The Preparation, Characterization, and Catalytic Behavior of MoVTeNbO Catalysts Prepared by Hydrothermal Synthesis

Botella, Pablo; Nieto, J.M. López; Solsona, Benjamín; Mifsud, A.; Márquez, Francisco

doi:10.1006/jcat.2002.3648

Cited by 157 publications

(150 citation statements)

References 27 publications

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“…Electron-accepting sites must be easily available to avoid pre-mature reduction of the adaptive binding site. This means that the number of surface locations where several active sites (if assumed that dimers are the units of active sites and not oligomers thereof) are at the same time available in the correct oxidation state will be quite low, giving a hint to the low levels of productivity [94,95] observed for such catalysts.…”

Section: Size and Functions Of Active Sitesmentioning

confidence: 99%

Active Sites for Propane Oxidation: Some Generic Considerations

Schlögl

2011

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Based on experimental observations about structure and dynamics of the reactive surface of the M1 phase some considerations are made about the nature and size of active sites. In analyzing the stoichiometry of the reactions following activation of propane it occurs that for dehydrogenation small sites are desirable being just sufficient to re-activate oxygen without kinetic hindrance. For deeper oxidation to acrylic acid (AA) the sites should be larger to accommodate all redox equivalents and oxygen species required for one transformation. A qualitative model for size and composition of the active site is made. It is likely that the active site consists on a VxOy species of strictly 2-D nature. This follows the structural suggestion for the active site on the a-b-plane of the M1 structure. The role of Te in moderating the active site is discussed. The suggestions are discussed in comparing requirements for oxidative dehydrogenation of propane (ODP) with those for AA synthesis.

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Section: Size and Functions Of Active Sitesmentioning

confidence: 99%

Active Sites for Propane Oxidation: Some Generic Considerations

Schlögl

2011

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“…By now, three classes of catalyst systems, VPO-type catalysts [1,2], heteropoly compounds catalysts (HPC) [3,4] and multi-component metal oxides catalysts (MMO) [5][6][7][8][9][10], have been studied for the selective oxidation of propane to acrylic acid. MMO catalysts are commonly considered to have a possibility to substitute the traditional catalysts in the existing industrial two-step process via propylene.…”

Section: Introductionmentioning

confidence: 99%

“…MMO catalysts are commonly considered to have a possibility to substitute the traditional catalysts in the existing industrial two-step process via propylene. Among those catalyst systems, Mo-V-Te-Nb oxide catalyst is the most promising one [7][8][9][10]. An appropriate MoVTeNb metal ratio is critical to the formation of catalyst active phase, according to the two patents of Ushikubo and Lin [7,8], the catalysts with metal ratio of 12 O x catalyst for propane oxidation is mainly due to its the intrinsic characteristics.…”

Section: Introductionmentioning

confidence: 99%

Effects of reaction conditions on the selective oxidation of propane to acrylic acid on Mo–V–Te–Nb oxides

Zhu

Yang

et al. 2004

Catalysis Today

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“…Usually the synthesis is performed at T = 448 K in nitrogen atmosphere applying a synthesis time of 48 h [23][24][25][26][27][28][29].…”

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confidence: 99%

“…López Nieto and co-workers conducted the synthesis under these conditions in a Teflon-lined stainless-steel autoclave using different metal-containing compounds and various nominal metal stoichiometries [23,24,[27][28][29]. Generally, phase mixtures including Mo 5 MO 3.33 (M = Mo, V, Nb) were obtained after heat treatment for 2 h at 873 K in nitrogen of the hydrothermally prepared precursor.…”

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confidence: 99%

Preparation of Phase-Pure M1 MoVTeNb Oxide Catalysts by Hydrothermal Synthesis—Influence of Reaction Parameters on Structure and Morphology

et al. 2008

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This work presents a detailed investigation of the preparation of MoVTeNbO x catalysts by hydrothermal synthesis. Phase-pure synthesis of M1 has been achieved applying the metals in a molar ratio Mo/V/Te/Nb = 1/0.25/ 0.23/0.12. Raman, UV/Vis spectroscopy, and SEM/EDX analysis show that the elements are inhomogeneously distributed in the initial suspension that is formed after mixing the metal salts in an aqueous medium. Iso-and heteropoly anions of molybdenum, free telluric acid as well as supramolecular polyoxometalate clusters are observed in the solution, whereas all metals have been found in the precipitate. Complete rearrangement of molecular building blocks under hydrothermal conditions is essential for formation of phase-pure materials. Optimized synthesis conditions with respect to temperature and time result in the formation of a precursor consisting of nano-structured M1 characterized by an extended periodic organization in the [001] direction and a fairly homogeneous distribution of the elements. Residual ammonium containing supramolecular species in the precursor result in the formation of phase mixtures during the subsequent crystallization by heat treatment in inert gas. Phase-pure M1 exhibits a distinct degree of flexibility with respect to the chemical composition that becomes obvious by incorporating Nb not exclusively into pentagonal bi-pyramidal units, but also into octahedral coordinated positions as shown by EXAFS. Anisotropic growth of the needle-like M1 crystals has been observed during the final heat treatment performed at 873-923 K in inert atmosphere disclosing a potential method to control the catalytic properties of MoVTeNbO x catalysts.

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The Preparation, Characterization, and Catalytic Behavior of MoVTeNbO Catalysts Prepared by Hydrothermal Synthesis

Cited by 157 publications

References 27 publications

Active Sites for Propane Oxidation: Some Generic Considerations

Active Sites for Propane Oxidation: Some Generic Considerations

Effects of reaction conditions on the selective oxidation of propane to acrylic acid on Mo–V–Te–Nb oxides

Preparation of Phase-Pure M1 MoVTeNb Oxide Catalysts by Hydrothermal Synthesis—Influence of Reaction Parameters on Structure and Morphology

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