Diffusion in multicomponent gas adsorption on MSC5A, chromatographic study
1. Introduction The combination of chromatographic method and moment analysis of the response peaks is one of the useful techniques to study adsorption equilibrium and adsorption rate. Perturbation chromatography with the mixed multi component adsorbate gas carrier (two adsorbates) has been applied to several studies on adsorption. In this work, perturbation chromatography with multi component gas carrier (two adsorbates with inert gas) and non-equilibrium thermodynamics liner law was applied for discussion of the interference effect and the displacement effect (those are cross effects) on mass transfer in multi component gas adsorption. Moment analysis method and stop & go simulation method were utilized to obtain each mass transfer parameters of adsorbate gases. Dependency of micropore diffusion on amount adsorbed and correlation of micropore diffusion with chemical potential driving force for microporous adsorbent were discussed. Also, cross effect were discussed. Ruthven already pointed the dependency of micropore diffusivity on amount adsorbed in single component adsorption. Tondeur et al gave general background on multi component perturbation chromatography for the first moment only.
A chromatographic study of diffusion of single components and binary mixtures of gases in 4A and 5A zeolites
Results of a chromatographic study of diffusion of light hydrocarbons and other permanent gases in 4A and 5A zeolites are reported. The data for CF4 and iC4Hm, on 4A sieve (no penetration of the zeolite lattice) suggest that micropore diffusion occurs primarily by a Knudsen mechanism. The majority of the measurements were made with small particles of crushed commercial pelleted zeolites under conditions of intracrystalline diffusion control. The dominance of intracrystalline resistance is shown by the similarity in the time constants obtained with different sizes of particle and the results are generally consistent with earlier gravimetric data. The data for the binary systems containing two adsorbed species are consistent with the simple hypothesis that each species in the mixture diffuses independently with the same intrinsic mobility as for single component diffusion at the same temperature. However, the actual diffusivity of a species in the binary mixture may differ from the pure component diffusivity due to differences in the form of the quilibrium isotherms. 
 
 
 
On presente les resultats d'une etude chromatographique de la diffusion d'hydrocarbures legers et d'autres gaz permanents dans des zeolithes 4A et 5A. Les resultats, dans le cas du CF4 et de l'iCH4Hm, sur le tamis moleculaire 4A (absence de penetration du reseau de la zeolithe), suggerent que la diffusion dans les micropores se fait essentiellement par un mecanisme de Knudsen. On a fait la majeure partie des mesures en employant des petites particules de zeolithes commerciales, pelletisees et broyees dans des conditions impliquant le controle par la diffusion intracristalline. La predominance de la resistance intracristalline est indiquee par la similitude des constantes de temps obtenues avec des particules de differentes dimensions et par le fait que les resultats correspondent de maniere generale avec des donnees gravimetriques obtenues anterieurement. Les donnees relatives aux systemes binaires contenant deux composants adsorbes sont conformes a l'hypothese simple selon laquelle chaque composant du melange diffuse independamment avec la měme mobilite intrinseque que lorsqu'il s'agit de la diffusion d'un simple composant a la měme temperature. Toutefois, la diffusivite effective d'un composant dans le melange binaire peut differer de la diffusivite du composant pur, par suite de differences dans la forme des isothermes d'equilibre.
Rates of sorption and diffusion of hydrocarbons in zeolites
The kinetic patterns of sorption, desorption, and sorbate exchange have been studied for several C2-C5 hydrocarbons in synthetic zeolites of the mordenite, T and Y structures. The rate observations can best be represented by a model of sorption on interstitial sites in the solid, rather than by a model based on the analogy with macroporous sorbents. Two cases of interstitial diffusion have to be distinguished for this purpose. The number of vacant sites changes in time during the process of sorption, whereas it can remain constant if one sorbate is exchanged against another one. Rate measurements for both types of processes are reported and their interrelation is discussed.