DFT-based microkinetic studies on methanol synthesis from CO 2 hydrogenation over In 2 O 3 and Zr-In 2 O 3 catalysts.

Density functional theory (DFT) calculations and microkinetic simulations were performed to study the structure-performance relationship of In 2 O 3 and Zr-doped In 2 O 3 catalysts for methanol synthesis, focusing on the In 2 O 3 (110) and Zr-doped In 2 O 3 (110) surfaces. These surfaces are expected to follow the oxygen vacancy-based mechanism via the HCOO route for CO 2 hydronation to methanol. Our DFT calcualtions show that the Zr-In 2 O 3 (110) surface is more favorable for CO 2 adsorption than the In 2 O 3 (110) surface, and although the energy barriers are not lowered, most intermediates in the HCOO route are stablized with the introduction of the Zr dopant. Microkinetic simulations suggest that the CH 3 OH formation rate is improved by ∼10 times and CH 3 OH selectivity increased significantly from 10% on In 2 O 3 (110) to 100% on the Zr1-In 2 O 3 (110) catalyst model at 550 K. We find that the higher CH 3 OH formation rate and CH 3 OH selectivity on the Zr1-In 2 O 3 (110) surface than those on the In 2 O 3 (110) surface can be attributed to the slightly increased O V formation energy and the stablization of the reaction intermediates, whereas the much lower CH 3 OH formation rate on the Zr3-In 2 O 3 (110) surface is due to the much higher O V formation energy and the over binding of the H 2 O at the O V site.