Direct Catalytic Conversion of Ethanol to C5+Ketones: Role of Pd-Zn Alloy on Catalytic Activity and Stability

Abstract

Ethanol can be used as a platform molecule for synthesizing valuable chemicals and fuel precursors. Direct synthesis of C(5+)ketones, building blocks for lubricants and hydrocarbon fuels, from ethanol was achieved over a stable Pd-promoted ZnO-ZrO(2)catalyst. The sequence of reaction steps involved in the C(5+)ketone formation from ethanol was determined. The key reaction steps were found to be the in situ generation of the acetone intermediate and the cross-aldol condensation between the reaction intermediates acetaldehyde and acetone. The formation of a Pd-Zn alloy in situ was identified to be the critical factor in maintaining high yield to the C(5+)ketones and the stability of the catalyst. A yield of >70 % to C(5+)ketones was achieved over a 0.1 % Pd-ZnO-ZrO(2)mixed oxide catalyst, and the catalyst was demonstrated to be stable beyond 2000 hours on stream without any catalyst deactivation.