Synthesis of Methanol and Dimethyl Ether from CO2 and H2 Under Flow-Circulation Conditions

Abstract

In the context of utilization of carbon dioxide emissions, a study of the CO2conversion to methanol and dimethyl ether (DME) under flowcirculation conditions, when a part of converted gas returns to the reactor, was carried out. Experimental data on the synthesis of methanol (commercial catalyst Megamax 507) and direct synthesis of DME (Megamax 507/commercial zeolite ZVM, weight ratio 1/1) are reported. In the methanol synthesis from syngas, vol.%: H2 – 76.6, CO2– 19.8, N2 – 3.6 performed at 240–260 °C and pressure 5.3 MPa, a high conversion of CO2was reached: 84–99.6% at a low selectivity of the side reaction (CO synthesis, not higher than 4.7 %). The maximum specific yield of methanol at 260 °C was 1.24 kg(kgcat·h)–1. Special-purpose experiments demonstrated that the methanol synthesis is accompanied by a small heating (up to 10 °C) at the catalyst bed inlet, which testifies to polytropicity of the reactor. In the synthesis of DME, the DME yield referred to bifunctional catalyst was within 0.16–0.33 kg(kgcat·h)–1depending on the conditions. Therewith, the conversion of methanol to DME was not lower than 42 %, the conversion of CO2was within 79–96 %, and the DME synthesis proceeded under nearly isothermal conditions.