有序介孔限域的镍/钴基金属氧化物材料的构建及其催化甲烷二氧化碳重整反应性能研究

The traditional Ni, Co based non-noble metal catalysts for carbon dioxide reforming of methane reaction are commonly inclined to suffer rapid deactivation due to the thermal sintering of the metallic active sites and severe carbon deposition over the catalyst surface. In view of the disadvantages of traditional catalysts, the present project plans to construct a series of Ni, Co based ordered mesoporous metal oxides with excellent structural properties, such as excellent porosity structure, good crystallinity, superior thermal stability, via soft template assisted “one-pot” evaporation induced self-assembly (EISA) strategy, which will be directly utilized as the catalysts for carbon dioxide reforming of methane reaction. The influence of various factors during the preparation process on the physicochemical properties and catalytic properties of the materials will be investigated and the rule of the preparation chemistry and structure-efficacy relationship will be determined. This project will take the advantage of the “one-pot” strategy and in situ introduce the Ni, Co active sites into the ordered mesoporous framework, whose “confinement effect” will effectively suppress the thermal sintering of the metallic active sites under carbon dioxide reforming of methane reaction conditions. Besides, the obtained mesoporous materials are usually provided with large surface areas, big volumes, and uniform pore sizes by regulating preparation parameters, which will provide the gaseous reactants with sufficient “accessible” active centers. Therefore, these series mesoporous catalysts will promise outstanding catalytic activities and stabilities. Furthermore, some in situ dynamic characterization techniques will be also developed and used to investigate the activation mechanisms of CH4, CO2 stable molecules as well as carbon deposition behavior over these mesoporous catalysts surface from the molecular level.

本项目针对甲烷二氧化碳重整反应镍/钴非贵金属基催化剂易于发生金属活性组分热烧结和表面积碳而导致快速失活的缺点，拟采用软模板“一锅法”挥发诱导自组装策略构建一类具有孔结构优良、结晶性好、热稳定性高等优点的镍/钴基有序介孔金属氧化物材料用于催化甲烷二氧化碳重整反应，研究材料制备过程中各种因素对材料理化性质和催化性能的影响，确定制备化学规律与构效关系。该研究拟将镍、钴活性中心原位引入到有序介孔骨架之中，介孔骨架的“限域效应”可以有效抑制金属活性位的热烧结；通过对合成条件的调控，制备具有大比表面、大孔容、均一孔径等优点的材料，可以为气态反应物提供充足的活性位。因此，这一类有序介孔催化剂将会表现出优于传统负载型催化剂的催化活性和稳定性。此外，本项目拟发展一些原位动态表征技术，尝试从分子水平研究甲烷二氧化碳重整反应条件下稳定小分子CH4、CO2在介孔催化剂表面活化与定向转化机制及积碳行为。

本项目针对甲烷二氧化碳重整反应镍/钴基非贵金属催化剂易于发生金属活性中心热烧结和表面严重积碳而发生快速积碳失活的缺点，设计并成功运用软模板“一锅法”挥发诱导自组装策略制备了一类具有孔结构优良、结晶性优异、热稳定性高等优点的镍/钴有序介孔金属氧化物材料，并用来催化甲烷二氧化碳重整反应，并系统地研究了材料制备过程中各种合成条件对催化材料理化性质和催化性能的影响，确定了制备化学规律与构效关系，为开发一类在催化化学领域具有广泛应用价值的新催化材料体系提供了理论指导和技术支持。该研究通过“一锅法”合成策略成功地将镍、钴活性中心原位引入到有序介孔骨架之中，介孔骨架的“限域效应”有效地抑制了金属活性位的热烧结；通过对合成条件的精确调控，成功制备出具有大比表面、大孔容、均一孔径等优点的材料，可以为气态反应物提供充足的活性位，表现出比传统负载型催化剂更优异的催化活性和稳定性。本项目发展了原位动态质谱表征技术，从分子水平研究了甲烷二氧化碳重整反应条件下稳定反应小分子在催化剂表面活化与定向转化机制以及积碳行为。此外，在该项目的支持下我们将该系列镍/钴有序介孔金属氧化物催化材料成功运用到二氧化碳甲烷化催化过程，有效抑制了金属活性中心的热烧结；为了改善Ni基催化剂的低温甲烷化催化活性，研究者尝试在介孔骨架中原位引入碱土和稀土氧化物，调节材料界面性质，利于二氧化碳低温活化并降低了反应活化能。这将为未来开发低温高效二氧化碳甲烷化催化剂打下初步基础，也拓宽了二氧化碳资源化利用的途径。