Microporous structure and enhanced hydrophobicity in methylated SiO2 for molecular separation

H.L. Castricum, A.S. Ashima sah, Marjo C. Mittelmeijer-Hazeleger, Cindy Huiskes, Johan E. ten Elshof

Research output: Contribution to journalArticleAcademicpeer-review

32 Citations (Scopus)

Abstract

Methylated microporous silica with high thermal stability and tuneable hydrophobicity was obtained by acid-catalysed sol–gel hydrolysis and condensation of mixtures of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES). The gels exhibited a trend towards smaller ultramicropores with increasing methyl content, while in addition some supermicropores were formed with sizes of around 2 nm. For low MTES concentration, dilution prior to gelation and ageing resulted in materials with clearly smaller ultramicropores, whereas only a minor effect of dilution on structure was found at high MTES concentration. The small ultramicropore size in diluted materials can be associated with a higher extent of condensation of mainly TEOS monomers. Stable structures formed from MTES in an early stage of synthesis may explain the particular micropore structure of MTES-rich gels. With increasing methyl content and with dilution of the sol, the affinity of the surface to water was strongly decreased. The applicability of microporous silica in wet atmospheres may thus be improved by methylation, and their pore structure modified by adaptation of the recipe, which would be highly relevant for industrial gas and liquid separation by inorganic membranes.
Original languageUndefined
Pages (from-to)1509-1517
Number of pages9
JournalJournal of materials chemistry
Volume17
Issue number15
DOIs
Publication statusPublished - 2007

Keywords

  • IR-59175
  • METIS-242613

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