铈锰复合氧化物在杂环类农药废水SCWO中的催化特性

Although supercrtical water oxidation (SCWO) shows a promising prospect for the innocent treatment of heterocyclic pesticides wastewater, strict operation conditions prevent the development of this technology. A Ce-Mn composite oxides catalyst is proposed to decrease reaction conditions and increase the removal rate of pollutants. In this project, we focus on the catalytic mechanism of Ce-Mn composite oxides in supercritical water oxidation of heterocyclic pesticide wastewater. It includes that: ① with the results of products analysis, analyze the influence of catalysts on bond breaking of compounds and the pathways of oxidation reaction in the treatment of typical carbon-containing and nitrogen-containing organics from wastewater; ② on the basis of software simulation and experimental verification, develop a catalytic reaction kinetic model and predict the change rule of the concentration of intermediates; ③ combining the characterization analysis of new and used catalysts, reveal the production and exiting form of salts and carbon deposits on the catalyst surface and its influence on catalyst activity; ④ screen out the catalyst carrier of Ce-Mn composite oxides in supercritical water oxidation of pesticide wastewater and obtain the data on catalyst activity and stability. This project is intended to develop a novel idea for selection of new mixed metal oxides catalysts. The research achievements will be of improtant theoretical value and potential application prospect for the catalytic theory of mixed metal oxides catalysts and innocent treatment of high-concentration refractory wastewater.

超临界水氧化技术在杂环类农药废水的无害化处理方面具有光明的应用前景，但是苛刻的反应条件限制了该技术的发展。本项目提出使用Ce-Mn复合氧化物催化剂以降低反应条件。拟针对Ce-Mn复合氧化物在杂环类农药废水超临界水氧化中的催化特性展开研究，内容包括：①以废水中最主要的含碳和含氮有机物作为处理对象，通过产物分析判断催化剂对模型化合物的断键规律及氧化反应的路径；②利用软件模拟与实验验证，建立催化反应的动力学模型，预测中间产物的浓度变化规律；③结合催化剂的表征分析，揭示无机盐及积碳在催化剂表面的产生与存在形态及其对催化剂活性的影响；④通过长周期连续式实验筛选出Ce-Mn复合氧化物催化剂的载体，获得催化剂的活性、稳定性等数据。本项目意在为复合氧化物催化剂的选择拓展新的思路，研究成果对丰富催化剂的催化理论、促进高浓度难降解有机废水的无害化处理具有重要的学术意义和现实意义。

超临界水氧化技术（SCWO）在处理杂环类农药废水等高浓度废水方面具有极大的技术优势。采用催化剂能降低反应条件、提高污染物去除效率，是SCWO的重要研究方向之一。项目以提高污染物去除效率、探索催化机制为主要目标，采用浸渍法、氧化还原法和共沉淀法，筛选和制备了Ce-Mn各种复合氧化物催化剂。通过模拟废水实验发现，采用共沉淀法制备的催化剂对氨氮氧化的去除效果更佳。基于中间产物的定性和定量分析，建立了杂环类有机物的超临界水氧化反应网络和动力学模型，该模型可以合理预测反应中主要物质的转化关系，嘧啶类、吡啶类和氨氮是主要的含氮中间化合物。通过表征分析，提出了复合催化剂的催化机理，催化剂的载体为金红石TiO2，活性组分为Mn2O3，CeO2为催化反应的助剂和供氧体，MnO2释放活性氧是催化反应的关键步骤，CeO2加速了活性氧产生的速率。揭示了Ce-Mn复合氧化物催化剂失活的主要原因是表面积碳的沉淀和累积。本项目的研究成果对丰富催化剂的催化理论、促进高浓度难降解有机废水的无害化处理具有重要的学术意义和现实意义。