isotherms for zeolites with the same pore structure but with different charges in their
channels, as is shown in Fig. 4. The sample studied was a ZSM-5 zeolite with two
Si/Al molar ratios, 12.5 and 500. The former had more protons in its structure;
therefore, a higher interaction with nitrogen is expected, as clearly observed in
Fig. 4b. The argon isotherms (Fig. 4a) show identical isotherms for both samples
according to the same pore structure, indicating an absence of interaction between
the gas and the surface of the sample.
Fig. 3 N 2 and Ar at 77 K and Ar at 87 K adsorption isotherms on ITQ-29 zeolite. Ar adsorption
isotherm at 87 K adapted with permission from Fraccarollo et al. [23]. Copyright (2017) American
Chemical Society
Fig. 4 High-resolution adsorption isotherms for ZSM-5 zeolites: (a) Ar isotherms at 87 K, and (b)
N 2 isotherms at 77 K. Reproduced with permission from Elsevier
Critical Overview of Textural Characterization of Zeolites by Gas Adsorption
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