X-ray photoelectron spectroscopy investigation of nitrogen and sulphur functionalities during pyrolysis of Dongqu coal mine and Yachen coal mine of Shanxi province

In this paper, samples from Dongqu coal mine and Yachen coal mine in Shanxi Province were pyrolysed at 300 to 900°C. The X-ray Photoelectron Spectroscopy (XPS) was carried out to study the occurrence characteristics of nitrogen and sulphur in raw coal and semi-coke coal at different temperatures. The results showed that with the increase of pyrolysis temperature, pyrrole transforms into pyridine; quaternary nitrogen content decreases gradually; and nitrogen oxide content increases first and then decreases at high temperatures. The inorganic sulphur in coal is transformed into organic sulphur at high temperatures, and thiol (thioether) and pyrite in both coals are decomposed completely at 600°C. Desulphurisation should focus on unstable and abundant inorganic sulphur. Understanding the occurrence characteristics and transformation rules of nitrogen and sulphur in coal through the results of this study is of great significance for promoting coal processing and utilisation, and reducing environmental pollution. [Received: January 14, 2024; Accepted: July 07, 2024]