Positive Effect of Carbon Monolith Porosity Sealing with MgO in the CO2 Hydrogenation to CH4 Using NiO-CeO2 Active Phase

Abstract

Carbon monolith supports have been manufactured using 3D printed channels template and resorcinol-formaldehyde carbonizable resin. These carbon monoliths were loaded with NiO-CeO₂ nanoparticles (Np) as the active phase and tested for CO₂ hydrogenation to CH₄, focusing on the effect of sealing the carbon porosity with MgO. The MgO coating improves CO₂ conversion to CH₄ by preventing the NiO-CeO₂ nanoparticles from settling within the microporous structure of the carbon support, where gas diffusion limitations hinder access to the active phase. This was confirmed by SEM images, which evidence the introduction of NiO-CeO₂ (Np) into the carbon matrix of the bare carbon monolith support and the accumulation of the active phase at the surface of the monolith channels once the porosity is sealed. Other characterization techniques like N₂ adsorption and Hg porosimetry, confirm that the porosity is blocked by MgO. On the other hand, it has been demonstrated that there is not a relevant chemical effect of MgO on the NiO-CeO₂ (Np) catalytic performance for the carbon monoliths supported catalysts, because the contact between the MgO and NiO-CeO₂ phases is poor due to the dispersing effect of carbon.