Synthesis of ketones from glycerol and 1,2-propanediol using copper and nickel catalysts: Unraveling the impact of reaction phase and active metal

Catalysts based on nickel-aluminum and copper–aluminum were synthesized through the coprecipitation method with a Ni or Cu content of 28 mol%, expressed as Ni/(Ni + Al) or Cu/(Cu + Al). The catalysts were calcined at 675 °C and thoroughly analyzed using various characterization techniques (ICP-OES, N2 adsorption–desorption, NH3-TPD, CO2-TPD, XRD, H2-TPR and elemental analysis). The samples were tested in two different reaction systems, gas phase at atmospheric pressure and liquid phase at 34 absolute bar, to investigate the production of ketones from glycerol and 1,2-propanediol under reaction conditions of 227 °C and a mass of catalyst/reagent mass flow rate ratio (W/m) of 10 gCatalyst·min/gReagent. The characterization results revealed catalysts with high specific surface area and nickel and copper metallic particles, exhibiting good catalytic activity towards liquid products. Gas phase reactions favored the generation of acetol and carbon deposits, which were minimal in liquid phase reactions. The active metal played a crucial role, and it was demonstrated that copper, with a higher number of acidic sites, exhibited greater selectivity towards ketones than the nickel catalyst. The best performance was achieved by the CuAl catalyst in the gas phase reaction of glycerol, with a conversion of 67.0 ± 4.0 %, a carbon selectivity to acetol in the liquid products of 61.4 % and a yield to acetol of 119.8 mgAcetol/gGlycerol.