In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS) was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR), shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures.
Preparation of silica by sol-gel method using formamide
Published 2001 in Materials Research-ibero-american Journal of Materials
ABSTRACT
PUBLICATION RECORD
- Publication year
2001
- Venue
Materials Research-ibero-american Journal of Materials
- Publication date
2001-07-01
- Fields of study
Materials Science, Chemistry
- Identifiers
- External record
- Source metadata
Semantic Scholar
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- crack-free silica gels
Silica gel monoliths that remain intact without visible cracking after preparation and thermal treatment.
Aliases: crack-free gels
- cross-linked structure
An interconnected network architecture in the silica gel matrix.
Aliases: more cross-linked structure, interconnected network
- formamide
An organic drying additive added to the silica sol at an alkoxide/formamide molar ratio of 1/1.
- mesoporosity
A pore-size regime characterized by mesopores in the silica gels.
Aliases: mesoporous structure
- microporosity
A pore-size regime characterized by micropores in the silica gels.
Aliases: microporous structure
- si-o-si bonds
Siloxane linkages that connect silicon atoms in the silica network.
Aliases: siloxane bonds
- sol-gel processing
A synthesis route that converts a precursor solution into a silica gel through hydrolysis and condensation.
Aliases: sol-gel method
- tetraethyl orthosilicate (teos)
The silicon alkoxide precursor used to form the silica gel network.
Aliases: TEOS, tetraethylortosilicate
REFERENCES
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