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.
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