A Comparison of LSCF-6428 and Bys for the Oxidative Conversion of Methane and Ethane

Abstract

Results are reported for a comparative study of Bi1.5Y0.3Sm0.2O3-δ (BYS) and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428) in terms of their respective OCM activities, interactions with ethane, and stabilities in reducing environments. The results show that BYS is a superior OCM catalyst, having rates that are nearly 6 times greater and yields that are more than two times higher than those of LSCF-6428. On the other hand, using in situ dynamic XRD, BYS was observed to undergo a phase transformation at about 700 °C when in the presence of methane at pressures as low as 0.1 atm. Higher methane pressures resulted in more severe crystalline changes and could not be inhibited by the addition of 3% oxygen. The catalytically active species appear to be the oxides of BYS constituent cations, all of which are known OCM catalysts. LSCF-6428, on the other hand, is somewhat more resistant to methane and can be stabilized at high methane pressures by the addition of 3% oxygen. At OCM temperatures, neither material catalyzed ethane reactions. Instead, ethane underwent gas-phase oxidative dehydrogenation and thermal cracking reactions.