Highly selective hydrogenation of 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl)furan over metal-oxide supported Pt catalysts: The role of basic sites

Catalytic hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) is an important reaction for biomass valorization. We report that metal oxides (including MgO, ZnO, SiO2 and TiO2) supported Pt catalysts show vastly different BHMF selectivity towards the hydrogenation of HMF. The basic metal oxide MgO supported Pt catalyst affords 99 % selectivity of BHMF, while the typical acidic metal oxide TiO2 supported Pt catalyst displays only 28 % selectivity of BHMF. HMF chemisorption on these catalysts show that the basic sites of metal oxide bonding to the CO group of HMF promote the BHMF selectivity, while the acidic sites of metal oxide favor the adsorption of CC group of HMF, which decreases the BHMF selectivity. It is proposed that the cooperation between basic sites and Pt atoms (activating H2) boosted the BHMF selectivity. Comprehensive studies including reactivity, recyclability, stability, solvent effect on the Pt/MgO catalyst were also carried out.