Characterization of dynamic adsorption regimes in synthetic and natural porous structures using lattice Boltzmann simulations.

This paper presents the first systematic study on the characterization of dynamic adsorption regimes of gas in porous media using the ratio of inter- to intraparticle diffusion coefficients. The effect of the ratio between the two diffusion coefficients on the adsorption dynamics was investigated in combination with the adsorbent particles size and the disorder parameter, which numerically describes pore space heterogeneity, by mathematical modelling using the lattice Boltzmann simulations for fluid flow and the convective-diffusive transport of an adsorbate dissolved in a fluid. To characterize the dynamic adsorption regimes, for the first time, a relationship between the surface and total adsorption amount was used. The obtained results during simulations in two-dimensional synthetic porous structures showed that the size of the adsorbent particle strongly affects the surface and the total adsorption dynamics. An increase in the particle size promotes an increase in the rate of surface adsorption. Depending on the ratio of inter- to intraparticle diffusion coefficients, increasing particle size promotes either an acceleration or slowdown of the total adsorption dynamics. The results revealed in two-dimensional structures were verified by simulations in three-dimensional digital models of natural sandstones, which were obtained using X-ray computed tomography. • Adsorption dynamics regimes are characterized using diffusion coefficients. • Reducing particle size can both speed up and slow down total adsorption dynamics. • Pore space heterogeneity decelerates total adsorption dynamics. • The results obtained for 2D structures are validated for 3D natural rocks. [ABSTRACT FROM AUTHOR]