含钌双功能催化剂上苯加氢烷基化反应性能

Performance of Benzene Hydroalkylation over Ru-Containing Bifunctional Catalysts

采用介微孔复合结构分子筛作为载体,并采用金属-配合物自组装、离子交换和等体积浸渍多种方法,对加氢烷基化双功能催化剂上的金属颗粒尺寸以及分布位置进行了调控,制备了酸中心与金属中心(双中心)位置分布不同的双功能催化剂。其催化苯加氢烷基化反应评价结果显示,双中心的相对分布对主产物环己基苯的选择性没有显著影响,但对苯的转化率以及副产物环己烷、二环己基苯的选择性表现出明显的差异,原因是催化剂上金属与载体间作用力、金属颗粒尺寸及尺寸分布的不同造成催化剂加氢性能的差异,影响了后续烷基化反应。采用金属孔道封装和双功能催化剂机械混合的方法,验证了溢流氢存在。溢流氢形成与扩散在反应中克服了微孔的扩散限制,使双中心之间的距离对苯加氢烷基化催化性能的影响减小。

The bifunctional catalysts for benzene hydroalkylation were prepared by the methods of metal complexes self-assembly,ion exchange and impregnation using micro-mesoporous Y zeolite as carriers.The metal particle size and the distribution of acid centers and metal centers(the two centers)on the catalysts were regulated.The evaluation results of benzene hydroalkylation over these catalysts showed that the distribution of the two centers did not significantly affect the selectivity of the main product cyclohexylbenzene,however the conversion of benzene as well as the selectivity of by-products cyclohexane and dicyclohexanebenzene were obviously different.That was attributed to the different metal-support interaction,as well as the size and distribution of metal particles,which resulted in differences in the hydrogenation performance and affected the subsequent alkylation reaction.The existence of overflow hydrogen was verified by using metal pore encapsulation and mechanical mixing of two different functional catalysts.The formation and diffusion of overflow hydrogen overcome the diffusion limitation of micropores in the reaction,reducing the influence of the distance between the two centers on catalytic performance of benzene hydroalkylation.