The measurement of sorption performed with volumetric methods normally gives no information about heat flow and enthalpy. If the heat of sorption is of interest, a second experiment is needed.
The Gravimetric Sorption Analyzer (High Pressure TG-DSC), which measures both weight change (TGA Thermogravimetry) and (DSC) Differential Scanning Calorimetry– signal, provides a much faster alternative. Within one experiment, the sorption capacity as well as heat of sorption can be measured.
The figure above shows the DSC- measurement-part of the adsorption of Hydrogen on a Pt/Al catalyst at a pressure of 15 bar and a temperature of 80°C. The evolved heat is 30,5 J/g.
The heat of sorption was directly determined during the sorption experiment and shows a clear peak. In the curve above, the time from hydrogen introduction to sorption reaction was monitored to show how fast the sample interacts with the atmosphere.
