Small-Angle Scattering Indicates Equilibrium Instead of Metastable Capillary Condensation in SBA-15 Mesoporous Silica.
Langmuir
; 40(33): 17444-17453, 2024 Aug 20.
Article
in En
| MEDLINE
| ID: mdl-39110604
ABSTRACT
Questions about the origin of the adsorption/desorption hysteresis in mesoporous materials are as old as sorption experiments themselves. The historical conception that underlines most existing methods to extract pore size distributions from sorption data assumes that adsorption is a metastable process and that desorption takes place at thermodynamic equilibrium. In this work, we measure nitrogen and argon sorption on a series of 14 SBA-15 ordered mesoporous silicas and use small-angle X-ray scattering to independently determine their pore sizes. We find that capillary condensation systematically occurs close to thermodynamic equilibrium according to a Derjaguin-Broekhoff-de Boer calculation. Our analysis suggests that many earlier works have significantly underestimated the actual pore size in SBA-15 materials. It also highlights the critical role of the reference isotherm used to calibrate the fluid-solid interaction in the models.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Langmuir
Journal subject:
QUIMICA
Year:
2024
Document type:
Article
Affiliation country:
Belgium
Country of publication:
United States