La and Co-based materials for ammonia decomposition: activity, stability and structural changes

The La$_{0.9}$Sr$_{0.1}$Sc$_{0.9}$Co$_{0.1}$O$_{3-\delta}$ (LS) and La$_{0.9}$Sr$_{0.1}$CoO$_{3-\delta}$ (LC) phases and composite materials based on them were synthesized. There are data in the literature on the activity of pure or modified forms of LC in ammonia decomposition, but there are no data on the activity of the LS phase and LS–LC composites. Therefore, the stability and activity of LS–LC composites and initial LS and LC in ammonia decomposition were investigated. The best result in the decomposition of ammonia at 700$^\circ$C and WHSV of 60000 ml NH$_3$ $\cdot$ g$_{cat}^{-1}$ $\cdot$ h$^{-1}$ shows LC – 99%, the worst LS – 80%. Under the same conditions, the activity of samples LC, 40LS–60LC and 50LS–50LC remains unchanged for 40 hours. It was found that during ammonia decomposition, the LC phase decomposes to form cobalt and La(OH)$_3$ nanoparticles, but the LS phase does not undergo significant changes, which is confirmed by X-ray diffraction, IR spectroscopy, Raman spectroscopy and TEM.