铈基/有序介孔TiO2-MO2 (M = Si, Zr) 双功能催化剂的构建及在含氯 VOCs 低温催化氧化反应中的应用

The negative effect of Cl-VOCs on environment and human health is increasingly serious. The removal of Cl-VOCs has been one of the most significant problems in air pollution control. Catalytic oxidation technology is considered to be the most feasible process to remove Cl-VOCs from environment. However, the key point of this method is the development of eco-friendly catalyst with high activity and stability at low temperature. In the present project, firstly, ordered mesoporous TiO2 modified by Si or Zr is prepared by evaporation induced self-assembly. Superficial acid sites, thermal stability, and anti-chlorine capability of ordered mesoporous TiO2 increase with the addition of Si or Zr elements. Then the Ce-based active component is supported on modified TiO2 to obtain highly dispersed Ce-based catalyst via the confinement effects of support, which leads to rich redox sites on the surface of Ce-based catalyst. Therefore, bi-functional catalyst of Ce-based/ordered mesoporous TiO2-MO2 (M = Si, Zr) is constructed with synergism between active component and ordered mesoporous support. Finally, the structures and properties of Ce-based catalyst and probe reaction are thoroughly studied to explore the structure-activity relationship as well as chlorobenzene reaction mechanism over Ce-based catalyst. Based on the theoretical direction of structure-activity relationship and reaction mechanism, further optimization of Ce-based catalyst is indispensable to remove chlorobenzene by low-temperature catalytic oxidation on Ce-based with high activity and stability.

Cl-VOCs对环境和人类健康的危害越来越严重，Cl-VOCs的消除已成为大气污染治理最重要的问题之一。催化氧化法是消除Cl-VOCs最可行的方法，其关键在于开发无毒、低温高活性和高稳定性的催化剂。本项目拟采用挥发诱导自组装法将Si或Zr引入TiO2，制备改性的有序介孔TiO2，从而提高TiO2表面的酸性位、热稳定性和抗氯中毒能力。然后在改性的有序介孔TiO2载体上负载Ce-基活性组分，利用有序介孔的限域效应获得高分散Ce-基催化剂，以提高催化剂表面的氧化还原位，从而构建一种活性组分与有序介孔载体相互协同的Ce-基/有序介孔TiO2-MO2 (M = Si, Zr)双功能催化剂。通过对Ce-基催化剂结构性质和探针反应的研究，揭示催化剂的构效关系，推断及验证氯苯在Ce-基催化剂表面的反应机理，从而为Ce-基催化剂的优化提供理论指导，最终实现Ce-基催化剂上氯苯的低温高活性高稳定性催化氧化。

Cl-VOCs由于其高毒性、反应惰性和容易使催化剂中毒的特点，为生态环境和人体健康造成了非常严重的影响。因此，Cl-VOCs的净化和消除对环境治理和人们的身体健康具有非常重要的意义。催化氧化法被认为是当前Cl-VOCs消除最可行最易工业化的方法，其关键在于开发无毒、低温高活性和高稳定性的催化剂。本项目研究中采用了挥发诱导自组装的方法制备了有序介孔TiO2，并将Si和Zr分别引入有序介孔TiO2骨架结构中，制备了有序介孔TiO2-SiO2和TiO2-ZrO2载体，然后在其表面负载了Ce基活性组分，如CeMnOx，CeNbOx，CeSnOx等，利用载体的介孔孔道对Ce基活性组分进行了限域分散，构建了一种活性组分在载体表面均匀分散，且与有序介孔载体具有相互作用的Ce基/有序介孔TiO2-MO2(M = Si, Zr)催化剂。结果表明Ce基/TiO2-SiO2或Ce基/TiO2-ZrO2具有高的比表面积和强的氧化还原性，在邻二氯苯（o-DCB）的低温催化氧化消除反应中表现出了高的反应活性和稳定性，Ce12.5Nb2.5/Ti8Si2催化剂上o-DCB消除的T90仅为339℃。Ce基/有序介孔TiO2-MO2(M = Si, Zr)催化剂在o-DCB催化氧化消除中的高反应性能，一方面是因为铈基金属氧化物具有丰富的表面氧空位和高的氧存储能力，另一方面是因为载体TiO2具有较好的电子转移能力，Si和Zr的掺杂提高了催化剂的酸性位、热稳定性和抗氯中毒能力，而研究发现催化剂的酸性和氧化还原性以及二者之间的相互协同作用对o-DCB的催化氧化消除具有非常重要的影响。另外，通过表面晶格氧和表面活性氧的表征，结合In-situ FTIR，我们探究了Ce基/TiO2-ZrO2催化剂表面o-DCB的催化氧化消除反应机理，发现o-DCB的消除遵循MvK反应机理。依托本青年基金，项目团队在国外SCI期刊上发表论文17篇，协助培养研究生5名（其中2名在读），圆满完成了全部研究内容和预期目标。