Automated cold volume calibration of temperature variation in cryogenic hydrogen isotope sorption isotherm

Abstract

The gas adsorption isotherm requires accurate measurement for the analysis of porous materials which is used as an index of surface area, pore distribution, adsorption amount of gas. Basically, adsorption isotherms of porous materials were measured conventionally at 77K and 87K using liquid nitrogen and liquid argon. The cold volume calibration in such conventional way was simply done by splitting into two zone (cold and worm volume) through controlling level sensor in Dewar filled with liquid nitrogen or argon. As a result, the BET measurement for textural properties is mainly limited to the N2 or Ar gas. In order to investigate the other gases at various temperature independently, a novel temperature control system for sample cell is required, and consequently the cold volume calibration at various temperature become more important. In this study, the cryocooler system is newly installed in commercial BET device for controlling the sample cell temperature, the automated cold volume calibration of temperature variation for various gases (e.g. hydrogen isotopes) is introduced. This developed calibration method presents reliability and reproducibility of the cryogenic measurements of hydrogen isotope separation in porous materials, and also provide the large flexibility for performing various other gases with temperature.