Integration of Interfacial and Alloy Effects to Modulate Catalytic Performance of Metal-Organic-Framework-Derived Cu-Pd Nanocrystals toward Hydrogenolysis of 5-Hydroxymethylfurfural

Abstract

Selective formation of 2,5-dimethylfuran (DMF) by hydrogenolysis of lignocellulosic biomass-derived 5-hydroxymethylfurfural (HMF) is highly desirable for renewable liquid biofuel production. Here we have synthesized Cu-Pd bimetallic nanoparticles embedded in carbon matrix (Cu-Pd@C) by simple pyrolysis of Pd-impregnated Cu-based metal-organic frameworks (MOFs) followed by conventional hydrogenation route. It was found that Cu-Pd@C-B (solid-gas-phase hydrogenation route) with Cu-Pd bimetallic alloying exhibited brilliant catalytic performance at 120 degrees C under 15 bar H-2 pressure to produce liquid DMF biofuel with 96.5% yield from HMF as compared with the Cu-Pd@C-A catalyst (liquid phase hydrogenation route), which gave 46.4% yield under the same conditions. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) studies reveal that Pd in Cu-Pd@C-B catalyst is electronically promoted by Cu with the unique intrinsic synergy of increased Pd-Pd bond distance and decreased Cu-Cu bond length, which eventually modulate the local atomic structural environment and result in enhanced catalytic activity. Moreover, the entrapped bimetallic nanoparticles with carbon shells in Cu-Pd@C-B catalyst further protect the active catalytic site from migration, aggregation, and leaching during hydrogenolysis reaction and improve the stability of the catalyst.