稀土(铈)基催化剂的掺杂改性及其NH3-SCR反应性能和作用机制的研究

As one of the main pollutants in the formation of haze which is harmful to the environment and human health, nitrogen oxide (NOx) is the current focus of emission reduction. The selective catalytic reduction of NOx by NH3 (NH3-SCR) has been proved to be one of the most effective approaches for the elimination of NOx from stationary sources (e.g., coal-fired power plants) and mobile sources (e.g., diesel vehicles). Considering the excellent catalytic performance for NOx elimination and abundant resources of rare earth element, we will investigate the effect of modification by doping with different ions and preparation method on the properties of the cerium support, which is aimed at further enhancing the catalytic performance and sulfur-resistance of ceria-based catalysts for low temperature NH3-SCR. Moreover, the influence of structure and properties of the modified support on the coordination structure, dispersion state, redox property, and surface acidity of the active species will be investigated deeply by a series of characterization means. Finally, we attempt to use some in-situ characterization techniques to study the changes of gaseous reactant molecules and their interaction with catalyst in the reaction process, making efforts to explore the NH3-SCR reaction mechanism at molecular and atomic level and then approach the structure-activity relationship of these cerium-based catalysts. Through the implementation of this project, it is expected to provide theoretical guidance for the fabrication of new efficient deNOx rear earth catalysts and promote the progress of environmental protection techniques.

当前我国雾霾等大气环境问题日益严峻，氮氧化物(NOx)这一主要污染物对生态环境和人体健康危害极大，是我国目前的减排重点。氨选择性催化还原(NH3-SCR)技术是目前消除固定源(如燃煤电厂)和移动源(如柴油车) NOx排放的最有效手段之一。基于铈基材料在NOx催化消除方面的优异性能以及我国丰富的稀土资源，本项目拟通过对铈基载体的掺杂改性来提高负载型铈基催化剂的低温NH3-SCR反应活性和抗硫性。研究不同元素掺杂离子和制备方法对其结构、性质以及催化剂表面活性组分的状态和相互作用的影响规律。借助多种原位表征手段考察反应过程中反应物分子的物种演变等信息，从分子原子层面深入探讨催化剂表面的NH3-SCR反应作用机制。探究此类催化剂的构效关系，构建“载体结构和性质-负载活性物种-反应活性”之间的内在联系。项目的实施将为设计开发新型高效NOx消除稀土催化剂提供理论指导，推进环境保护技术的进步。

本项目针对当前大气污染的严峻形势，结合铈基催化材料的优异性能和我国丰富的稀土资源，以研究NOx催化消除的高效催化剂为目的，围绕“铈基载体改性→催化剂的结构表征→催化性能”的思路，从不同角度开展了稀土（铈）基催化剂在氨选择性催化还原反应中的一系列工作。①考察了不同掺杂元素、价态、制备方法、制备条件、负载量和形貌等因素对掺杂改性的铈基催化剂的性质和NH3-SCR催化性能的影响规律；② 阐明了载体改性等手段对活性组分的影响以及铈基载体与活性组分之间相互作用的变化，为科学调变铈基催化剂的性质提供了科学依据；③ 借助于多种原位表征手段追踪吸附物种和催化剂表面在反应中的变化历程，揭示了催化剂与反应物分子之间的相互作用及其与反应活性之间的关系；构建“载体表面结构-负载活性物种-反应物分子”的内在联系，从分子层面探讨了铈基催化剂NOx消除反应的微观过程及催化作用机制。初步建立了组成、结构与催化性能之间的构效关系，为开发设计高效实用的NOx净化催化剂提供相关的理论参考。已发表研究论文3篇，获授权专利1项。