Construction of structure-matching In-Ni catalysts for the selective hydrogenation of α-methylacrolein

Abstract

The fundamental challenge in the gas-phase selective hydrogenation of α,β-unsaturated aldehydes to α,β-unsaturated alcohols lies in the construction of microscopic environment for the preferential hydrogenation of C = O bond along with the preservation of C = C bond under the reductive atmosphere. Herein, we proposed a structure-matching strategy for the catalyst design, in which In component in metallic form and oxide form are interplayed with metallic Ni and Al₂O₃ support, respectively. The fabrication of In-Ni intermetallic compound stokes up the desirable electropositive-electronegative environment (In^δ+-Ni^δ-) for the adsorption of polar carbonyl group. The In species in the In-oxo form are engaged in the network of Al₂O₃ support in the formation of In-O-Al-O entities, which stabilizes the heterolytically dissociated H species to match the preferential saturation of polar C = O bond. Therefore, the resulting In-Ni-Al₂O₃ catalyst achieves a selectivity of 77.2 % to methallyl alcohol with a conversion of 53.8 % in the gas-phase hydrogenation process, which present a striking contrast to the outcomes upon the counterpart Ni-Al₂O₃ (non-selectivity to methallyl alcohol). Such structure-matching strategy enriches the fundamental understandings and basis for the rational design of catalysts for the selective hydrogenation of unsaturated aldehydes.