Surface ZnO on zirconia is highly active for high temperature methanol synthesis

• DOI: 10.1016/j.jcat.2024.115389
• Publication Date: 2024-02-23T16:37:51Z
• Authors: M.T. Nikolajsen; J.-C. Grivel; A. Gaur; L.P. Hansen; L. Baumgarten; N.C. Schjødt; U.V. Mentzel; J.-D. Grunwaldt; J. Sehested; J.M. Christensen; M. Høj
• Keywords: Zinc; info:eu-repo/classification/ddc/540; Carbon dioxide; ddc:540; Chemistry & allied sciences; Methanol; Zirconia; 540

Zinc containing mixed metal oxides and supported zinc oxide are stable selective methanol synthesis catalysts at temperatures where a subsequent to hydrocarbons reaction can occur directly. This work provides fundamental insights into ZnO-based high temperature catalysts. A pronounced support effect was observed, ZrO2 provided beneficial while SiO2 exerted detrimental compared bulk ZnO. Preparing co-precipitated ZnO-ZrO2 showed that the initial activity correlated with amount of amorphous ZnO on surface catalytic increased time stream as migrated out solid solution onto surface. Hence active phase appeared be species not in ZrO2. Operando XAS coupled modulation excitation spectroscopy unravelled partly reduced under operating conditions, ZnOx, x approximately equal 0.98. In-situ DRIFTS further uncovered ZnOx activated CO2 formed via carbonate, formate methoxide species. XPS finally withdrew electrons from ZnO, facilitating oxygen abstraction form which turn facilitated activation CO2.