Relationship between Organic Sulfur Occurrence and Coalification Stage: Insights from Thermodynamic Simulation and X-ray Photoelectron Spectroscopy

Abstract

Organic sulfur in coal can pollute the atmosphere due to the emission of SO x gas during coal combustion and utilization. Although the relative distributions of the different organosulfur functional groups change with progressive coalification (maturity), how these groups are incorporated in the macromolecule structures of coals and the role they play in the coalification process remain ambiguous. The purpose of this study, then, is to elucidate these relationships by using thermodynamic simulation with a reactive force field program, calculation of the C–S bond dissociation energies of four types of organosulfur functional groups, X-ray photoelectron spectroscopy (XPS) analysis of seven coal samples, and published data to determine the changes in the types and proportions of organosulfur functional groups in three coalification stages (0–1, 1–2, and >2% Ro). The results show that the bond stabilities follow the order Cal–S < S–S < Car–S. Disulfides and thioethers occur in lower contributions in the coalification stage of 0–2% Ro, while mercaptans present in a relatively higher proportion. The contribution of sulfone increases and exceeds a half in organosulfur at 1–2% Ro; the major role of sulfur turns from edge bond (0–1% Ro) to bridge bond (1–2% Ro) gradually. Thiophene decreases in the 0–1% Ro coalification stage and increases in relatively high proportions in the 1–2% Ro coalification stage. When the coalification stage is above 2% Ro, the contributions of sulfides, sulfone, and mercaptan decrease, while that of thiophene increases, and sulfur gradually acts as a thiophenic ring bond. These results demonstrate that the role of organosulfur in the macromolecular skeleton of coal changes with progressive coalification.

Improving Li–S Batteries by a Separator Decorated with Ternary Metal Organic Frameworks from Spent Li-Ion Batteries

“…The strong S 2p3/2 contributions at 160.2 (S T –1 ) and 161.4 eV (S B 0 ) indicates the presence of long-chain LiPSs around 2.3 V. However, the S T –1 and S B 0 peaks almost vanished when discharged to 2.1 V due to the consumption of the long-chain LiPSs. It proves the fast and complete LiPSs conversion of NCM-MOFs . Furthermore, it is obvious that the peak representing thiosulfate undergoes a significant decrease from 2.3 to 2.1 V. Similar results were also observed in Nazar et al’s work that may provide a sideview of the highly efficient thiosulfate conversion during the charge–discharge process.…”

“…It proves the fast and complete LiPSs conversion of NCM-MOFs. 49 Furthermore, it is obvious that the peak representing thiosulfate undergoes a significant decrease from 2.3 to 2.1 V. Similar results were also observed in Nazar et al's work 50 that may provide a sideview of the highly efficient thiosulfate conversion during the charge−discharge process.…”