Dimethyl Ether Carbonylation to Methyl Acetate over HZSM-35

Abstract

Dimethyl ether (DME) carbonylation to methyl acetate (MA) was comparatively investigated over HZSM-35 and mordenite (HMOR) zeolites. The HZSM-35 catalyst showed rather high selectivity and stability without obvious deactivation for 32 h on-stream at 473 K with a MA yield of ~11%. On the other hand, the HMOR catalyst showed similar initial activity, but the yield of MA rapidly decreased to only 5% after 20 h on-stream. It was further revealed that the deposition rate of coke over the HZSM-35 catalyst was much lower than that on the HMOR zeolite, indicating that the formation rate of coke was strongly dependent on the pore sizes of the zeolites. The pore structure of HZSM-35 having a one-dimensional channel 10 member-ring (10-MR) and a perpendicularly intersected one-dimensional 8 member-ring (8-MR) channel effectively limited the formation of aromatic compounds which act as the precursors of coke. HZSM-35 catalyst showed rather high selectivity and stability for dimethyl ether carbonylation at 473 K without obvious deactivation for 32 h on-stream.