Modifying Spinel Precursors for Highly Active and Stable Ni-based CO2 Methanation Catalysts

In CO2 methanation, spinel phases are often considered as undesirable leading to deactivation. However, they can also be considered as well-dispersed solid solutions suitable as catalyst precursors leading to the formation of highly active and finely dispersed active sites. Though, spinels such as NiAl2O4, which form when Ni/Al2O3 supported catalysts are used, require high reduction temperatures to become active. To obtain a suitable catalyst precursor, the reducibility of such spinels must be improved so that it can be activated under conventional conditions. The undesirable spinel phase is modified by introducing manganese, known to distort the spinel structure, to form Ni0.9MnxAl2-xO4 (0 <= x <= 2) as a new catalyst precursor. These exhibit significantly improved reducibility at low temperatures. By adjusting the manganese content, a methane yield of 38.7 % was achieved at 350 degrees C under the conditions used, which is more than twice that of the supported Ni/Al2O3 reference catalyst (SPP2080-IMRC).