Reaction Mechanism of Ethanol on Model Cobalt Catalysts: DFT Calculations

Abstract

In the present work, the density functional theory calculations analysis are performed to study the reaction mechanisms and catalytic activity of ethanol reactions over Co0, Co2+, and Co3+ sites. Adsorption situations and the reaction cycles for ethanol reactions on cobalt catalysts were clarified. The mechanisms include the dehydrogenation steps of ethanol and the C–C cleavage step. The present calculation results show that the mechanism of ethanol reaction on Co0 site is CH3CH2OH → CH3CH2O → CH3CHO → CH3CO → CH3+CO, and the final products are CO and H2. H2 is formed by the combination of adsorbed H species. On Co2+ site, the mechanism is CH3CH2OH → CH3CH2O → CH3CHO, and the main final product is CH3CHO species. On Co3+ site, the mechanism is CH3CH2OH → CH3CH2O → CH3CHO → CH2CHO → CH2CO → CHCO → CCO → COCO → CO → CO2, and the final products are CO2 and H2O. The rate-limiting step on Co0, Co2+, and Co3+ sites is the form of CH3CHO species. The possible reasons for the different catalytic activities may be...