Microwave-assisted synthesis of La1-xBxMnO3.15 (B = Sr, Ag; x=0 or 0.2) via manganese oxides susceptors and their activity in methane combustion

La1-xBxMnO3.15 perovskites (B = Sr, Ag; x = 0 or 0.2) were synthesised from metal nitrates in a short time (ca. 15 min) using microwave irradiation. The manganese oxides formed, after metal nitrates decomposition, are efficient microwave receptors and absorb energy strongly at 2450 MHz (microwave frequency). This absorption increased the microwave power loss in the material and led to local heating which provided the necessary energy for La1-xBxMnO3.15 formation. X-ray powder diffraction indicated the formation of crystalline La1-xBxMnO3.15 perovskites. The solids were also characterised by TPR and SEM techniques. The La1-xBxMnO3.15 perovskites were used as catalysts for catalytic combustion of methane. It was found that the catalytic activity of microwave-synthesised perovskites is better than that observed with the corresponding perovskites synthesised by conventional process. Finally, sintering of perovskites was carried out under microwave radiation and the catalytic behaviour of sintered catalysts is described. (C) 2005 Elsevier B.V. All rights reserved.