Synthesis of tri-level hierarchical SAPO-34 zeolite with intracrystalline micro–meso–macroporosity showing superior MTO performance

Abstract

Hierarchically porous zeolites with different levels of porosity have emerged as an important class of materials because of their enhanced mass transport and improved catalytic performance. Silicoaluminophosphate zeolite SAPO-34 is one of the best catalysts for methanol-to-olefin (MTO) conversion, but suffers from rapid deactivation due to the narrow 8-ring pore openings. To overcome this inherent diffusion bottleneck and improve the MTO performance, in this work, tri-level hierarchically porous SAPO-34 zeolite with intracrystalline micro–meso–macroporosity has been first synthesized by an Al-rich method coupled with the use of the polyethylene glycol 2000 polymer under hydrothermal conditions. The as-synthesized hierarchically porous SAPO-34 catalysts exhibit superior catalytic performance in the MTO reaction with about six times prolonged catalytic lifetime and nearly 5% improvement of selectivity for ethylene and propylene compared to the conventional microporous SAPO-34.