Highly Active Sm2O3-Ni Xerogel Catalysts for CO2 Methanation

We report on a new synthesis route for pure Sm2O3 andSm(2)O(3)-Ni xerogels by modifying the well-known epoxide addition method. The resulting xerogels are used to prove the suitability of samaria as a highly effective catalyst support and to determine the optimal Ni loading. Therefore, a set of five catalysts with Ni loadings between 4 wt% and 89 wt% Ni was prepared and fully characterized by X-ray diffraction, N-2 physisorption, transmission electron microscopy and H-2 temperature-programmed reduction. Catalytic measurements reveal that the catalyst with 39 wt% Ni shows the best catalytic performance, outperforming even highly active literature known systems. Stability runs indicate that the catalyst deactivates independently of the Ni loading as well as conversion level over 600 min due to, most likely, carbonate formation. This deactivation, however, is reversible by a simple regeneration step. As shown by simultaneous CO2/CO methanation measurements, the Ni-Sm2O3 catalysts are also highly efficient for CO methanation. In this case, CO is preferentially converted to methane compared to CO2.