A reference low-pressure CO₂ adsorption isotherm for zeolite 13X: results of an interlaboratory study

This paper reports the results of an international interlaboratory study sponsored by the Versailles Project on Advanced Materials and Standards (VAMAS) and led by the National Institute of Standards and Technology (NIST) on the measurement of low-pressure CO₂ adsorption isotherms at 25 °C on zeolite 13X (NIST research grade test material 10257). Eighteen laboratories participated in the study and contributed 21 datasets. From these data, a consensus reference isotherm, along with the 95% uncertainty interval (U _k=2 ), were determined and reported. Results indicate the material is suitable for development into NIST reference material, which will become the first zeolitic reference material in beaded form at NIST.

The online version contains supplementary material available at https://doi.org/10.1007/s10450-026-00701-3.