THE KINETICS OF GASIFICATION OF MICROPOROUS CARBON WITH OXYGEN - A FRACTAL APPROACH

The kinetics of gasification of Sibunit synthetic carbon with oxygen i s studied at T = 480-550 degrees C. The apparent activation energy of the process is E-a = 155 +/- 15 kJ/mol at a degree of gasification x b elow 0.7. The classical and fractal analyses of the data obtained by t he transmission electron microscopy, small-angle X-ray scattering, and low-temperature nitrogen adsorption techniques are used to study vari ations in the structure of Sibunit carbon during its gasification. The kinetics of gasification is controlled by two competing factors: a sm oothing of the carbon surface during gasification, which is accompanie d by a decrease in the gasification rate, and an increase in the surfa ce area of the pores accessible to the reactant, which, in contrast, c auses an increase in the gasification rate. A Monte Carlo simulation o f gasification of Sibunit carbon by reactive consumption of a determin istic fractal cluster shows that the assumptions on the chemical unifo rmity of the cluster surface and on the existence of a fractal system of pores make it possible to adequately model the kinetics of gasifica tion and variations in the structure of this carbon material at x > 0. 2.