Construction of a sol–gel derived ternary CuZn/FeOx nanostructure for catalytic transfer hydrogenation of furfural

Abstract

Catalytic transfer hydrogenation of furfural to 2-methylfuran in the presence of isopropanol was systematically investigated over a series of sol–gel derived CuZn/FeO_x catalysts. Different from the conventional methods, characterization studies suggested the existence of surface-rich Cu⁰ and Cu⁺ species in the sol–gel derived samples, mainly due to the promoted co-reduction of the homogeneous ternary compositions. The synthesis method and pre-reduction regulated the active copper sites with an optimized electronic environment and the surface Cu⁺/Cu⁰ proportion. The former determined the generation of Cu⁰ acting as the real sites instead of a mature CuZn alloy phase, whilst the latter was responsible for the generation of surface acid sites modulating the selectivity of products. The superior performance of the CuZn/FeO_x catalyst could be attributed to the ternary synergy induced by the sol–gel method. The final yield of 2-methyl furan reached 91% using Cu/FeO_x(280) at 210 °C with a fast reaction rate of 8.6 μmol_2-MF g_Cu⁻¹ s⁻¹.