Effects of gas- and solid-phase additives on oxidative dehydrogenation of propane on strontium and barium hydroxyapatites

Effects of the introduction of tetrachloromethane (TCM) into the feedstream for the oxidative dehydrogenation of propane have been investigated on str ontium and barium hydroxyapatites (SrHAp and BaHAp) with and without treatm ent with Cu2+ and Pb2+. Activities on SrHAp were greater than those on BaHA p in the absence of TCM. Upon adding TCM into the feedstream for propane ox idation on both SrHAp and BaHAp, the conversion of propane decreased while the selectivity to propylene increased with increasing time-on-stream, as o bserved in the oxidation of other alkanes on hydroxyapatites. While the tre atment of both hydroxyapatites with lead resulted in the decrease of the yi eld of propylene regardless of the addition of TCM, activities on those cat alysts doped with copper were improved in the presence of TCM. Particularly SrHAp treated with Cu2+ afforded approximately 80% selectivity to propylen e at 16% conversion of propane at 0.5 h on-stream with TCM and this activit y was kept for 6 h on-stream. A direct contribution of TCM to control of th e reduction of Cu2+ in the catalyst leads to the improvement of the catalyt ic performance. (C) 2001 Elsevier Science B.V. All rights reserved.