Enhancing propene selectivity in methanol and/or butene conversion by regulating channel systems over ZSM-5/ZSM-48 composite zeolites

Abstract

Abstract ZSM-5/ZSM-48 composite zeolite was synthesized via an one-pot method by using mixed templates of cetyltrimethyl ammonium bromide (CTAB) and 1,6-hexamethylenediamine (HDA), and its catalytic performance was tested in methanol-to-olefin reaction (MTO), butene conversion and co-reaction of methanol with butene. The results show that the amount of added CTAB plays a vital role in the synthesis of ZSM-5/ZSM-48 composite zeolite. The increase in the amount of CTAB in the synthesis gels leads to an increase in the content of zeolite with MFI structure, a higher specific surface area, more Al atoms located at channel intersections and more acid sites than ZSM-48 synthesized by the conventional method with HDA as a template. The catalytic results show that ZSM-5/ZSM-48 composite zeolite gives much higher propene selectivity in MTO reaction, butene conversion and co-reaction compared with ZSM-5, ZSM-48 and their mechanical mixtures due to that the combined effect of catalyst acidity and pore structure promotes the olefin-based cycle and inhibits the aromatization and hydride transfer reactions.