Diffusional activation energy, variation

Variation of diffusional activation energy with van der Waals radius (aG) for diffusion in 4A and 5A zeolites... 

Figure 5. Variation of diffusional activation energy with carbon number for n-paraffins in 5A zeolite crystals. (Data from refs. 9, 21, 22, 29, 15.)...

FIGURE 5.12. Variation of diffusional activation energy with van der Waals diameter for diffusion in 4A and 5A zeolites and 5A molecular sieve carbon. Van der Waals diameters are estimated according to Eq. (2.5) from values of the van der Waals co-volume b) given in the Handbook of Physics and Chemistry, 55lh ed. C.R.C Press 1974, (Diffusivity data are from refs. 1-3, 48, 49,51-53, and 81.)... 

For systems in which the diffusivity ratio is smaller a more gradual variation in diffusivity and diffusional activation energy with ion exchange is predicted. The theoretical curve calculated from this model provides a good representation of the experimental data for diffusion of butane in Na-Ca zeolite A, as may be seen from Figure 5.13b. 

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