Fluffy mesoporous Al2O3 supported Ag–In2O3 schottky junction catalysts for selective hydrogenation of CO of α,β-unsaturated aldehydes

Unsaturated alcohols (UOLs) are important fine chemical intermediates. Thus, it is of great significance to design and prepare catalysts for highly selective hydrogenation of CO of α,β-unsaturated aldehydes (UALs). In this paper, a fluffy mesoporous Al2O3-supported Ag–In2O3 catalyst (Ag-In2O3/f-m-Al2O3) was synthesized by employing a two-solvent method, in which Ag and In2O3 form a Mott–Schottky junction and lead to electron transfer from In2O3 to Ag. Electron-rich Ag repels the CC bond owing to “four-electron repulsion”, and electron-deficient In2O3 acts as the electrophilic site to adsorb the O atom of the CO bond, thus improving the selectivity towards UOLs. In addition to a larger specific surface area and smaller mass transfer resistance, the fluffy mesopore Al2O3 exhibits a large number of Lewis acid sites, which can further improve UOL selectivity. With the help of Ag–In2O3/f-m-Al2O3, high UOL selectivity can be obtained from UALs containing aliphatic, aromatic and heterocyclic groups. This elaborate design of the catalyst could contribute to the highly selective hydrogenation of UALs to UOLs.