Stable and highly efficient HMDS terminated m-Cresol inhibitor for inhibiting coal spontaneous combustion

A stable and highly efficient 1, 1, 3, 3, 3-hexamethyldisilazane (HMDS) terminated m-Cresol inhibitor was synthesized based on the protection-deprotection strategy. The inhibitory effect of HMDS terminated m-Cresol inhibitor on spontaneous combustion of lignite was explored through temperature-programmed oxidation tests, in-situ infrared analysis and thermogravimetric analysis. Results show that, the oxidation of active phenolic hydroxyl groups in the m-Cresol inhibitor can be hindered by the protection of HMDS. After encountering coal, the HMDS terminated inhibitor can be gradually deprotected to regenerate the m-Cresol inhibitor that contains massive active phenolic hydroxyl groups, thus improving the chemical inhibition efficiency of coal spontaneous combustion. For the coal sample inhibited with HMDS terminated m-Cresol inhibitor, the initial contents of the active functional groups are lower and more stable during heating, and the inhibition rate reaches 70% at 130 °C. Moreover, the crossing-point temperature rises by 32.4 °C–181.2 °C. The activation energy increases by 11 kJ/mol and 18 kJ/mol at below and above 130 °C respectively. The peak temperature at maximum weight loss rate rises by 65 °C–431.2 °C, and the corresponding residual carbon rate increased by 31.3%–61.6%. The inhibition mechanism of the HMDS terminated m-Cresol inhibitor on coal spontaneous combustion was deduced.