Intraparticle diffusion mechanisms in SC sunflower oil hydrogenation on Pd

Authors

  • E. Ramírez,

    1. Dept. of Chemical Engineering, ETS Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, E-08028 Barcelona, Spain
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  • M. A. Larrayoz,

    Corresponding author
    1. Dept. of Chemical Engineering, ETS Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, E-08028 Barcelona, Spain
    • Dept. of Chemical Engineering, ETS Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, E-08028 Barcelona, Spain
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  • F. Recasens

    1. Dept. of Chemical Engineering, ETS Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, E-08028 Barcelona, Spain
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Abstract

In this work, intrinsic kinetics were decoupled from reactant diffusivities in the SC sunflower oil hydrogenation reaction on Pd/C using a steady-state diffusion and chemical reaction model under isothermal conditions in order to obtain low trans and stearic final products. A numerical solution combined with nonlinear parameter fitting was employed to solve this model. First, runs with small size of catalyst (0.4 mm) allowed to obtain kinetic constants irrespective of the diffusivity settings. Then, in a second set of runs, reactions were repeated on larger sizes of catalyst (up to 1 mm), that is, in the diffusion-limited regime. The results show that while hydrogen is transported by bulk pore diffusion, the oil seem to diffuse by surface diffusion. Diffusivity of H2 is about 10 times that of triglycerides. The overall diffusivity for triglycerides is about 10−8 m2/s, and changes 3 times with an increase in pressure, and 20 times with an increase in T. Linoleate selectivity (SLO) and specific isomerization (Si) also improve with decreasing the diffusion path. © 2005 American Institute of Chemical Engineers AIChE J, 2006

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