Adsorptive characterization of porous solids: Error analysis guides the way

• A detailed uncertainty analysis has been performed for N2 adsorption measurements.
• The error in properties derived from N2 adsorption has been determined.
• Reliability of BET surface area is very dependent on determination procedure.
• BJH-pore size distributions may very well yield highly inaccurate results.
• Guidelines have been posed to improve accuracy in adsorption measurements.

Adsorptive characterization using nitrogen at 77 K is one of the most widely used techniques to assess textural properties of porous solids, such as pore volume, specific surface area and pore size distributions. Based on a thorough error analysis the influence of experimental uncertainties on the accuracy of volumetric nitrogen adsorption isotherms and derived properties using the most popular methods is analyzed in detail, comprising the pore volume and specific surface area determined using the method posed by Brunauer, Emmet and Teller (BET) and the pore size distribution according to the method developed by Barrett, Joyner and Halenda (BJH). Based on series of isotherms measurements with different sorbents (MOFs, zeolite, activated carbon and alumina) and on examples from literature (MIL-101), the extensive error analysis shows that these methods may yield highly inaccurate or even statistically irrelevant (BJH) results. To improve the meaningfulness of derived properties and to minimize statistical uncertainties, practical recommendations and guidelines are proposed for experimental operation variables and data analysis.

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