Adsorption of gaseous hydrocarbons on activated carbon: Characteristic kinetic curve

The internal diffusion coefficients, D i , of pure methane, ethane and ethylene as well as some of their binary and ternary mixtures, have been calculated at 20°C for solid particles of a commercial activated carbon. It has been observed that the contribution of the surface migration mechanism to the global mass transfer process inside the adsorbent particles can be as much as 70–80%. Values for the surface migration coefficient D s have also been calculated from the relation D i = D g + KD s , where K is a dimensionless mean slope factor. Values found for both coefficients are of the same order of magnitude as those reported in the literature for similar systems. All the values for the internal diffusion coefficients of these pure components and their mixtures fit into a single correlation curve, the characteristic kinetic curve of the adsorbent.