Evaluation of CO2 Gasification Reactivity of Different Coal Rank Chars by Physicochemical Properties

The isothermal and non-isothermal CO2 gasification of eight different coal rank chars was conducted by a thermogravimetric analyzer (TGA), and the reactivity index and peak temperature were obtained to express the gasification reactivity. In addition, the physicochemical properties of these chars, such as the alkali index, Brunauer-Emmett-Teller surface area (S-BET), micropore area (S-mic), and carbon crystalline structure, were examined by an inductively coupled plasma (ICP) spectrometer, N-2 adsorption, and X-ray diffraction (XRD). The CO2 chemisorption was also measured by a TGA, and the total, strong, and weak chemisorbed volumes (C-total, C-str and C-wea) were obtained. All of these properties were used to evaluate the CO2 gasification reactivity of these chars. The results show that the gasification reactivity of chars decreases with an increasing coal rank. In comparison to the other properties, the C-total and C-str are the best parameters for predicting the gasification reactivity, and the linear correlation coefficients between C-total/C-str and gasification reactivity can reach up to 0.90 or even 0.98. It suggests that the CO2 chemisorption can be used to evaluate the gasification reactivity of different coal rank chars.