Bi2O3 modification of HZSM-5 for methanol-to-propylene conversion: evidence of olefin-based cycle

Abstract

Bi₂O₃-modified HZSM-5 catalysts were prepared via a traditional wetness impregnation approach, and used for the methanol-to-propylene conversion reaction. The selectivity for propylene increases significantly with bismuth loading, while that for ethylene shows the opposite trend. However, the Bi₂O₃/HZSM-5 catalysts have significantly lower capacities for methanol conversion than the parent HZSM-5. The underlying causes are the reduced acid site strength, narrower pore openings, and reduced pore width in Bi₂O₃/HZSM-5. This work provides insights into the olefin-based cycle operation for methanol-to-olefin reactions using modified HZSM-5 catalysts.