Paving the way to transfer hydrogenation of CO2 with bio-derived glycerol over Ni supported zeolite catalysts

The CO₂ transfer hydrogenation with bio-glycerol over a Ni-zeolite was systematically studied to produce formic and lactic acids. The alkaline hydrothermal reactions without a catalyst and with Ni-zeolite heterogeneous catalyst were explored, focusing on the effects of base types and concentrations, reaction atmosphere and temperature. In alkaline hydrothermal reactions without catalyst, NaOH demonstrated superior performance at 1 M. A Ni/NaZSM-5 catalyst showed astounding performance giving 9.3 mol-L⁻¹-g⁻¹ lactic acid and 6.5 mol-L⁻¹-g⁻¹ formic acid at 250 °C after 2 h. Notably, the zeolite showed resistance to the highly basic conditions of the reaction medium. For the first time, CO₂ conversion in aqueous phase was reported addressing the complexity of CO₂ solubility. A reaction network was proposed including the diverse glycerol transformations not yet studied for this system. Overall, this study sheds light on the understanding of this complex reaction system and the potential of Ni-supported zeolites for sustainable CO₂ utilisation.