3 resultados para Materiali nanostrutturati, titania, fotoelettrolisi.
Resumo:
Palladium, platinum bimetallic catalysts supported on η-Al2O3, ZSM-5(23) and ZSM-5(80), with and without the addition of TiO2, were prepared and used for low temperature total methane oxidation (TMO). The catalysts were tested under reaction temperatures of 200-500 °C with a GHSV of 100,000 mL g-1 h-1. It was found that all four components, palladium, platinum, an acidic support and oxygen carrier were needed to achieve a highly active and stable catalyst. The optimum support being 17.5% TiO2 on ZSM-5(80) where the T10% was observed at only 200 °C. On addition of platinum, longer time on stream experiments showed no decrease in the catalyst activity over 50 h at 250 °C.
Resumo:
The initial rate of the photocatalysed oxidation of methylene blue, MB, by dissolved oxygen in solution, ri(MB), is measured for a series of titania on glass samples exhibiting a wide range of activities. The samples used include two different types of commercial self-cleaning glass and a lab-made sol-geltitania film. The activities of these samples are also assessed using a resazurin-based photocatalyst activity indicator ink, i.e. Rz paii, for which the initial rates of the photocatalysed reduction of Rz were measured, ri(Rz). A plot of ri(MB)vs. ri(Rz) reveals a goodstraight line, thereby demonstrating a linear correlation (for TiO2films on glass at least) between the slow (usually hours) photocatalysed oxidation of organic materials, such as MB, and the fast (typically minutes) photocatalysed irreversible reduction of a dye, like Rz, in a paii. The possible use of paii technology for assessing, in a simple, quick and inexpensive manner, photocatalytic films both in the laboratory and in situ is discussed briefly.
Resumo:
Composite NiFe2O4–TiO2 magnetic catalysts were prepared by mechanochemical synthesis from a mixture of titania supported nickel ferrite nanoparticles and P25 titania (Evonic). The former provides fast and efficient heating under radiofrequency field, while the latter serves as an active catalyst or catalyst support. The highest heating rate was observed over a catalyst prepared for a milling time of 30 min. The catalytic activity was measured over the sulfated composite catalysts in the condensation of aniline and 3-phenylbutyric acid in a stirred tank reactor and in a continuous RF heated flow reactor in the 140–170 °C range. The product yield of 47% was obtained over the sulfated P25 titania catalyst in the flow reactor.
