Regulating the Interaction within Pd-Cu Dual Metal Sites for Selective Hydrogenation of Furfural Using Ambient H₂ Pressure

Abstract

Selective hydrogenation of furfural (FF) to furfuryl alcohol (FA) using ambient H 2 pressure over a Cr-free catalyst is a sustainable upgrading process for cellulosic carbohydrates. The synergistic catalysis of dual metal sites is vital for selective activation of complex chemical bonds in biomass compounds. In this work, a Pd-CuO x nanocomposite catalyst was synthesized by a facile one-pot hydrolysis-precipitation method. For comparison, Pd/CuO x, Pd/Cu 2 O, and Pd/CuO supported-catalysts were prepared by the adsorption method. The Pd-CuO x catalyst showed 100% selectivity of FA with full conversion of FF at 120 °C under 1 bar of H 2 within 4 h. The obtained initial reaction rate of FF (25 mol FF mol Pd –1 h –1 ) and productivity of FA (72 mol FA mol Pd –1 h –1 ) represented outstanding results in the literature. Besides, this catalyst exhibited remarkable stability during five consecutive reuses without metal leaching. It was disclosed that the valence state of Cu and Pd-Cu interactions played critical roles in determining the intrinsic activity of the prepared Pd-Cu catalysts. Various characterizations combined with kinetic experiments and in situ chemisorption clearly unraveled adsorption and activation processes of the C═O bond and H 2 molecule on Pd 0, Cu 0, and Cu 1+ sites. To the best of our knowledge, this work provided the first insight into synergistic catalysis for hydrogenation of FF over a Pd-Cu bimetallic catalyst.