Research on imidazolium ionic liquid inhibiting coal oxidation thermo-kinetics parameters

In China, coal spontaneous combustion (CSC) is one of the major disasters which threaten the protection and utilization of coal resource.When coal fire happens, numerous coal resources would be depleted, resulting in enormous economic loss.Meanwhile, toxic and harmful gases produced by the coal oxidation and combustion would damage the ecosystem.The inhibition technology has achieved favorite results in CSC prevention.Ionic liquid (IL) has excellent physical and chemical properties and environmental protection advantages.Therefore, it has received extensive attention in the field of CSC prevention.CSC is caused by the reaction of coal and oxygen, and the reaction energy is provided by self-activation.To investigate the effect of imidazolium-based IL on the oxidation thermo-kinetics of coal, a thermal analysis experiment was conducted.The Flynn-Wall-Ozawa (FWO) method was used to calculate the apparent activation energy (E_a) and pre-exponential factor (A) of coal oxidation.Using the Popescu method, the mechanism function was calculated.The results showed that when the conversion (α) is constant, as the heating rate increases, a certain degree of hysteresis occurs, at the same degree of oxidation temperature.The IL treatment of coal samples (IL-tc) changes their reaction mechanism function, which increases coal oxidation reaction path.It is transformed from one-dimensional diffusion to multi-dimensional diffusion.Before coal ignition, as α increases, the values of E_a and A increase.However, after coal ignition, as the α increases, the values of E_a and A begin to decrease gradually.The IL increases the threshold of the coal molecules to become activated molecules, reduces the reaction speed of the activated molecules, and plays a role in inhibiting CSC varying degrees.When α=0.2-0.6, the E_a value of IL-untc is the lowest, indicating that IL has a certain degree inhibiting effect on coal.This study has a guiding role in the prevention and control on CSC.