Gas Phase Hydrogenation of Furaldehydes via Coupling with Alcohol Dehydrogenation over Ceria Supported Au-Cu

Abstract

We have investigated the synthesis and application of Au-Cu/CeO2 (Cu: Au = 2) in the continuous gas phase (P = 1 atm; T = 498 K) coupled hydrogenation of 5-hydroxymethyl-2-furaldehyde (HMF) with 2-butanol dehydrogenation. STEM-EDX analysis revealed a close surface proximity of both metals in Au-Cu/CeO2 post-TPR. XPS measurements suggest (support → metal) charge transfer to form Auδ− and strong metal-support interactions to generate Cu0 and Cu+. Au-Cu/CeO2 promoted the sole formation of 2,5-dihydroxymethylfuran (DHMF) and 2-butanone in the HMF/2-butanol coupling with full hydrogen utilisation. Under the same reaction conditions, Au/CeO2 was fully selective to DHMF in standard HMF hydrogenation (using an external hydrogen supply), but delivered a lower production rate and utilised less than 0.2% of the hydrogen supplied. Exclusive -C=O hydrogenation and -OH dehydrogenation is also demonstrated for the coupling of a series of m-substituted (-CH3, -CH2CH3, -CH2OH, -CF3, -N(CH3)2, -H) furaldehydes with alcohol (1-propanol, 1-butanol, 2-propanol, 2-butanol, cyclohexanol) dehydrogenation over Au-Cu/CeO2, consistent with a nucleophilic mechanism. In each case, we observed a greater hydrogenation rate and hydrogen utilisation efficiency with a 3–15 times lower E-factor in the coupling process relative to standard hydrogenation. Our results demonstrate the feasibility of using hydrogen generated in situ through alcohol dehydrogenation for the selective hydrogenation of m-furaldehydes with important industrial applications.

Advanced Room-Temperature Synthesis of 2,5-Bis(hydroxymethyl)furan—A Monomer for Biopolymers—from 5-Hydroxymethylfurfural

“…A high yield of BHMF was obtained only at the temperature of 220 °C in the presence of 2-propanol as a hydrogen donor. However, when molecular hydrogen was used as a reducing agent, no conversion was noted by the authors …”

“…However, when molecular hydrogen was used as a reducing agent, no conversion was noted by the authors. 27 Catalysts with supported platinum nanoparticles are the most optimal choice: they provide higher activity in 5-HMF hydrogenation reaction than ruthenium or gold catalysts. 28 At the same time, the hydrogenation on Pt-containing catalysts proceeds more selectively than that on palladium, while avoiding overhydrogenation and not affecting the furan ring of 5-HMF.…”

Phenylacetylene hydrogenation coupled with benzyl alcohol dehydrogenation over Cu/CeO2: A consideration of Cu oxidation state

“…Several catalysts have now been employed, primarily noble multi-metallic systems including bimetallic (e.g. Co-Ru [5] and Au-Cu [6]) and alloy catalysts (e.g. NiRuPtAu [7] and PdCu [3]).…”

Effect of the formation of NiCu alloy and use of biomass-derived furfural on the catalytic hydrogenation of furfural to THFA

“…The traditional production of tetrahydrofurfuryl alcohol is carried out in two steps from furfural with furfuryl alcohol as intermediate (Scheme 1). The reaction can be performed in liquid or gas phase [3]. Scheme 1.…”