Influence of inlet gas composition on dimethyl ether carbonylation and the subsequent hydrogenation of methyl acetate in two-stage ethanol synthesis

Abstract

Ethanol was synthesized indirectly from dimethyl ether (DME), CO, and H₂ using a system of two fixed bed reactors in series. In the first stage of DME carbonylation over an HMOR catalyst, the presence of H₂ decreased DME conversion and methyl acetate (MA) selectivity by suppressing the reaction of CO with the intermediate methyl. In the improved scheme, H₂ was introduced directly into the following MA hydrogenation stage. As a result, the high DME conversion was maintained. The in situ Fourier transform infrared spectra of the Cu/SBA-15 catalyst show that CO was adsorbed mainly on Cu⁺, which disrupted the balance between Cu⁺ and Cu⁰ in the hydrogenation. Moreover, methane and some methanol were generated by the hydrogenation of methyl and methoxyl groups derived from DME decomposition.