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Materials-based gas capture and storage is an increasingly important area of research. Robust and accurate determination of material properties is required for judicial selection of materials for specific applications and for engineering materials–based systems at scale. One key property is the strength of the adsorbate–adsorbent interaction often quantified via the isosteric enthalpy of adsorption. The heat of adsorption can be measured directly through calorimetry; however, a more widely used approach is to apply the Clausius-Clapeyron (CC) equation to adsorption isotherms collected at different temperatures. While this approach appears to be straightforward, there exist multiple variants in the application of themore » methodologies employed. This raises the question on how these variations may or may not affect the determined results. Presented here is a discussion of the most common methodologies and a comparison of indirect determinations (via CC) of the isosteric enthalpy of adsorption by different laboratories on identical material. Included in that comparison are discussions on the measurement and analysis reproducibility. Importantly, details of the methodologies are shown to be critical when comparing enthalpies among laboratories, and different methodologies contribute to significant discrepancies and artifacts in the results. Recommendations are provided to promote robust determination and the reporting thereof.« less

Abstract Hydrogen storage by cryoadsorption on porous materials has the advantages of low material cost, safety, fast kinetics, and high cyclic stability. The further development of this technology requires reliable data on the H ₂ uptake of the adsorbents, however, even for activated carbons the values between different laboratories show sometimes large discrepancies. So far no reference material for hydrogen cryoadsorption is available. The metal‐organic framework ZIF‐8 is an ideal material possessing high thermal, chemical, and mechanical stability that reduces degradation during handling and activation. Here, we distributed ZIF‐8 pellets synthesized by extrusion to 9 laboratories equipped with 15 differentmore » experimental setups including gravimetric and volumetric analyzers. The gravimetric H ₂ uptake of the pellets was measured at 77 K and up to 100 bar showing a high reproducibility between the different laboratories, with a small relative standard deviation of 3–4 % between pressures of 10–100 bar. The effect of operating variables like the amount of sample or analysis temperature was evaluated, remarking the calibration of devices and other correction procedures as the most significant deviation sources. Overall, the reproducible hydrogen cryoadsorption measurements indicate the robustness of the ZIF‐8 pellets, which we want to propose as a reference material.« less