K2CO3-catalyzed gasification of coal of different ranks in supercritical water for hydrogen production: A general kinetic model with good coal adaptability

Supercritical water gasification (SCWG) of coal provides a new solution for the green transformation and upgrading of traditional coal industry. Considering the good coal adaptability of SCWG and the excellent catalytic performance of K2CO3, a new kinetic model was developed in this work for predicting the catalytic gasification characteristics of coal of different ranks in supercritical water (SCW). In this model, various ranks of coal are characterized by the combination of three types of primary coal in different proportions, and the proportions can be obtained based on elemental analysis data and matrix computation. The SCWG of various ranks of coal can be considered as a combination of reactions of three types of primary coal in SCW. The model contains a total of 18 reactions, and various intermediates are represented by phenol and a high-carbon hydrocarbon. K2CO3-catalyzed SCWG experimental data of three different coal samples obtained in an improved quartz tube reactor system were used for the determination of model kinetic parameters. Then the experimental results of catalytic SCWG of other coal samples were used for the model validation, and it was found that the model can effectively predict the variations of gaseous products within an acceptable error. Afterward, the model was used to predict carbon gasification efficiency and gas compositions for coal of different ranks and to analyze carbon distribution and reaction rates for specific coal. The proposed kinetic model fits well with the good coal adaptability of SCWG technology, and it has great significance for the promotion of SCWG technology.