| Autor: |
Richard P. K. Wells, Graham J. Hutchings, Christopher J. Kiely, Jonathan K. Bartley, Jean Claude Volta, Luisa Sartoni |
| Rok vydání: |
2004 |
| Předmět: |
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| Zdroj: |
Journal of Molecular Catalysis A: Chemical. 220:85-92 |
| ISSN: |
1381-1169 |
| DOI: |
10.1016/j.molcata.2004.03.052 |
| Popis: |
The doping of vanadium phosphate catalysts by low levels of gallium is described an discussed. VOHPO 4 ·0.5H 2 O precursors doped with Ga were prepared using a two stage method in which V 2 O 5 is initially reacted with isobutanol before reaction with H 3 PO 4 and Ga(acac) 3 . These were transformed to (VO) 2 P 2 O 7 by reaction with 1.7% n -butane in air at 400 °C for 72 h. The materials were characterised using a combination of powder XRD, BET surface area measurement, laser Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The addition of 0.1 mol% Ga significantly enhances the activity of the catalyst. The effect is due in part to a structural effect as the surface area of the catalyst is increased by ca. 50–100% when up to 1 mol% Ga is added. However, the intrinsic activity (mol maleic anhydride produced/m 2 /h) is also significantly enhanced at these low doping levels. Hence, the promotional effect is considered to be due to both structural and electronic effects. The source of Ga was found to be and experiments were carried out with Ga 2 O 3 and GaPO 4 in place of Ga(acac) 3 . GaPO 4 was found to give some enhancement in activity, but neither Ga 2 O 3 nor GaPO 4 gave an enhancement in surface area. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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