The beneficial use of zeolites as shape-selective catalysts in petrochemical and refinery processes has been widely demonstrated. In order to maximize the catalytic activity and selectivity and to minimize catalyst decay, it becomes crucial to select the appropriate zeolite topology and to control the zeolite’s chemical composition (Si/Al ratio, acid site density), the crystallite morphology and size (pore length, number of channel intersections). All these parameters will determine the number and the distribution of the active sites as well as the diffusion pattern.

Two case studies will be presented here, both focused on the rational design of zeolite-based catalysts for upgrading low value streams into chemicals of industrial interest, such as BTX aromatics or propene. First, we will show the benefits of a catalyst based on beta/ZSM-5 aggregates of single crystals obtained by means of a one-pot co-crystallization procedure for the direct conversion of a heavy reformate stream to the more valuable xylenes. The close proximity of these crystals leads to highly effective multifunctional catalysts, able to enhance the consecutive dealkylation/transalkylation required for high xylene selectivity. In a second approach, we will show how to increase the efficiency of ZSM-5-based catalysts for propene production by butene cracking to propene by properly adjusting their crystal size, morphology and Si/Al ratio, factors that were seen to have a strong influence on activity, selectivity and catalyst life.