Mossbauer study of carbon-supported spinel clusters catalysing oxidative decomposition of hydrogen sulphide: role of the labile surface oxygen

Activity-structure relationships have been studied in the oxidative decompo sition of hydrosulphur. Structure-organized magnetic nanoclusters of non-st oichiometric magnetite Fe3O4+delta with mean sizes [d] similar to 10-15 nm and non-stoichiometry parameters delta similar to 0.12-0.13 were shown to b e active compositions of carhon-supported catalysts, For the gas how of air (1.5 vol,%), CH4 (98.0 vol,%) and H2S (0.5 vol.%) the coal-supported magne tite nanoclusters were found to convert 100% H2S into elemental sulphur at 150 degrees C and atmospheric pressure. A model of the surface-active centr es is discussed in terms of the anion vacancy and surface labile oxygen for mation. Copyright (C) 2000 John Wiley & Sons, Ltd.