(694f) Pure and Binary Adsorption of 1,2,4 Tri Methyl Benzene and 1,3 Di Isopropyl Benzene On Alumina

The adsorption of large molecules on adsorbents is very limited in the adsorption literature. In this study we report on the adsorption of pure compounds 1,2,4 tri methyl benzene and 1,3 di isopropyl benzene on Alumina, followed by the adsorption of different combinations of  mixtures of the components.

A new apparatus and experimental technique has been designed for this study. An adsorption column 12 inches in length and 1 inch diameter is filled with AA-300 2.5 X 4 mesh Alcan Activated Alumina and placed in an oven. Two helium lines are connected to the column. One helium line is passed through a 0-50 ml flowmeter, thence through a bubbler of either liquid the exit of which passes through a gas coalescer in preparation for entry into the column. The bypass helium line is fitted with a microvalve controller for flow adjustment, combined with the first helium line and then both streams enter the column as one. The outcome of the column is monitored with a PROLAB mass spectrometer.

The Alumina column is activated at 270 °C for 6 hours by passing helium only using the bypass line. After activation the column is isolated and the oven temperature adjusted to the isotherm temperature. For isotherm measurement, the bubbler flow is minimized and monitored and the bypass helium line flow is maximized. Fifteen minutes are used for coalescer wetting during which the outlet is not fed to the column. Then the system is opened to the alumina column and mass spectrometer and the starting time noted. The flow is fed to the column until steady state is achieved with the outlet pressure being recorded. The bypass flow is reduced by 2 units on the microvalve, and additional loading enters the column until a new equilibrium pressure is established. This procedure is continued for 5 to 7 steps until the bypass flow is turned off. All the time the flow through the bubbler is maintained constant and continuously monitored. The final outlet recorded pressure is the equilibrium pressure from the bubbler. From mass balances at each step, the equilibrium loading at the various pressures can be established after allowance for a dead volume calibration. The system is regenerated in preparation for the next isotherm measurement. For the measurement of binary isotherms a second bubbler is employed and a similar procedure employed..

The system will be modeled using the isotherms employed by Brandani et al. (2003).

Reference

Brandani, F., D. M. Ruthven, and C. G. Coe. "Measurement of adsorption equilibrium by the zero length column (ZLC) technique. Part 1: Single component systems." Ind. Eng. Chem. Res., 2003: 1451-1461.

KEYWORDS:, pure isotherms, binary isotherms, 1,2,4 tri methyl benzene, 1,3 di isopropyl benzene Alumina,