Our recent research on hydrogenation of biomass platform chemicals has made new progress, and the work “aqueous phase hydrogenation of levulinic acid to 1,4-pentanediol” has been published on the Chemical Communications (2014, 50, 1414-1416), which was selected as Cover Story in Chem. Commun..

The selective hydrogenation of carboxylic acids to their corresponding alcohols or diols is a very important reaction in the biomass refinery. Levulinic acid is a very important platform chemical which can be produced by the chemical treatment of lignocellulose. As the product of the simultaneous hydrogenation of the carbonyl and carboxyl groups in levulinic acid, 1,4-pentanediol can be used as a potential monomer for the production of polyesters. However, due to the preferable intermolecular esterification, most of the research regarding the hydrogenation of levulinic acid was focused on its conversion to g-valerolactone (GVL).

To the best of our knowledge, there is no report about the direct selective hydrogenation of levulinic acid to 1,4-pentanediol over a heterogeneous catalyst. In this work, a Mo modified Rh/SiO₂ (Rh–MoO_x/SiO₂) catalyst was first used for the aqueous phase hydrogenation of levulinic acid and exhibited high selectivity to 1,4-pentanediol at low temperature (353 K). The reaction pathway and the reason for the promotion effect of Mo were explored. From the reactions of some model compounds, it was found that the modification of Mo promoted the hydrogenation of the carboxyl group over the Rh/SiO₂ catalyst, which was responsible for the higher selectivity of 1,4-pentanediol over the Rh–MoO_x/SiO₂ catalyst.