Direct conversion of furfural to 1,5-pentanediol over a nickel–cobalt oxide–alumina trimetallic catalyst

The use of a Ni–CoOx–Al₂O₃ mixed metal–metal oxide catalyst was proposed for the one-pot direct conversion of furfural (FFA) to 1,5-pentanediol (1,5-PDO), which afforded a high yield (47.5%) at 160 °C and at an initial H₂ pressure of 3 MPa for 6 h in ethanol. Proximity between the Ni⁰ and oxygen-vacant CoO_x (O_v–CoO_x) sites favored the dissociative adsorption of H₂ molecules on Ni⁰ and subsequent hydrogen spillover to O_v–CoO_x. The hydrogenation of the C[dbnd]O group of FFA produced furfuryl alcohol, which was then adsorbed on the Co^δ+ center of the O_v–CoO_x site in a η¹–(O)–alcoholic configuration, where subsequent C–O bond cleavage produced 1,5-PDO. Catalytic activity loss through the oxidation of the Ni⁰ and O_v sites could be mitigated by reactivation under H₂. Thus, the developed Ni–CoOx–Al₂O₃ catalyst has potential for efficient, low-cost, and environmentally friendly 1,5-PDO production from FFA.