Effect of A-site metal on methane combustion on 2% Pd / AMn1-x Fe x O3 (A = Ba, La, Pr; x = 0.4, 0.6, 1) perovskites

Barium, lanthanum, and praseodymium perovskites were prepared by malic acid complexation. Surface areas of the La and Pr perovskites were between 17.1 and 21.6 m² g⁻¹. The moderate low surface areas (5.7 m² g⁻¹) observed for corresponding barium perovskites were due to the high calcination temperatures. The calcination temperature also affected the shapes and sizes of the perovskite particles. According to SEM images the nanoparticles of the La and Pr perovskites were spherical, whereas those of barium perovskites were flakes. The conversion of methane increased in the order of A-site metal Ba < Pr < La. The CH₄ conversion after SO₂ treatment correlated with size of the perovskite particles: the smaller the particles the better the activity. The highest methane conversion after SO₂ treatment was achieved with lanthanum perovskite with B-site metal combination Mn_0.4Fe_0.6.