Abstract: The influence of steam on catalytic performance for the oxidative coupling of methane(OCM) over Ba²⁺ promoted La₂ O₃ catalysts was studied. It was shown that the presence of a suitable amount of steam led to a significant increase of the yield and selectivity to C₂ hydrocarbons, a decrease of selectivity to carbon monoxide and some increase of selectivity to carbon dioxide with increasing the amount of water in the feed was also observed. The activity and selectivity of the catalysts are more sensitive to the effect of steam with the variation of Ba²⁺ content in the catalysts at a relatively low temperature(650℃). The comparative experiments for OCM with methane-oxygen mixture diluted with nitrogen or steam were carried out in order to investigate the role of steam.

Key words: Effect of steam, Methane oxidative coupling, La-Ba system catalysts