HIERARCHICAL ZEOLITES AS A NEW FRONTIER IN FCC CATALYSIS: A SHORT REVIEW
Zeolites Y and ZSM-5 has been used extensively as part of Fluid Catalytic Cracking (FCC) catalyst blend. Owing to the dwindling global light oil reserves and large volume of heavy feedstock, it is important to optimize such catalysts and design new ones. One approach for improving the performances of zeolite catalyst is to develop its hierarchical structure. In the present review, various strategies employed for developing hierarchical structures are considered, with emphasis on the Top-Down and Bottom-Up approaches. These involved operations such as Dealumination, Desilication, Irridation, Mixed approach, Soft templating, Zeolitization and Hard templating strategies. Hierarchical ZSM-5 has currently being used along with USY in Vacuum Gas Oil (VGO) and Heavy Gas Oil (HGO) processing for possible use in the FCC. While top-down approaches (Dealumination, Desilication, Irradiation, Mixed approach), with specific emphasis on demetallation, are currently being employed on an industrial scale due to their facile nature, more specialized methods i.e. the bottom-up methods are currently being harnessed to become facile, and are generally more efficient in producing ordered hierarchical structures, with hard templating using carbonaceous materials showing the most promise, and therefore given particular attention. Our current approach on hierarchical zeolite Y for FCC catalysis is going to be emphasized.