Binary Adsorption Measurements With Net Adsorption Framework

The net adsorption thermodynamic framework was introduced by Gumma and Talu (Langmuir 2010, 26(22), 17013-17023).  Net adsorption fundamentally differs from excess and absolute adsorption by the placement of Gibbs dividing surface which is necessary to quantify any adsorption process.  Net adsorption is a natural choice for microporous solids.  It removes any ambiguity in adsorption phenomena by circumventing questionable measurements and quantities such as; 1) solid volume necessary for excess adsorption (typically based on non-adsorbing helium assumption), and 2) pore volume necessary for absolute adsorption (typically based on liquid density assumption in micropores). 

This paper presents the first set of net adsorption data collected for pure and binary mixtures of methane, carbon dioxide, ethylene and propylene in silicalite at several temperatures.  The measurement techniques are discussed and contrasted with primarily excess adsorption.  Advantages and disadvantages are discussed.  Data is examined for thermodynamic consistency and compared to ideal adsorbed solution predictions for both net and excess adsorption.