Dehydration of THF Using Different Zeolites

Malmali, Mohammad Mahdi | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40928 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Molaei Dehkordi, Asghar
  7. Abstract:
  8. The aim of this work was to investigate the performance of different kinds of Linde type A zeolite (LTA) for the dehydration of Tetrahydrofuran (THF)-water solution. Batch experiments were carried out to evaluate the effect of various operating parameters such as contact time, initial concentration, mixing temperature (10, 15,and 25 C), amount of adsorbent, and zeolite type(3A, 4A, and 5A zeolites). In theoretical studies, we took the advantage of several types of equilibrium model isotherms such as Langmuir, Freundlich, Dubin-Kaganer-Radushkevich (DKR) to describe the experimental adsorption data. Besides, three adsorption kinetic models including pseudo-first-order, pseudo-second-order, and intraparticle diffusion were used to obtain adsorption kinetic trends. The experimental data is in an appropriate agreement with modeling results. From experimental results it was found that Linde type A zeolites have promising capability for adsorption of water from liquid solution efficiently. Besides, The adsorption of tetrahydrofuran (THF) + water mixture on zeolite molecular sieves was carried out using a fixed-bed column. A pore diffusion model (PDM) was proposed to predict the adsorption breakthrough curves in a fixed bed with respect to initial concentrations and feed flow rates. The equilibrium behavior was shown to fit a Langmuir isotherm. A mathematical modeling for the adsorption process is developed and illustrated for THF- water mixture. The model deals with the effect of axial dispersion and inter- and intraparticle mass-transfer resistances at isothermal operating conditions. Four types of molecular sieves (3A, 4A, 5A, and 13X) were used. Orthogonal collocation was used to solve the coupled non-linear parabolic partial differential equations for simultaneous adsorption, which include the effects of axial diffusion in the fluid, the film resistance, and internal diffusional resistance of particles. Felberg’s Runge-Kutta methods were used to solve the dimensionless 4N-coupled ordinary differential equations. Moreover, the influences of the bed Reynolds number, Peclet number, and the diameter of the spherical molecular sieves on the breakthrough curve were investigated.

  9. Keywords:
  10. Drying ; Adsorption ; Dehydration ; Molecular Screens ; Zeolite ; Packed Bed Column ; Orthogonal Collocation

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