Studies On Multicomponent Adsorption Equilibrium Of Gas Mixture On Porous Solids

The theory of gas mixture adsorption is the thermodynamic basis of the adsorption process design. Most models available are based on an assumption that the adsorbed phase is a sort of saturated liquid. Such models achieved some degrees of success and, of course, had some limitation. In addition, these models are still not sufficiently verified due to the lack of experimental data of multicomponent adsorption.A new set of experimental equilibrium data of a four-component gas mixture were complemented in this dissertation. Adsorption isotherms of pure CO2, CH4, N2 and H2 on activated carbon JX-101 were firstly collected with a volumetric method for 283-328K and pressures up to 30×105Pa. Then the adsorption equilibrium data of the CO2-CH4-N2-H2 mixture of various composition on the same activated carbon were collected with a dynamic method for a temperature range 283K to 328K and up to pressure 30×105Pa.Eight models to predict multicomponent adsorption equilibrium were selected from literature and tested with the new set of experimental data and their prediction performance was evaluated with the experimental data. It was shown that all models made a poor prediction for H2 adsorption, but the average relative error of prediction of the MPSD model is relatively stable, and the FHVSM model yielded the least error for the mixture composed of supercritical components. A new method was proposed to predict the adsorption equilibrium of gas mixture. The difference in the adsorption mechanism between the sub- and supercritical components, the surface heterogeneity of adsorbents and the molecular interaction between the adsorbates were all accounted for in the proposed model. Prediction performance of the new model was verified with the new set of experimental data as well as the data published previously in literature. Improvement in the prediction of equilibrium adsorption was shown for a wide variety of gas mixture. Therefore, the new model can be applied for the prediction of adsorption equilibrium of mixtures composed of sub- and/or supercritical gases on activated carbons.