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.