Page 195 - Gas Adsorption Equilibria

Chapter 4

VOLUMETRIC – GRAVIMETRIC
MEASUREMENTS

Abstract Combined volumetric and gravimetric measurements allow one to determine the
coadsorption equilibria of binary gas mixtures without sorptive gas analysis, i. e.
without using a gas chromatograph or mass spectrometer. The experimental setup,
a basic theory and several examples of this method are presented. Two
modifications of it, namely densimetric – gravimetric and densimetric - volumetric
measurements are outlined. These especially are suited to do quick but still
accurate measurements of binary coadsorption equilibria for industrial process
control and / or design. These methods also can be used to measure adsorption
of gases and vapors on walls of vessels, tubes or surfaces of any other solid
materials. List of symbols. References.

1. INTRODUCTION

Volumetric / manometric measurements, Chap. 2, and gravimetric
measurements, Chap. 3, can be performed simultaneously on the same gas
adsorption system in a single instrument. For pure gas adsorption this will not
lead to basically new information on the system as both methods lead to the
same result, i. e. the reduced mass of the adsorbate phase, cp. Eqs. (2.4) and
(3.5). However, for binary gas mixture adsorptives these measurements allow
one to determine the masses of both components of the adsorbate without
analyzing the (remnant) adsorptive gas mixture, i. e. without needing a gas
chromatograph or a mass spectrometer. Measurements of this type seem to
have been performed first in the authors’ group in 1989 and published in 1990,
cp. [4.1-4.3], [2.20], [3.20, 3.22] for and gas mixtures at
ambient temperature up to pressures of 12 MPa. In fact this method can be
used for any binary gas adsorptive with non-isomeric components, i. e.
components with different molecular masses. Meanwhile this method has been
commercialized by BEL – Japan, Osaka, with this company offering a fully