OXIDATION OF DISPERSE CARBON MATERIALS

It is proposed to consider the process of carbon materials oxidative activation from the positions of topochemical reactions involving chemisorption of the activating agent (oxidizer) on the material surface active centers followed by chemical interaction. Such an approach makes it possible to control the process of creating a carbon material with the desired characteristics of the porous space. It is assumed that the oxidizer chemisorption active centers are amorphous carbon, which is localized on the material crystallites boundaries. The change in the length of these boundaries will lead to a change in the process rate. It is shown that the number of such active centers on the carbon material surface depends on the size of the crystallites. It will have a significant impact not only on the rate of activation, but also on the possibility of the process flow on the surface or with porosity formation. Mathematical models describing the carbon sample specific surface changing in the oxidation process are proposed. They allow quantifying the proportion of carbon that is oxidized on the sample surface or with pores formation, as well as quantifying the number of pores. It is shown that the ratio of pore formation and surface oxidation processes depends on the oxidation temperature, the oxidizer nature and its flow rate. The proportion of porosity formation decreases with the increase in the oxidant flow rate and the increase in temperature. It was experimentally shown that in order to obtain a material with a more developed porous space and a high specific surface it is preferable to use carbon dioxide as an oxidizing agent.

sorbent, specific surface, activation, oxidizer, pore formation, burn, crystallites, mathematical model

1. Henschke B., Schubert H., Blocker J., Atamny F., Schlogi R. Mechanistic aspects of the reaction between carbon and oxygen. Thermochim. Acta. 1994; 234: 53-83.

2. Sergeev V.M. Chemical interaction of carbon materials with oxygen-containing gases. Khimiya tverdogo topliva = Solid Fuel Chemistry. 1999; 6: 66-71. (in Russ.)

3. Balykin V.P. Zum einfluss der mischbedingungen auf die bildung der bindemittelschicht in kohlenstoffpech-kompositionen. Freiberger forschungshefte: Vorträge zum Bergund Hüttenmännischen Tag 1990 in Freiberg. Leipzig, 1992. S. 118-129.

4. Herawan S.G., Ahmad M.A., Putra A., Yusof A.A. Effect of CO2 flow rate on the Pinang frondbased activated carbon for methylene blue removal. The Scientific World Journal. Volume 2013. Article ID 545948, 6 pages. http://dx.doi.org/10.1155/2013/545948.

5. Efremova O.A. Catalytic regularities of gasphase oxidation of artificial carbon materials: Ph.D. (Eng.) Thesis. Chelyabinsk, 2006. 145 p. (in Russ.)

6. Baklanova O.N., Knyazeva O.A., Drozdov V.A., Gulyaeva T.I., Talzi V.P., Likholobov V.A., Surovikin Yu.V., Gorbunova O.V. Effect of the modification conditions of the carbon material Sibunit on its texture changes. Solid Fuel Chemistry. 2015; 49(1): 20-24. DOI: 10.7868/S002311771501003X.

7. Plaksin G.V., Baklanova O.N., Lavrenov A.V., Likholobov V.A. Carbon materials from the Sibunit family and methods for controlling their properties. Solid Fuel Chemistry. 2014; 48(6): 349-355. DOI: 10.7868/S0023117714060036.

8. Baklanova O.N., Likholobov V.A., Lavrenov A.V., Puchkov S.S., Pyanova L.G. Carbon materials properties regulation of the Sibunit family for catalytic and sorption applications. Proceed. of the 10th Int. Conf. “Carbon: Fundamental Problems of Science, Materials Science, Technology”. Russia, Moscow, Troitsk. 6–9 June 2016. P. 52. (in Russ.)

9. Pyanova L.G., Baklanova O.N., Likholobov V.A., Lavrenov A.V., Sedanova A.V. Modified carbon sorbents: Synthesis, properties and application. Proceed. of the 10th Int. Conf. “Carbon: Fundamental Problems of Science, Materials Science, Technology”. Russia, Moscow, Troitsk. 6–9 June 2016. P. 359. (in Russ.)

10. Mukhin V.M., Tarasov A.V., Klushin V.N. Active carbons of Russia. Moscow: Metallurgiya Publ., 2000. 352 p. (in Russ).

11. Tesner P.A., Golovina N.B., Gorodetskii A.E. Kinetics of the formation of pyrolytic carbon from methane. Khimiya tverdogo topliva = Solid Fuel Chemistry. 1976. 1: 129-135. (in Russ.)

12. Peshnev B.V., Filimonov A.S., Baulin S.V., Sledz O.S., Asilova N.Yu. The pyrocarbon formation mechanism during the hydrocarbon pyrolysis process. Tonkie khimicheskie tekhnologii / Fine Chemical Technlolgies. 2017; 12(4): 36-42. (in Russ.)

13. Filimonov A.S., Peshnev B.V., Surovikin Yu.V., Trofimova N.N., Asilova N.Yu. Carbon surface influence on the pyrocarbon formation regularities. Vestnik MITHT (Fine Chemical Technlolgies). 2014; 12(6): 99-102. (in Russ).

14. Peshnev B.V. Technology for obtaining highly absorbent materials based on carbon nanofibers: D.Sc. (Eng.) Thesis. Moscow, 2007. 288 p. (in Russ.)

15. Pechuro N.S., Pesin O.Yu., Estrin R.I., Roiter L.A. The method of complex analysis of soot (method "COMPAS"). Promyshlennost’ sinteticheskogo kauchuka, shin i rezinovikh tekhnicheskikh izdelij (Industry of Synthetic Rubber, Tires and Rubber Technical Products). 1987; 2: 16-19. (in Russ.)