Brunauer-Emmett-Teller Areas from Nitrogen and Argon Isotherms Are Similar.

Despite recommendations from the 2015 International Union of Pure and Applied Chemistry (IUPAC) technical report, surface areas of porous materials continue to be characterized by an N adsorption isotherm using the Brunauer-Emmett-Teller (BET) method. In this study, we provide the basis for such a practice by carrying out systematic large-scale molecular simulations on homogeneous and heterogeneous model surfaces. Specifically, we investigated the purported "orientational effect" of the N molecule on these surfaces. Grand canonical Monte Carlo (GCMC) simulation results from 257 diverse metal-organic frameworks show that the BET areas from Ar and N are similar in the range of 250-7500 m/g with a mean deviation of 4%. Detailed analyses based on the consistency criteria for BET equations reveal that the large deviation (>10%) between the BET areas from Ar and N are materials specific and more prone to materials that are not able to satisfy the 3 and 4 consistency criteria. For materials that satisfy all four consistency criteria, the BET areas predicted from Ar and N isotherms are comparable.