Applications of single pellet theory to the modeling of fouling deactivation of heterogeneous catalysts
Thesis/Dissertation
·
OSTI ID:5600017
A simple pore filling model is developed for fouling deactivation of microporous catalysts under conditions of no axial diffusion. This model is then extended to include effects of intraparticle diffusion, pore shape, and nonuniform initial activity distributions. Three different types of fouling deactivation are considered: (1) Inactive fouling - fouling involving only physical deposition on the catalyst: (2) Active fouling - fouling in which new active sites are created by the deposit; and (3) Hardshell fouling - active fouling limited to the surface of the deposit. For each fouling mechanism, the macropore-filling model gives a simple analytic expression for average pellet activity which utilizes Thiele-type parameters. The model is compared against published experimental data for deactivation by coking and deactivation by demetallation (in petroleum residue hydrodesulfurization processes). The model gives good qualitative and quantitative results for both single pellets and ideal reactors. Because of its mathematical simplicity and relative accuracy, the macropore filling model is particularly suitable for use in reactor design. The question of the existence of an optimal pore size for residual hydrodesulfurization catalysts is also examined using the pore filling model. When the fouling deactivation which occurs during hydrodesulfurization is accounted for, the existence of a unique optimal pore size becomes questionable.
- Research Organization:
- Cincinnati Univ., OH (USA)
- OSTI ID:
- 5600017
- Country of Publication:
- United States
- Language:
- English
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