Effects of K2CO3 and Ca(OH)2 on CO2 gasification of char with high alkali and alkaline earth metal content and study of different kinetic models

Abstract

The CO2 gasification of South Open-pit Mines coal from Zhundong field of China using Ca(OH)2 or K2CO3 as catalyst with different loading methods and contents were conducted in thermogravimetric analysis. Comparison of the gasification reactivity and rate of coal loaded various concentration of Ca(OH)2 concluded that the increase of Ca(OH)2 loading pronouncedly improved the reactivity and rate for grinding method, nevertheless, for impregnation and high pressure method the increase of Ca(OH)2 loading observed a similar catalytic effect on char gasification. However, the catalytic effect of K2CO3 revealed that the catalytic activity increased with the increase of K2CO3 loading for three loading method. For the same catalyst loading, the highest catalytic gasification reactivity achieved for Ca(OH)2 and K2CO3 were the loading methods of high pressure and grinding, respectively. In addition, the gasification of raw char, K2CO3 loaded char and Ca(OH)2 loaded char were quantitatively evaluated by kinetic analysis using shrinking core, random pore and modified random pore models.