Dimethyl ether synthesis from CO2 and H2 over Cu/ZnO-ZrO2-Al2O3 and zeolite

Abstract

Dimethyl ether (DME) is one of higher-valued product from CO2 conversion. In this study, the two steps of DME synthesis from CO2 in a batch reactor, including CO2 hydrogenation to methanol through ethanol-assisted method and methanol dehydration to DME, were investigated. The addition of 10 wt.% ZrO2, Al2O3 and ZrO2-Al2O3 as a promoter into Cu/ZnO was investigated to enhance the catalytic performance in methanol synthesis. Suitable types of zeolite (ZSM-5 and ferrierite) for methanol dehydration reaction were also determined. The catalysts were characterized by TGA, SEM-EDX, H2-TPR, NH3-TPD, BET and XRD. For the ethanol-assisted methanol synthesis, the Cu/ZnO/ZrO2 catalyst provided the highest CO2 conversion and methanol yield of 82.1% and 60.8%, respectively, since the addition of ZrO2 decreased CuO crystallites size and increased surface area of catalyst. For methanol dehydration to DME, ferrierite provided relatively highest methanol conversion (47.09%) and DME yield (2.69%) due to its strongest acidity. The system with Cu/ZnO/ZrO2 and ferrierite provided the highest DME productivity at 0.4385 mmolDME/gcat. Furthermore, under this conditions ethylene was produced as a valued by product of 1.33% yield or 5.45 mmolEthylene/gcat from dehydration of ethanol.