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Study on Room Temperature Oxidation Characteristics of Primary Active Sites in Low-Rank Coal from Western Mining Areas After Vacuum Desorption.

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Title: Study on Room Temperature Oxidation Characteristics of Primary Active Sites in Low-Rank Coal from Western Mining Areas After Vacuum Desorption.
Authors: Xu, Tianshuo1 (AUTHOR), Lu, Wei1 (AUTHOR) wei.lu@aust.edu.cn, Li, Jinhu1 (AUTHOR), Sun, Jianhong1 (AUTHOR), Wang, Yang1 (AUTHOR), Huang, Juejie1 (AUTHOR)
Source: Combustion Science & Technology. 2025, Vol. 197 Issue 19, p6294-6318. 25p.
Subjects: Oxidation, Carbon monoxide, Desorption, Coal mining safety, Lignite, Energy industries
Abstract: CO exceeding safety limits during room temperature oxidation (RTO) in low-rank coal mines, particularly in western regions, has garnered significant attention. This study systematically investigates the oxidation behavior of primary active sites in low-rank coal and their role in CO generation and safety limit exceedance. A vacuum desorption apparatus combining vacuum drying with cyclic oxidation technology was used to remove moisture and gases from coal samples under low-temperature, high-vacuum conditions, while accumulating oxidation gases. The oxidation process was studied comprehensively through RTO experiments across different coal types, cyclic desorption-oxidation tests on a single coal sample, and analyses using low-temperature nitrogen adsorption, XPS, and in-situ ESR. The results showed that CO and CO₂ concentrations continuously increased during RTO for all coal types. Samples subjected to vacuum desorption exhibited significantly higher oxidation activity, revealing the involvement of previously concealed active sites. As desorption cycles increased, oxidation capacity gradually weakened, with a marked decrease in the initial oxidation rate by Cycle 4, suggesting progressive depletion of exposed active sites. Changes in pore structure and functional groups indicate that pore characteristics and C-C/C-H structures influence oxidation reactions. In-situ free radical experiments revealed that when primary active sites remained intact, desorption significantly exposed concealed free radicals, particularly alkyl radicals. However, as active sites were depleted, subsequent desorption did not significantly increase free radical exposure, limiting further oxidation. CO was less affected by coal pore adsorption compared to CO₂, making it a more reliable indicator of oxidation intensity. This study provides insights into gas evolution during RTO of primary active sites in coal and offers theoretical guidance for addressing Coal spontaneous combustion and CO exceedance in low-rank coal mines. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:CO exceeding safety limits during room temperature oxidation (RTO) in low-rank coal mines, particularly in western regions, has garnered significant attention. This study systematically investigates the oxidation behavior of primary active sites in low-rank coal and their role in CO generation and safety limit exceedance. A vacuum desorption apparatus combining vacuum drying with cyclic oxidation technology was used to remove moisture and gases from coal samples under low-temperature, high-vacuum conditions, while accumulating oxidation gases. The oxidation process was studied comprehensively through RTO experiments across different coal types, cyclic desorption-oxidation tests on a single coal sample, and analyses using low-temperature nitrogen adsorption, XPS, and in-situ ESR. The results showed that CO and CO₂ concentrations continuously increased during RTO for all coal types. Samples subjected to vacuum desorption exhibited significantly higher oxidation activity, revealing the involvement of previously concealed active sites. As desorption cycles increased, oxidation capacity gradually weakened, with a marked decrease in the initial oxidation rate by Cycle 4, suggesting progressive depletion of exposed active sites. Changes in pore structure and functional groups indicate that pore characteristics and C-C/C-H structures influence oxidation reactions. In-situ free radical experiments revealed that when primary active sites remained intact, desorption significantly exposed concealed free radicals, particularly alkyl radicals. However, as active sites were depleted, subsequent desorption did not significantly increase free radical exposure, limiting further oxidation. CO was less affected by coal pore adsorption compared to CO₂, making it a more reliable indicator of oxidation intensity. This study provides insights into gas evolution during RTO of primary active sites in coal and offers theoretical guidance for addressing Coal spontaneous combustion and CO exceedance in low-rank coal mines. [ABSTRACT FROM AUTHOR]
ISSN:00102202
DOI:10.1080/00102202.2024.2427722