SURFACE AND BULK PROPERTIES OF STOICHIOMETRIC AND NONSTOICHIOMETRIC STRONTIUM HYDROXYAPATITE AND THE OXIDATION OF METHANE

摘要

The oxidation of methane on near-stoichiometric strontium hydroxyapatites pretreated at 873, 1048 and 1123 K in O-2 has been examined in the presence and absence of tetrachloromethane (TCM) as a gas-phase additive at 973 K, Under these conditions, strontium hydroxyapatite, regardless of its stoichiometry, is converted, at least in part, to Sr-3(PO4)(2). On introduction of TCM to the feedstream, the selectivities to carbon monoxide, ethane, and ethylene are increased while the conversion of methane is decreased. Qualitatively similar effects of TCM on the oxidation were observed on Sr-3(PO4)(2) prepared by an independent procedure. Strontium chlorapatite, formed from the apatites and phosphate during the oxidation in the presence of TCM, as shown from XRD, contributes to the increased selectivity to CO and decreased conversion of methane. (C) 1996 Academic Press, Inc. [References: 41]