Ce-promoted Ni/Al2O3 catalyst for enhanced sustainable syngas production from CO2 reforming of crude glycerol

Journal article, 2025

Dry reforming of glycerol (GDR) presents an alternative approach to syngas production by converting glycerol, a byproduct of biodiesel, with CO2. This study systematically investigated the effect of Cerium doping on Ni/Al2O3 catalyst synthesized via the wetness sonicated-assisted impregnation method. The effect of Ce promotion was studied at 0.5–3 wt%, conducted temperatures ranging from 650 to 750 °C and glycerol to CO2 ratios from 1:0 to 1:4 in a fixed-bed reactor. The results show that Ce doping enhances catalyst basicity and modifies surface morphology by enlarging the CeOx–nickel aluminate pore volume and reducing NiO crystallite size, thereby facilitating the formation of a synergistic NiO–NiAl2O4 active phase. Consequently, the improved adsorption of CO2 molecules enhances glycerol conversion and significantly increases CO yield. The results show that the H2/CO ratio in the syngas ranges from 0.8 to 1.2, with values below 2 being suitable for the Fischer-Tropsch reaction. Among the examined catalysts, the 1Ce10Ni/Al2O3 catalyst, benefiting from an improved glycerol conversion of ∼60 %, correlates with higher yields of H2 (53 %) and CO (73 %), showing a notable 1.5 times improvement in glycerol conversion and 1.3–1.6 times greater yields of hydrogen and CO compared to the catalyst unpromoted catalyst, at reaction temperature of 700 °C. This finding underscores the substantial influence of CeOx doping on catalytic performance, highlighting the critical role of optimizing the H2/CO ratio to achieve maximum glycerol conversion efficiency. Furthermore, the apparent glycerol activation energy decreases significantly from 60.21 kJ mol⁻¹ to 35.99 kJ mol⁻¹, demonstrating that Ce promotion contributes to the superior activity of 1Ce10Ni/Al2O3 compared to its unpromoted Ni/Al2O3. In general, the glycerol to CO2 ratio (GCR) were the dominant parameters influencing reaction products, with the optimized GCR found to be 1:1.