Vanadium dispersion and catalytic activity of Pd/VOx/SBA-15 catalysts in the Wacker oxidation of ethylene
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Tartalom: http://www.journals.elsevier.com/microporous-and-mesoporo...
Archívum: MTA Könyvtár
Gyűjtemény: Status = Published


Type = Article
Cím:
Vanadium dispersion and catalytic activity of Pd/VOx/SBA-15 catalysts in the Wacker oxidation of ethylene
Létrehozó:
Barthos, Róbert
Hegyessy, András
Klébert, Szilvia
Valyon, József
Dátum:
2015
Téma:
QD02 Physical chemistry / fizikai kémia
QD03 Inorganic chemistry / szervetlen kémia
Tartalmi leírás:
Transmission electron microscopy (TEM), X-ray diffractometry (XRD), in situ diffuse reflectance ultra
violet e visible (UVeVis) spectroscopy, and temperature-programmed reduction by hydrogen (H2-TPR)
were used to identify the vanadia forms in vanadium-containing SBA-15 preparations (VOx/SBA-15).
Wacker type supported Pd/VOx/SBA-15 catalysts were obtained by introducing Pd into VOx/SBA-15
samples using conventional impregnation method. The activity of the catalysts was tested in the gas
phase partial oxidation of ethylene by O2 in the presence of H2O (Wacker oxidation). VOx/SBA-15 sample
was obtained by micelle-templated synthesis using vanadium-containing synthesis gel. The vanadium
became incorporated in the silica structure from the gel in near to atomic dispersion. This catalyst was
quite active in ethylene oxidation to CO2 but had low Wacker activity. Isolated, polymeric and bulk
vanadia species were identified in the VOx/SBA-15 prepared by wet impregnation/calcination method.
The specific surface area of the sample was found to be smaller than that of the neat SBA-15 support
because some pores were blocked by vanadia agglomerates. The corresponding Pd/VOx/SBA-15 catalyst
showed high selectivity for acetaldehyde formation but the activity was relatively low due to low
accessible active surface. A third VOx/SBA-15 sample was obtained by applying directed surface reaction
between silanol groups of dehydrated SBA-15 and anhydrous solution of vanadyl acetylacetonate. Large
number of accessible Pd/VOx sites were present in the corresponding Pd/VOx/SBA-15 catalyst. Latter
catalyst induced ethylene oxidation to acetaldehyde with high yield at temperatures <~160 0C and with
good yield to acetic acid at temperatures >~160 0C.
Típus:
Article
PeerReviewed
Formátum:
text
Azonosító:
Barthos, Róbert and Hegyessy, András and Klébert, Szilvia and Valyon, József (2015) Vanadium dispersion and catalytic activity of Pd/VOx/SBA-15 catalysts in the Wacker oxidation of ethylene. MICROPOROUS and Mesoporous Materials, 207. pp. 1-8. ISSN 1387-1811
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