Highly Selective Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Bis(hydroxymethyl)tetrahydrofuran in Water over a Palladium-Based Single-Atom Catalyst

Abstract The selective hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF) is extremely crucial in the field of biorefinery, but it remains a great challenge under moderate reaction conditions. In this work, we developed a palladium-based single-atom catalyst (Pd/LaNiO3) by using LaNiO3 as an acid-base bifunctional support. The systematic characterization results showed that Pd was atomically dispersed and was steadily anchored on LaNiO3 via the Pd-O bond. Moreover, compared with Pd/La2O3 and Pd/NiO, Pd/LaNiO3 displayed moderate electron transfer (from Pd to LaNiO3) and oxygen vacancies, leading to the proper acid-base property and hydrogenation ability, which could not only facilitate the selective activation of the C=O bond and C=C bond, but also restrain the cleavage of the C-O bond and furan ring. Due to the synergistic effects of Pd and LaNiO3, Pd/LaNiO3 exhibited satisfactory catalytic performance, affording 100.0% HMF conversion and 99.2% BHMTHF selectivity with an exceptional turnover frequency of 277.1 h–1 at 130 °C for 1 h under the pressure of 2 MPa H2. In addition, the analysis of reaction processes revealed that the primary hydrogenation of the C=O bond followed by the subsequent hydrogenation of the C=C bond was the main pathway for the formation of BHMTHF. More importantly, Pd/LaNiO3 also worked well for the selective hydrogenation of various biomass-derived carbonyl compounds, which showed enormous potential for the production of high-value-added fine chemicals.