Porous structure features of carbon materials with extended-surface

The article provides a general overview of the production methods and applications of carbon materials with a large specific surface area. The following materials were taken as objects for the study: SK-AG-3 granular activated carbon produced by OJSC «Sorbents of Kuzbass», Kemerovo, activated cellulose fiber produced by the Krasnoyarsk Chemical Fiber Plant after carbonation, graphitization, and gas-phase activation at 900 °C in carbon dioxide current, Busofit-T carbon fabric produced by OJSC «SvetlogorskKhimvolokno», thermally expanded fluorinated graphite produced by OJSC «Siberian Chemical Combine». The porous structure of these materials was investigated by low-temperature volumetric nitrogen adsorption at the ASAP 2020 unit. Nitrogen adsorption-desorption isotherms were recorded in a relative pressure range of p/p0 = 0.05÷1.0 at 77 K. The specific surface area was estimated by the BET method based on the adsorption isotherm at p/p0 = 0.05÷0.30. The specific surface area was 485, 1241, 1156 and 290.5 m2/g for activated carbon, activated carbon fibers, Busofit-T fabric and thermally expanded graphite, respectively. The volume of mesopores and their size distribution were calculated by the Barrett-Joyner-Нalenda (BJH) method in a pressure range of p/p0 = 0.35÷0.95. The volume of micropores and their size distribution were calculated by the Horvath-Kawazoe method using the nitrogen adsorption-desorption isotherm in a relative pressure range of p/p0 = 0.00÷0.01. These methods were also used to determine the average diameter of mesopores and micropores. A comparative analysis of the results obtained was carried out. A relationship between the internal structure of the investigated materials and the porous structure properties was traced. It was shown that activated carbon, fibers, and carbon fabrics are microporous materials, and thermally expanded graphite has a mesoporous structure.