Synthesis and catalysis of new metal sulfide cluster in shape-selective reaction space

用光谱学方法研究了硫化钴/钼的性质及其催化作用。结果表明，金属硫化物的催化作用是由簇大小、价态和中心原子的配位决定的。通过各种方法对各因素进行单独控制是开发活性加氢处理催化剂的关键。本研究旨在为新型催化剂的设计提供依据。采用钴钼（Co-Mo）催化剂对苯并噻吩进行了硫化后加氢脱硫。在硫化氢（H_2S）气氛中扩大了协同效应。用NO探针对Co-Mo催化剂表面进行了观察，发现硫化物的协同作用是由前驱体氧化物的协同作用演变而来的。通过对比连续硫化和还原预处理的催化剂活性，研究了硫化对催化剂HDS活性的影响。这些活性试验表明，虽然预硫化可以提高催化剂的固有活性，但预还原即使在长时间的硫化后也会导致催化剂活性的恶化。对预硫化和/或预还原Co-Mo催化剂进行了光谱研究，结果表明，预还原引起的催化剂活性的恶化与硫化钼的大小有关。在沸石笼中成功地引入钼双簇，维持了钼-钼键。Mo/沸石催化剂的活性低于常规Mo/Al_2O_3催化剂，H_2S气氛对Mo/沸石催化剂活性的恶化影响显著。结果表明，硫化钼在沸石笼中的粒径是有限的。采用螯合剂在水溶液中制备Co-Mo/Al_2O_3催化剂。螯合物添加催化剂的HDS活性高于市售Co-Mo/Al_2O_3催化剂，且在Al_2O_3上同时负载钴和钼时，其促进效果最为显著。结果表明，螯合剂具有提高Co表面密度的作用；因此，增加了活性位点。少

We have studied the character and catalysis of cobalt/molybdenum sulfides by means of spectroscopic method. According to the results it is concluded that catalysis of metal sulfide is determined by cluster size, valence and coordination of the center atom. Individual control of each factor by various method is essential to develop the active hydrotreating catalyst. This study was performed to attain the basis for new catalyst design.Hydrodesulfurization (HDS) of benzothiophene was carried out over cobalt-molybdenum (Co-Mo) catalyst after sulfurization. The synergic effect was extended in hydrogen sulfide (H_2S) atmosphere. Co-Mo catalysts surface was observed by means of NO probe to fine that the synegy of the sulfides evolved from that of the precursor oxides. The effect of sulfiding on the catalyst HDS activity was investigated by comparing the activities of catalysts which were pretreated by sequential sulfiding and reducing. These activity tests showed that while presulfiding induc … More ed intrinsic activity of the catalyst, prereduction induced a deteriorating effect on the catalyst activity even after a prolonged sulfidation. Spectroscopic studies on the presulfided and/or prereduced Co-Mo catalyst were conducted and it was shown that the deteriorating of the catalyst activity induced by the prereduction was related to the size of molybdenum sulfide.Molybdenum dicluster was successfully introduced into zeolite cage maintaining the Mo-Mo bond. The activity of Mo/zeolite catalyst is lower than conventional Mo/Al_2O_3 catalyst and the deteriorating effect of H_2S atmosphere on the catalyst activity is remarkable on Mo/zeolite. There results imply that the size of molybdenum sulfide was limited in zeolitecage.Co-Mo/Al_2O_3 catalyst was prepared using chelating agent in an aqueous solution. The HDS activity of the chelate-added catalyst was higher than the commercially available Co-Mo/Al_2O_3 catalyst and the promoting effect was most remarkable when cobalt and molybdenum were simultaneously supported on Al_2O_3. It was suggested that the chelating agent has a role of increasing Co surface density ; thus, increasing the active site. Less