A Controllable Synthesis and Catalytic Behavior Study of Micro- and Mesoporous Zeolites Made by Rotational Intergrowths

Abstract

Zeolites are considered as one of the key heterogeneous catalysts in refinery operations and petrochemistry processes. Researchers have been actively exploring new designs or concepts to foster the applications of zeolites in other fields. To improve the accessibility of active sites and reduce the diffusion limitations within micropores, various hierarchically organized pore systems have been architected based on the conventional microporous zeolites. Advances in zeolite synthesis and hierarchical structure design could bring about opportunities for new catalytic applications as well as improvements of current technological processes. However, the multilevel pore architectures complicate the understanding of their catalytic behaviors. Therefore, this dissertation has addressed the attempts on understanding the structure—activity relationship in hierarchical zeolites for maximal catalytic advantages and future rational catalyst design. Self-pillared pentasil (SPP) zeolite was selected as a prototype of hierarchical zeolites, and its formation mechanism was studied at the beginning of this dissertation. Different strategies were then developed to tailor the SPP zeolite structure and mesoporosity. Catalytic behavior of SPP zeolites was explored through studies of model reactions (i.e., benzyl alcohol self-etherification and alkylation with mesitylene). Key structural attributes to selectivity and catalytic efficiency were determined through kinetic studies. A quantitative analysis towards the catalytic contributions and diffusion resistance could assist the practical applications of SPP zeolites and other similar hierarchical zeolites in the future.