Automated determination of high-temperature and high-pressure gas adsorption isotherms using a magnetic suspension balance

Abstract

A gravimetric experimental device allowing the measurement of pure gas adsorption isotherms is presented. The mass measurement is performed by a Rubotherm magnetic suspension balance instrumented in such a way to allow completely automated adsorption isotherm measurements for pressures ranging from 0 to 10 000 kPa and for temperatures from 303 to 423 K. Its main originality is that, although it works at high temperature, all the components in contact with the adsorbate are at the experimental temperature so that it is possible to study adsorbates which condensate at high-pressure and ambient temperature. This paper provides a detailed experimental procedure, the measurement accuracy and some comments on the advantages and drawbacks of the method. As examples of experimental results, adsorption isotherms of nitrogen and butane on activated carbon (F30-470, Chemviron Carbon) at five temperatures (303, 323, 343, 363 and 383 K) are presented. As a first step of a general study devoted to the comparison of high-pressure adsorption measurement techniques, the 303 K nitrogen adsorption isotherm is compared to data obtained for the same system but with a volumetric apparatus working in narrower ranges of temperature and pressure.

First international inter-laboratory comparison of high-pressure CH 4 , CO 2 and C 2 H 6 sorption isotherms on carbonaceous shales

“…Comparative studies between the gravimetric and manometric methods performed with N2 and CO2 on activated carbons showed a very good agreement (De Weireld et al, 1999;Belmabkhout et al, 2004;Gensterblum et al, 2009Gensterblum et al, , 2010. Both, the manometric and the gravimetric techniques have been used extensively in gas sorption studies on a wide variety of microporous materials (e.g.…”

“…Some laboratories use in-house modifications of these devices in order to adapt them for specific experimental conditions -e.g. high temperatures (De Weireld et al, 1999;Dreisbach et al, 2002), insitu moisture equilibration (Billemont et al, 2011). Several studies use an in-house built gravimetric device (e.g.…”

A Complete Set of Experimental Devices for the Determination of the Gas Separation Capacity of Adsorbents

“…Measurements of the mass uptake of the adsorbent sample are achieved by a magnetic balance. This method allows for the direct measurement of the amount adsorbed versus time (De Weireld et al, 1999).…”

European inter-laboratory comparison of high pressure CO2 sorption isotherms II: Natural coals

“…The most common procedures to determine excess sorption isotherms of gases are the manometric (TU Delft, RWTH Aachen) (Busch et al, 2003a,b), van Hemert et al, 2007) and the gravimetric (U Mons) methods (De Weireld et al, 1999;Bae and Bhatia 2006;Fitzgerald et al, 2006;Ottiger et al, 2008). Both methods are well established and known to provide accurate excess sorption isotherms for simple and well-characterized sorption systems (e.g.…”