Modelling diffusion-limited gasification of carbons by branching pore models

A kinetic model of gasification of porous carbon particles characterized by broad pore size distributions is developed. The interaction between the intrinsic kinetics of surface oxidation and intraparticle diffusion of reactants is modelled, taking into account the wide variation of local diffusivities within the pore space as the length scale of pores changes. In particular, the model considers the configurational diffusion mechanism, which dominates transport in pores whose size is of the order of the diffusing molecule size. The model is based on the iterated application of Thiele analysis to branching pore sequences of different topology. Computations are directed to investigate the sensitivity of the model to the pore space topology, to the parameters of the pore structure and to variables determining the rate of surface reaction and of intraparticle diffusion.