Abstract
This paper selects two typical compounds containing organic sulfur as model compounds. Then, by analyzing the chromatograms of gaseous low-temp oxidation products and GC/MS of the extractable matter of the oxidation residue, we summarizing the mechanism of low-temp sulfur model compound oxidation. The results show that between 30 °C to 80 °C, the interaction between diphenyl sulfide and oxygen is mainly one of physical adsorption. After 80 °C, chemical adsorption and chemical reactions begin. The main reaction mechanism in the low-temp oxidation of the model compound diphenyl sulfide is diphenyl sulfide generates diphenyl sulfoxide, and then this sulfoxide is further oxidized to diphenyl sulphone. A small amount of free radicals is generated in the process. The model compound cysteine behaves differently from diphenyl sulfide. The main reaction low-temp oxidation mechanism involves the thiol being oxidized into a disulphide and finally evolving to sulfonic acid, along with SO2 being released at 130 °C and also a small amount of free radicals. We also conducted an experiment on coal from Xingcheng using X-ray photoelectron spectroscopy (XPS). The results show that the major forms of organic sulfur in the original coal sample are thiophene and sulfone. Therefore, it can be inferred that there is none or little mercaptan and thiophenol in the original coal. After low-temp oxidation, the form of organic sulfur changes. The sulfide sulfur is oxidized to the sulfoxide, and then the sulfoxide is further oxidized to a sulfone, and these steps can be easily carried out under experimental conditions. What’s more, the results illustrate that oxidation promotes sulfur element enrichment on the surface of coal.
Highlights
Spontaneous coal combustion is a severe disaster ocurring widely in coal industry
It is generally acknowledged that pyrite as the main component of inorganic sulfur exerts an important effect on coal spontaneous combustion
By adopting X-ray photoelectron spectroscopy (XPS) technology, we investigated the sulfur form changes in coal samples before and after low-temp oxidation so as to further study the role organic sulfur plays in spontaneous coal combustion
Summary
Spontaneous coal combustion is a severe disaster ocurring widely in coal industry. It occurs during the coal exploitation process, and during the processes of coal transport and storage. The organic sulfur in coal will be broken down into smaller molecules, making further desulphurization easier They believe that low-temp oxidation can convert organic sulfur in coal to S=O and –SO2 groups [6,30,34]. Due to the -oxidized features of organic sulfur, people have conducted plenty of studies on desulphurization that have yielded fruitful results [34,39], but scholars have seldom researched the changes in organic sulfur functional groups during the process of coal low-temp oxidation in air [6], let alone the effect of organic sulfur on the characteristics of spontaneous coal combustion. By adopting XPS technology, we investigated the sulfur form changes in coal samples before and after low-temp oxidation so as to further study the role organic sulfur plays in spontaneous coal combustion
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
