空间限域纳米脱硝催化剂的分子设计及其性能研究

Selective catalytic reduction (SCR) of nitrogen oxides (NOx) is one of the most challengeable issues in air pollution control, which has received intense research interest in the field of material chemistry, catalysis chemistry, environmental chemistry and engineering. Owing to the low catalytic efficiency, easy deactivation of the traditional catalysts in the case of on-line usage, in this project, we propose to extensively explore the metal-oxide nanocatalysts within space-confined mesoporous materials for SCR of NOx, where the mesopore serves as the confined space for the preparation of highly dispersed nanocatalysts, and surface function of mesopore will be modified at molecular scale for the purpose of sulphur/water resistance. Based on our previous achievements and the unique advantages of catalytic co-efficiency, multiple metal-oxide nanocatalysts developed in our group were chosen as the catalyst. The methods for preparing the space-confined catalysts in mesoporous materials will be extensively studied, and the key factors which affect the catalytic performance, as well as the property of sulfate/water resistance, will be carefully investigated. Furthermore, the confined mesoporous space, mesostructures, constituents and morphologies will be tuned for the purpose of studying and understanding their effects to the catalysts, the performance of SCR processes and sulfate/water resistant. Finally, the relationship between mesoporous materials, nanocatalysts, and performance of SCR of NOx will be demonstrated..It could be expected that the research results of this proposal will not only enrich the candidate catalysts, extend the potential possible application filed of mesoporous materials, but also provide valuable scientific data for the design and preparation of novel SCR catalysts at molecular scale, and offer basic catalytic data for potential application of SCR of NOx process.

氮氧化物选择性催化还原是材料化学、催化化学、环境化学及工程等多学科的交叉研究热点之一。本项目针对过渡金属氧化物催化剂存在的低效、失活等问题，提出利用载体的介孔空间实现对催化剂颗粒的限域，获得分散均匀、高活性的纳米催化剂；提出在分子尺度上改变介观结构及表面的性质从而实现对催化剂抗硫、抗水性能的改善。在已有工作的基础上，依据过渡金属氧化物催化协同效应的原理，以多元金属氧化物作为催化中心，研究空间限域的催化剂制备方法，明确介孔基载体脱硝催化剂制备的关键影响因素；通过分子设计，调节限域空间、改变介观结构、组份等，系统地研究它们对催化剂纳米颗粒、脱硝效率及抗硫抗水性能的影响，阐明介孔基材料作为载体与催化剂纳米颗粒及脱硝效率三者之间的关系。本项目既能够丰富脱硝催化剂载体的种类，拓展介孔基材料的应用领域，也能够从分子水平上为设计开发新抗硫抗水纳米脱硝催化剂提供重要的基础科研数据，为应用研究提供可靠依据。

来源于电厂和机动车燃烧排放的氮氧化物去除是大气污染控制的研究热点之一，将氨气通入氮氧化物中进行选择性催化还原是控制氮氧化物污染的主流技术。本项目利用载体的介孔空间实现对催化剂颗粒的限域生长，获得分散均匀、高活性的纳米催化剂，同时在分子尺度上改变介观结构及表面性质实现催化剂抗硫、抗水性能的改善。首先研究介孔二氧化钛负载过渡金属氧化物用于选择性催化脱硝，成功探索出一种高分散催化剂的制备方法。其次，采用定量浸渍法将铈锰元素载入有序介孔硅载体SBA-15中，在中低温催化条件下，它在长期反应中表现出优异的活性和稳定性，抗水能力明显得到改善，中毒催化剂的活性可通过煅烧轻易恢复。将催化剂整合用于钢厂不锈钢酸洗尾气的脱硝处理，催化剂在为期三个月的中试内表现出优异的脱硝效率。同时，该催化剂的低运行温度（180℃）可节省大量的燃气消耗。本项目的完成将为选择性催化还原去除氮氧化物的实际应用提供理论基础和技术支持。