Physical Adsorption of Gases at High Pressures: Argon and Methane onto Graphitized Carbon Black

Abstract

A gravimetric method for the determination of surface excess isotherms of compressed gases on solid adsorbents is described. Buoyancy corrections are minimized by using a symmetric‐beam microbalance and by compensating the volume of the adsorbent. — Isotherms of argon and methane onto Graphon (a graphitized carbon black) are determined up to 150 bar at −20, 0, 25, and 50°C, corresponding to bulk densities up to the critical density for methane, and more than half the critical density for argon. Surface excess isotherms exhibit a maximum at about 0.4 to 0.5 of the critical density. The range of applicability of simple isotherm equations for higher gas pressures is discussed briefly.

Gas adsorption microcalorimetry and modelling to characterise zeolites and related materials

“…Adsorption is defined in terms of 'enrichment of material or increase in the density of a fluid in the vicinity of an interface' [4,34]. One can consider excess or absolute [35,36] quantities. Generally the concept of a Gibbs Dividing Surface or 'GDS' is considered where an arbitrary dividing surface is chosen in the volume in which adsorption can take place.…”

Multicomponent adsorption on activated carbons under supercritical conditions

“…Adsorption of supercritical fluids in microporous RR adsorbents at high pressure has some features that are distinct from the adsorption of vapors at temperatures below the critical temperature [1][2][3][4][5][6][7][8][9][10]. The main peculiarity of highpressure gas adsorption is that adsorption excess passes through a maximum with increased pressure.…”

Studies on the Transition Behavior of Physical Adsorption from the Sub- to the Supercritical Region: Experiments on Silica Gel

“…Liquid cannot exist at above-critical temperatures; therefore, it cannot be the real state of supercritical adsorbate, and the saturation pressure will not be the upper limit of adsorption. The adsorption of supercritical gases is referred to as supercritical adsorption (6) or high-pressure adsorption (7). In fact, the nature of supercritical adsorbate and the mechanism of adsorption at above-critical temperatures are still a question under study.…”