Analysis of the Process of Methane Pyrolysis in

Polydisperse Porous Medium

I.L. Maikov and V.M. Zaichenko

Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13/19, Moscow, 125412, Russia

Abstract

The paper deals with the results of theoretical investigation of the process of methane pyrolysis an a polydisperse medium. A separate porous particle (macroparticle) is treated and this particle consists of different microparticles, which intersect randomly. A kinetic equation is used to describe the dynamics of a polydisperse system of microparticles in the process of methane pyrolysis. The reaction rate on the reaction surface of the particle is of the order of n with respect to the gas reactant. The reactant is delivered to the porous macroparticle via external diffusion layer outside of the particle and internal diffusion layer in the particle pores. A generalization of the expression for porosity for a polydisperse medium is made. Comparison is made of the times required for filling the pores for different initial size distributions of particles. A general analytical expression is derived describing the dependence of variation of the inner reaction surface on the degree of metamorphism of the porous skeleton for an arbitrary initial size distribution of particles. Comparison is made of the dependences of the degree of metamorphism of porous skeleton on dimensionless time for different initial distributions, namely, monodisperse, uniform, and normally logarithmic with varying dispersion. It has been demonstrated that a polydisperse medium may be described by an effective structure parameter.