Alumina-supported Vanadium Oxide Research Articles

DFT: Kinetics effect with Oxidation of cyclohexenol with air over alumina supported Vanadium oxide catalyst

Cyclohexenon is a chemical of commercial importance. It can be easily converted to Cyclohexenon oxime which isa monomer for production of nylon-6. Attempt have there for made to produce Cyclohexenon at industrial scale. In the present work Cyclohexenol is oxidized with molecular oxygen over vanadium catalyst to Cyclohexenon in a fixed bed reactor. The catalyst was characterized with x-ray diffraction for its phase purity. The reaction parameters were optimizes to get maximum conversion of cyclohexenol and best selectivity of Cyclohexenon. The product was confirmed by producing its derivatives thus reaction of reaction method with, 2-4dinitrophenylhydrazine produced corresponding hydrazones, and reaction with hydroxylamine produced Cyclohexenon oxime.

VOx/γ‐Al2O3 Catalysts for Propane Dehydrogenation Prepared by “Impregnation‐Solid Phase Reaction” Method with Aluminum Hydroxide as Support Precursor

AbstractThe alumina supported vanadium oxide catalysts (VOx/γ‐Al2O3) were prepared by wet impregnation‐solid phase reaction method with aluminum hydroxide as support precursor. The prepared catalysts were characterized by N2 adsorption–desorption, UV–vis, X‐ray photoelectron spectroscopy and Raman spectroscopy. The performances of the catalysts were tested for propane dehydrogenation (PDH) reaction. The results indicate that the loading of vanadium on the aluminum hydroxide can influence the surface morphology of the catalysts and greatly improve the specific surface area of the resulted VOx/γ‐Al2O3 compared to pure γ‐Al2O3 support. The vanadium content markedly influences the polymerization degree of surface VOx species and catalytic performances of VOx/γ‐Al2O3 catalysts for PDH. Among all samples, the 2.9VOX/γ‐Al2O3 catalyst (vanadium content is 2.9 wt.%) possesses the maximum specific surface area and harmonious polymerization degree of VOX species. It exhibits the best catalytic performances during the 8 h of PDH reaction. Meanwhile, the 2.9VOx/γ‐Al2O3 catalyst possesses high regeneration stability and the highest TOF (turnover frequencies) value of 9.0×10−3 s−1, which is evidently higher those of previous works. After 7 reaction–regeneration cycles, the initial activity and propene selectivity can be almost restored.

Watching vanadium catalysts dehydrogenate propane

Produced at the multi-million-metric-ton level, propylene ranks as one of the main building blocks in petrochemistry. Refineries produce the light olefin, which is then converted to polypropylene and other compounds, primarily by cracking naphtha and other petroleum starting materials. Low-cost supplies of propane from shale gas have prompted some manufacturers to make propylene, instead, via propane dehydrogenation (PDH), a process commonly mediated by platinum and chromium catalysts. Vanadium-based catalysts, which would bypass the high cost and toxicity concerns associated with the other metals, look like promising alternatives. But mechanistic details of vanadium PDH catalysts remain unknown, limiting scientists’ ability to improve them. To address that shortcoming, a research team led by Jinlong Gong of Tianjin University prepared alumina-supported vanadium oxide catalysts and probed their PDH activity with vibrational spectroscopy, computations, and other methods. The team found that pretreating the catalysts with hydrogen forms V-OH groups, which promote the PDH reaction

Vanadium Supported on Alumina and/or Zirconia Catalysts for the Selective Transformation of Ethane and Methanol

Vanadium supported on pure (Al2O3, ZrO2) or mixed zirconia-alumina (with Al/(Al + Zr) ratio of 0.75 or 0.25) catalysts have been prepared by wet impregnation, using homemade prepared supports. The catalysts have been characterized and tested in the oxidative dehydrogenation (ODH) of ethane and in the methanol aerobic transformation. The catalytic performance strongly depends on the nature of the metal oxide support. Thus, activity decreases in the order: VOx/ZrO2 > VOx/(Al,Zr-oxides) > VOx/Al2O3. On the other hand, at low and medium ethane conversions, the selectivity to ethylene presents an opposite trend: VOx/Al2O3 > VOx/(Al,Zr-oxides) > VOx/ZrO2. The different selectivity to ethylene at high conversion is due to the lower/higher initial ethylene formation and to the extent of the ethylene decomposition. Interestingly, VOx/(Al,Zr-oxides) with low Zr-loading present the lowest ethylene decomposition. The catalytic results obtained mainly depend on the nature of the supports whereas the role of the dispersion of vanadium species is unclear. In methanol oxidation, the catalysts tested present similar catalytic activity regardless of the support (Al2O3, ZrO2 or mixed Al2O3-ZrO2) but strong differences in the selectivity to the reaction products. Thus, dimethyl ether was mainly observed on alumina-supported vanadium oxide catalysts (which is associated to the presence of acidic sites on the surface of the catalyst, as determined by TPD-NH3). Formaldehyde was the main reaction product on catalysts supported on Zr-containing oxides (which can be related to a low presence of acid sites). In this article, the importance of the presence of acid sites in ethane ODH, which can be estimated using the methanol transformation reaction, is also discussed.

Gas phase oxidation of furfural to maleic anhydride on V2O5/γ-Al2O3 catalysts: Reaction conditions to slow down the deactivation

An alumina-supported vanadium oxide catalyst (13.9wt.% vanadium oxide) has been characterized by different techniques and tested in the gas phase oxidation of furfural. These studies have shown that the catalyst unavoidably deactivates by deposition of maleates and resins over the surface. Full regeneration is accomplished by burning off these deposits at 773K. The studies have also demonstrated that if the primary contact occurs at temperatures at which furfural conversion is low and then the temperature is increased in a low- to high-temperature mode, intense deposition of maleates and resins takes place and the catalyst is rapidly deactivated. The increase of the temperature does not result in removal of deposits but accelerates the deposition. Under this protocol, the yield of maleic anhydride never exceeded 30%, irrespective of the reaction conditions (temperature and O2/furfural mole ratio). In contrast, if the catalyst first contacts the reaction mixture at high oxidizing potential, then the rate of maleate and resin deposition is much slower, and so is the deactivation rate, and the catalyst can display a higher yield of maleic anhydride for a longer period of time. A high oxidizing potential can be attained at a high reaction temperature (close to full conversion). A higher oxidizing potential at a given high temperature can be accomplished by increasing the O2/furfural mole ratio. Thus, for example, first contacting the catalyst at 593K (full conversion), 1vol.% of furfural, and O2/furfural mole ratio=10, obtained an initial maleic anhydride yield of 68%, and the yield was still greater than 50% after 15h on stream. On contacting at 573K with 1vol.% furfural and 20vol.% O2, the maleic anhydride yield was initially close to 75% and was above 60% after 15h.

Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

Nano alumina-supported V2O5 catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO2 as an oxidant. High surface area nano-alumina was prepared and used as support for V2O5 as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW, respectively. The V2O5 loading was varied on nano-alumina from 5 to 30wt%. The support and catalysts were characterized by X-ray diffraction (XRD), Barett–Joyner–Halenda (BJH) pore-size distribution, N2-adsorption isotherms, Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and temperature programed desorption (TPD-NH3). The characterization results indicated that V2O5 is highly dispersed on alumina up to 30%-V2O5/γ-Al2O3-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600°C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (∼100%) toward styrene production were obtained using 10% V2O5/γ-Al2O3-MW catalyst treated with microwave.

Oxidative dehydrogenation of cyclohexane over alumina-supported vanadium oxide nanoliths

Featuring highly ordered one-dimensional nanopores, anodic aluminum oxide (AAO) makes an ideal substrate for fabrication of catalysts by atomic layer deposition (ALD). Vanadium oxide (VOx) catalysts supported on AAOs and prepared by ALD and incipient wetness impregnation are characterized by X-ray fluorescence and ultraviolet–visible (UV–Vis) spectroscopy. At low loadings (<4 V/nm 2) the supported VOx are mostly isolated monomers; polyvanadate domains are gradually formed as the surface vanadium content increases. The catalytic performance at a series of loadings (<3–32 V/nm 2), and hence different forms of VOx, for the oxidative dehydrogenation (ODH) of cyclohexane are investigated. Compared to the catalysts prepared by incipient wetness impregnation, the ALD VOx catalysts show specific activities that are between 2 and 7.5 times higher. This reflects a better dispersion of the catalytic species on the surface as synthesized by ALD. In the cyclohexane ODH reaction with the supported ALD VOx, the kinetic orders and activation energies are comparable to kinetics data reported previously for the supported VOx. The results indicate that the ALD technique can be applied as an alternative approach to synthesize the supported VOx catalysts and achieves very good dispersion even at loadings above one monolayer (8 V/nm 2). In the ODH reaction, polyvanadate sites are shown to be more active, overall, than monovanadate sites. However, numerical modeling of the reaction pathways indicates that the olefin formation rate is ∼3 times faster on monomeric VOx sites than on polymeric VOx. By comparing the ODH of cyclohexane and the oxidations of cyclohexene and benzene, we find that both the sequential path and the direct path (the direct conversion from cyclohexane to benzene) are important in the oxidation process of cyclohexane.

Precursor Effect on the Molecular Structure, Reactivity, and Stability of Alumina-Supported Vanadia

This work studies the influence of specific vanadium precursors on alumina-supported vanadium oxide catalysts. Vanadyl sulfate, ammonium metavanadate, and vanadyl acetylacetonate were used as precursors. All catalysts have the same surface vanadium coverage (4 V atoms/nm2). The structural features of surface vanadium oxide species were studied by 51V-NMR, UV−vis, and Raman spectroscopy. The vanadium precursor determines the strength of interaction between supported VOx species and alumina. The reducibility of vanadium ions was estimated by conventional TPR/TPO cycles. The structural and electronic changes during reduction/oxidation cycles were studied by in situ Raman and UV−vis spectroscopy (TPR/TPO-Raman, TPR/TPO-UV−vis). Surface sulfate species reduce concomitantly to surface vanadium oxide species.

Resonance Raman Spectroscopic Study of Alumina-Supported Vanadium Oxide Catalysts with 220 and 287 nm Excitation

We present detailed resonance Raman spectroscopic results excited at 220 and 287 nm for alumina-supported VO(x) catalysts. The anharmonic constant, harmonic wavenumber, anharmonic force constant, bond dissociation energy, and bond length change in the excited state for double bonded VO and single bonded V-O were obtained from fundamental and overtone frequencies. Totally symmetric and nontotally symmetric modes could be discerned and assigned on the basis of the overtone and combination progressions found in the resonance Raman spectra. Selective resonance enhancement of two different vibrational modes with two different excitation wavelengths was observed. This allowed us to establish a linear relationship between charge transfer energy and VO bond length and, consequently, to assign the higher-energy charge transfer band centered around 210-250 nm in the UV-vis spectra to the VO transition.

The role of lattice oxygen in the oxidative dehydrogenation of ethane on alumina-supported vanadium oxide

The oxidative dehydrogenation (ODH) of ethane on alumina-supported vanadia was investigated with the aim of understanding the effects of lattice oxygen and vanadium oxidation state on the catalyst ODH activity and ethene selectivity. Transient-response experiments were carried out with both a fully oxidized sample of 10 wt% VO(x)/Al(2)O(3) (7 V nm(-2)) and a sample that had been partially reduced in H(2). The experimental results were analyzed to determine the rate coefficients for ethane ODH, k(1), and ethene combustion, k(3). The rate of ODH was found to depend solely on the concentration of reactive oxygen in the catalyst, but not on the means by which this oxygen concentration was attained (i.e., by H(2)versus C(2)H(6) reduction). On the other hand, the ethene selectivity observed at a given concentration of active oxygen was found to depend on the composition of the reducing agent, higher ethene selectivities being observed when H(2), rather than C(2)H(6), was used as the reducing agent. It is proposed that the higher ethene selectivity achieved by H(2)versus C(2)H(6) reduction might be due to a lower ratio of V(4+) to V(3+) cations attained upon reduction in H(2) for a given extent of V(5+) reduction. This interpretation is based on the hypothesis that ethene combustion is initiated by C(2)H(4) adsorption on V(n+) cations present at the catalyst surface and that the strength of adsorption decreases in the order V(5+) > V(4+) > V(3+) consistent with the decreasing Lewis acidity of the cations.

Liquid phase oxidation of dibenzothiophene with alumina-supported vanadium oxide catalysts: An alternative to deep desulfurization of diesel

Alumina-supported vanadium oxide catalysts were prepared by different methods as thermal spreading, incipient wetness impregnation of ammonium metavanadate and sol–gel synthesis of alkoxide precursors, with different vanadium loadings, in order to increase the performance in oxidative desulfurization (ODS) of dibenzothiophene. The catalysts were characterized by several techniques: X-ray diffraction, UV–vis DRS, Raman spectroscopy, FT-IR of adsorbed pivalonitrile, and TPR. As additional experimental techniques, SEM–EDX and N 2 adsorption–desorption were applied, to obtain elemental analyses and textural properties. Results evidenced the presence of different superficial V species, which depend on both vanadium loading and preparation method, while significant differences in ODS activity were observed due to the catalysts preparation method.

An Overview on the Dehydrogenation of Alkylbenzenes with Carbon Dioxide over Supported Vanadium–Antimony Oxide Catalysts

Utilization of carbon dioxide as a soft oxidant for the catalytic dehydrogenation of ethylbenzene (CO2-EBDH) has been recently attempted to explore a new technology for producing styrene selectively. This article summarizes the results of our recent attempts to develop effective catalyst systems for the CO2-EBDH on the basis of alumina-supported vanadium oxide catalysts. Its initial activity and on-stream stability were essentially improved by the introduction of antimony oxide as a promoter into the alumina-supported catalyst. Insertion of zirconium oxide into alumina support substantially increased the catalytic activity. Modification of alumina with magnesium oxide yielded an increase of catalyst stability of alumina-supported V–Sb oxide due to the coking suppression. Carbon dioxide has been confirmed to play a beneficial role of selective oxidant in improving the catalytic performance through the oxidative pathway, avoiding excessive reduction and maintaining desirable oxidation state of vanadium ion (V5+). The positive effect of carbon dioxide in dehydrogenation reactions of several alkylbenzenes such as 4-diethylbenzene, 4-ethyltoluene, and iso- and n-propylbenzenes was also observed. Along with the easier redox cycle between fully oxidized and partially reduced vanadium species, the optimal surface acidity of the catalyst is also responsible for achieving high activity and catalyst stability. It is highlighted that supra-equilibrium EBDH conversions were obtained over alumina-supported V–Sb oxide catalyst in CO2-EBDH as compared with those in steam-EBDH in the absence of carbon dioxide.

Application of AXAFS Spectroscopy to Transition‐Metal Oxides: Influence of the Nearest and Next Nearest Neighbour Shells in Vanadium Oxides

The influence of changes in coordination number, interatomic distances, and oxidation state on the intensity and centroid position of the Fourier transform (FT) of the atomic X-ray absorption fine structure (AXAFS) peak of vanadium oxide bulk model compounds and alumina-supported vanadium oxide clusters has been investigated. Using Na3VO4 and V2O5 as model compounds, it has been shown that the nearest neighbour shells have a pronounced influence on the AXAFS intensity; specifically, a 40 % decrease in intensity was observed between these two compounds. Secondly, the influence of partial reduction of the vanadium oxide species has been determined; this led to a 50 % decrease in the AXAFS intensity and to an increase in the centroid position. Furthermore, the influence of the vanadium oxide loading has been assessed. A non-linear relationship between the vanadium oxide loading and the AXAFS intensity has been found, indicating that the AXAFS intensity is sensitive to the formation of V-O-V bridging bonds between the vanadium VO4 clusters. The results show that AXAFS can be used to probe the relative energy level of the vanadium valence orbitals.

Feasibility Study of the Oxidative Dehydrogenation of Ethane in an Electrochemical Packed-Bed Membrane Reactor

The feasibility of the oxidative dehydrogenation of ethane to ethylene with alumina-supported vanadium oxide catalyst (VOx/γ-Al2O3) in an electrochemical packed-bed membrane reactor was investigated at temperatures between 500 and 620 °C with molar ratios of oxygen to ethane of 0.06−3.10. An oxygen-ion-conducting yttria-stabilized zirconia (YSZ) membrane was employed in a reactor of Au|YSZ|Pt, and the oxygen flux transferred across the membrane was controlled over the faradic coupling of oxygen-ion conduction and the external current between the electrodes. The oxidative dehydrogenation of ethane with electrochemically supplied oxygen in the membrane reactor was compared to that obtained with gaseous dioxygen in a conventional packed-bed reactor. The selectivity to ethylene was found to decrease as a function of supplied oxygen in both investigated operating modes. For all investigated oxygen/ethane molar ratios, the selectivity ratio, SCO2/SCO, was found to be clearly higher in the electrochemical than in the packed-bed reactor mode. The electrochemical oxygen supply significantly promoted CO2 formation, whereas the ethane conversion and ethylene selectivity were almost equal in the two investigated reactors. The experimental results indicate that, in the electrochemical operation, additional oxygen species exist in the system and are especially reactive in the total oxidation reactions.

Oxidative dehydrogenation of ethane to ethylene over alumina-supported vanadium oxide catalysts: Relationship between molecular structures and chemical reactivity

The influence of vanadium oxide loading in the supported VO x /Al 2O 3 catalyst system upon the dehydrated surface vanadia molecular structure, surface acidic properties, reduction characteristics and the catalytic oxidative dehydrogenation (ODH) of ethane to ethylene was investigated. Characterization of the supported VO x /Al 2O 3 catalysts by XPS surface analysis and Raman spectroscopy revealed that vanadia was highly dispersed on the Al 2O 3 support as a two-dimensional surface VO x overlayer with monolayer surface coverage corresponding to ∼9 V/nm 2. Furthermore, Raman revealed that the extent of polymerization of surface VO x species increases with surface vanadia coverage in the sub-monolayer region. Pyridine chemisorption-IR studies revealed that the number of surface Brønsted acid sites increases with increasing surface VO x coverage and parallels the extent of polymerization in the sub-monolayer region. The reducibility of the surface VO x species was monitored by both H 2-TPR and in situ Raman spectroscopy and also revealed that the reducibility of the surface VO x species increases with surface VO x coverage and parallels the extent of polymerization in the sub-monolayer region. The fraction of monomeric and polymeric surface VO x species has been quantitatively calculated by a novel UV–Vis DRS method. The overall ethane ODH TOF value, however, is constant with surface vanadia coverage in the sub-monolayer region. The constant ethane TOF reveals that both isolated and polymeric surface VO x species possess essentially the same TOF value for ethane activation. The reducibility and Brønsted acidity of the surface VO x species, however, do affect the ethylene selectivity. The highest selectivity to ethylene was obtained at a surface vanadia density of ∼2.2 V/nm 2, which corresponds to a little more than ∼0.25 monolayer coverage. Below 2.2 V/nm 2, exposed Al support cations are responsible for converting ethylene to CO. Above 2.2 V/nm 2, the enhanced reducibility and surface Brønsted acidity appear to decrease the ethylene selectivity, which may also be due to higher conversion levels. Above monolayer coverage, crystalline V 2O 5 nanoparticles are also present and do not contribute to ethane activation, but are responsible for unselective conversion of ethylene to CO. The crystalline V 2O 5 nanoparticles also react with the Al 2O 3 support at elevated temperatures via a solid-state reaction to form crystalline AlVO 4, which suppresses ethylene combustion of the crystalline V 2O 5 nanoparticles. The molecular structure–chemical characteristics of the surface VO x species demonstrate that neither the terminal V O nor bridging V O V bonds influence the chemical properties of the supported VO x /Al 2O 3 catalysts, and that the bridging V O Al bond represents the catalytic active site for ethane activation.

Characterization and reactivity of SnO2-doped V2O5/γ-Al2O3 catalysts in dehydrogenation of isobutane to isobutene

Abstract Alumina-supported vanadium oxide catalysts (V 2 O 5 ∼ 10 wt.%) with and without SnO 2 were tested in the dehydrogenation of isobutane at 590 °C under atmospheric pressure and were characterized by BET, XPS, TPR, XRD and RAMAN. It is found that the electron interaction exists between V and Sn oxide species on the surface of support. The doping of appropriate amount of SnO 2 leads to that the surface vanadia of catalysts is more reduced and is more highly dispersed than undoped catalyst. V 2 O 5 /γ-Al 2 O 3 catalyst with 3 wt.% of SnO 2 , exhibited higher reactivity in dehydrogenation of isobutane to isobutene.

Catalytic destruction of NH 3 and SO 2 over alumina supported transition metal oxides

The catalytic destruction of NH 3 and SO 2 has been examined over a series of alumina supported transition metal oxide catalysts in the laboratory. It was found that alumina supported vanadium oxide is the best candidate for this reaction. These studies show that employing a feed containing 4% NH 3 + 3% SO 2 and a residence time of 0.75 s at 700 °C, conversions of 100 and 87.7% for NH 3 and SO 2, respectively, can be achieved over fresh alumina supported vanadium oxide with the main products being only N 2, water and sulfur. The effect of pretreatment of the catalyst by sulfidation was also examined in this study. Based on these results it was shown that feeding a simulated industrial sour water stripper gas (SWSG) plus oxygen over alumina supported vanadium oxide at 750 °C with a residence time of 4 sec, resulted in an NH 3 conversion of 100%, while no SO 2 was detected in the products.

Catalytic dehydrogenation of ethylbenzene with carbon dioxide: promotional effect of antimony in supported vanadium–antimony oxide catalyst

Alumina-supported vanadium oxide, VO x /Al 2O 3, and binary vanadium–antimony oxides, VSbO x /Al 2O 3, have been tested in the ethylbenzene dehydrogenation with carbon dioxide and characterized by S BET, X-ray diffraction, X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction and CO 2 pulse methods. VSbO x /Al 2O 3 exhibited enhanced catalytic activity and especially on-stream stability compared to VO x /Al 2O 3 catalyst. Incorporation of antimony into VO x /Al 2O 3 increased dispersion of active VO x species, enhanced redox properties of the systems and formed a new mixed vanadium–antimony oxide phase in the most catalytically efficient V 0.43Sb 0.57O x /Al 2O 3 system.

Preparation, characterization, and activity of Al 2O 3-supported V 2O 5 catalysts

A series of activated alumina-supported vanadium oxide catalysts with various V 2O 5 loadings ranging from 5 to 25 wt% have been prepared by wet impregnation technique. A combination of various physicochemical techniques such as BET surface area, oxygen chemisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermal gravimetric analysis (TGA), and Fourier transform infrared (FTIR) were used to characterize the chemical environment of vanadium on the alumina surface. Oxygen uptakes were measured at 370 °C with prereduction at the same temperature, which appears to yield better numerical values of dispersion and oxygen atom site densities. XRD and FTIR results suggest that vanadium oxide exists in a highly dispersed state below 15 wt% V 2O 5 loading and in the microcrystalline phase above this loading level. TPR profiles of V 2O 5/Al 2O 3 catalysts exhibit only a single peak at low temperature up to 15 wt% V 2O 5. It is suggested that the low-temperature reduction peak is due to the reduction of surface vanadia, which has been ascribed to the tetrahedral coordination geometry of the V ions. TPR of V 2O 5/Al 2O 3 at higher vanadia loadings exhibited three peaks at reduction temperatures, indicating that bulk-like vanadia species are present for these catalysts only at higher vanadia loadings, with V ions in an octahedral coordination. The TPR profiles of V 2O 5/Al 2O 3 catalysts indicate that at loadings lower than 15% vanadia forms isolated surface vanadia species, while two-dimensional structure and V 2O 5 crystallites become prevalent in highly loaded (>15% V 2O 5) systems. Liquid-phase oxidation of ethylbenzene to acetophenone has been employed as a chemical probe reaction to examine the catalytic activity. Ethylbenzene oxidation results reveal that 15%V 2O 5/Al 2O 3 is more active than higher vanadia loading catalysts.

Utilization of carbon dioxide as soft oxidant in the dehydrogenation of ethylbenzene over supported vanadium–antimony oxide catalysts

This work shows that carbon dioxide, which is a main contributor to the global warming effect, could be utilized as a selective oxidant in the oxidative dehydrogenation of ethylbenzene over alumina-supported vanadium oxide catalysts. The modification of the catalytically active vanadium oxide component with appropriate amounts of antimony oxide led to more stable catalytic performance along with a higher styrene yield (76%) at high styrene selectivity (>95%). The improved catalytic behavior was attributable to the enhanced redox properties of the active V-sites.