Reactivity and characterization of adsorbed oxygen on SrTi_(1-x)Mg_xO_(3-#delta#) catalysts for oxidative coupling of methane

摘要

The reactivity of oxygen species adsorbed on SrTi_(1-x)Mg_xO_(3-#delta#) catalysts with methane was investigated. Temperature programmed desorption of oxygen, temperature programmed surface reaction of methane, and electron spin resonance were used for the characterization of oxygen species. It is suggested that the adsorption site is formed by the substitution of Ti~(4+) in Sr-Ti perovskite-type oxides with added Mg~(2+). It was found that this oxygen species was able to convert methane to ethane at a temperature as low as 550 K. Without CO_2 on the surface, C_2 hydrocarbons were formed with high selectivity in the CH_4 + O_2 reaction. On the other hand, CO and CO_2 were formed on the catalyst with CO_2 pre-adsorption.