| 1. |
- Mintova, S., et al.
(författare)
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Growth of silicalite-1 films on gold substrates
- 1997
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Ingår i: Microporous Materials. - 0927-6513 .- 1873-3107. ; 11:3-4, s. 149-160
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Tidskriftsartikel (refereegranskat)abstract
- The crystallization of thin continuous silicalite-1 films on modified gold surfaces prepared at 100°C in clear precursor solutions has been studied by grazing angle X-ray diffractometry, infrared spectroscopy, dynamic light scattering, scanning electron microscopy, Kr adsorption and ellipsometry. The gold surfaces were pre-treated with a silane coupling agent, gamma-mercaptopropyltrimethoxysilane, and hydrolysed in an acidic solution, pH < 4, to create a modified negatively charged interface on which positively charged colloidal silicalite-1 seed crystals were adsorbed. The colloidal seed crystals are believed to be preferentially adsorbed with their {010} face parallel to the Au surface. Continued growth of the oriented seed crystals in a following hydrothermal step results in the formation of a continuous thin oriented crystalline film. The mechanism for the formation of silicalite-1 films on Au is discussed
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| 2. |
- Shoeman, Brian J., et al.
(författare)
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The synthesis of discrete colloidal crystals of zeolite beta and their application in the preparation of thin microporous films
- 2001
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Ingår i: Journal of porous materials. - 1380-2224 .- 1573-4854. ; 8:1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- Stable colloidal suspensions containing discrete crystals of zeolite Beta with particle sizes less than 150 nm were synthesized within a wide composition range. Crystallization of colloidal zeolite Beta was facilitated by low water and sodium contents and by high TEAOH contents. Solid samples obtained after drying were characterized using XRD and FT-IR. Thin (ca. 130 nm) films of zeolite Beta were grown on a Ta-substrate using colloidal crystals of zeolite Beta as seeds
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| 3. |
- Tosheva, Lubomira, et al.
(författare)
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A method for the preparation of silicalite-1 microspheres
- 1999
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Ingår i: Studies in Surface Science and Catalysis. - 0167-2991. ; 125, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Silicalite-1 containing microspheres were prepared by a new method based on the use of anion exchange resins as shape directing templates. The resins were hydrothermally treated in a synthesis solution yielding silicalite-1 at 100°C and finally removed by calcination. The resultant material consists of hard, solid and white spherical particles with a shape and size identical to the ion exchange resin used. Characterization of samples taken out after different times of treatment showed that an amorphous silica is formed at the beginning of the treatment. This amorphous silica shows structural changes with time parallel to which silicalite-1 starts to form. The crystallization reaction discontinues after a treatment time of about 48 h. A calcined sample obtained after 48 h contains a large amount of amorphous matter and the additional hydrothermal treatment does not substantially improve the crystallinity of the product. Silicalite-1 microspheres of a very high crystallinity were obtained by a two-step procedure using an initial treatment at 100°C followed by a secondary treatment at a higher temperature.
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| 4. |
- Valtchev, V., et al.
(författare)
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Deposition of continuous silicalite-1 films on inorganic fibers
- 1997
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Ingår i: Microporous Materials. - 0927-6513 .- 1873-3107. ; 8:1-2, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- Silicalite-fiber composites were prepared by a new method for the synthesis of molecular sieve films. The method consists of two steps: in the first one, the surface charge of the support is reversed by treatment with a cationic polymer solution and a monolayer of negatively charged colloidal molecular sieve seed crystals is adsorbed on the surface. The second step consists of hydrothermal treatment of the support in a molecular sieve precursor solution resulting in the formation of a continuous film of molecular sieve. The method was applied to carbon, ZrO2, Al2O3, mullite, ceramic and pyrex glass fibers. The crystallization of continuous silicalite-1 films on all types of fibers was confirmed by SEM, XRD, FTIR, DTA analyses and BET surface area measurements.
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