Fig. 1. The five steps are (a) CO2 molecule diffusion from
the bulk gas phase to the exterior of gas film (bulk diffusion), (b)
CO2 molecule diffusion through the gas film (film diffusion), (c)
CO2 molecule diffusion in the pore among the agglomerate particles
(interparticle diffusion), (d) CO2 molecule diffusion in the pore
among the crystalline grains (intraparticle diffusion) and (e) CO2
molecule interacts with the adsorbent (surface adsorption).