Perovskites as Precursors for Ni/La₂O₃ Catalysts in the Dry Reforming of Methane: Synthesis by Constant pH Co‐Precipitation, Reduction Mechanism and Effect of Ru‐Doping

Abstract

LaNiO 3 perovskite is an interesting precursor for Ni/La 2 O 3 catalysts for the dry reforming of methane at high temperatures. Precursors have been synthesized by co‐precipitation without, with 2.5 at %, and with 5 at % Ru doping. The presence of Ru leads to a stabilization of the perovskite structure and hinders the decomposition into NiO and Ruddlesden‐Popper mixed oxides La n +1 Ni n O 3 n +1 , which was observed for the Ru‐free sample upon calcination at 1000 °C ( n = 3). Upon reduction in hydrogen, a mechanism involving at least two steps was observed and the first major step was identified as the partial reduction of the precursor leading to a LaNiO 2.5 ‐like intermediate. The second major step is the reduction to Ni metal supported on La 2 O 3 independent of the Ru content of the catalyst. In the presence of Ru, indications for Ni‐Ru alloy formation and for a higher dispersion of the metallic phase were found. The catalytic activity in DRM of the catalyst containing 2.5 % Ru was superior to the catalysts with more or without Ru. Furthermore, the propensity of coke formation was reduced by the presence of Ru.