Microporous and Mesoporous Materials vol:145 issue:1-3 pages:188-193
Brunauer-Emmett-Teller (BET) theory is a popular method to interpret nitrogen adsorption isotherms for determining the specific surface area. Besides the monolayer capacity n(m) the BET equation depends on one single additional parameter C that is adjusted to fit the experimental adsorption curves. BET analysis is key in surface characterization and is widely applied even when the underlying assumptions are not strictly justified. For example, disregarding its weaker physical interpretation, the BET surface area is generally accepted as an important characterization of microporous materials. However, whereas the accuracy of the adsorption techniques has tremendously increased in recent years, experimentally derived BET values do not yet meet the same standards. The reason for this is due to some intrinsic ambiguities in its fitting procedure. In this letter, we propose a procedure that is uniquely defined, given a certain pressure range, and is independent of arbitrary experimental details such as the distribution of data points. It puts an equal weight on both monolayer and multilayer formation and gives an additional reproducible measure that is related to the inherent deviation from the BET behavior. (C) 2011 Elsevier Inc. All rights reserved.