Transformation of sulfur and nitrogen during Shenmu coal pyrolysis

• Published in: Fuel (Guildford) 2018-11, Vol.231, p.134-144
• Main Authors: Hou, Jili, Ma, Yue, Li, Shuyuan, Shi, Jian, He, Lu, Li, Jia
• Format: Article
• Language: English
• Subjects: Benzothiophene; Carbonyl sulfide; Carbonyls; Coal; Coal tar; Dibenzothiophene; Hydrogen sulfide; Nitrogen; Nitrogen compounds; Pyrolysis; S/N transformation; Sulfates; Sulfur; Sulfur compounds; Sulfur dioxide; Tar; TG/GC-FTIR-MS; XPS
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2018.05.046

•Transformations of S/N were comprehensively analyzed during coal pyrolysis.•The proportion of sulfate and thiophenic sulfur increased with temperature rising.•Pyrrolic nitrogen transformed to the more stable pyridinic nitrogen after 500 °C.•S/N mainly remained in semicoke and less distributed in coal tar and gas. Transformation of sulfur and nitrogen and properties of pyrolysates (semicoke, retorting gas, coal tar) during Shenmu coal pyrolysis were investigated using XPS, TG-FTIR-MS, GC–MS and GC-PFPD. The results showed that total sulfur content in the semicoke decreased gradually and turned to sulfate sulfur and thiophenic sulfur with increasing pyrolysis temperature. In Shenmu coal, predominant nitrogen species consisted of pyrrolic and pyridinic compounds. Total nitrogen content was decreased, resulting from mutual conversion of different nitrogen compounds. The composition of retorting gas from TG-FTIR indicated that H2S began to release at 400 °C and reached maximum at about 600 °C. This trend was consistent with the release of carbonyl sulfide (500–650 °C) and SO2. GC-PFPD analysis revealed that detected sulfur compounds in coal tar were benzothiophene, dibenzothiophene and thiophene with the contents of 0.141%, 0.110% and 0.0004%, respectively. In coal tar, 57 kinds of nitrogen-containing compounds were identified using GC–MS, in which basic nitrogen was 0.90% and non-basic nitrogen was 0.23%.