Two-component model for catalyst deactivation
•Equations on asphaltene and coke concentrations in the catalyst pellet is studied.•Model depends on long-time of pellet deactivation and short-time of Fick’s diffusion.•The model is non-homogeneous: characteristics of a catalyst depend on space and time.•There is good correspondence between experim...
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Veröffentlicht in: | Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2019-12, Vol.378, p.122176, Article 122176 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | •Equations on asphaltene and coke concentrations in the catalyst pellet is studied.•Model depends on long-time of pellet deactivation and short-time of Fick’s diffusion.•The model is non-homogeneous: characteristics of a catalyst depend on space and time.•There is good correspondence between experimental data and obtained coke concentration.
Texture evolution of alumina hydrotreating catalyst was theoretically modeled using geometrical characteristics calculated via Monte-Carlo methods and methods of the graph theory. In the prescribed model deactivation was specified by monotonic increase of alumina grain radius, which imitated deposition of coke and metal species onto the pore surface. A novel two-component nonhomogeneous model was designed based on the diffusion of asphaltene molecules inside the cylindrical pellet according to Fick’s law and deposition of the coke particles from heavy oil on the surface of the catalyst. The model resulted in non-monotonous coke distribution with a distinct maximum in the inner region of the pellet, which, nevertheless, shifts to the center at later deactivation stages due to the higher hydrogenation performance of pellet border region. Model can be applied to describe profiles of coke depositions during deactivation process for a pellet with an arbitrary boundary. |
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ISSN: | 1385-8947 1873-3212 |
DOI: | 10.1016/j.cej.2019.122176 |