Improved chemoselective hydrogenation of crotonaldehyde over bimetallic AuAg/SBA-15 catalyst

[Display omitted] •Unusual crotonaldehyde hydrogenation on bimetallic AuAg/SBA-15 catalysts.•High crotonyl alcohol selectivity under high dihydrogen pressure and low CRAL/H2.•Special C2M2 di-σ bonded CRAL surface species on bimetallic AuAg/SBA-15 catalysts. Bimetallic AuAg/SBA-15 catalysts were disclosed to efficiently catalyze vapor-phase chemoselective hydrogenation of crotonaldehyde (CRAL) with improved hydrogenation rate and selectivity to crotonyl alcohol (CROL). The CRAL hydrogenation rate and product distribution were remarkably influenced by reaction parameters such as the reaction pressure and CRAL/hydrogen ratio. Ag decoration on Au/SBA-15 effectively stabilized bimetallic AuAg nano-alloy particles in small size and promoted the catalytic stability. In situ FT-IR investigation revealed that unusual C2M2 di-σ bonded CRAL surface species with reinforced symmetric δ(CH3) IR band under the “metal-surface selection rule” (MSSR) were formed on bimetallic AuAg/SBA-15. The stronger CRAL chemisorption on bimetallic AuAg/SBA-15 surfaces than on monometallic Au/SBA-15 was possibly due to the relatively strong ligating of CO bond on Ag active sites and the enhancement of the co-adsorption of the conjugated double bonds of CRAL. Synergistic interaction between Au and Ag active sites for the activation of HH, CC and CO bond may be the origin of positive effect of Ag decoration on Au/SBA-15.