CATALYTIC ACTIVITIES OF K2CO3 SUPPORTED ON SEVERAL OXIDES FOR CARBON COMBUSTION

Catalytic activities of K2CO3 supported on several oxides and carbon i tself were studied for the combustion of carbon at 673-773 K. K2CO3 su pported on a perovskite oxide, La0.8Sr0.2Cr0.5Mn0.45Pt0.05O3 (LSCMP), exhibited higher activity than that supported on the other supports in cluding carbon itself used in this study, the carbon conversion achiev ing nearly 100% above 723 K. K2CO3 supported on another perovskite oxi de, LaMn0.8Cu0.2O3 (LMC), exhibited a high activity comparable to that of LSCMP, although LSCMP and LMC alone showed very limited activity. The mixture of LSCMP with K2CO3/carbon increased the activity and achi eved the conversion of 100%. Catalytic active species were found to ha rdly flow out from the reaction zone when LSCMP was present in the car bon layer. In contrast, they easily flew out downstream as proved by t he catalytic combustion of carbon bed placed at downstream when LSC MP was absent in the upstream carbon bed. Roles of LSCMP in the catalyti c combustion may be to accelerate reductive activation of alkali metal salts to the active species, to allow sublimation them to the carbon, and to hold the active species in the reaction zone under the catalyt ic combustion conditions.