钴、钌在加氢脱硫催化剂中的助剂作用

以CO, NO, H_2, O_2作为探针分子, 应用红外光谱法和化学吸附法研究了还原态Co-Mo/Al_2O_3, Ru-Mo/Al_2O_3和Ru-Co-Mo/Al_2O_3催化剂中Co, Ru的助剂作用。结果表明, Co担载在Mo/Al_2O_3上, 由于Co与Al_2O_3之间的相互作用减弱, Co中心上吸附CO和NO的能力增强, 改变了Mo中心吸附CO, NO, H_2,O_2的能力, 表现出Co-Mo/Al_2O_3上的Co中心性质显著地不同于Co/Al_2O_3。Ru担载在Mo/Al_2O_3或Co-Mo/Al_2O_3催化剂上, Ru自身的吸附CO, H_2, O_2能力降低, 但促进了MoO_3的还原, 使CO, NO, H_2, O_2在Mo中心上的吸附量增加。可以认为, Ru的作用是活化, 解离氢, 通过溢流氢促进配位不饱和的Mo中心生成。Ru的这种作用比Co明显。

STUDY ON PROMOTION OF COBALT AND RUTHENIUM IN REDUCED CATALYSTS FOR HYDRODESULFURIZATION BY IR-SPECTROSCOPY AND CHEMISORPTION

IR-spectroscopy and chemisorption in accompanying with CO, NO, H_2, O_2 as probe molecules have been used to elucidate the function of cobalt and ruthenium in the reduced Co-Mo/Al_2O_3, Ru-Mo/Al_2O_3, Ru-Co-Mo/Al_2O_3 catalysts. It is found, the location of cobalt has a partial block effect on Mo sites in its low oxidation state for adsorbing CO, NO, H_2, O_2 probes on reduced Co-Mo/Al_2O_3 catalysts, the intensities of CO and NO bands on Co sites are increased and the NO bands are shifted to the higher freqency side by about 20cm~(-1) in comparing with that on Co/Al_2O_3 catalysts. In contrast to cobalt, uptake of CO, NO, H_2,O_2 probes are increased evidently on the Mo sitesin the coordination unsaturated state with the addition of ruthenium in the Ru-Mo/Al_2O_3 and Ru-Co-Mo/Al_2O_3 catalysts. It is suggested that ruthenium can promote the dissociation of hydrogen and the spilling of active hydrogen over Mo sites, which will be beneficial to the formation of more coordination unsaturated Mo sites.