Spontaneous Combustion Risk of Coal-based Activated Carbon

ABSTRACT

Coal-based activated carbon (CBAC) is widely used in several industrial processes and daily life, however, it is susceptible to spontaneous combustion during storage and transportation. Therefore, it is essential to probe the spontaneous combustion risk of CBAC. The oxidation process of briquetting material sample (BM), carbonized material sample (CM), and activated material sample (AM) was studied via thermogravimetric (TG–DTG) analysis. The oxidation mechanism of the samples was investigated via the proximate and ultimate analyses, Fourier transform Infrared (FTIR) spectroscopy, and nitrogen adsorption. Kinetic characteristics of the samples during the combustion were determined using the Kissinger–Akahira–Sunose (KAS) method. Five characteristic temperature points and the five stages of the samples during oxidation were obtained. With an increase in the heating rate, the hysteresis phenomenon was observed during thermal decomposition and combustion of AM in TG–DTG curves. The heating value of BM, CM, and AM were 6678, 6705, and 6776 cal g^–1, respectively. AM has a developed pore structure that leads to enhanced oxygen adsorption and limited heat transfer, easy to induce spontaneous combustion. The main functional groups of AM were hydroxyl groups and aromatic hydrocarbons, especially hydroxyl groups that played a key role in the spontaneous combustion of AM. The apparent activation energy (E_a) during the combustion of BM, CM, and AM were 110.70, 85.90, and 111.80 kJ mol^–1 from the KAS method, respectively. These results are expected to facilitate a better understanding of CBAC spontaneous combustion.

KEYWORDS:

• Thermal analysis
• characteristic temperature
• kissinger–akahira–sunose
• apparent activation energy
• functional group

Acknowledgments

This work was supported by the National Natural Science Foundation of China [grant number: 51974233].

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Funding

This work was supported by the National Natural Science Foundation of China [51974233].