Simulation Study of Multi-Component Gas Adsorption On MSC5A by Chromatographic Method

Simulation Study of Multi-Component Gas Adsorption on MSC5A

By Chromatographic Method

K. Chihara, *M. Nomoto, Y. Amari, Y. Teramura, H. Nakamura,

Department of Applied Chemistry, Meiji University

 1-1-1, Higashi-mita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan

E-mail:chihara@isc.meiji.ac.jp

 

1. Introduction

The combination of chromatographic method and moment analysis of the response peaks is one of the useful techniques to study adsorption equilibrium and adsorption rate. Perturbation chromatography with the mixed multi component adsorbent gas carrier (two adsorbates) has been applied to several studies on adsorption. In this work, perturbation chromatography with multi component gas carrier (two adsorbates with inert gas) and non-equilibrium thermodynamics liner law was applied for discussion of the interference effect and the displacement effect (those are cross effects) on mass transfer in multi component gas adsorption as previous study  for different gas mixture (He, CO₂, C₂H₄). The study of mixed gases (C₂H₄ and CO₂) was experimented in temperature of 313K, 323K,333K. Moment analysis method and stop & go simulation method were utilized to obtain each mass transfer parameters of adsorbate gases.

2. Experiment

The apparatus was similar to a conventional gas chromatograph. Adsorbent particles (molecular sieving carbon 5A, 20/30 mesh, Japan Enviro Chemical Ltd.,) were packed in a column. Carrier gas was a mixture of two or three components among He, CO₂, C₂H₄. Perturbation pulse was introduced into the carrier gas stream. Introduction of pulses was performed by 6-way valve. The pulse size was 1cc, which meant injection period was 1.4 sec. Then pulse response was detected by TCD cell. Output signal of TCD was transmitted to a personal computer through RS232C. This signal was also transmitted to the personal computer. Simulated chromatogram by a personal computer can be overlapped on experimental chromatogram shown in the monitor screen. Further, moment of pulse response, which is shown in the monitor screen, can be automatically calculated by the personal computer.

Numerical solution for multicomponent chromatogram in time domain could be obtained by appropriate model equations with experimental conditions. This simulated chromatogram can be compared with experimental chromatogram to determine the equilibrium and the adsorption kinetic parameters. Here Markham-Benton equation as for adsorption equilibrium and linear driving force (LDF) approximation as for adsorption kinetics were adapted for numerical calculation, which was based on stop & go method. In particular, LDF model of adsorption kinetics was based on non-equilibrium thermodynamics. Overall mass transfer coefficients (Ksav) for LDF model were determined.

3. Conclusion and Discussion

Fig.1 show experimental and simulation results in an example case of binary adsorbate carrier mixed with He and an adsorbate pulse for MSC5A. Experimental conditions were 313 K, column pressure 5 atm, flow rate 25 cm/sec and He(10%)+CO₂(30%)+C₂H₄(60%)mixed gas carrier with C₂H₄ pulse.  Good agreements between experimental chromatogram and simulated chromatogram, which were based on the modeling of Stop & Go method, were observed in case of perturbation chromatography with mixed adsorbate gas carrier. There was not a big difference in comparing accounted simulation curve with not accounted simulation curve.

Fig.1 He(10%)+CO₂(30%)+C₂H₄(60%)mixed gas carrier with C₂H₄ pulse