Investigation of K2CO3‐Catalyzed Pyrolysis and Steam Gasification of Coal Char

Pyrolysis and steam gasification experiments of coal char with and without K2CO3 were performed using a thermogravimetric analyzer to investigate the effect of catalyst loading method on gasification reactivity at different temperatures (650–800 °C), and an additional redox cycle experiment of catalyzed char‐steam gasification was conducted in a fixed‐bed reactor. The results showed that, at low temperature, the solution impregnation method had a larger effect on the gasification reactivity than the physical blending method; at temperatures above 700 °C, the differences of two methods diminished due to the high mobility of potassium. In catalytic pyrolysis, the release of CO and CO2 indicated that K2CO3 reacted with carbon. The redox cycle experiments suggest that the potassium reacted with carbon to produce intermediates of the form K2O2C, K2OC, and K2C. The K2C intermediate may help to explain the release of more H2 during the initial period of catalytic coal char–steam gasification. New redox cycle: In this study, the process of potassium‐catalyzed steam gasification of coal char is divided into two parts and a new redox cycle is proposed. At low temperatures, the K2OC or K2C reacts with H2O to release H2 without CO, and upon heating the reactor, the K2O2C reacts with K2CO3 to release CO. The reaction mechanism could explain the release of more H2 in the initial period of gasification.