A Comparative Study of ZnO−CuO−Al2O3/SiO2−Al2O3 Composite and Hybrid Catalysts for Direct Synthesis of Dimethyl Ether from Syngas

Two different strategies for the preparation of active dimethyl ether catalysts are evaluated using CuO−ZnO−Al2O3 and SiO2−Al2O3 as methanol synthesis and methanol dehydration catalysts components, respectively. Composite catalysts are prepared by mixing of the two freshly precipitated catalyst precursors and by coprecipitation methods, whereas hybrid catalysts are prepared by mechanical mixing of the two calcined catalyst components by grinding. Composite catalysts are partially deactivated during the catalyst preparation or calcination stages and therefore exhibit much lower activity, as compared to the hybrid catalysts toward syngas conversions.