258784 Azeotropic Adsorption Equilibrium of Mixed Organic Solvent On FAU Type High Silica Zeolite - Interpretation by Molecular Simulation and Do's Method

Tuesday, October 30, 2012
Hall B (Convention Center )
Taira Tatsuharu1, Chihara Kazuyuki2, Yamada Natssuki2, Suzuki Yusuke2 and Duong D. Do3, (1)science and engineering, meiji university, Kawasaki, Japan, (2)Science and Engineering, Meiji University, Kawasaki, Japan, (3)School of Chemical Engineering, University of Queensland, Brisbane, Australia

Azeotropic Adsorption Equilibrium of Mixed Organic Solvent on FAU Type High Silica Zeolite - Interpretation by Molecular Simulation and Do's method -

Kazuyuki Chihara*, Tatsuharu Taira, Natsuki Yamada, Yusuke Suzuki, Duong D. Do

Department of Applied Chemistry, Meiji University, Kawasaki, Kanagawa 214-8571, Japan

Fax: +81 - 44 - 934 - 7197 E-mail:chihara@isc.meiji.ac.jp

ABSTRACT

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 ethanol 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 ethanol 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 "2) by the Sorption simulation of binary adsorption equilibria for the system of EtOH-TCE(Fig.1). One phase containes EtOH and TCE (phase 1), and the other phase containes only EtOH (phase 2). The coordinates of two sites were determined. The ratio of EtOH 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. Total adsorption isotherm was observed as total of both phase shown as X-Y diagram as follows.

Binary adsorption equilibria for the system of EtOH-TCE of total concentration of 10000ppm are shown in Fig.2 and Fig.3 in form of X-Y diagram (X is the mole fractions of gas phase concentration of EtOH. Y is the amount adsorbed of TCE / total amount adsorbed). Fig.2 shows the experimental result. Fig.3 shows the simulation result.

Fig.1 Appearance of ethanol and trichloroethylene that adsorbs zeolite

image003.gifimage002.gif

Fig.2 The experimental result              Fig.3The simulation result

Total concentration of 10000ppm           Total concentration of 10000ppm

Reference list

Duong D Do,Adsorption Analysis:Equilibria and Kinetics.Imperial College Press,London(2000)

 


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