Kinetics and Mechanism of CO2 Gasification of Chars from 11 Mongolian Lignites

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This work investigated the kinetics and mechanism of CO2 gasification of chars from 11 types of Mongolian lignites (ash contents of 7–27 wt % dry) and the corresponding acid-washed (catalyst-free) lignites. The catalytic gasification contributed to 83–99% of the initial rate of char conversion to gas. The non-catalytic gasification obeyed first-order kinetics with respect to the fraction of unconverted char, 1 – X, with little or no effect of the physical property of char, such as specific surface area and porosity. The proposed kinetic model, which considered progress in parallel of non-catalytic and catalytic gasification, assumed the presence of three to four different types of catalysts together with a type of precursor, if necessary. The optimized kinetic parameters enabled quantitative description of the measured changes with time of X over its near entire range, X = 0–0.9995. The kinetic analysis revealed that the most and least active catalysts in each char had initial activities differing by 2–3 ...