This thesis is concerned with the development of sorption-effect chromatography as a rapid
method for the determination of binary gas-mixture adsorption isotherms.There are many
alternative non-chromatographic methods but these have inherent disadvantages the direct
experimental methods require excessive equilibration times and the predictive methods
require the respective pure-component isotherms and an ideal adsorbed phase. A computer
simulation has shown that for an alternative chromatographic method, good results will
only be obtained if both binary isotherms are close to linear.
Sorption-effect chromatography is characterised by the flowrate retention time (TN) which
measures the change in column inventory when a perturbation is made to the system. Along
with the standard composition retention time (Tx), this extra measurement allows the
gradient of each binary isotherm to be evaluated. Subsequent integration will give the
respective mixture isotherm. Three gas systems (nitrogen-argon, nitrogen-helium and
argon-helium) have been investigated over zeolite 5A at different temperatures. The results
confirm that the adsorbed phase amounts decrease, with increasing temperature and that
there are degrees of component interaction.
Experimentally, thermal fluctuations in the oven will cause noise on the flowrate record
making TN determination difficult. Isolation of the column from direct air flow was seen
to reduce the noise level. Also, using a computer simulation model, the heat of adsorption
for the above zeolite 5A systems will be easily dissipated preventing any unwanted gas
temperature rises; the comparatively small column diameter was found to be a significant
The employment of delay lines (empty tubes) in various locations has been investigated.
To directly determine TN it is necessary to used delay lines downstream of the column. Also,
the chromatographic method has been extended to determine mixture isotherms by
considering the change in average column pressure rather than the motion of a composition
front through the column. Delay lines situated upstream of the column are able to separate
these two effects, and preliminary results are satisfactory. However, the use of delay lines
anywhere in the system changes the measured retention times and the theory has to be
adjusted to account for this.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.