Realizing synergy between Cu, Ga, and Zr for selective CO2 hydrogenation to methanol

Hydrogenating CO2 to methanol with high yields and selectivity remains a kinetic challenge. We report ternary Cu-Ga-Zr catalysts with promising performances. Methanol productivity and selectivity were highest on coprecipitated samples containing approximately 20 wt% of each metal. At 7% isoconversion, this ternary system was more selective to methanol (60 ± 1%) than CuZrOx (51 ± 1%) and CuGaOx (53 ± 3%) at the same Cu loading. We uncover the importance of the Cu/Zr interface for CO2 adsorption, Cu/Ga interface for H adsorption, and metallic Cu for H–H dissociation. Methanol formation on these catalysts was found to be first order in H2, implying the reaction was likely to be rate-limited by hydrogen activation. In fact, the methanol space-time yield correlated linearly with the H2/D2 exchange rate. We propose a catalytic pathway wherein the production of the byproduct CO is hindered by the presence of adsorbed H. [Display omitted] •Intimate mixing of Cu, Ga, and Zr enhances CO2 hydrogenation activity to methanol.•Coprecipitation produces more active samples than impregnation at similar composition.•The presence of Ga promotes hydrogen adsorption and hinders CO formation.•CO2 has a poisoning effect on the sites responsible for H2 activation.•Methanol formation and H2 activation are linearly correlated across the catalysts.