Catalytic flameless combustion of methane over perovskites prepared by flame-hydrolysis

A set of perovskite-type catalysts of general formula LaBO3+/-delta (B = Co, Mn, Fe) and a sample of La2NiO4+/-delta were prepared by means of a recently proposed innovative flame-hydrolysis procedure. The catalysts were characterised by nanometer-size particles (20-60 nm), relatively high surface area (ca. 20 m(2)/g), high thermal stability and high phase purity. Their high activity for the catalytic flameless combustion of methane confirmed the validity and versatility of the preparation method. Temperature-programmed -desorption and -reaction, coupled with mass spectrometric analysis, allowed to better understand some aspects of the catalytic behaviour shown by the present samples for the cited reaction. In particular, an interesting correlation between the availability of oxygen at various temperatures, as revealed by the so-called alpha and beta oxygen desorption peaks, and reaction mechanism was found for the different B metals. (C) 2001 Elsevier Science B.V. All rights reserved.