Methane activation and oxidation over La _0.8 Sr _0.2 Ga _0.8 Mg _0.2 O ₃ : H/D exchange study

The mechanism of methane activation and oxidation over La0.8Sr0.2Ga0.8Mg0.2O3−α (LSGM) has been investigated using hydrogen isotope exchange with gas phase equilibration. The measurements have been conducted in a temperature range of 300–700 °C in pure methane and in a mixture of methane and hydrogen under pCH4 of 100, 200, and 500 Pa and pH2 of 200 Pa. LSGM has been shown to exhibit catalytic activity to C−H bond splitting in methane in the temperature range of 550–700 °C. The mechanism of methane activation comprises two parallel reaction pathways, with the first pathway related to CH3 and H species formation and the second pathway related to stepwise methane dissociation to carbon atoms. The ability of LSGM to consume hydrogen from methane is determined. The formation of carbon deposit and CO on LSGM decomposition was observed at temperature ≥ 750 °C.