Role of inherent water in low-temperature oxidation of coal

The role of water content in coal oxidation was studied using an isothermal flow reactor at atmospheric pressure and temperatures below 100degreesC. Transient rates of consumption of oxygen and production of CO2 and CO were measured during oxidation experiments, by means of an online dual-column micro gas chromatograph and an oxygen analyzer. Experiments were carried out with a bituminous coal at three levels of initial water content, i.e., 0.8, 2.0, and 3.0%. Comparisons of the rates of production of carbon oxides during the oxidation experiments indicated that inherent water plays a role in chemical reactions occurring during coal oxidation. It was also found that the rate of oxygen consumption decreases with increasing water content of a sample. The current observations suggest that inherent water present in coal pores may react with carbonyl species to form carboxyl species during the oxidation process.