Enhanced methanol synthesis from ethanol-assisted CO2 hydrogenation over Cu/ZnO/CeO2 catalyst by modulating surface intermediate reactivity
Journal
Applied Catalysis B: Environmental
Journal Volume
386
Start Page
126443
ISSN
09263373
Date Issued
2026-06-05
Author(s)
Abstract
Low-temperature methanol synthesis from CO2 hydrogenation has been achieved using ethanol as the catalytic solvent, which reacts with formate (forms from CO2 hydrogenation) to produce ethyl formate, a reactive intermediate that could hydrogenolyze into methanol under milder conditions. In this study, Cu/ZnO and Cu/CeO2 catalysts were compared for the methanol synthesis from ethanol-assisted CO2 hydrogenation. Reaction testing shows that the formation of ethyl formate favors on Cu/CeO2, whereas the conversion of ethyl formate to methanol prefers on Cu/ZnO. A series of ternary Cu/ZnO/CeO2 catalysts were rationally prepared and evaluated for ethanol-assisted CO2 hydrogenation. It is demonstrated that the methanol yield could be enhanced by tuning the Ce/(Ce+Zn) ratio of Cu/ZnO/CeO2 catalysts. The optimum methanol yield is achieved as a result of the balanced abilities of esterification of formate with ethanol and hydrogenolysis of ethyl formate with hydrogen, which is in line with the Sabatier principle. In-situ infrared spectroscopy reveals that with exposure to the CO2-H2 gas mixture, the bridged formate forms on both Cu/CeO2 and Cu/ZnO, after which converts into ethyl formate via esterification upon ethanol introduction. On Cu/CeO2, ethyl formate strongly binds to the surface oxygen vacancy, stabilizing in an η1-(O) adsorption geometry. In contrast, ethyl formate adsorbs on Cu/ZnO in a form of η2-(C,O) geometry, which readily converts into methanol via ester bond cleavage and hydrogenolysis. The findings in this study may serve as a guideline for the rational design of heterogeneous catalysts for low-temperature methanol synthesis.
Subjects
CO2 hydrogenation
Cu-based catalysts
In-situ infrared spectroscopy
Methanol
Oxygen vacancy
Publisher
Elsevier B.V.
Type
journal article