封装型丙烷脱氢催化剂的研究进展

Advances in encapsulated catalysts for propane dehydrogenation

丙烷脱氢制丙烯(PDH)是增产重要化学品丙烯的一条重要技术路线。PDH反应作为结构不敏感型反应,C—H活化仅需单个金属或金属-氧位点即可发生;而其C—C活化的竞争反应则需要在聚集态的金属或氧化物位点上才能发生,因此PDH催化剂的开发策略大多是通过限域效应或金属载体强相互作用等构筑亚纳米尺度的脱氢活性中心以提高催化性能。近年来,利用分子筛孔道的限域效应构筑稳定的亚纳米尺寸活性位成为了近年来PDH领域的研究热点。首先对分子筛封装金属物种材料进行归纳分类,介绍了合成策略,并讨论了金属物种进入分子筛微孔内部的定性和定量的表征方法;然后总结了分子筛封装型金属催化剂包括贵金属催化剂及非贵金属催化剂应用于PDH反应的最新合成研究进展,同时介绍了其催化机理和结构-性能构效关系;最后提出了目前分子筛封装金属催化剂在丙烷脱氢工艺中的局限性和未来发展方向,以期为丙烷脱氢催化剂的制备提供新的思路。

Propane dehydrogenation(PDH)to propylene is an important technological pathway for increasing the production of the vital chemical propylene.The PDH reaction,being a structure-insensitive process,requires only a single metal or metal-oxygen site for C—H activation to occur.However,the competing C—C activation reaction requires aggregation state metal or oxide sites to take place.Therefore,the development strategy of PDH catalysts often involves constructing sub-nanometer dehydrogenation active centers through confinement effects or strong metal-support interactions.In recent years,utilizing the confinement effect of zeolite channels to construct stable sub-nanometer-sized active sites has become a research hotspot in PDH field.The metal species encapsulated in zeolites were firstly systematically classified,synthesis strategies were introduced,and qualitative and quantitative methods for characterizing the entry of metal species into the micropores of zeolites were discussed.Then,the latest synthetic research progress of zeolite-encapsulated metal catalysts was summarized,including precious and non-precious metal catalysts for propane dehydrogenation reaction.Meanwhile,catalytic mechanisms and structure-function relationships were also discussed.Finally,the limitations and future development directions of zeolite-encapsulated metal catalysts in the propane dehydrogenation process were proposed to provide new insights for the preparation of metal-loaded zeolite propane dehydrogenation catalysts.