V(V) species in supported catalysts: Analysis and performance in oxidative dehydrogenation of ethane

Grygar, Tomáš Matys; Čapek, Libor; Adam, J.; Machovič, Vladimı́r

doi:10.1016/j.jelechem.2009.05.003

Cited by 18 publications

(8 citation statements)

References 59 publications

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“…It is well documented that vanadia catalysts are active in oxidative dehydrogenation reactions at about 450 °C where vanadia can participate in redox processes [20]. The H 2 -TPR results of the present work suggests that significant reduction of our supported VO x catalysts could be attained above 400 °C.…”

Section: Catalytic Activity Measurementssupporting

confidence: 59%

Wacker-Oxidation of Ethylene Over Pillared Layered Material Catalysts

et al. 2014

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This paper concerns the Wacker oxidation of ethylene by oxygen in the presence of water over supported Pd/VO x catalysts. High surface area porous supports were obtained from layer-structured materials, such as, montmorillonite (MT), laponite (LT) (smectites), and hydrotalcite (layered double hydroxide, LDH) by pillaring. Before introduction of Pd, supports MT and LDH were pillared by vanadia. The laponite was used in titania-pillared form (TiO 2 -LAP) as support of Pd/VO x active component. Acetaldehyde (AcH), acetic acid (AcOH) and CO 2 were the products with yields and selectivities, depending on the reaction conditions and the properties of the applied catalyst. Under comparable conditions the pillared smectite catalysts gave higher AcH yield than the pillared LDH catalyst. UV-vis spectroscopic examination suggested that the pillared smectites contained polymeric chains of VO 4 , whereas only isolated monomeric VO 4 species were present in the pillared LDH. The higher catalytic activity in the Wacker oxidation was attributed to the more favorable redox property of the polymeric than of the monomeric vanadia. The V 3+ ions in the polymeric species can reduce O 2 to O 2-ions, whereas the obtained V 5+ ions are ready to pass over O to Pd 0 to generate PdO whereon the oxidation of the ethylene proceeds.

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Section: Catalytic Activity Measurementssupporting

confidence: 59%

Wacker-Oxidation of Ethylene Over Pillared Layered Material Catalysts

et al. 2014

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“…The distinct shapes of both curves can be attributed to the appearance of pseudocapacitive reactions due to the presence of vanadium, which can insert-deinsert potassium ions 21 while changing its oxidation state. 22 The shape of TiO 2 -VO x voltammograms is similar but not the same as that reported for V 2 O 5 electrodes under the same conditions, 9 as expected due to the different vanadium surface species which are likely present. 22 In addition to the increased specific capacitance, the available voltage window for TiO 2 -VO x reaches 1.6 V in our aqueous electrolyte while that for pure TiO 2 is limited to smaller values (<1.2 V) due to irreversible processes (ESI, Fig.…”

Section: àmentioning

confidence: 50%

Surface modification of metal oxide nanocrystals for improved supercapacitors

Epifani

Chávez-Capilla

Andreu

et al. 2012

Energy Environ. Sci.

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“…It is essential to mention here the opinion of Rolison et al [23][24][25] that metal ions in the channels in the bulk of nonconducting zeolite should not produce electrochemical signal i.e., that intra-zeolite charge transfer to the zeolite bulk is not effective. We have recently confirmed this opinion by observing voltammetrically inactive isolated V(V) species in mesoporous silica [37,61]. The lack of electrochemical activity of Fe(III) monomers strongly attached to the permanent negative charges in the channels of non-conducting zeolites is hence understandable.…”

Section: Voltammetric Peaks C1 + C2 and C12mentioning

confidence: 62%