Nanocast LaNiO3 Perovskites as Precursors for the Preparation of Coke-Resistant Dry Reforming Catalysts

Dry reforming of methane is gaining great interest owing to the fact that this process efficiently converts two greenhouse gases (CH 4 and CO 2 ) into synthesis gas (CO + H 2 ), which can be further processed into liquid fuels and chemicals. Herein, a perovskite-derived nanostructured Ni/La 2 O 3 material is reported as an efficient and stable catalyst for this reaction. High-surface-area LaNiO 3 perovskite precursor is first synthesized by the method of nanocasting using ordered mesoporous silica SBA-15 as a hard template. The resulting nanostructured perovskite was found to possess high specific surface area as obtained from the BET method (150 m 2 g –1 ). The reduction behavior of the nanocast perovskite was monitored by performing the temperature-programmed reduction of hydrogen (TPR-H 2 ). It has been found that the complete destruction of perovskite structure occurs below 700 °C, leading to the formation of highly dispersed Ni 0 in La 2 O 3, as observed in the XRD pattern of the material after reduction. Similar behavior was observed for the LaNiO 3 perovskite synthesized using the conventional citrate process. However, the specific surface area of the former material was found to be much higher than that of the latter (50 m 2 g –1 ), which obviously resulted from the mesoporous architecture of the nanocast LaNiO 3 . It was found that the nanostructured Ni/La 2 O 3 obtained from the reduction of the nanocast LaNiO 3 exhibited high activity for the conversion of the reactant gases (CH 4 and CO 2 ) compared to the catalyst obtained from conventional perovskite, under the reaction conditions used in the present study. Particularly, no coke formation was observed for the mesoporous catalyst under the present conditions of operation, which in turn reflects the enhanced stability of the catalyst obtained from the nanocast LaNiO 3 . The improved performance of the nanostructured catalyst is attributed to the accessibility of the active sites resulting from the high specific surface area and the confinement effect leading to the stabilization of Ni nanoparticles.