EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Biogas is a renewable resource that can be used to produce green hydrogen. As the attempts to move towards a hydrogen economy are gathering pace, processes such as biogas dry reforming (BDR) are gaining significant attention. Ni-based catalysts have been extensively explored for this reaction because Ni has low price and exhibits good catalytic activity, especially if it is well dispersed on the support. However, they suffer from fast deactivation caused by carbon deposition. Perovskites with their unique structure, can be considered an alternative for catalyst precursors. In this work we synthesized four (4) different perovskites, namely LaNiO3, La0.8Ce0.2NiO3, La0.8Pr0.2NiO3 and La0.8Sm0.2NiO3, by employing a simple citrate sol-gel synthesis, and characterized the materials using XRD, N2 adsorption/desorption, CO2-TPD, H2-TPR, TEM and XPS. The materials were tested for the BDR reaction following three experimental protocols. The results of the first protocol (T = 500-800 oC, WHSV = 40,000 mL h-1 g-1) showed that all materials exhibited high catalytic activity, with high CO2 and CH4 conversions and high CO and H2 yields. It is interesting to note that at 800 oC, all materials exceeded the theoretical maximum of 66.67% methane conversion (according to the DRM reaction stoichiometry and the ratio of CH4:CO2 = 1.5:1, used herein), which suggests that CH4 decomposed to yield H2 and Carbon (C). In the second experimental protocol, the activation energy of the catalysts was calculated. To achieve this, we raised the WHSV at 200,000 mL h-1 g-1, using 0.15 g of the catalyst and appropriate feed flows to obtain significantly lower conversion (below 20%) compared to those defined by thermodynamic equilibrium, and the reaction was controlled by kinetics. In the third experimental protocol stability tests were carried out for up to 20h, with the results revealing that all prepared perovskites were particularly stable.