Polyacrylic acid as mesoscale template for synthesis of MFI zeolite with plentiful intracrystalline mesopores

Abstract Many great efforts have been devoted to the synthesis of hierarchically zeolites due to their potentially significant technological applications for catalytic reactions involving bulky reactant/products. In this work, we report a facile hydrothermal route to prepare mesoporous silicalite-1 with plentiful intracrystalline mesopores (5–20 nm) using poly (acrylic acid) (PAA) as a mesoscale template. During the crystallization process, the PAA chains served as the space occupant for intracrystalline mesopores, meanwhile, a small amount of amphiphilic organosilane (dimethyloctadecyl-[3-(trimethoxysilyl)-propyl]-ammonium chloride, TPOAc) acted as auxiliary template to enhance the connection between the growing crystal domains and the PAA chains. After calcination, the mesopore template PAA chains were burned out, and zeolite with intracrystalline mesopores could be obtained, giving rise to a combination of type I & IV N2 adsorption/desorption isotherms. The alkali metal salts in the synthesis system facilitated the formation of mesoporous structured zeolites. In order to enhance the acidic sites, mesoporous zeolite Al-ZSM-5 with intracrystalline mesopores was also synthesized by introducing aluminum source in the synthesis.