As an essential feature, models describing hydrogen adsorption in micropores should predict accurately saturation properties. However, in absence of bulk saturation parameters for the supercritical adsorbate this matter remains subject to discussions. We show how the decreasing region of excess adsorption isotherms can be used to estimate the adsorbed phase volume, density and pressure at saturation. The approach was implemented on a set of Metal-Organic Frameworks down to 50 K. The derived saturation properties are consistent with a micropore filling model, and independent Ar porosimetry measurements. The findings evidence that the adsorbed hydrogen phase can exhibit liquid state properties at supercritical temperatures. In addition, the nature of the adsorbed phase does not seem to depend on the type of adsorbent. These conclusions contrast with the current view on supercritical adsorption, in which it is assumed that no liquid is formed and the only possible mechanism involves monolayer coverage.

Saturation properties of supercritical hydrogen adsorbed in metal-organic frameworks: Experimental and modeling

243rd National Meeting (2012)

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