铈基纳米材料催化剂上氯代有机污染物的低温催化消除

The exhaust containing chlorinated organic volatile compounds (CVOC) presents persistent environmental pollution. Catalytic elimination of organic chlorinated hydrocarbons is most economical and reliable, because of the conversion at low temperature and high selectivity. In this proposal, solvent and water thermal synthesis, surfactant self-assembly will be used for preparing CeO2 nano-materials with different morphologies and lattice faces. The effect of nano-CeO2 mricrostructure on the ability to adsorb and activate oxygen, adsorption strength of Cl species and hydrolysis will be investigated. Through the introduction of Ru and some transitional metal oxides, the Ce-base materials can be modified with several levers so as to create the combination of several active sites for different reactions, realize the removal of Cl species from the catalyst surface, and exchange Cl species with active oxygen. Therefore, a strong adsorption of Cl species produced during CVOC decomposition resulting in the deactivation whish is serious question can be overcome. At the same time, the activities for CVOC oxidation at low temperature and HCl oxidation will be promoted and the activity for chlorination of CVOC will be inhibited. As a result, the chlorination may not proceed over Ce-based catalysts even in the presence of a small amount of Cl2. CVOC can be converted into HCl, H2O, and CO2 with high selectivity. And the system for stable catalytic elimination of CVOC at low temperature is established. If the project in proposal is successful, new method and think for catalytic elimination of CVOC at low temperature is provided for our country. And this project can obtain patents completely.

氯代烃类有机化合物的排放构成了对环境持久性的污染，其催化消除以低温转化和高选择性不造成二次污染而成为最经济、最可靠的方法。本申请提出通过溶剂热法、水热合成法、表面活性剂自组装等技术制备不同形貌、晶面的CeO2纳米材料，研究CeO2纳米微观结构对氧的吸附活化能力、Cl的吸附强度以及解理水分子的能力的影响；通过引入Ru和其他过渡金属氧化物，多层次的修饰Ce基催化材料，造就多种活性中心的结合，实现Cl的转移以及与活性氧的交换，克服现有Ce基催化体系中Cl的强吸附而导致失活问题；同时提高氯代烃类低温氧化活性和HCl氧化活性以及抑制氯代反应，使Ce基催化剂在Cl2的存在下不催化氯代反应，将氯代烃类化合物高选择性的转化成HCl、H2O、CO2，建立氯代烃类化合物低温消除长期稳定操作体系。本申请课题的研究成功，将为我国在氯代烃类的低温催化消除提供新思想和新方法，并获完全的知识产权。

采用水热合成、溶胶凝胶以及浸渍方法等方法完成了四类催化剂研制：Ru/TiO2-ZrO2、Ru/CexAly、Ru/CeO2和Ru/Co3O4催化剂。采用XRD、XPS、H2-TPR、NH3-TPD、CO2-TPD、Raman、FT-IR等手段表征了催化剂的微观结构，探讨结构与表面性质包括氧化还原性能、氧流动性、酸碱性、CVOC吸附性能等关系。结果表明Ti、V、Zr、Al掺杂CeO2引起其表面酸性和氧量增加；Ru化学价态和其与基质氧化物的相互作用有关。Ru与CeO2相互作用较强，能形成Ru-O-Ce物种；在缺陷的CeO2上，Ru物种能保持较高的氧化态。采用氯代脂肪烃、氯代烯烃、氯代芳香烃低温催化燃烧三个反应体系，完成了对Ru/过渡金属/稀土纳米复合材料催化剂的活性、选择性、稳定性的测试。Ru的加入极大提高了催化剂氧化活性，促进了无机Cl物种以Cl2离开催化剂表面。采用原位研究手段，探索了CVOC低温氧化机理。CVOC分子活化生成烷氧基或酚基化合物的中间体依赖于酸碱对的协同效应。通过降低表面Cl含量和提高氧化反应速率，Ru极大提高了CVOC转化成CO2的活性、稳定性、选择性。