Direct and transfer hydrogenation of furfural over MOF‐derived Pd‐Cu@C catalysts

Abstract

Owing to the self‐reducing ability of palladium acetate in solutions, an ethanol solution containing Pd0 particles was prepared and coated in‐situ into copper metal–organic framework (Cu‐MOF), forming Pd@Cu‐MOF in a coated structure. The Pd@Cu‐MOF was reduced under N2 or H2 to form carbon‐coated Pd‐Cu@C. The pyrolysis and carbonization of Cu‐MOF and the reduction of Cu2+ were studied. The Cu‐MOF under either N2 or H2 was pyrolyzed and carbonized, but the Cu2+ reduction mechanisms were different. The high‐temperature carbothermic reduction of Cu2+ under N2 produced Cu0, but during low‐temperature reduction under H2, the reducing H2 reduced Cu2+ to Cu0. Furfural hydrogenation experiments showed that compared with H2, the Pd‐Cu@C prepared under N2 reduction displayed higher furfural hydrogenation activity. The catalytic activity of Pd‐Cu@C prepared from in‐situ Pd0 coating was higher than the Pd/Cu@C prepared from the impregnation method. With i‐propanol as the solvent, the catalytic hydrogenation of furfural under H2 consisted of direct catalytic hydrogenation with molecular hydrogen as the hydrogen source and catalytic transfer hydrogenation with i‐propanol as the hydrogen donor. The catalytic activity of direct catalytic hydrogenation is higher than the catalytic transfer hydrogenation.