Characterisation by EPR and other techniques of La1-xCexCoO3+delta perovskite-like catalysts for methane flameless combustion

Two differently prepared series of La1-xCexCoO3 (x=0, 0.05, 0.1, 0.2), indi cated by A and C, have been analysed by EPR at temperature ranging between 95 and 295 K, both before and after their use as catalysts for methane flam eless combustion. At progressively lowering temperature, some samples showe d a narrowing Lorentzian-shaped pattern. This has been attributed to the fo rmation of ordered layer-like systems. A different behaviour has been notic ed with the x=0.1 samples of both series. The formation of spin bags and of spin glass has been hypothesised with these samples. A correlation between EPR spectra and catalytic performance has been highlighted. (C) 2001 Elsev ier Science B.V. All rights reserved.