Highly Nickel-Loaded γ-Alumina Composites for a Radiofrequency-Heated, Low-Temperature CO₂ Methanation Scheme

In this work, we joined highly Ni-loaded γ-Al₂ O₃ composites, straightforwardly prepared by impregnation methods, with an induction heating setup suited to control, almost in real-time, any temperature swing at the catalyst sites (i. e., "hot spots" ignition) caused by an exothermic reaction at the heart of the power-to-gas (P2G) chain: CO₂ methanation. We have shown how the combination of a poor thermal conductor (γ-Al₂ O₃ ) as support for large and highly interconnected nickel aggregates together with a fast heat control of the temperature at the catalytic bed allow part of the extra-heat generated by the reaction exothermicity to be reused for maintaining the catalyst under virtual isothermal conditions, hence reducing the reactor power supply. Most importantly, a highly efficient methanation scheme for substitute natural gas (SNG) production (X $$ up 98 % with >99 % S $$ ) under operative temperatures (150-230 °C) much lower than those commonly required with traditional heating setup has been proposed. As far as sustainable and environmental issues are concerned, this approach re-evaluates industrially attractive composites (and their large-scale preparation methods) for application to key processes at the heart of P2G chain while providing robust catalysts for which risks associated to nano-objects leaching phenomena are markedly reduced if not definitively suppressed.