Ammoxidation of ethylene to acetonitrile over chromium or cobalt alumina catalysts prepared by sol-gel method

作者：Ayari F^*; Mhamdi M; Delahay G; Ghorbel A

来源：Journal of Sol-Gel Science and Technology, 2009, 49(2): 170-179.

DOI：10.1007/s10971-008-1860-7

• Cobalt
• Chromium
• Alumina
• Sol-gel
• Ammoxidation
• Acetonitrile

Aseries of Cr/Al(2)O(3) and Co/Al(2)O(3) catalysts were tested in the selective ammoxidation of ethylene to acetonitrile. Catalysts were prepared either by sol-gel method or by impregnation with chromium or cobalt acetylacetonate salts. Physicochemical properties of catalysts were accomplished by several techniques such as chemical analysis, physisorption of N(2), X-ray diffraction (XRD), (27)Al MAS NMR, UV Visible diffuse reflectance (DRS) and Raman spectroscopy and temperature programmed reduction of H(2) (H(2)-TPR). Textural analysis reveals that mesoporous materials with pronounced surface areas were obtained using sol-gel procedure while impregnation of the support produces a moderate decrease of its surface area and pore volume. XRD analysis confirms the presence of highly dispersed metal species which reside essentially on the surface and measure less than 4 nm. Furthermore, (27)AlMAS NMR shows that for xerogels, part of metal species occupies sites on/in Al(2)O(3) in close vicinity of octahedral (27)Al. This, apparently, is not the case for aerogels. For Cr/Al(2)O(3) catalysts, isolated Cr(6+), mono and polychromate species were identified using DRS, Raman Spectroscopy and H(2)-TPR which seem to play a key role in the ammoxidation of ethylene. Furthermore, for cobalt doped catalysts, CoAl(2)O(4) was identified as active phase on the basis of DRS and H(2)-TPR results. From the supercritical drying, it results

• 出版日期2009-2