Vanadium Oxides as Oxidation Catalysts

Simard, G. L.; Steger, John; Arnott, R. J.; Siegel, L.

doi:10.1021/ie50547a047

Cited by 96 publications

(21 citation statements)

References 8 publications

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“…The effects of cation vacancies on the lattice parameters cannot be assessed. 3 An adequate explanation for the effects of Zn+2 and Mg+2 additions is not a t hand. In terms of a substitution mechanism, the presence of Znf2 or Mg+z a t Cd+* lattice positions should be without effect.…”

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confidence: 99%

The Thermal Decomposition of Cadmium Hydroxide

Löw¹,

Kamel²

1965

J. Phys. Chem.

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Differential thermal and thermogravimetric analyses of CdO 9 1 .65H20 showed that four processes were involved in the thermal decomposition. Isothermal weight loss determinations showed that, a t 300' and above, the decomposition to CdOo.80 was continuous. The composition of intermediates is uncertain because of the rapid and continuous reaction.The decomposition was accompanied by marked textural changes of the solid. Surface areas of pure hydroxide as well as samples containing 1 atom yo Li+, Znf2, Mgf2, or Alfa were measured after heating in vacuo for various times at temperatures from 150 to 500'. Alf3-addition inhibited and Lif-addition enhanced oxide sintering up to 400', through the destruction or creation of oxygen vacancies. At 450 and ZOOo both Alfa and Lif additions increased sintering, suggesting that a cation vacancy mechanism became dominant.Some oxide was formed as low as 265'.During a study of the surface properties of CdO, it became necessary to prepare well-defined CdO samples by various means, including the thermal decomposition of the hydroxide. Although some work has been reported on the isobaric and isothermal dehydration of cadmium hydroxide,1s2 the information available was incomplete. Additional work was required and, consequently, the thermal decomposition of doped and undoped cadmium hydroxides was studied. Experimental DetailsCadmium hydroxide was precipitated from the nitrate with a m m~n i a ,~ thoroughly washed and dried a t 100' in air. A portion of the powder was mixed with enough LiOH, Zn(NO&, Mg(N0&, or Al(N03)a solution to yield a stiff paste, which was dried a t 110'. The amounts of solutions and their concentrations were sufficient to result in hydroxide samples that, when converted to CdO, would contain 1 atom % of foreign cations. Differential thermal analyses (d.t.a.) were made a t linear heating rates of 10°/min., using Pt-10% Pt.Rh thermocouples. A slowly moving stream of purified nitrogen passed over the nickel detector block. Thermogravimetric analysis (t.g.a.) was made in air with a modified Ainsworth automatic recording balance, a t linear rates of 4.6'/min. from room temperature to 500°. Isothermal weight loss (i.w.1.) was measured in air with a modified analytical balance. Sitrogen adsorption isotherms and B.E.T. surface areas4 were obtained with an apparatus of conventional desigm6 The initial degassing of each sample was carried out overnight a t room temperature because of the instability of the hydroxide. Surface areas were then measured for a sequence of heat treatments of various durations in vacuo {at each temperature. The surface areas, 'each calculated from data a t six relative pressures, are given in m.2/g. of starting material. Experiments and ResultsD.t.a. Experiments. These experiments are described in somewhat greater detail than would normally be warranted, because electrical disturbances of the instrument brought about by CdO can be used to deduce information about the extent of the decomposition. In studying the hydroxide-oxide transformation, it ...

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confidence: 99%

The Thermal Decomposition of Cadmium Hydroxide

Löw¹,

Kamel²

1965

J. Phys. Chem.

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“…2,3 Several prior examples of on-surface metal−ligand coordination involved diatomic elimination (e.g., H 2 ), as in porphyrin 4,5 and terephthalic acid 6 metalation with surface-supported elemental metal, such that the resultant complexed metals adopted a +2 oxidation state. In our recent studies of direct donation of electrons into a redox-active tetrazine 7 or ketone-functionalized phenanthroline 8 a +2 metal oxidation state was achieved without diatomic elimination for platinum, chromium, and iron.…”

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confidence: 99%

Two- and Three-Electron Oxidation of Single-Site Vanadium Centers at Surfaces by Ligand Design

et al. 2015

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Rational, systematic tuning of single-site metal centers on surfaces offers a new approach to increase selectivity in heterogeneous catalysis reactions. Although such metal centers of uniform oxidation states have been achieved, the ability to control their oxidation states through the use of carefully designed ligands had not been shown. To this end, tetrazine ligands functionalized by two pyridinyl or pyrimidinyl substituents were deposited, along with vanadium metal, on the Au(100) surface. The greater oxidizing power of the bis-pyrimidinyltetrazine facilitates the on-surface redox formation of V(3+), compared to V(2+) when paired with the bis-pyridinyltetrazine, as determined by X-ray photoelectron spectroscopy. This demonstrates the ability to control metal oxidation states in surface coordination architectures by altering the redox properties of organic ligands. The metal-ligand complexes take the form of one-dimensional polymeric chains, resolved by scanning tunneling microscopy. The chain structures in the first layer are very uniform and are based on the same quasi-square-planar coordination geometry around single-site V with either ligand. Formation of a different, dimer structure is observed in the early stages of the second layer formation. These systems offer new opportunities in controlling the oxidation state of single-site transition metal atoms at a surface for new advances in heterogeneous catalysts.

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“…Die Deposition von Dieselruûpartikeln mit typischen Mobilitätsdurchmessern zwischen 20 und 300 nm bei Anzahlkonzentrationen von bis zu 10 8 cm ±3 wurde bislang ausschlieûlich für keramische Ruûpartikelfilter untersucht [2,3]. Bisherige Studien zeigen, dass der anzahlbezogene Gesamtabscheidegrad E 0 von Ruûpartikeln in konventionellen Oxidationskatalysatoren unter 5 % liegt [4].…”

Section: A R M I N M E S S E R E R H a N S -J O A C H I M S C H M Iunclassified

Aufbau und katalytische Aktivität hierarchisch nano‐strukturierter Oxid‐Katalysatoren – Teil 3: Einfluss der Calcinierungstemperatur auf Stabilität und katalytisches Verhalten geträgerter V₂O₅/TiO₂‐Katalysatoren

Stelzer¹,

Feldhoff²,

Caro³

et al. 2004

Chemie Ingenieur Technik

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Vanadium Oxides as Oxidation Catalysts

Cited by 96 publications

References 8 publications

The Thermal Decomposition of Cadmium Hydroxide

The Thermal Decomposition of Cadmium Hydroxide

Two- and Three-Electron Oxidation of Single-Site Vanadium Centers at Surfaces by Ligand Design

Aufbau und katalytische Aktivität hierarchisch nano‐strukturierter Oxid‐Katalysatoren – Teil 3: Einfluss der Calcinierungstemperatur auf Stabilität und katalytisches Verhalten geträgerter V₂O₅/TiO₂‐Katalysatoren

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Vanadium Oxides as Oxidation Catalysts

Cited by 96 publications

References 8 publications

The Thermal Decomposition of Cadmium Hydroxide

The Thermal Decomposition of Cadmium Hydroxide

Two- and Three-Electron Oxidation of Single-Site Vanadium Centers at Surfaces by Ligand Design

Aufbau und katalytische Aktivität hierarchisch nano‐strukturierter Oxid‐Katalysatoren – Teil 3: Einfluss der Calcinierungstemperatur auf Stabilität und katalytisches Verhalten geträgerter V2O5/TiO2‐Katalysatoren

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Aufbau und katalytische Aktivität hierarchisch nano‐strukturierter Oxid‐Katalysatoren – Teil 3: Einfluss der Calcinierungstemperatur auf Stabilität und katalytisches Verhalten geträgerter V₂O₅/TiO₂‐Katalysatoren