(395g) 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 (C₂H₄and
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 C₂H₄pulse.  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 C₂H₄pulse