Tuning NiCu/AlO(OH) catalysts for optimal glycerol hydrogenolysis to 1,2-propanediol

Abstract

Bimetallic NiCu catalysts supported on boehmite (AlO(OH)) with varying Ni and Cu loadings were synthesized through the sequential wet impregnation technique. The AlO(OH) support, characterized by unique properties and a high surface area, was synthesized using a hydrothermal treatment method. Various characterizations on the prepared series of NiCu/AlO(OH) catalysts confirmed the presence of strong Lewis acid sites, and the absence of large agglomeration. Optimization of Ni and Cu loadings on the support achieved the highest catalytic performance with 25 wt% Ni and 15 wt% Cu at 240 °C and 550 psi hydrogen pressure using 4 wt% catalyst loading, resulting in 92.7% 1,2-PD selectivity and 60.3% yield with 65.1% glycerol conversion in 6 h. Further optimization of operating conditions to make 1,2-PD was conducted within the range of temperature, pressure, and catalyst loadings of 200–230 °C, 350–750 psi, and 4–8 wt%, respectively, via central composite design using Design Expert software. The 25Ni–15Cu/AlO(OH) catalyst at 6 h was chosen for its high 1,2-PD activity, achieving a high glycerol conversion of 62% with a corresponding 1,2-PD yield of 53.4% (86.0% selectivity of 1,2-PD) under the optimization conditions of 240 °C, 515 psi, and 4.1 wt% catalyst loading, closely aligning with experimental efficiency.