Measurement of water vapor adsorption isotherms in mesoporous materials using the zero length column technique

摘要

Measurement of water adsorption isotherms is important for industrial applications and for the characterization of nanoporous materials. The zero-length column technique is used for the first time to measure the adsorption-desorption isotherm of water on a mesoporous adsorbent, SBA-15, up to 90% relative humidity at 298 K. The technique showed two key advantages; (a) The experimental flexibility for the measurement of continuous adsorption-desorption isotherms characterized by complex shapes and hysteresis loops; (b) The possibility to measure a complete set of adsorption-desorption isotherms and scanning curves in few days compared to several weeks needed with traditional gravimetric techniques. The adsorption isotherm measured was compared and validated against isotherms measured on a commercial gravimetric system designed for water vapor adsorption. For the system considered, the adsorption and desorption branches are very steep, and the zero-length column technique is shown to allow setting easily the starting point of the scanning curves. (C) 2019 Elsevier Ltd. All rights reserved.