GAS-ADSORPTION ISOTHERMS FROM COMPOSITION AND FLOW-RATE TRANSIENT TIMES IN CHROMATOGRAPHIC COLUMNS .1. BASIC THEORY AND A BINARY EXPERIMENTAL TEST

The theory of a new method of determining multicomponent gas adsorptio n isotherms is outlined. The method involves making a perturbation to the composition of a particular mixture of gas flowing through a chrom atographic column and recording the variation with time of the flow-ra te: in addition to the variation of the composition, of the gas leavin g the column. Proper interpretation of these measurements enables the change in adsorption of all of the components in the column to be dete rmined. As an illustration; an experimental apparatus was built to det ermine the adsorption of nitrogen-argon mixtures on 5A molecular sieve at 50 degrees C. The method is potentially fast, possibly taking only a few minutes for each composition. For a particular carrier gas comp osition, the change in composition was made in two ways: one by adding a small stream of argon, and the other by adding a small stream of ni trogen. Comparison of the results obtained by these two experiments sh owed a systematic difference between them. This difference was probabl y due to the pressure in the column changing when the small stream of perturbation gas was added.