Reducibility, heats of re-oxidation, and structure of vanadia supported on TiO2 and TiO2–Al2O3 supports used as vanadium traps in FCC

Martínez, Silvia; Morales, Rosario; Rodrı́guez, A. G.; Pedraza, Francisco; Handy, Brent E.

doi:10.1016/j.tca.2005.01.055

Cited by 9 publications

(9 citation statements)

References 17 publications

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“…Polyvanadates were reported [2,3,9,49] to be prevailing species on TiO 2 surface at moderate loading before shcherbinaite crystallization; no other support studied in this work has such preference. The nature of the V(V) species on titania has not been clarified from the structural point of view.…”

Section: Electrochemical Behaviour Of V-oxides Supported On Tiomentioning

confidence: 65%

“…The nature of the V(V) species on titania has not been clarified from the structural point of view. Martínez et al [9] reported that these polyvanadate species on TiO 2 has no terminal V@O bonds. Decavanadate, one of the well defined polyvanadate structures, a 3-D cluster of condensed [VO 6 ] octahedra, has also no free V@O bonds.…”

Section: Electrochemical Behaviour Of V-oxides Supported On Tiomentioning

confidence: 99%

“…The most important V(V) species on the catalyst supports are monomeric [VO 4 ] À , vanadate dimeric or oligomeric chain-or sheet-like structures, polyvanadate anions, and 3-D nano-and microstructures of V 2 O 5 at higher V-loadings. Crystalline V 2 O 5 is most reliably detected by X-ray diffraction [3,6,7], while non-crystalline V(V) species are mostly detected by UV-vis spectroscopy (DRS), Raman or IR spectroscopy [2][3][4][5][7][8][9], and temperature programmed reduction (TPR) [5,7,9,10]. Electron spectra are sensitive to the degree of V-oxide oligomerization or polymerization to oxides: the more extensive condensation of VO x polyhedra producing V-O-V bonds, the more the absorption bands are shifted from UV region to Vis region [11,12].…”

Section: Introductionmentioning

confidence: 99%

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

Grygar

Čapek

Adam

et al. 2009

Journal of Electroanalytical Chemistry

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Section: Electrochemical Behaviour Of V-oxides Supported On Tiomentioning

confidence: 65%

Section: Electrochemical Behaviour Of V-oxides Supported On Tiomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Grygar

Čapek

Adam

et al. 2009

Journal of Electroanalytical Chemistry

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“…The amount of acetaldehyde released thus depends on the reducibility of the vanadia nanoclusters present on the material surface. It is well established that the reducibility of vanadia clusters depends on both the chemical identity of the anchoring material (support), and the cluster domain size . The presence of two peaks on the TPD profile, thus suggests a distribution of vanadia clusters with different reducibility.…”

Section: Resultsmentioning

confidence: 99%

Supported Vanadium Oxide Clusters in Partial Oxidation Processes: Catalytic Consequences of Size and Electronic Structure

2017

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The catalytic activity for ethanol partial oxidation of vanadium oxide (VOx) anchored on titanium oxide was correlated to their electronic structure. In situ Raman spectroscopy and temperature‐programmed desorption (TPD) experiments indicate that the presence of catalytically active VOx moieties is very sensitive to vanadia loading: highly dispersed VOx predominantly exists at low VOx contents whereas larger vanadia clusters coexist at higher VOx loadings. In situ UV/Vis spectroscopy revealed that a significant fraction of these larger clusters remain reduced during catalysis, and thus do not fully participate in catalytic turnovers. The electronic structures of model VOx nanoclusters of different sizes (monomer, dimer, trimer, and one‐dimensional polymers) were investigated by using periodic density functional theoretical calculations. Results indicate that their electronic structures are significantly affected by their size. Our analysis also revealed that the formation of reduced VOx species (V4+) during catalysis is concomitant to the reduction of adjacent Ti cations (Ti3+). Theoretically calculated optical absorption spectra matched the experimental spectroscopic results obtained under in situ reaction conditions. Furthermore, the determination of defect formation enthalpies reported previously as the main descriptor for catalytic activity of vanadia nanoclusters, predicted that isolated monomeric VOx clusters predominantly take part in catalytic turnovers.

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“…MgO and CaO can react with V 2 O 5 to form Mg 2 V 2 O 7 and Ca 2 V 2 O 7 at the regenerator [9]. Martinez et al report the decrease in the mobility of V with TiO 2 /Al 2 O 3 [10].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of vanadium traps occluded in resid fluidized catalytic cracking (RFCC) catalyst for high gasoline yield

Jeon

Park

Woo

2006

Applied Catalysis A: General

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Reducibility, heats of re-oxidation, and structure of vanadia supported on TiO2 and TiO2–Al2O3 supports used as vanadium traps in FCC

Cited by 9 publications

References 17 publications

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

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

Supported Vanadium Oxide Clusters in Partial Oxidation Processes: Catalytic Consequences of Size and Electronic Structure

Evaluation of vanadium traps occluded in resid fluidized catalytic cracking (RFCC) catalyst for high gasoline yield

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