Composition Control of Pd-based Bimetallic Alloys to Boost Selective Hydrogenation of Furfural in Aqueous Micelles

Composition control of bimetallic alloys to regulate the hydrogenation of furfural into high value-added derivatives is an important strategy for catalyst design, but remains a great challenge. In this work, we present a simple and sustainable strategy to construct Pd-based bimetallic alloys by reducing metal precursors dissolved in an aqueous solution of the sugar-based surfactant GluM. An obvious elemental composition-dependent selective hydrogenation of furfural in GluM aqueous micellar solution was observed - the Pd1Cu9 alloy exhibits a remarkable selectivity (99.9%) to furfural alcohol, whereas the Pd1Ni3 alloy can achieve deep-hydrogenation to tetrahydrofurfuryl alcohol with a high selectivity (96.2%). Experimental and theoretical investigation indicated that the excellent selectivity was attributed to the alloy effect and solvent effect, which provide different dissociative adsorption abilities of H2 on the surface and the hydrogen bonding interactions facilitating H transfer in aqueous micelles, respectively. Notably, GluM micelles are not only employed to stabilize Pd-based bimetallic alloys, but also to enrich the furfural in water to improve the hydrogenation catalytic activity. Besides, this work on bimetallic alloy composition and H-shuttle in aqueous phase provides a new research direction for selective hydrogenation of furfural. The high selectivities of FA (Sel. 99.9% for Pd1Cu9) and THFA (Sel. 96.2% for Pd1Ni3) were obtained under mild reaction conditions in environmentally benign micellar catalytic systems.