具有新型结构的RuNiCo基催化剂构筑及其催化加氢协同机理研究

The core problem in the research of catalysts containing noble metal is to improve the utilization efficiency of precious metal and keep their high catalytic performance, selectivity and stability. In this project, it is proposed to effectively use the synergetic effect among noble metal - transition metal - transition metal hydroxide related species, and the catalyst with the novel structure - Ru nanoclusters islands supported on transition metal/transition metal hydroxides nanoparticles is constructed, using carbon black as catalyst support, denoted as Ru/TM/TMOH/C, where TM = Ni, Co or NiCo; TMOH = Ni(OH)2, Co(OH)2 or Ni(OH)2-Co(OH)2. The principle of regulating nanostructure of above-mentioned catalysts is investigated; with the hydrogenation of aromatics as the model reaction, the relationship between their nanostructures as well as the ratio of surface species and their catalytic performance in aromatic hydrogenation is explored; the accurate mechanism of synergetic effect (“mechanism of specialization and cooperation of multiple active sites” or “synergetic effect of interface electrons”) in the catalyst with novel nanostructure for hydrogenation reaction is further illustrated by such techniques as temperature programmed desorption mass spectrometry (TPD-MS), in-situ sum frequency generation vibrational spectroscopy (in-situ SFG) and in-situ synchrotron radiation X-ray absorption (in-situ XAS). This study can serve as theoretical basis and technical support for the synthesis of low-cost novel multi-metallic synergetic hydrogenation catalysts with high catalytic performance and selectivity, and also enrich the fundamental theory of multi-metallic catalysis, and thus has significant values in theory and applications.

提高贵金属利用率，并保证高催化活性、选择性及稳定性是含贵金属催化剂研究的核心问题。本项目提出利用贵金属-过渡金属-过渡金属氢氧化物的协同效应，以炭黑为载体，构筑具有“小岛状钌纳米团簇负载于过渡金属/过渡金属氢氧化物纳米颗粒”新型结构的催化剂，记作Ru/TM/TMOH/C，其中TM为Ni、Co或NiCo；TMOH 为Ni(OH)2、Co(OH)2或Ni(OH)2-Co(OH)2。本项目将研究上述催化剂纳米结构调控规律；以芳烃加氢为模型反应，探究其纳米结构及各表面物种比例与其催化加氢性能的关系；采用程序升温脱附质谱、原位和频光谱与原位同步辐射X射线吸收等技术阐明该新型纳米结构催化剂催化加氢协同效应机理（“多活性位分工协同”或“界面电子效应协同机制”）。本研究将为合成低成本、高效率、高稳定性、多元金属协同的加氢催化剂提供理论依据和技术支持，也可丰富多元金属催化基础理论，具有重要的理论与应用价值。

贵金属催化剂在化工、能源、医药及环保等领域有非常重要应用。但贵金属资源稀缺，价格昂贵，高成本制约着贵金属催化剂在工业上的广泛应用，提高贵金属利用率，并保证高催化活性、选择性及稳定性是含贵金属催化剂研究的核心问题。本课题提出了利用贵金属-过渡金属-过渡金属氢氧化物的协同效应，以炭黑为载体，构筑了具有“小岛状钌纳米团簇负载于过渡金属/过渡金属氢氧化物纳米颗粒”新型结构的催化剂，记作Ru/TM/TMOH/C，其中TM为Ni、Co或NiCo；TMOH 为Ni(OH)2、Co(OH)2或Ni(OH)2-Co(OH)2。并研究了上述催化剂纳米结构调控规律，揭示了催化剂合成工艺条件与其纳米结构之间的关系；以芳烃（及其他底物）加氢为模型反应，探究了其纳米结构及各表面物种比例与其催化加氢性能的关，建立了RuNiCo催化加氢构效关系，发现Ru/TM/TMOH/C结构催化剂在温和反应条件下具有优异的催化加氢性能；采用了程序升温脱附质谱、原位和频光谱与原位同步辐射X射线吸收等技术阐明了新型纳米结构催化剂催化加氢协同效应机理（“多活性位分工协同”），证明了具体的协同机理为：以苯加氢为例，Ru/NiCo/Ni(OH)2-Co(OH)2/C催化加氢协同作用机理，Ru/NiCo/Ni(OH)2-Co(OH)2/C具有“小岛状Ru纳米团簇负载于NiCo/Ni(OH)2-Co(OH)2纳米颗粒”结构，在室温下，Ni与Co难以活化H2，而贵金属Ru却很容易吸附并活化H2。因此，小尺寸的Ru纳米团簇优先吸附与活化H2；苯被Ni(OH)2-Co(OH)2吸附与活化；NiCo起着氢溢流“桥梁”作用将活化了的氢物种（表示为H*）转移至活化了的苯上，发生加氢反应，最终生成环己烷。本研究将为合成低成本、高效率、高稳定性、多元金属协同的加氢催化剂提供理论依据和技术支持，也可丰富多元金属催化基础理论，具有重要的理论与应用价值。