富含Cu(I)物种的CuOx/PN-CeO2设计及其选择性氧化CO催化性能研究

Preferential oxidation of CO (CO-PROX) in H2-rich stream is of great practical significance to promote the application of hydrogen energy technology in fuel cells. Owing to their excellent catalytic performance and low cost, CuO-CeO2 catalysts have attracted great attention in this field. However, the CuO-CeO2 catalysts also face to many challenges including the low catalytic activity at low temperatures, the narrow working temperature window and the interference of the in-situ released H2O and CO2, which increase the temperature at which the reactive copper species reduces from +2 to +1. The modulation of the interfacial copper species with low oxidation state is the key point to solve those problems. Herein, with the help of a spontaneous surface redox chemical reaction, photo-assisted deposition or impregnation methods, we propose to introduce the active species of CuOx on the porous CeO2 nanorods with a high concentration of oxygen vacancies. Series of CuOx/CeO2 catalysts with abundant Cu(I) species are targets through various strategies including adjusting the surface/interface physicochemical properties, CuOx composition and the synergistic electronic interactions between active species (CuOx) and supports (CeO2). The combinations of the catalytic performance test and series of ex- and in- situ characterizations as well as the theoretical calculations are employed to understand the relationship between surface/interface physicochemical properties of CuOx/CeO2 nanomaterials, CuOx composition and catalytic performance, provide insights on the structure-activity relationship of catalysts at multi-scales or even at atomic level, and deliver catalytic mechanism. All of understanding would benefit the design of the high-performed catalysts for CO-PROX. This project is of great significance to promote the cross fusion of chemistry, materials, environment, energy and other fields.

选择性氧化富氢中CO对推动氢能在燃料电池的应用具有重大的现实意义。CuO-CeO2催化剂以良好的活性和优越的经济性成为该领域的研究重点。但该类催化剂有低温活性差和操作温度窗口不够宽的问题。水和二氧化碳也会使活性铜物种由+2还原到+1价的温度升高，降低其活性。解决问题的关键在于保持低价态的铜。本项目拟利用具有高缺陷浓度的多孔CeO2纳米棒为基底，借助表面自发氧化还原、光沉积或浸渍的方式将CuOx活性物种引入纳米棒上，调控表/界面、CuOx组成和活性中心与载体的协同效应，实现富含Cu(I)物种的低温铜铈催化剂。通过性能测试、(非)原位表征手段，结合理论计算，揭示铜铈催化剂表/界面态与CuOx组成和催化性能之间的关系；加深在多尺度甚至原子水平上对催化剂构效关系的认知，为指导和设计高性能的CO选择性氧化催化剂提供理论和实验基础。本项目对促进化学、材料、环境和能源等领域的交叉融合具有重要意义。

设计高性能的多相催化剂体系和开发先进催化工艺流程对化学化工行业的可持续发展和“双碳”目标的实现具有重要的科学意义和应用价值。多相催化剂的催化性能与载体的结构和形貌、活性物种的负载方式、模板剂的诱导等有着密切的关系。本项目针对不同载体形貌对催化剂结构性能的影响以及软模板表面活性剂在催化剂形成过程中的诱导作用，尝试了不同类型催化体系的设计思路。取得的主要成果如下：1. 无表面活性剂存在的情况下，以无孔CeO2纳米棒为载体，初步发展了一套简单高效的制备富含Cu(I)物种的低温CuOx/CeO2催化材料的新方法，基本明确了材料表/界面态、各组成相互作用与催化性能之间的关系。2. 传统表面活性剂CTAB存在下，优化合成条件，一步法获得了大比表面积、高耐热性能的稀土镧基柱撑黏土材料，建立了其负载PtOx纳米晶催化剂的理化性质与催化性能之间的构效关系，通过催化剂系统表征明确了催化剂的催化作用机制。3. 向传统表面活性剂CTAB分子两端中插入外来基团形成了新的表面活性剂，详细探索了新表面活性剂与各类化合物的相互作用，通过加入几种对外界环境刺激产生响应的添加物构筑了一系列多重响应型的智能蠕虫状胶束体系，进行了性能与结构分析、体系筛选和优化及机理分析。基于以上研究成果，基本完成了本项目之初设定的研究目标，获得了一系列高性能的新催化体系和模板剂，为理性设计新催化体系提供了新的选择和技术参考。