Hydrogenation of Biomass-Derived Furfural to Tetrahydrofurfuryl\nAlcohol over Hydroxyapatite-Supported Pd Catalyst under Mild Conditions

Abstract

Tetrahydrofurfuryl\nalcohol (THFAL), as a green industrial solvent,\ncan be obtained directly from biomass-derived furfural with 100% conversion\nand 100% yield over a hydroxyapatite-supported Pd catalyst (Pd-HAP)\nunder relatively mild conditions (40 °C, 1 MPa H₂,\nand 3 h) in 2-propanol. At room temperature and reacting for 8 h,\nthe yield of THFAL was more than 99%. By capturing the intermediates,\ntwo pathways were proposed as follows: (1) Furfural was partially\nhydrogenated to furfuryl alcohol, and then, furfuryl alcohol was further\nhydrogenated to THFAL. (2) Furfural and 2-propanol first formed 2-(isopropoxymethyl)­furan\n(2-IPMF) via etherification, and then, 2-IPMF was ultimately converted\nto THFAL. The Pd-HAP catalyst was characterized by various techniques\nincluding XRD, SEM, TEM, HAADF-STEM, XPS, and ICP-AAS. The results\nrevealed that the outstanding catalytic performance of Pd-HAP was\nattributed to the quasicoordination effect between Pd and HAP, which\nnot only contributed to highly dispersed and stable Pd nanoclusters\nbut also led to better activation of hydrogen. The recyclability of\nthe Pd-HAP catalyst was also investigated and proved its stability\nin the conversion of furfural and high selectivity toward THFAL.