Oxidation of sulfur dioxide over supported solid V2O5/SiO2 and supported molten salt V2O5?Cs2SO4/SiO2 catalysts: molecular structure and reactivity

Photocatalytic Methanol Oxidation by Supported Vanadium Oxide Species: Influence of Support and Degree of Oligomerization

“…Supported vanadium oxide catalysts have been extensively studied as thermal heterogeneous oxidation catalysts for a variety of catalytic reactions, including oxidative dehydrogenation (ODH) of alkanes, methanol oxidation to formaldehyde, the oxidation of SO 2 to SO 3 during selective catalytic reduction of NO x with NH 3 and in sulfuric acid production, or o ‐xylene oxidation to phthalic anhydride In those applications, the dependence of the catalytic performance on the nature of the support and the degree of oligomerization of the supported vanadium oxide species has been a matter of intense debate over the past few decades , , , , . Additional complexity arises from the observation that the nature of the oxide support, particularly its point of zero charge (pzc) and the nature of its surface hydroxyl groups (amount and basicity), strongly influences the oligomerization tendency of the supported vanadium oxide phase under hydrated or dehydrated conditions, respectively, (for a detailed discussion see ref …”

Vanadia-Based Catalysts for the Sulfur Dioxide Oxidation StudiedIn Situby Transmission Electron Microscopy and Raman Spectroscopy

“…17,20,49 The latter compound is regarded as the active species for catalyzing the SO 2 oxidation reaction. 18,44 This shows that molten V V compound and V IV compounds (both liquid and solid) can coexist simultaneously under SO 2 oxidation reaction at 450 °C. The Cs-rich sample shows identical spectral features, but their appearance and disappearance occur at different times.…”

“…Previous in situ Raman spectroscopy studies of SO 2 oxidation catalysts and model catalysts − were performed in atmospheres of O 2 /N 2 and SO 2 /N 2 and of SO 2 /O 2 /N 2 in the ratio 0.4:4:95.6. The latter composition contains all the reactant gas species for SO 2 oxidation, but the partial pressure of SO 2 is 10 times lower than that of O 2 compared to the feed gas to the first bed of a typical industrial SO 2 oxidation reactor operating with SO 2 /O 2 /N 2 in the ratio 10:10:80.…”

“…However, the dimeric vanadium complex (VO) 2 O­(SO 4 ) 4 4– is commonly regarded as the important species for catalyzing the SO 2 oxidation reaction. The functionality of this complex has been proposed to involve the attachment of O 2 and SO 2 to the active vanadium complex followed by the oxidation of SO 2 into SO 3 . − In order to make the catalytically active complexes more accessible to the gas phase and thereby optimize the activity, it is important to enlarge the gas–melt interface and, hence, the dispersion of the molten film on the porous support. Moreover, the catalytic activity can be enhanced by the addition of different alkali metals, e.g., Na, K, Rb, and Cs. , Among these alkali metals, Cs gives the most significant activity enhancement at low reaction temperatures .…”

VOx Modified H-Beta Zeolite for Dimethyl Ether Direct Oxidation to Polyoxymethylene Dimethyl Ethers

“…At the same time, the redox sites are provided by vanadium oxide that has very important redox properties in catalysts due to the capacity to adopt multiple oxidation states. Vanadium oxide-based catalysts are widely used in catalytic oxidation, such as the selective oxidation of methanol to formaldehyde [17], oxidation of SO 2 to SO 3 [18] and oxidative dehydrogenation of propane [19]. So vanadium oxide modified H-beta catalyst is applied to the selective oxidation of DME to DMMx, and the related work is seldom reported, in addition, we observed the formation of DMM 2 , indicating that the further growth of C-O occurred in our research.…”