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Communications on the theory of diffusion and reaction - VI. The effectiveness of spherical catalyst particles in steep external gradients

✍ Scribed by I. Copelowitz; R. Aris

Publisher
Elsevier Science
Year
1970
Tongue
English
Weight
824 KB
Volume
25
Category
Article
ISSN
0009-2509

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✦ Synopsis

When a spherical catalyst particle in which a non-isothermal reaction is taking place is subject to a very steep gradient of external conditions, its effectiveness factor is a function of these gradients as well as of the Thiele modulus evaluated for equatorial conditions. It is shown how the effectiveness factor can be calculated for the asymptotic cases of small and large Thiele modulus. For endothermic reactions a knowledge of the asymptotic ratios suffices to give a reasonably good approximating formula. For exothermic reactions a useful approximation to the effectiveness factor curve can be sketched. An external gradient tends to stabilize the reaction in the sense of reducing the range of Thiele modulus in which more than one steady state obtains.

πŸ“œ SIMILAR VOLUMES

Communications on the theory of diffusio
Communications on the theory of diffusion and reactionβ€”VIII Variational bounds on the effectiveness factor
✍ S. Rester; R. Aris πŸ“‚ Article πŸ“… 1972 πŸ› Elsevier Science 🌐 English βš– 932 KB

It is shown how upper and lower bounds to the effectiveness factor may be obtained by variational methods. The formulae are developed to be capable of handling mass transferresistance at the surface of the catalyst particle, a diffusion coefficient which depends upon position in the particle, and a

Communications on the theory of diffusio
Communications on the theory of diffusion and reaction β€” IV Combined effects of internal and external diffusion in the non-isothermal case
✍ B. Hatfield; R. Aris πŸ“‚ Article πŸ“… 1969 πŸ› Elsevier Science 🌐 English βš– 664 KB

If there 1s both internal and external resistance to the transfer of heat and matter to a catalytic pticle some mterestmg combmatlons of effects may arise Since multiple steady states can be obtained when only one of the resistances IS considered, there IS a range of parameters for which five steady