稀土金属氧化物优势晶面诱导的非贵金属有序合金催化剂及C2选择性加氢机制研究

Focusing on the C2 selective hydrogenation in the important petrochemical processes, we aim to design and fabricate a highly performed non-noble bimetallic catalysts with controllable atom arrangement induced by the selective facet exposure of rare-earth metal oxides (REO). Due to the disorder atom arrangement of multi-metallic catalysts prepared by traditional impregnation methods, this program will focus on the fabrication of highly ordered non-noble bimetallic alloy catalysts induced by exposed facet of REO support. Furthermore, the effects of atomic arrangement mode and proportion on the adsorption/activation of reactants and desorption behavior of product will be revealed. Based on the above understanding, the structure of catalytic active centers highly matched with the molecular orbitals of the reactants will be constructed, which will favor to enhance the activity and selectivity in catalytic hydrogenation reaction. This project aims to the maximum exposure of preferable crystal facets of REO and the insight into the induction mechanism of facet on dispersion structure and atom distribution. Furthermore, it is also of significance to understand the influence of order degree and dispersion of active center on the adsorption and desorption behavior of reactant and product molecules. A novel method for preparing fine structure of supported non-noble bimetallic catalysts will be established, especially the precise control of order degree of bimetallic atom. In addition, the project of preparing highly performed C2 hydrogenation catalyst based on facet induction of support can provide important reference for the structural design and controllable synthesis of other efficient non-noble catalysts.

本项目围绕重要石油化工过程C2选择性加氢反应，以稀土金属氧化物（REO）负载的非贵金属催化剂为创新研究对象，针对传统方法在制备多金属催化剂过程中存在原子排布有序程度难以控制的问题，开展基于REO载体晶面诱导金属原子排布高度有序的非贵金属合金催化剂的研究，并揭示原子排布方式和比例对反应物吸附活化及产物脱附行为的影响，通过构筑与反应物分子轨道高度匹配的催化活性中心结构，实现C2选择性加氢性能强化。通过研究，解决“稀土金属氧化物晶面结构的精细调控及其对非贵金属有序合金结构的诱导机制”和“与反应物吸附活化和产物脱附方式相匹配的非贵金属原子有序化程度精准控制”两个关键科学问题。项目实施将建立一种负载型非贵金属催化剂精细结构调控的新方法，尤其在多金属原子排布有序程度精准控制方面产生新的突破。此外，基于载体晶面诱导法制备高性能C2加氢催化剂的思路，可为其它高效非贵金属催化剂的结构设计与可控合成提供借鉴。

按照项目任务要求，围绕重要石油化工过程C2选择性加氢反应，开展了稀土金属氧化物优势晶面诱导的非贵金属有序合金催化剂及选择性加氢机制研究，获得了预期研究成果。首先，基于金属氧化物晶面和配位结构可调控的特点，通过调变制备过程中的碱浓度、晶化温度以及气氛还原条件等，获得了系列不同晶面选择性暴露的金属氧化物（CeO2,Al2O3,Co3O4）。以其作为载体，利用不同晶面上不饱和配位位点与非贵金属前驱体产生相互作用的差异性，在原子层面上对多元金属组分还原速率进行调控与匹配，诱导构筑了高度分散且多金属原子几何排布高度有序的非贵金属合金催化剂，揭示了载体晶面/配位诱导法对活性组分合金有序化程度及分散度的促进作用，建立一种原子几何排布高度有序的非贵金属合金催化剂制备的新方法。将载体晶面/配位诱导法拓展至其他双金属和类金属体系中，探究其普适性，获得了系列有序合金催化剂共性制备规律。进一步，通过在C2选择性加氢反应中进行构效关系研究，阐明了多原子排布有序化对乙炔分子吸附活化方式、强度及乙烯分子脱附的影响规律，构筑了与反应物/产物分子轨道高度匹配的催化活性中心结构，实现了C2选择性加氢性能强化。通过项目研究，项目负责人在ACS Catal., J. Catal., Small, AICHE J., Chem. Eng. Sci.等化工/化学领域高水平期刊上发表SCI学术论文10篇；基于创新性学术思想申请国家发明专利3项，构筑了自主知识产权体系。完成项目计划任务。综上所述，本项目在实现理论创新的同时，也具有实际应用价值，获得的具有潜在应用前景的负载型非贵金属有序合金催化材料对于提高催化加氢反应的效率及目标产物的选择性，节约贵金属资源，贯彻化工行业可持续发展战略具有重要意义，且研究成果和思路对其他非贵金属合金催化剂的可控合成及其在煤化工、石油化工、精细化工过程中的性能强化提供借鉴。