Synergistically catalytic hydrogenation of CO ₂ and CO to methanol over Ga ₂ O ₃ promoted Cu/ ZnO / Al ₂ O ₃

Abstract

Abstract Efficient conversion of CO 2 and CO is pivotal for CO 2 hydrogenation to methanol given the synthesis loop recycle generally employed in practice. However, competitive adsorption of CO and CO 2 at active sites reduces methanol production. In this study, multi‐functional active sites were constructed over Ga 2 O 3 ‐modified Cu/ZnO/Al 2 O 3 (CuZnAlGa) for synergistic hydrogenation of CO 2 and CO to methanol. Incorporating the Ga 2 O 3 promoter effectively dispersed Cu particles, formulated extra Cu‐Ga sites active for CO 2 adsorption and Ga sites for H 2 dissociation (Ga‐H), enhancing H 2 and CO 2 activation as well as promoting non‐competitive CO 2 /CO adsorption. Under 240°C, 5 MPa, and 6000 mL g cat −1 h −1 , the CuZnAlGa catalyst achieved a methanol space–time yield of 517 g kg cat −1 h −1 with excellent stability, outperforming the commercial methanol synthesis catalysts. The formate pathway, involving formate and methoxy as critical intermediates, is the predominant route for methanol formation. The Ga 2 O 3 promoter accelerates formate formation and further hydrogenation to methoxy.