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The phenomenon of hot spot temperature and the effect of CO_2 in thefeed on the catalytic performance were studied in the oxidative coupling ofmethane over the La_2O_3/CaO(LC)and SrO-La_2O_3/CaO(SLC)catalysts.There was an abrupt change in the activity of the catalyst when the reactiontemperature increased from 873 to 923 K if no inert gas was used in the feed.This is mainly caused by the total oxidation of methane,releasing the combus-tion heat and resulting in a local over-heated spot in the catalyst bed.Then thereaction of oxidative coupling of methane was initiated.It is found that the ad-dition of CO_2 in the feed caused a severe effect on the catalytic performances ofthe SLC catalysts,especially if the SrO content was high.But no effect couldbe detected for the LC catalyst.The deactivation of the SLC catalyst is mainlyattributed to the formation of SrCO_3,which is inactive or much less active thanthe surface SrO species and is difficult to dissociate at the reaction condition.
The phenomenon of hot spot temperature and the effect of CO_2 in the feed on the catalytic performance were studied in the oxidative coupling of methane over the La 2 O 3 / CaO (LC) and SrO-La 2 O 3 / CaO (SLC) catalysts. There was an abrupt change in the activity of the catalyst when the reactiontemperature increased from 873 to 923 K if no inert gas was used in the feed.This is mainly caused by the total oxidation of methane, releasing the combus-tion heat and resulting in a local over-heated spot in the catalyst bed. There was activity of oxidative coupling of methane was initiated. It is found that the ad-dition of CO_2 in the feed caused a severe effect on the catalytic performances of the SLC catalysts, especially if the SrO content was high. could be detected for the LC catalyst. The deactivation of the SLC catalyst is mainly attributable to the formation of SrCO 3, which is inactive or much less active thanthe surface SrO species and is difficult to dissociate at the reaction condition.