Mechanistic insights into coke suppression in the methanol-to-olefins process via CeO2 doping to SAPO-34

Abstract

This study provides novel mechanistic insights into the transformative role of cerium oxide (CeO₂) incorporation into SAPO-34 for the methanol-to-olefins (MTO) process. By integrating experimental findings with molecular dynamics (MD) simulations, the work elucidates specific pathways through which CeO₂ mitigates coke formation. MD simulations reveal that CeO₂ suppresses the formation of CHO-θ intermediates, key precursors to coke, while enhancing coke removal through improved CO₂ activation and the Boudouard reaction. Catalytic testing corroborates these findings, demonstrating enhanced durability for up to 600 min and a total olefin selectivity of up to 83.9%. Structural and chemical modifications, such as reduced crystallite size, increased mesoporosity, and redistributed acid sites, were characterized using advanced techniques (XRD, FT-IR, FESEM, and NH₃-TPD). These modifications optimize the balance between weak and strong acid sites, facilitating efficient methanol conversion and olefin production. The integration of mechanistic insights with experimental results underscores the innovative role of CeO₂ in improving SAPO-34's catalytic efficiency, selectivity, and operational stability, establishing SP-Ce as a cutting-edge catalyst for industrial MTO applications.