Exploring CO₂hydrogenation to methanol at a CuZn–ZrO₂interfaceviaDFT calculations

Abstract

Multi-component heterogeneous catalysts are among the top candidates for converting greenhouse gases into valuable compounds. Combinations of Cu, Zn, and ZrO2 (CZZ) have emerged as promisingly efficient catalysts for CO2...

Computational Exploration of Subnano Zn and Cu Species on Cu/ZrO2: Implications for Methanol Synthesis

“…In our previous study, we found that CO 2 attaches to the Cu component through the carbon atom with both oxygens binding to the nearest Zr cations. 17 The adsorption energy is −0.63 eV, which is comparable to that at the most stable adsorption site on ZrO 2 . Our earlier work demonstrated that incorporating Zn into the Cu matrix at the interface can strengthen CO 2 adsorption by up to 0.66 eV compared to the Cu-only interface.…”

“…3,4,13,15,17,81 From these results, one can conclude that certain sites are more optimal for the binding of different reaction intermediates, as some (such as COOH) adsorb more strongly to the Cu−ZrO 2 interface, while others (such as HCOO) bind on the ZrO 2 alone. A correlation has been identified between CO 2 adsorption strength and the binding of other intermediates, including COOH, HCO, and H 2 CO. 17 It should be noted that, although promising, the strongly exothermic CO 2 adsorption does not directly imply that later hydrogenation steps are selective toward methanol or other desired products. While the binding of further intermediates and their elementary reactions were excluded from the present study, the Zn y O z species may also act as favorable active sites for later hydrogenation steps.…”

“…It was suggested that at this stage, the adsorption may be strong enough to lead to catalyst poisoning and thus reduced conversion activity. While the free energies of the adsorbed molecules were not determined here, the strongly exothermic CO 2 binding to ZnO monomers as well as the known stability of HCOO on zirconia 13,17,81 may pose similar challenges if the barriers for further hydrogenation steps are high. In the past, the intermediate networks along both pathways have been studied on zirconia, Cu/CuZn surfaces, and metal−oxide interfaces.…”

“…Our earlier work demonstrated that incorporating Zn into the Cu matrix at the interface can strengthen CO 2 adsorption by up to 0.66 eV compared to the Cu-only interface. 17 Here, we investigate the adsorption of CO 2 on ZnO monomers on ZrO 2 , Cu(111), and the Cu−ZrO 2 interface to further quantify the promoting effect of ZnO.…”

“…Threecomponent models have emerged recently in order to represent those kinds of active sites. 16,17,23 In our previous study, we employed a zirconia-supported Cu nanorod with and without Zn incorporated into the interface between the rod and support. 17 The model served as a representative of twoand three-component metal support interface sites and was used to elucidate the role of a dilute interfacial CuZn alloy.…”