Dimethyl Ether Synthesis from CO2 Hydrogenation on a CuO−ZnO−Al2O3−ZrO2/HZSM-5 Bifunctional Catalyst

A CuO−ZnO−Al 2 O 3 −ZrO 2 + HZSM-5 physical mixture bifunctional catalyst with a high activity for dimethy ether (DME) synthesis was used for CO 2 hydrogenation. Various factors that affect catalyst activity, including the reaction temperature, pressure, and space velocity, were investigated. CO 2 conversion reached 0.309, and DME and methanol yields were 0.212 and 0.059 with a stoichiometric ratio of H 2 to CO 2 of 3 at 523 K, 5 MPa, and a space velocity of 6000 mL/(g cat·h). Well-studied kinetic models for methanol synthesis and methanol dehydration, respectively, were used to fit the experimental data and the kinetic parameters in the rate equations for DME synthesis were obtained by regression. A simulated process for CO 2 hydrogenation indicated that a higher DME yield can be obtained with CO recycle that will also give a CO-free product.