It was found that ethane was formed by the stoichiometric reaction between methane and an adsorbed oxygen species on SrTi1-xMgxO3-δ with high selectivity (> 80 %) at much lower temperatures (550-750 K) than those typically used for the catalytic reaction. The properties of the adsorbed oxygen species were investigated by means of temperature programmed desorption, and the role of Mg2+ was studied using XRD, BET, and the measurements of the exchange rate between lattice oxide ions and gas phase oxygen. The added Mg2+ ions seem to be located at the surface and bulk Ti4+ site of Sr-Ti mixed oxides, where oxide ion defects are formed because of differences in ion charges. Surface oxide ion defects play an important role in oxygen adsorption, while bulk defects promote the mobility of oxide ions. SrTi0.5Mg0.5O3-δ was initially active for oxidative coupling of methane at low temperature (873 K), but combustion of methane predominated under steady state conditions, due to a change in adsorbed oxygen species induced by the adsorption of COx.
|Number of pages||13|
|Journal||ACS Symposium Series|
|Publication status||Published - 1996 Dec 1|
ASJC Scopus subject areas
- Chemical Engineering(all)