A reference high-pressure CO 2 adsorption isotherm for ammonium ZSM-5 zeolite: results of an interlaboratory study

• Published in: Adsorption : journal of the International Adsorption Society Vol. 24; no. 6; p. 531
• Main Authors: Nguyen, H G T, Espinal, L, van Zee, R D, Thommes, M, Toman, B, Hudson, M S L, Mangano, E, Brandani, S, Broom, D P, Benham, M J, Cychosz, K, Bertier, P, Yang, F, Krooss, B M, Siegelman, R L, Hakuman, M, Nakai, K, Ebner, A D, Erden, L, Ritter, J A, Moran, A, Talu, O, Huang, Y, Walton, K S, Billemont, P, De Weireld, G
• Format: Journal Article
• Language: English
• Published: United States 2018
• Subjects: Interlaboratory study; RM 8852; Reference adsorbent material; Surface excess adsorption; Carbon dioxide; ZSM-5; Reference isotherm; High-pressure adsorption isotherm
• ISSN: 0929-5607; 1572-8757

This paper reports the results of an international interlaboratory study led by the National Institute of Standards and Technology (NIST) on the measurement of high-pressure surface excess carbon dioxide adsorption isotherms on NIST Reference Material RM 8852 (ammonium ZSM-5 zeolite), at 293.15 K (20 °C) from 1 kPa up to 4.5 MPa. Eleven laboratories participated in this exercise and, for the first time, high-pressure adsorption reference data are reported using a reference material. An empirical reference equation [ -surface excess uptake (mmol/g), -equilibrium pressure (MPa),  = -6.22,  = 1.97,  = 4.73, and  = 3.87] along with the 95% uncertainty interval (  = 0.075 mmol/g) were determined for the reference isotherm using a Bayesian, Markov Chain Monte Carlo method. Together, this zeolitic reference material and the associated adsorption data provide a means for laboratories to test and validate high-pressure adsorption equipment and measurements. Recommendations are provided for measuring reliable high-pressure adsorption isotherms using this material, including activation procedures, data processing methods to determine surface excess uptake, and the appropriate equation of state to be used.