| Abstract Scope |
NIST Reference Material RM 8852 (ammonium ZSM-5 zeolite) is one of three zeolitic reference materials currently available at NIST. As a reference material, it has proved to be useful in an interlaboratory study on the measurement of high-pressure surface excess carbon dioxide adsorption isotherms on at 20 °C up to 4.5 MPa, resulting in the first ever high-pressure reference isotherm data. Reference isotherm data were expanded to other temperatures, including 15 °C, 25 °C, and 35 °C, and the isosteric heat of adsorption was estimated from absolute isotherms derived from the surface excess reference data. The material has been characterized by powder X-ray diffraction pattern, argon isotherm at 87 K, Brunauer–Emmett–Teller surface area, pore size distribution, pore volume, skeletal density, and thermal gravimetric analysis, and most recently the crystal structure of the zeolite containing adsorbed Ar has been determined and refined using synchrotron X-ray powder diffraction data. |