Conversion of furfuryl alcohol to 1,5-pentanediol over tetrametallic Cu/CoOx/MgO/Al2O3 mixed metal oxide catalyst

The hydrogenolysis of furfuryl alcohol to 1,5-pentanediol is investigated over a tetrametallic Cu/CoO_x/MgO/Al₂O₃ catalytic system. Activity and characterization results suggested the specific roles of each metal: Cu⁰ dissociates H₂, whereas CoO_x, as a reducible oxide, generates Co^δ+ sites next to oxygen vacancies where furfuryl alcohol adsorbs. Activated hydrogen spills over from Cu⁰ to these coordinatively unsaturated Co^δ+ sites, enabling the hydrogenolysis of furfuryl alcohol to 1,5-pentanediol. Furthermore, Cu⁰ aids in the reduction of Co oxide species at lower temperatures during the catalyst activation, thereby promoting the generation of uncoordinated Co^δ+ sites. The presence of MgO decreases overall acidity, resulting in reduced hydrogenolysis of furfuryl alcohol to 2-methylfuran and increased selectivity towards 1,5-pentanediol. Finally, the presence of Al₂O₃ in the catalyst enhances metal dispersion reducing the furanic ring hydrogenation to yield tetrahydrofurfuryl alcohol. With the optimized catalyst, a 43.8 % 1,5-pentanediol yield is obtained at 160 °C for 4 h in ethanol, achieving a TOF of 27.4 mol_1,5-PDO mol⁻¹_A.S. h⁻¹.