Catalytic steam gasification of coal by physical mixing of K-exchanged brown coal.

Abstract

The application of KCl to the catalytic gasification of higher-rank coal char was investigated. K-exchanged brown coal was prepared from KCl using an ion-exchange method. The K-loaded coal was physically mixed with a higher-rank coal. The mixture was gasified in steam with a thermobalance.The effects of the mixing pattern and the caking property of higher-rank coal on the catalytic effectiveness of K-excbanged coal were examined. The catalytic effectiveness of physical mixing of K-loaded brown coal was compared with that of physical mixing of Ni-loaded brown coal.Rate enhancement by physical mixing of K-exchanged Yallourn coal was almost independent of both the caking property of higher-rank coal and the chemical state of potassium catalyst before mixing. Direct contact between K-exchanged coal and higher-rank coal was required for this catalytic coal gasification system. EPMA analysis showed that potassium catalyst easily transferred from Yallourn coal to higher-rank coal char surface, whereas no transfer of Ni catalyst was observed. Potassium was a highly suitable catalyst for catalytic gasification by the physical mixing method.