Mesoporous LaNi1-xMnxO3 perovskite with enhanced catalytic performance and coke resistance synthesized via glycine-assisted spray pyrolysis for methane dry reforming

LaNiO3 perovskite is of great interest as a catalyst for methane dry reforming. Partial substitution of Ni with Mn can improve structural stability and lower carbon deposition. In this study LaNi1-xMnxO3 perovskite (x = 0, 0.4, and 1) was synthesized using glycine-assisted ultrasonic spray pyrolysis to modify the morphology of the product, which improved the overall performance of the catalyst in the methane dry reforming. Glycine combustion in the pyrolysis process significantly increased the catalyst specific surface area and it also changed the morphology from sub-micron solid spherical particles to hollow or shell-like particles. Mn significantly stabilized the perovskite structure and in the LaNi0.6Mn0.4O3, exsolved Ni nanoparticles decorated a perovskite substrate. Mn also increased the basic sites and helped to remove the carbon deposition. The lattice oxygen in the perovskite substrate can react with the deposited carbon and as a result, virtually no carbon was observed in the time-on-stream experiments at 700 °C and 20 h. The combined effect of Mn addition and the morphological features of the glycine-assisted perovskite resulted in significant improvement of the CH4 and CO2 conversion and stability of the catalyst.