Investigation into the Relationship between Oxygen-Containing Groups and the Release of Na and Cl during Preoxidation and Pyrolysis of Na-Enriched Zhundong Coal

Abstract

Following the low-temperature preoxidation of Zhundong coal, the relationship between oxygen-containing functional groups and the release of Na and Cl during pyrolysis was systematically investigated using a one-stage quartz fluidized-bed/fixed-bed experimental system. The different forms of Na were quantified by sequential extraction and inductively coupled plasma optical emission spectrometry (ICP-OES), while the different forms of Cl were quantified using the Eschka method and X-ray photoelectron spectroscopy (XPS). Fourier transform infrared (FTIR) spectroscopy was also employed to characterize the functional groups. During oxidation at 200 °C, large quantities of Cl were released, and oxygen-containing functional groups were produced. In addition, inorganic Na was converted into organic Na through ion exchange between Na and the oxygen-containing groups. In this study, NaCl was loaded onto the acid-washed coal sample, but it was found that the release of Na and Cl was not coordinated during pyrolysis...