Abstract: A series of CuO-TiO₂-ZrO₂ mixed oxides with different CuO mass fractions (50%-80%) were prepared by co-precipitation and characterized by X-ray diffraction (XRD), N₂ physisorption, temperatureprogrammed reduction of hydrogen (H₂-TPR), temperature-programmed desorption of carbon dioxide (CO₂-TPD) and hydrogen (H₂-TPD), and reactive N₂O adsorption techniques. The prepared CuO-TiO₂-ZrO₂ samples were mixed physically with HZSM-5 zeolite to synthesize dimethyl ether (DME) from CO₂ hydrogenation in a fixed bed reactor at 250°C, 3.0 MPa, gas hourly space velocity (GHSV) of 1500 mL·g^-1· h^-1, and volume ratio of 2.8 for H₂ to CO₂. We found that the conversion of CO₂ increased with an increase in CuO content, reached a maximum at a CuO content of 70% and then decreased. The selectivity of DME increased with an increase in CuO content initially and remained essentially constant when the CuO content was ≥70%. Thus, the yield of DME reached a maximum of 13.2% at 70% CuO content. The productivity of the oxygenated compounds (including methanol and DME) on the CuO-TiO₂-ZrO₂/HZSM-5 catalysts is closely related to the metallic copper surface area.

Key words: Hydrogenation of CO₂, Dimethyl ether, CuO-TiO₂-ZrO₂ mixed oxide, Zeolite HZSM-5, Bifunctional catalyst