Catalytic activity and activation mechanism of potassium carbonate supported on perovskite oxide for coal char combustion

Abstract

High activity catalyst system of K2CO3 supported on perovskite and its reaction mechanism for carbon materials were studied. It showed higher catalytic activity at lower temperature region than the case using γ-alumina supporter or K2CO3 alone. And also, the catalyst supported perovskites showed one third smaller of catalyst loss after the reaction than that with the alumina supporter or K2CO3 alone. Catalytic activation of K2CO3 supported LaMn1−xCuxO3 system was considered to be progress by two factors. First, K2CO3 has to be decomposed into K+ and CO32- ions. Second, decomposed K+ ions are activated with oxygen at the lower temperature than K2CO3 activation temperature. On oxide surface of support, K2CO3 was found to exist in partially dissociated form. In addition, perovskites had the active oxygen at the surface. K+ ions were able to be activated with the active oxygen on the surface of perovskites at the low temperature. The releasing temperature of the active oxygen could be controlled by Cu substitution in LaMn1−xCuxO3 system. Using these properties, we synthesized a high activity K2CO3 supported on perovskite catalyst for carbon combustion. Oxygen contents of perovskite could be reduced easily. And also, the reduced state could be re-oxidized to the original oxygen level. This reversible property of oxygen contents of perovskites was considered to be the reason of high recovery of catalyst (K+).