Effect of dehydration on porous structure of monolithic aerogels based on fibrous aluminum oxyhydroxide
| Autor: | A. S. Pogosyan, T. Yu. Grankina, N. V. Serebryakova, O. K. Krasil’nikova |
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| Rok vydání: | 2011 |
| Předmět: |
Materials science
Organic Chemistry Inorganic chemistry technology industry and agriculture Metals and Alloys chemistry.chemical_element Aerogel medicine.disease Surfaces Coatings and Films Amorphous solid Adsorption chemistry Chemical engineering Transmission electron microscopy Aluminium Specific surface area Materials Chemistry medicine Dehydration Porosity |
| Zdroj: | Protection of Metals and Physical Chemistry of Surfaces. 47:583-589 |
| ISSN: | 2070-206X 2070-2051 |
| Popis: | Aluminum oxide monolithic aerogels (PMAOs) with specific surfaces of up to 400 m2/g and densities of up to 0.004 g/cm3 were obtained by the direct oxidation of metallic aluminum by water vapors. Studies of the obtained aerogels using the methods of scanning and transmission electron microscopy showed that a freshly prepared aerogel represents the amorphous structure from alumina fibrous with a diameter of about 5 nm. Parameters of a porous aerogel structure were determined from the isotherms of adsorption of nitrogen vapors at 77 K. It is shown that the specific surface area decreases by 50% upon the dehydration of aerogel by temperature pretreatment at 900°C until the phase transition temperature is reached. At the same time, heat treatment at temperatures above 1200°C results in a phase transition at which significant contraction of structure occurs and the specific surface area decreases to 20 m2/g. The number of primary adsorption centers was obtained from comparative plots of water vapor adsorption. It was found that preliminary dehydration only slightly affects the number of primary centers of water adsorption. |
| Databáze: | OpenAIRE |
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