Char used in this study was provided by Shaanxi Coal and Chemical Industry Group Co. Ltd, as a by-product in low-rank coal pyrolysis processes. In order to eliminate heat and mass transfer limitations, the sample was ground and sieved to particle sizes of less than 0.074 mm. The proximate and ultimate analyses of the samples were carried out and the results are given in Table 1 .
The experiments were completed using a thermogravimetric analyzer (TGA/DSC1/1600HT, Mettler-Toledo). In each test, about (10 ± 0.2) mg samples were loaded into an Al2O3 crucible under an air atmosphere, with an air flow rate of 50 mL min−1. The furnace temperature was increased from 30 °C to 850 °C. All samples were tested at four different heating rates of 15, 20, 25, and 30 °C min−1, respectively.
The experiments were completed using a thermogravimetric analyzer (TGA/DSC1/1600HT, Mettler-Toledo). In each test, about (10 ± 0.2) mg samples were loaded into an Al2O3 crucible under an air atmosphere, with an air flow rate of 50 mL min−1. The furnace temperature was increased from 30 °C to 850 °C. All samples were tested at four different heating rates of 15, 20, 25, and 30 °C min−1, respectively.