Methanation of CO2 over High Surface Nickel/Aluminates Compounds Prepared by a Self-Generated Carbon Template

Catalytic gas-phase hydrogenation of CO2 into CH4 was tested under three different nickel/aluminate catalysts obtained from precursors of hexaaluminate composition (MAl16O19, M = Mg, Ca, Ba). These catalysts were prepared using a carbon template method, where carbon is self-generated from a sol-gel that contains an excess of citric acid and the Al and M salts (Ba2+, Ca2+, Mg2+) by two-step calcination in an inert/oxidizing atmosphere. This procedure yielded Ni particles decorating the surface of a porous high surface area matrix, which presents a typical XRD pattern of aluminate structure. Ni particles are obtained with a homogeneous distribution over the surface and an average diameter of ca 25-30 nm. Obtained materials exhibit a high conversion of CO2 below 500 degrees C, yielding CH4 as a final product with selectivity >95%. The observed trend with the alkaline earth cation follows the order NiBaAlO-PRx > NiCaAlO-PRx > NiMgAlO-PRx. We propose that the high performance of the NiBaAlO sample is derived from both an appropriate distribution of Ni particle size and the presence of BaCO3, acting as a CO2 buffer in the process.

Automated summary

This study tested the catalytic gas-phase hydrogenation of CO2 into CH4 using three different nickel/aluminate catalysts obtained from hexaaluminate precursors (MAl16O19, M = Mg, Ca, Ba). The catalysts were prepared using a carbon template method, resulting in Ni particles decorating the surface of a porous high surface area matrix. The materials exhibited high conversion of CO2 below 500 degrees C, with CH4 as the main product. The NiBaAlO catalyst showed the highest performance, possibly due to the appropriate distribution of Ni particle size and the presence of BaCO3 acting as a CO2 buffer.