor photo-induced charge carrier separation, thereby significantly improving the photocatalytic and ozone catalytic activities. The excellent catalytic performance of mesoporous P-Mn-TiO2 for toluene degradation and outlet ozone elimination was ascribed to the formation of highly reactive oxidizing species such as O(1D), O(3P), and ·OH via the catalytic decomposition of O3 adsorbed on the oxygen vacancy sites containing Mn and phosphate groups on the catalyst surface. In the VUV-PCO process, toluene was first destructed via VUV photolysis and oxidized by residual O3 generated from VUV photolysis and the active oxygen species formed in the presence of the catalyst. Finally, toluene and the generated intermediate products were oxidized and degraded to CO2 and H2O through VUV-PCO. In addition, the outlet ozone byproduct was simultaneously eliminated by the multifunctional catalyst.

Key words: Surface phosphation, Mn doping, VUV-PCO, Toluene, Ozone catalytic oxidation

MSC2000: 

  • O643