Measurement of Water Adsorption Equilibrium and Kinetics Using the ZLC Technique

We present a new configuration of the zero length column apparatus designed specifically to measure adsorption equilibrium and kinetics for vapours at near saturation conditions. We demonstrate its use using water on different adsorbents including mesoporous materials showing non-type I isotherms.

The initial study was shown to reproduce with high accuracy the desorption curves generated using a Quantachrome Aquadyne gravimetric system, including scanning desorption curves in the hysteresis region. The significant improvement gained by using the ZLC lies in the time required for generating the desorption curves as well as the fact that thousands of equilibrium points are obtained from a single experiment. The full characterisation of a sample is reduced to one week compared to 6 to 8 weeks on the gravimetric system, therefore indicating a significant potential in using this approach to characterize the properties of nanoporous materials.

Results on various commercial pellets will be presented, both below and inside the hysteresis region. Experiments at higher flowrates reveal that the kinetic behaviour in the hysteresis region is quite complex and further analysis is required