Release of nitrogen during thermochemical conversion of Shenhua bituminous coal under Ar, CO2, and air atmospheres

Abstract

AbstractCoal thermochemical conversion processes unavoidably generate gaseous pollutants, endangering the environment or influencing synthetic processes downstream. In order to display the differences in release behaviours of nitrogen among different coal thermochemical conversion stages, the nitrogen release characteristics of Shenhua bituminous coal under Ar, CO2, and air atmospheres were investigated using X‐ray photoelectron spectrum (XPS) and thermogravimetry‐mass spectrometry (TG‐MS). Results indicate that the reaction atmosphere has an important influence on nitrogen release. The total released mass of nitrogen when using 100 g raw coal in the whole experiment under Ar, CO2, and air atmospheres is 0.54, 0.64, and 0.75 g, respectively. The organic forms of nitrogen in raw coal and coal char are pyridine nitrogen (N‐6), pyrrole nitrogen (N‐5), quaternary nitrogen (N‐Q), and nitrogen oxide (N‐X). While in the coal ash, the sub‐peaks of N‐Q and N‐X disappear entirely, leaving only N‐5 and N‐6 sub‐peaks. The released nitrogen‐containing gas consists of NH3, HCN, NO, and NO2 during experiments in CO2 and air atmospheres. However, only NH3 and HCN are detected during experiments in the Ar atmosphere. The revolution characteristics of NH3 and HCN under Ar and CO2 atmospheres are similar.