380778 Study about Adsorption Equilibrium of Azeotropic Mixture on FAU Type High Silica Zeolite - Interpretation By Molecular Simulation and Do's Method -
Study about Adsorption Equilibrium of Azeotropic Mixture on FAU Type High Silica Zeolite- Interpretation by Molecular Simulation and Do's method -
Kazuyuki Chihara*, Shintaro Kume, Natsuki Yamada, Tatsuharu Taira, Duong D. Do
In recent years, instead of the chlorofluorocarbon specified as the ozone-depleting substance, a chlorinated organic compound, hydrocarbon, alcohol, etc. are used as an alternative washing solvent, and they are used as a mixed solvent in many cases. Therefore, adsorption operation of binary systems is needed. Furthermore, since azeotropic adsorption may happen, in the case of the design of a solvent recovery system and operation, those adsorption equilibria are required as basic data. IAS theory can't treat the azeotropic adsorption. We applied the method of treating the azeotropic adsorption, that is, to treat the adsorbed phase as a combination of two independent adsorbed phases, and the IAS theory is applied for each adsorbed phase (Do, 2000).
In this study, the adsorption equilibrium of the FAU type high silica zeolite was obtained by analyzing the adsorption phenomenon, using a Gravimetric adsorption experiment device and a molecular simulation. The adsorbate used was 2-propanol and trichloroethylene, which are the system of azeotropic mixture. The experiments were carried out using a batch system with circulation flow of the adsorbate mixture around the adsorbent to prevent the concentration distribution in gas phase, changing the total concentration and composition of 2-propanol and trichloroethylene, by stepwise dosing of mixed solvent vapor. For this system, one azeotropic point appeared. Simulation module in Materials Studio (Accelrys Inc.) was used throughout MC simulations. It calculated by the Sorption module, and the adsorption isotherm was obtained.
Two kinds of adsorption site or adsorption phase were observed in the cell (25.08 x 25.08) by the Sorption simulation of binary adsorption equilibria for the system of IPA-TCE (Fig.1). One phase containes IPA and TCE (phase 1), and the other phase containes only IPA (phase 2). The coordinates of two sites were determined. The ratio of IPA amount adsorbed on both sites were counted from the simulated adsorbed cell. The ratio was found to be constant through the simulation. Using this constant ratio, the simulated or experimentally obtained amount adsorbed were divided for phase 1 and 2. Then adsorption isotherms were determined for both phases. Phase 1 was expressed as extended Langmuir. Phase 2 was expressed as Langmuir.
Fig.1 Appearance of 2-propanoll and trichloroethylene that adsorbs zeolite
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