Zirconia-modified copper catalyst for CO_2 conversion to methanol from DFT study

摘要

The hydrogenation of carbon dioxide (CO2) to methanol on (ZrO2)(3)/Cu(1 1 0) interface has been investigated by periodic density functional theory (DFT) calculations. With regard to the adsorption of all the species involved in methanol synthesis, the species prefer to adsorb on the interface between Cu(1 1 0) surface and (ZrO2)(3) cluster and through C-Cu and O-Zr bonds. The adsorption energies of unsaturated species are increased on (ZrO2)(3)/Cu (1 1 0) interface compared to that on Cu(1 1 0) surface. Formate (HCOO), hydrocarboxy (COOH) and reverse water gas shift (RWGS) pathways in the reaction network of CO2 + 3H(2) - CH3 OH + H-2 O were considered. In HCOO pathway, the binding CO2* primarily hydrogenates to bi-HCOO*, which hydrogenates subsequently to HCOOH*, H2COOH*, H2CO*, H3CO* and CH3OH*. The formation of H2CO* and OH* through H2COOH* decomposition has the highest reaction barrier of 1.39 eV, which is lower than the rate-limiting step of cis-COOH* dissociation with an activation barrier of 1.46 eV in RWGS pathway. COOH* is facile to go through HCOOH* intermediate comparing with the formation of t,t-COHOH* in COOH pathway, indicating that CH3OH is mainly produced via HCOOH channel in the reaction scheme on ZrO2/Cu(1 1 0) interface. The formation of byproducts such as HCOOH, H2CO and CO is significantly inhibited over (ZrO2)(3)/Cu(1 1 0) interface, showing a high selectivity for producing CH3OH. These results demonstrated that (ZrO2)(3)/Cu(1 1 0) is a potential candidate catalyst for methanol production via CO2 hydrogenation.