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Modeling Catalyst Deactivation in Catalytic Wet Air Oxidation of Phenol in Fixed Bed Three-Phase Reactors

Golestani, Akram | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40443 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Kazemeini, Mohammad; Khorasheh, Farhad
  7. Abstract:
  8. In the present work, wet air oxidation of phenol over 7/3 MnO2/CeO2 composite oxide catalyst in trickle-bed and packed-bubble column reactors was modeled. Complexity of wet air oxidation reactions and catalyst poisoning with carbonaceous groups, on the surface and in the pores of catalyst, make the modeling process complicated. Plurality of mass balance equations which are confirmed in the catalyst pellet and in dynamic and static bed phase, also the equation of catalyst deactivation, lead us solve them simultaneously. In addition, the equations are two dimension and unsteady state and carbon of oxidation intermediates are present which make the modeling process more complicated. We are facing with diffusion and reaction in liquid mass balance equations and with variety of mass transfers between dynamic and static liquid zones. The main problem for solving the equations is the plurality of hydrodynamic parameters. The presence of dynamic and static mass transfer coefficients between liquid and catalyst surface, mass transfer coefficients between dynamic and static zones, liquid axial dispersion coefficient, liquid holdups and wetting efficiency are increased our difficulties. The variation of dynamic and static phenol concentrations and the phenol concentration in catalyst pellet are obtained. Also, the variation of catalyst deactivation with time in radial pellet distance and bed height are determined. In this project, we investigated effective factors on phenol conversion and catalyst life time in both trickle-bed and packed-bubble column reactors which finally lead us to the same results. Accordingly decreasing the inlet phenol concentration, superficial liquid velocity and catalyst pellet diameter result in increasing catalyst life time and conversion rate. With increasing wetting efficiency and dynamic mass transfer coefficient, the phenol conversion will increased but catalyst deactivation will severely decreased. Ultimately, we found that both trickle-bed and packed-bubble column reactors have same operation in catalyst deactivation process and the only difference between them is the rate of their phenol conversion which is higher in packed-bubble columns
  9. Keywords:
  10. Phenol ; Catalytic Activity ; Trickle Bed Rector ; Bubble Column ; Wet Air Oxidation

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