Graphene oxide-assisted synthesis of core–shell structured ZSM-5 zeolites and their catalyst texture effect on the catalytic performance in the acid-catalyzed o-methylation of cyclohexanone with methanol

Abstract

Tailoring the crystallization process to realize targeted material texture/porosity is a major challenge in zeolite synthesis, which facilitates the practical application of zeolites. In the present work, core–shell structured ZSM-5 zeolites were successfully synthesized through a graphene oxide (GO)-assisted hydrothermal method and characterized by XRD, SEM, NH₃-TPD and N₂ adsorption–desorption analysis. GO sheets have dual roles in the formation of core–shell structured ZSM-5 zeolites. GO nanosheets attached to the outer surface of large ZSM-5 crystal cores not only tailor the growth of crystal planes but also induce the formation of ZSM-5 nanocrystal layers. Compared to the conventional ZSM-5 zeolite, due to the c-axis oriented ZSM-5 cores and unique core–shell structure, the core–shell structured ZSM-5 zeolites expose more accessible acidic sites and shorten the diffusion path for molecules, leading to an enhanced catalytic activity for the o-methylation of cyclohexanone with methanol.