Highly efficient catalytic transfer hydrogenation of 5‐hydroxymethylfurfural to 2,5‐dimethylfuran over Cu_xZnAl catalysts

Abstract

Transformation of biomass-based feedstocks to fuels or valuable chemicals is of great importance to reduce our reliance on fossil resources. In this work, 2,5-dimethylfuran (DMF) production through catalytic transfer hydrogenation of 5-hydroxymethylfurfural (5-HMF) in liquid phase was investigated over ternary Cu x ZnAl catalysts using isopropanol as hydrogen donor. The excellent catalytic performance of the Cu x ZnAl catalysts can be attributed to the welldispersed Cu species with optimal proportions of Cu 2+ , Cu 0 , and Cu + . The synergistic effect of Cu 0 and Cu + is proposed to be responsible for the high hydrogenation/hydrogenolysis activity of 5-HMF. Using the Cu 2 ZnAl-600-300 catalyst (calcinated at 600 C and reduced at 300 C), 91.7% DMF yield was achieved under 180 C within 4 h. High-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, H 2 temperature-programmed reduction, NH 3 temperature-programmed desorption, and X-ray photoelectron spectroscopy were performed to investigate the structure-performance relationship and the reasons for the high catalytic performance of Cu 2 ZnAl-600-300.

Advances in Selective Hydrogenation of 5-Hydroxymethylfurfural over Heterogeneous Metal Catalysts

“…The analysis of pH effects on the conversion of HMF to various reduction products led to an improvement in the Faraday efficiency of DMF production, reaching 28%. Tong Wang et al explored the catalytic transfer hydrogenation of 5-HMF in the liquid phase for the delivery of DMF employing isopropanol as the hydrogen donor over a ternary CuxZnAl catalyst [56]. At 180 • C and 4 h of reaction, the DMF yield reached 91.7%.…”

Coupling Cu+ Species and Zr Single Atoms for Synergetic Catalytic Transfer Hydrodeoxygenation of 5-Hydroxymethylfurfural

“…Only several Cu-, − Ni-, and Ru-based , catalysts have been designed and applied for the HDO of HMF to DMF with isopropanol ( i -PrOH) as both the solvent and hydrogen donor. Particularly, inexpensive Cu-based catalysts are very attractive for this reaction because the full 3d valence band of Cu produces strong repulsion to the antibonding orbital of the furan ring, which could lead to the preferential adsorption of carbonyl group of HMF and minimize the hydrogenation/hydrogenolysis of a furan ring. − However, the intrinsic catalytic activity of Cu for the C–O bond hydrogenolysis is low, resulting in a sluggish kinetic for the dehydroxylation reactions. , …”

“…37−39 However, the intrinsic catalytic activity of Cu for the C−O bond hydrogenolysis is low, resulting in a sluggish kinetic for the dehydroxylation reactions. 31,40 One of the efficient approach to promote the hydrogenolysis of C−O bond is to increase the content of Cu + species of the Cu-based catalysts because it can function as the Lewis acid sites to smooth the cleavage of C−O bond. 31,37,38 In addition, it has been reported that the Cu + species also serves as the active sites for the i-PrOH hydrogenation because of its better adsorption performance toward C�O and C−O bonds than Cu 0 species.…”