Critical Overview of Textural Characterization of Zeolites by Gas Adsorption

JHONNY VILLARROEL ROCHA; DEICY BARRERA; JOSÉ J. ARROYO GÓMEZ; KARIM SAPAG

New Developments in Adsorption/Separation of Small Molecules by Zeolites

Springer

Año: 2020; p. 1 - 15

Porous materials with pores within molecular size are essential to solveseveral technological problems taking advantage of their textural properties relatedto their exposed surface and porosity. Among these materials, zeolites are in thepodium, with technological and industrial applications, which are directly related topore properties (e.g., size, surface chemistry, among others). To obtain their texturalproperties, there are several techniques, but gas adsorption plays an important role,and it is among the most widely used for this purpose. Despite being a populartechnique, with nitrogen at 77 K as the reference probe molecule to obtain adsorptionisotherms, the estimation of the textural properties is not a trivial procedure. On theother hand, it is possible to perform adsorption measurements with different gases atdifferent temperatures and pressures, whereby is crucial the choice of adequate analysis conditions because the adsorption-desorption isotherm will be the uniqueinformation obtained from the experiment. Once the data are obtained, a carefulselection of methods and models to analyze them is mandatory to evaluate the texturalproperties of the samples in a reliable and reproducible manner. Particularly forzeolites, due to their pore sizes and the presence of surface functional groups, theapplication of this characterization technique is not straightforward, thus needing topay attention to the previous knowledge that exists about this type of materials, tocarry out the experiment as well as to choose the appropriate methodology for datatreatment. In this chapter, we introduce an overview of the experimental procedureand data treatment to obtain the more reliable textural properties for zeolites.