晶面调控的钛基复合金属氧化物纳米材料对二恶英类氯代芳烃污染物的热催化氧化降解研究

The improvement of the reaction efficiency by the tuned crystal-facet is the recent research hotspot. The thermal catalytic oxidative degradation of dioxin-like chlorinated aromatics pollutants, over the titanium-based composite oxide nanomaterial tuned by TiO2 crystal facets, will be performed. It will be of great significance for the real reduction of the toxic refractory POPs unintentionally produced (UPPOPs) during the industrial process and the development of new control principle. In this project, it will explore the preparation of the titanium-based composite oxide nanomaterials containing manganese, cerium and iron, tuned by anatase TiO2 crystal facets. The interaction between the exposed facets and the doped components will be analyzed. The redox nature of the facet-tuned nanomaterials will be studied. Under the atmosphere which simulates industrial exhaust gas, the effect of the facet-tuned titanium-based composite oxide nanomaterials to the thermal catalytic oxidative degradation of the polychlorinated biphenyl or chlorobenzene model compounds will be studied, to determine the reactive nanomaterial. The intermediate oxidative products will be deeply analyzed by the comprehensive techniques, especially Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry with high resolution. The correlation among the crystal facet, redox nature and oxidative products will be built up. The interfacial oxidative degradation mechanism will be revealed. This study will provide a theoretical basis for the development of the reduction techniques of UPPOPs.

通过晶面调控来提高反应效率是近年来研究的热点。开展晶面调控的钛基复合金属氧化物纳米材料对二恶英类氯代芳烃污染物的热催化氧化降解研究，对于彻底削减和消除工业过程中无意产生的有毒难降解的持久性有机污染物向环境中的排放和发展控制技术新原理具有重要意义。本项目将探索构筑二氧化钛不同暴露晶面调控的锰、铈、铁掺杂的钛基复合金属氧化物纳米材料，分析不同暴露晶面与添加组份之间的相互作用，探究氧化还原特性的差异，在模拟工业尾气的气氛下，研究晶面调控对多氯联苯或氯苯类模型化合物热催化氧化降解活性的影响，评价出高效降解二恶英类氯代芳烃污染物的晶面调控纳米材料，联合傅里叶变换离子回旋共振质谱（FTMS）等多种手段全面鉴定中间体氧化产物，构建出晶面调控-氧化还原性质-中间体氧化产物的构效关系，揭示微界面氧化降解过程机制，为无意产生的持久性有机污染物的污染治理和环境修复技术的发展和应用提供理论借鉴。

通过晶面调控来提高氯代芳烃污染物催化效率是近年来研究的热点。本研究成功合成了三种TiO2晶面，对氯苯热催化降解活性顺序为{001}晶面 > {101}晶面 > {201}晶面。将过渡金属Mn、Ce负载于三种晶面上，对氯苯降解活性为Ce-Mn/{201}-TiO2 > Ce-Mn/{101}-TiO2 > Ce-Mn/{001}-TiO2。TiO2{201}晶面与Mn、Ce相互作用较强，促进了活性组分在载体上的分散，增强了活性氧物种及氧空位的生成，显著提高了负载后催化剂的氯苯降解活性。氯苯首先吸附于表面酸性位点，进而在酸位点上发生亲核取代生成苯醌类物种，由于苯醌自身不稳定，会继续被氧化为马来酸盐和羧酸盐等中间产物，最后被活性氧物种深度氧化为CO2和H2O。为提高催化材料的氯苯降解稳定性，通过NaBH4还原浸渍法将Ru、Pd、Rh分别负载于TiO2{001}晶面上。Ru/{001}-TiO2表现出优异的氯苯降解活性、CO2选择性及稳定性，可在250℃实现氯苯完全降解，且产生最少的多氯副产物。NaBH4可增强{001}-TiO2的Lewis酸位点、超氧自由基和表面羟基物种。然而，仅增强活性位点是不够的，有效氯物种脱附以防止催化剂发生氯中毒，以及持续不断产生活性氧物种来促进氯苯及中间产物深度氧化，也是设计催化剂的关键。该核心问题被Ru0 "↔ " Ru4+循环有效解决。整个过程遵循Mars and Van Krevilen机制。NaBH4增强的活性位点和Ru0 "↔ " Ru4+循环协同作用实现了有效且可持续的氯苯催化氧化。至此，在Environ. Sci. Technol., Appl. Catal. B: Environ., Environ. Pllut., Sci. Total Environ.等期刊发表学术论文6篇，授权国家发明专利1项。