CATALYSTS FOR DIRECT PRODUCTION OF DIMETHYL ETHER FROM SYNTHESIS GAS

Abstract

Catalytic systems based on a copper-zinc catalyst (methanol synthesis) and HZSM-5 zeolites (dehydration of methanol to dimethyl ether (DME)) were studied as catalysts for direct production of DME from syngas. Nitrogen adsorption, temperature-programmed desorption of NH3, and IR spectroscopy were used to characterize zeolitic catalysts with the silica modulus from 20 to 200. The catalytic performance of mixed catalysts in the synthesis of DME from syngas were studied in a high-pressure flow type reactor. Test conditions were: temperature 473–553 K, pressure of 3 MPa, the feed flow rate of 48 mL/min with the ratio H2/CO = 2. The catalyst activity was studied in dependence on the acidity and degree of crystallinity of the zeolite — the characteristics determined by its silica module. The highest yield of DME (39 vol.%) was obtained using a HZSM-5 catalyst with a silica module of 30 at a temperature of 493 K. The results provide a basis for creating highly active bifunctional catalysts for the synthesis of DME from synthesis gas.