Pyrrolidone derivative-induced synthesis of hollow beta zeolite: formation mechanism and catalytic application in alkylation reaction

Abstract

Hollow zeolites are highly desired for the petrochemical industry owing to their virtue in mass transfer, site accessibility, and shape selectivity. Herein, we provide a facile pyrrolidone derivative-assisted strategy to directly synthesize hollow beta and ZSM-5 zeolites. On basis of time-resolved characterization analyses, we discover for the first time that the addition of pyrrolidone derivatives can regulate the relative incorporation rates of Si and Al species and induce the formation of metastable solid intermediates possessing a Si-rich core and an Al-rich surface. Subsequently, the spatially heterogeneous distribution of elements throughout the crystals promotes the spontaneous dissolution-recrystallization of the Si-rich core, leading to the generation of a hollow structure. The hollow beta catalysts show superior catalytic performance in the alkylation of benzene with isobutylene. Our findings will provide some useful guidance for the fabrication of hollow zeolites that are largely demanded in the petrochemical industry.