Search results for " Wells-Dawson"
showing 5 items of 5 documents
Enhanced (photo)catalytic activity of Wells-Dawson (H6P2W18O62) in comparison to Keggin (H3PW12O40) heteropolyacids for 2-propanol dehydration in gas…
2016
Abstract Catalytic and photocatalytic 2-propanol dehydration to propene at atmospheric pressure and a temperature range of 60–120 °C were carried out in gas-solid regime by using bare and supported Keggin H 3 PW 12 O 40 (PW 12 ) and Wells-Dawson H 6 P 2 W 18 O 62 (P 2 W 18 ) heteropolyacids (HPAs). Binary materials were prepared by impregnation of the HPAs on commercial SiO 2 and TiO 2 . The Wells-Dawson was in any case more active than the Keggin heteropolyacid and the differences were enhanced when the supported samples were used. In particular, Wells-Dawson HPA supported on TiO 2 and under irradiation showed the highest activity. The HPA species played the key role both in the catalytic …
Local structure of the supported Keggin and Wells-Dawson heteropolyacids and its consequence on their (photo)catalytic activity
2018
Heteropolyacids supported on boron nitride and carbon nitride for catalytic and catalytic photo-assisted alcohol dehydration
2021
Keggin H3PW12O40 (PW12) and Wells-Dawson H6P2W18O60 (P2W18) heteropolyacids (HPAs) are photo(catalysts) for various acid-promoted and redox catalytic reactions. Their activity increases if they are deposited on certain supports as metal oxides or carbon materials. Although the surface area and acid-base interactions of the HPAs with supports are considered as key factors for the performance of the binary material, the role of the local structure changes in the HPAs upon their immobilization on solids must be also of primary importance, directly affecting both acidity and photoredox properties. Here, the (photo)catalytic performance of Keggin and Wells-Dawson heteropolytungstates supported o…
Local Structure of Supported Keggin and Wells-Dawson Heteropolyacids and Its Influence on the Catalytic Activity
2019
[EN] Keggin [PW12O40]3– and Wells–Dawson [P2W18O62]6– heteropolyanions are nanosized transition-metal-oxygen clusters belonging to the heteropolyacids (HPAs) family. They are widely used as catalysts due to their high Brønsted acidity, and their dispersion on solid supports favors the accessibility to their acid sites generally increasing the catalytic activity. A series of binary materials composed of Keggin or Wells–Dawson HPAs and SiO2, TiO2, and ZrO2 have been prepared by impregnation or solvothermal methods. Remarkable differences have been found in the catalytic activities among the unsupported and supported HPAs. These differences have been correlated in the past to the structural ch…
Reazione catalitica e fotocatalitica di disidratazione in fase gas-solido del 2-propanolo in presenza di eteropoliacidi "Keggin" e "Wells-Dawson" sup…
2015
La disidratazione catalitica e fotocatalitica di 2-propanol a propilene è stata effettuata usando eteropoliacidi di Keggin H3PW12O40 (PW12) e Wells-Dawson H6P2W18O60 (P2W18). Sono stati utilizzati sia supportani che non. Materiali binari sono stati preparati per l'impregnazione degli eteropoliacidi su supporti commerciali: SiO2 (Aldrich) e TiO2 (Evonik P25). I materiali sono stati caratterizzati e la loro (foto) attività catalitica rispetto alla disidratazione 2-propanol evaluata in regime gas-solido utilizzando un reattore continuo a pressione atmosferica e un range di temperatura fra 60 e 120 ° C. Inoltre, per gli esperimenti fotoassititi il reattore è stato illuminato da un LED UV. Impor…