Evaluation of the stability of pure silica MCM-41 toward water vapor

Journal Article · Tue Dec 21 04:00:00 EST 1999 · Langmuir

DOI:https://doi.org/10.1021/la9904915· OSTI ID:20013637

Carrott, M M.L.R.; Candeias, A J.E.; Carrott, P J.M.; Unger, K K

Water vapor adsorption/desorption isotherms at 298 K and XRD measurements and nitrogen isotherms at 77 K before and after exposure to water vapor were determined on pure silica MCM-41 samples; samples had different pore widths and were prepared by different synthesis methods, including hydrothermal and room-temperature procedures. It was found that prolonged exposure to water vapor provoked structural alterations in all of the MCM-41 materials studied, the most significant effects being a loss of pore shape uniformity and a large decrease in pore size and, in consequence, pore volume. Analysis of the results suggests that these alterations are due to expansion of the pore walls as well as, in some cases, to a collapse involving rupture of the walls. It is also confirmed that silylation is effective in stabilizing the pore structure but only at the expense of much lower pore volume and pore width.

• Research Organization: Univ. of Evora (PT)
• OSTI ID: 20013637
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 26 Vol. 15; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ADSORPTION
DESORPTION
MOLECULAR SIEVES
PORE STRUCTURE
SILICATES
WATER VAPOR