نتایج جستجو برای: vanadia loading
تعداد نتایج: 76752 فیلتر نتایج به سال:
The partial oxidation of methanol to formaldehyde was studied over highly dispersed vanadia supported on mesoporous silica SBA-15 (VOx/SBA-15). VOx/SBA-15 catalysts were prepared by a novel grafting/ion-exchange method and characterized using UV-VISand Raman spectroscopy. The resulting surface vanadium oxide species (0 – 2.3 V/nm), grafted on the inner pores of the SBA-15 silica matrix, consist...
A series of vanadia catalysts supported on the mesoporous silica SBA-15 are synthesized using an automated laboratory reactor. The catalysts contain from 0.6 up to 13.6V atoms/nm and are structurally characterized by various techniques (BET, XRD, SEM, TEM, Raman, IR, UV/Vis). Samples containing up to 3.1V/nm are structurally rather similar. They all contain a mixture of tetrahedral (VOx)n speci...
supported vanadia catalyst was successfully synthesized using wet impregnation of gamma-alumina to study propane oxidative dehydrogenation (pod). the prepared catalysts were characterized with xrd, bet, and tpr tests. in a broad temperature range (340 to 630°c), effects of vanadia loading (2.7, 5.4, and 9 wt%) and propane to oxygen ratio (3/1 to 1/3) were investigated on propane conversion as w...
Reactivity of V2O5 Catalysts for the Selective Catalytic Reduction of NO by NH3: Influence of Vanadia Loading, H2O, and SO2 Michael D. Amiridis,∗,1 Israel E. Wachs,† Goutam Deo,† Jih-Mirn Jehng,† and Du Soung Kim† ∗Research Division, W.R. Grace & Co.-Conn., Columbia, Maryland 21044; and †Zettlemoyer Center for Surface Studies and Department of Chemical Engineering, Lehigh University, Bethlehem,...
Supported vanadia catalyst was successfully synthesized using wet impregnation of gamma-Alumina to study Propane Oxidative Dehydrogenation (POD). The prepared catalysts were characterized with XRD, BET, and TPR tests. In a broad temperature range (340 to 630°C), effects of vanadia loading (2.7, 5.4, and 9 wt%) and propane to oxygen ratio (3/1 to 1/3) were investigated on propane conversion as w...
Supported vanadia catalyst was successfully synthesized using wet impregnation of gamma-Alumina to study Propane Oxidative Dehydrogenation (POD). The prepared catalysts were characterized with XRD, BET, and TPR tests. In a broad temperature range (340 to 630°C), effects of vanadia loading (2.7, 5.4, and 9 wt%) and propane to oxygen ratio (3/1 to 1/3) were investigated on propane conversion as w...
High-surface-area mesoporous CexZr1-xO2 materials synthesized through a surfactant-assisted approach of nanocrystalline particle assembly are utilized as promising support for VOx-based catalysts. The catalytic properties the resultant VOx/CexZr1-xO2 nanocatalysts evaluated by oxidative dehydrogenation propane using microreactor-GC system. It is indicated that catalyst particles ...
Recent debates over the active site structure of supported vanadia/silica catalysts have suggested the existence of a surface vanadium peroxo-oxo "umbrella" structure. This study definitively demonstrates with Raman and UV-vis spectroscopy that the surface vanadia peroxo-oxo umbrella-like structure is not present for both hydrated and dehydrated supported vanadia catalysts such as supported van...
Vanadia was incorporated in the 3-D mesoporous material TUD-1 with a loading of 2% w/w vanadia. The performance in the selective photo-oxidation of liquid cyclohexene was investigated using ATR-FT-IR spectroscopy. Under continuous illumination at 458 nm a significant amount of product, i.e. cyclohexenone, was identified. This demonstrates for the first time that hydroxylated vanadia centers in ...
The effect of the suppport on oxidative dehydrogenation activity for vanadia/ceria systems is examined for the oxidation of methanol to formaldehyde by use of well-defined VO(x)/CeO(2)(111) model catalysts. Temperature-programmed desorption at low vanadia loadings revealed reactivity at much lower temperature (370 K) as compared to pure ceria and vanadia on inert supports such as silica. Densit...
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