Influence of cerium promotion on Ni–Mg–Al catalysts derived from hydrotalcite structure for dry reforming of methane

Abstract

This study investigates the impact of cerium promotion on NiMgAl catalysts for methane dry reforming (DRM) at 750 °C. A series of NiMgAl-Ce oxides with varying cerium content NiMgAlCe-x (x: rate of substitution of aluminium by cerium) were synthesized via co-precipitation method, aiming to enhance catalytic activity through the incorporation of nickel into hydrotalcite structures and cerium promotion. The obtained systems calcined at 800 °C, reduced at 750 °C and used catalysts were characterized by ICP, BET, XRD, SEM, H₂-TPR, TPO and O₂-TG analysis. The results demonstrate that cerium content influences specific surface area, with higher cerium promoting increased surface area but hindering catalytic activity and improved carbon resistance of the catalysts.. Activity improved with reaction temperature, with NiMgAl achieving the highest conversion, with CH₄ conversion dropping from 16% at 450 °C to 95.0% at 750°C. Stability tests at 750 °C, revealed decreased activity in cerium-containing catalysts. On the other hand in the case of catalysts without prior reduction, the catalytic activity of NiMgAlCe-1 and NiMgAlCe-2 catalysts are better, however, the NiMgCe solid presents a total catalytic inertia. This result suggests that the presence of aluminium is bringing a Lewis acidity favours this reducibility suggesting an influence on redox behaviour. Carbon fibers formation was observed, but it did not significantly affect reactor performance.