宽操作温度窗口和高稳定性的NOx选择性还原催化剂的研究

It is imperative to control the exhaust emission of diesel vehicles for the environmental protection, which are mainly consisted of large amount of NOx and particulate matters (PM). Selective catalytic reduction (SCR) is the most effective technology among the various post-treatment methods for eliminating NOx in diesel exhaust emission. Based on the state VI Emission Standards for diesel vehicles, this research object is to develop high-performance SCR catalysts. (1) For zeolite-type NH3-SCR catalyst, its catalytic reaction mechanisms and the effect of water and SO2 on the properties of active sites and acidic sites over the SCR catalysts will be investigated. Based on these results, the approach to improving its water-resistant, sulfur-resistant and high-temperature stability will be studied. With the help of adding rare earths, highly stable zeolite-type catalyst with wide operational temperature window will be obtained; (2) the HC-SCR oxide-type catalysts will be explored. Based on the research on the HC-SCR reaction mechanism, we will propose the scheme for design and preparation of HC-SCR oxide catalysts through careful coordination between its redox property and adsorption/activation ability for the HC reducing agents; (3) studying the preparation method of monolithic zeolite-type catalyst with directional partition coating and improvement of the catalytic activity of monolithic SCR catalyst by the combining effect of different active coatings or nano-particles . With the implementation of this project, we can well know the SCR reaction mechanism of NO reduction, and propose the scheme for design and preparation of the high effective NH3-SCR and HC-SCR catalysts, which has the scientific and practical significance for the development of a proprietary diesel exhaust NOx purification technology.

柴油车尾气以NOx和颗粒物为特征，选择性催化还原(SCR)是消除其NOx排放的有效方法。本项目以满足国VI排放标准为背景，以高性能SCR催化剂的研究为目标：①针对NH3-SCR分子筛催化剂，在阐明催化反应机理和水、硫对活性中心和酸中心影响机制的基础上，研究改善其耐水、耐硫和耐高温性能的途径，充分发挥稀土在催化剂中的作用，制备出宽操作温度窗口和高稳定性的催化剂；②烃类(HC)-SCR氧化物催化剂的探索研究，基于对HC-SCR反应机理的研究成果，协调催化剂的氧化能力和对HC吸附及活化能力，提出高性能HC-SCR催化剂的设计思路和制备方法；③研究分子筛型整体式SCR催化剂的定向分区涂覆和制备技术，通过不同活性涂层或纳米催化剂粉体的复合，提高其整体性能。本项目的实施，可加深对SCR催化反应的认识，提出高性能NH3-SCR和HC-SCR催化剂的设计和制备技术，提升我国柴油车尾气催化净化技术的水平。

柴油车尾气以NOx和颗粒物为特征，选择性催化还原(SCR)是消除其NOx排放的有效方法。本项目以满足国VI排放标准为背景，以高性能SCR催化剂的研究为目标，充分发挥稀土在催化剂中的作用，制备出宽操作温度窗口和高稳定性的NH3-SCR催化剂和烃类(HC)-SCR催化剂，并且研究分子筛型整体式SCR催化剂的制备技术，为工业化应用奠定基础。.在NH3-SCR分子筛催化剂研究方面，设计和制备了Fe和Cu掺杂的ZSM-5、β和SSZ-13等系列分子筛催化剂，揭示了制备方法和条件、添加稀土和配合物对活性金属在分子筛中的分布和存在状态的影响规律，发展了调变活性金属在分子筛中存在状态的新方法。经优化制得的Cu-SSZ-13分子筛，可在175-650 oC温度窗口实现NOx转化率≥80%，而且具有优异的抗水抗硫和耐高空速等性能。在此基础上，开发了分子筛整体式催化剂的制备工艺，目前与凯龙高科技股份有限公司进行战略合作，进行产业化研发；在NH3-SCR氧化物催化剂研究方面，围绕MnOx低温SCR催化剂，采用Sm、Co、Ti等金属对其单金属或双金属掺杂，提出了通过固溶体结构抑制MnOx高温相变，同时调变其氧化还原性能和表面酸性的新机制，促进NOx和NH3的吸附和活化，经优化制得的Ti-Sm-MnOx复合氧化物催化剂可在70-230 oC温度窗口实现NOx转化率≥90%，为目前文献报道的具有最高低温活性的催化剂；在CH-SCR催化剂研究方面，针对最具代表性的Ag/Al2O3催化剂，揭示了γ-Al2O3载体形貌对Ag活性位状态和C3H8-SCR活性的影响机制，在420-590oC温度窗口实现NOx转化率≥80%。.发表基金项目标注的SCI论文15篇，包括1篇Environ. Sci. Technol.、2篇Appl. Catal. B: Environ.和1篇ACS Catal.，其中2篇ESI高被引论文；获得授权中国发明专利4件。项目负责人詹望成获得2019年国基金优秀青年科学基金资助，入选2017年上海市浦江人才计划；培养博士生2名，硕士生5名。