Validated methane adsorption isotherms up to 7.5 MPa on a reference Na-Y zeolite at near ambient temperatures

Reference gas adsorption isotherms are useful for validating equilibrium data obtained from various techniques and for ensuring that experimental systems are operating correctly. In this work, we extend an interlaboratory study on a NIST reference zeolite (Na-Y, RM8850) to two additional temperatures above and below the original 298.15 K, validating the results via independent measurements using two different techniques. Volumetric experiments on a novel Adsorption Differential Volumetric Apparatus (ADVA-270) were carried out at The University of Edinburgh, and gravimetric experiments were performed at Hiden Isochema using a proprietary XEMIS microbalance. Both techniques provided highly accurate results and an excellent match between the two independent measurements using less than 150 mg of sample. Absolute equilibrium data were modelled using a Langmuir-virial isotherm to obtain an accurate concentration dependence of the heat of adsorption.