Sorption measurements performed using volumetric methods typically do not provide information about heat flux and enthalpy.
If the heat of sorption is of interest, a second experiment is required. The gravimetric sorption analyzer (high-pressure TG-DSC), which measures both the change in weight (thermogravimetry, TGA) and the signal from dynamic differential scanning calorimetry (DSC) , offers a significantly faster alternative.
Both the sorption capacity and the heat of sorption can be measured in a single experiment.
The figure above shows the DSC measurement of hydrogen adsorption on a Pt/Al catalyst at a pressure of 15 bar and a temperature of 80 °C.
The heat generated is 30.5 J/g. The heat of sorption was measured directly during the sorption experiment and shows a distinct peak.
In the graph above, the time from hydrogen introduction to the sorption reaction was monitored to show how quickly the sample interacts with the atmosphere.
