应用同步辐射软X射线谱学技术原位研究Cu基双金属催化剂的结构及其催化反应机理

Synchrotron radiation soft X-ray spectroscopies have been demonstrated to be powerful techniques for studying the catalyst structures and reaction mechanism. Oxide-supported Cu-based bimetallic catalysts are widely used in many industrial catalytic reactions such as CO2 conversion to methanol. In this proposal, targeting to many fundamental key problems encountered during the applications of these catalysts, we plan to address these problems through the approach of so-called “model catalysis”. We will prepare oxide-supported Cu-based bimetallic model catalysts on ordered oxide thin films under the controllable conditions in ultrahigh vacuum and in-situ study their surface morphologies, chemical and electronic structures and thermal stabilities using multiple synchrotron radiation based techniques in combination with conventional surface science techniques such as scanning tunneling microscopy. Moreover, the adsorption/reaction process and mechanism of probing molecules like CO, CO2 and methanol on the surfaces of model catalysts, and the effects of oxide supports on the dispersion, thermal stability and adsorption/reaction properties of Cu-based bimetallic catalysts will be explored. In addition, by investigating the changes in the electronic structures, morphologies and adsorption/reaction properties of Cu with different second metals, we will try to figure out the nature of the synergistic catalytic effects of Cu-based bimetallic catalysts. Combined with theoretical calculations, we will gain deep fundamental understandings of the intrinsic relationship between the structures and catalytic properties of Cu-based bimetallic catalysts at the atomic-molecular level. On the basis of the knowledge gained from these model catalysts, we will try to design and prepare real oxide-supported Cu-based bimetallic catalysts and test their catalytic performances in some reactions such as CO2 hydrogenation to methanol.

同步辐射软X射线谱学技术是探究催化剂结构和催化反应机理强有力的研究手段。本项目针对工业上广泛应用的氧化物负载型Cu基双金属催化剂使用中存在的诸多关键科学问题，拟通过“模型催化”的方式，在真空中可控制备氧化物薄膜负载的Cu基双金属模型催化剂；利用多种同步辐射软X射线谱学技术结合STM等，原位研究Cu基双金属模型催化剂的表面结构、形貌、电子结构和热稳定性；研究CO、CO2和甲醇等探针分子在催化剂表面的化学吸附及反应的过程和机理；考察不同氧化物衬底对Cu基双金属催化剂分散度、热稳定性和吸附及反应性能的影响；探索Cu与不同金属组成双金属催化剂的电子结构、形貌及吸附性能的差异，获得Cu基双金属催化剂表面协同催化的机制。结合理论计算，从原子-分子水平上揭示Cu基双金属催化剂的结构与催化性能之间的内在联系。并依据这些研究结果，精确设计并制备Cu基双金属实际催化剂，测试其在CO2加氢等反应中的性能。

发展并利用同步辐射软X射线谱学技术对于揭示催化剂的构效关系和催化反应机理至关重要。本项目提出通过“模型催化”的方式，从原子-分子水平上揭示工业上广泛应用的氧化物负载型Cu基双金属催化剂的结构与催化性能之间的内在联系，并在此基础上精确设计并制备Cu基双金属实际催化剂，测试其在CO2加氢等反应中的性能。依托本项目的资助，我们在合肥光源设计并实现了多种探测模式的近边软X射线吸收谱（NEXAFS）技术，包括全电子产额（TEY）、部分电子产额（PEY）和全荧光产额（TFY）的NEXAFS技术；开展了在有序有序氧化物薄膜表面可控制备纳米铜基等单金属以及双金属模型催化剂的生长、形貌、电子结构及热稳定性研究，深入探索了单金属以及双金属与载体之间的相互作用，获取了氧化物表面缺陷位对纳米颗粒分散度的影响、热稳定性和吸附反应机理等信息；开展了探针分子（CO2、H2、H2O、甲醇等）在Cu基双金属催化剂表面上的吸附和反应机理的研究，提出了分子与催化剂表面的相互作用和分子活化过程的微观模型；开展了实际氧化物负载的Cu基双金属催化剂的可控制备及其催化CO2加氢和CO氧化性能研究，考察了CuCo合金催化剂的活性相组成对合成气制高碳醇性能的影响。基本完成项目的预定研究目标。依托本项目，共发表标注项目资助的SCI论文40篇，授权实用新型专利1项，技术转让项目1项。培养出站博士后1名，毕业博士生5名、硕士生5名。参加国际会议6次，参加国内会议12次；邀请国外专家来实验室访问或讲学11人次，线上邀请国外专家讲学12人次，举办国际会议3次。