An experimental study on single-step dimethyl ether (DME) synthesis from hydrogen and carbon monoxide under various catalysts

Dimethyl ether (DME) is a potential and green substitute to diesel and liquefied petroleum gas. In this study, DME synthesized from hydrogen and carbon monoxide (i.e. syngas) through a single step process is investigated to figure out the reaction characteristics. The influences of reaction temperature, H-2/CO molar ratio, and prepared catalyst on DME synthesis are investigated, while the space velocity is fixed at 15,000 mL (g(cat) h)(-1). The results indicate that the optimal reaction temperature for DME synthesis develops at 220 degrees C where the chemical kinetics and thermodynamic equilibrium are in a comparable state. Increasing H-2/CO ratio increases the CO conversion but lowers the H-2 conversion. The maximum DME yield is 2.3 g (g(cat) h)(-1) which occurs at H-2/CO = 1. The addition of palladium (Pd) into a Cu-ZnO-Al2O3 catalyst intensifies the CO conversion and DME yield of a gas mixture with syngas and 10 vol% of CO2. This is the consequence of hydrogen spillover which is able to increase the stability of active Cu against CO2 oxidation. The results also suggest that the dehydration catalyst with higher acidity gives lower DME selectivity and yield. The higher the CO2 concentration in syngas, the lower the CO conversion and DME yield. The present study has provided comprehensive insights into DME synthesis which is conducive to DME production in industry. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.