Boosting the Selective Hydrogenation of Renewable Unsaturated Aldehydes to Alcohols Via Hydrogen Spillover Over Different Ceo2 Crystal Faces

Abstract

The hydrogenation of biomass derived unsaturated aldehydes to alcohols is attractive but challenging due to the easier hydrogenation of C=C compared to C=O. Herein, Rh/CeO2(110) and Rh/CeO2(111) catalysts were designed and assembled for the selective hydrogenation of unsaturated aldehydes, such as 5-(hydroxymethyl)furfural (HMF), to corresponding alcohols. The yield of 2,5-bis(hydroxymethyl)furan (BHMF) was 97.2% for Rh/CeO2(110) and 59.6% for Rh/CeO2(111). Rh/CeO2(110) exclusively catalyzed the C=O bond hydrogenation, while Rh/CeO2(111) also promoted the further hydrogenolysis of the C-OH bond. This selectivity was attributed to the stronger adsorption of C=O groups on CeO2(110), leading to enhanced HMF conversion into BHMF. Moreover, the sufficient oxygen vacancies on the CeO2(110) surface promoted hydrogen spillover over Rh/CeO2(110), facilitating the hydrogenation of unsaturated aldehydes. This work demonstrates that modifying the catalyst's interfacial structure can control both selective hydrogenation and hydrogen spillover, offering a good approach for selectively hydrogenating unsaturated aldehydes and bio-based platform molecules.

Keywords: selective hydrogenation, biomass-based chemicals, hydrogen spillover, oxygen vacancies, unsaturated aldehydes, oxides supported-metal catalyst