Flame-spray pyrolysis preparation of perovskites for methane catalytic combustion

A flame spray pyrolysis apparatus was set up and optimised for the preparation of perovskitic mixed-metal oxides in nanoparticle-size powder form. LaCoO3 was chosen as test catalyst, aiming at correlating crystallinity, surface area, particle size, catalytic activity, and durability with some fundamental operating parameters of the apparatus. In particular, the feeding rate of the precursor solution, the flow rate of the O2/CH4 mixture for the igniter, and flow rate and linear velocity of the main dispersing-oxidising oxygen were thoroughly analysed. The activity of the prepared samples was tested for the catalytic flameless combustion of methane, a reaction requiring the proper combination of catalyst activity and thermal stability. Provided that a crystalline perovskitic phase forms, activity increases with increasing surface area of the powder. In contrast, the higher the initial sintering of catalyst particles within the flame, the higher is thermal stability. Tuning up the operating parameters allows us to properly address the desired catalyst properties.