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

Sanfiz, A. Celaya; Hansen, Thomas Willum; Girgsdies, Frank; Timpe, Olaf; Rödel, Eva; Ressler, Thorsten; Trunschke, Annette; Schlögl, Robert

doi:10.1007/s11244-008-9106-z

Cited by 65 publications

(29 citation statements)

References 43 publications

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“…These particles spontaneously interlocked, thus generating a highly aggregated microstructure of HT-M1. [32,33,35] Heat activation of the H 2 O 2 -washed powder does not lead to any significant changes in the phase composition; the as-prepared W-M1 catalyst is single-phase M1 (Figure 4 A). Higher magnification images of this product clearly reveal the multistep structuring of the lateral surface of the cylindrical particles and a flat termination of the basal planes (inset in Figure S1B The XRD patterns for the hydrothermally derived catalyst crystallized through annealing at 873 K in Ar for 2 h prove the phase-purity of the HT-M1 catalyst (Figure 4 A).…”

Section: Resultsmentioning

confidence: 99%

“…Accordingly, the catalytic relevance of the crystallographic (001) planes (basal planes of elongated M1 particles) has been intensively discussed in the literature. [6,16,[28][29][30][31][32][33][34][35] Subsequent annealing in an inert atmosphere is necessary to crystallize the solids and to derive balanced oxidation states of the key elements. The situation is further complicated by the facts that the M1 phase is only accessible in a certain compositional range and that the surface composition of the active catalyst is extremely sensitive towards operation conditions.…”

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confidence: 99%

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Synthesis of MoVTeNb Oxide Catalysts with Tunable Particle Dimensions

et al. 2011

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IntroductionDuring the last three decades, complex multimetal oxides have captured the interest of researchers as potential catalysts for alkane activation. [1][2][3][4][5] In the oxidative dehydrogenation of ethane [5] and the selective oxidation of propane to acrylic acid, [6] selectivities of approximately 80 % have been achieved at high alkane conversion over mixed oxides based on Mo, V, Te, and Nb. The active catalysts are typically composed of the two different bronze-like compounds Mo 7.8 V 1.2 Te 0.937 NbO 28.9 and Mo 4.31 V 1.36 Te 1.81 Nb 0.33 O 19.81 , which are referred to in the literature as the M1 and M2 phases, respectively. [7][8][9][10][11][12][13] The activation of the CÀH bonds in the alkane molecule has been attributed primarily to the M1 phase. [6,[14][15][16][17][18] A synergistic effect of M2 in M1-M2 phase mixtures has also been discussed. [19] High crystallinity of the catalyst is required to achieve the utmost catalytic performance, implying the hypothesis that the development of active ensembles on the surface of M1 is governed by well-defined structural features. Accordingly, the catalytic relevance of the crystallographic (001) planes (basal planes of elongated M1 particles) has been intensively discussed in the literature. [10,[20][21][22][23][24][25] However, restricted applicability and resolution of spectroscopic and crystallographic methods strongly limit the knowledge regarding the molecular structure and electronic details of the M1 surface termination. The situation is further complicated by the facts that the M1 phase is only accessible in a certain compositional range and that the surface composition of the active catalyst is extremely sensitive towards operation conditions. [26] Because of the broad parameter space that determines the catalytic response of M1, development of controlled synthesis methods to produce well-defined, phase-pure materials is strongly required. This is important for gaining a deeper insight into the catalytic versatility of M1, which would provide a unique guide to design and discover new catalysts for selective oxidation.In general, MoVTeNb oxide catalysts are prepared by coprecipitation with subsequent rapid evaporation of the solvent [3,27] or by hydrothermal synthesis. [6,16,[28][29][30][31][32][33][34][35] Subsequent annealing in an inert atmosphere is necessary to crystallize the solids and to derive balanced oxidation states of the key elements. [36,37] At the state of the art, it is still a nontrivial experimental task to synthesize phase-pure M1 catalysts in a controlled manner. Particularly, it is difficult to avoid an intrinsic formation of the byproducts, such as the M2 phase, Te, (Mo 0.93 V 0.

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Section: Resultsmentioning

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Synthesis of MoVTeNb Oxide Catalysts with Tunable Particle Dimensions

et al. 2011

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“…The hydrothermal synthesis of MoVTeNb oxide nanoparticles (M1 phase) illustrates the high degree of selectivity that can be achieved through a carefully tuned hydrothermal process. [68] After a multitude of parameter optimizations, for example, of the reaction time, the temperature, the reactor inlay, and the stirring mode, XANES/ EXAFS studies demonstrated that the hydrothermal reaction is the crucial step leading to a homogeneous mixed-oxide phase with all five cations incorporated. Post-treatment at 550 8C then affords a crystalline product for catalytic applications.…”

Section: Hydro-and Solvothermal Methodsmentioning

confidence: 99%

“…[142] 1,4-Butanediol turned out to be the optimal surface stabilizer during the reaction, because it limits the particle growth and prohibits agglomeration. Finally, the Mo-V-Te-Nb-O system [68] has not only been accessed with hydrothermal and spray-drying methods, [143] but also with microwave irradiation as a heat source. [144] In this case, the MW-approach led to the formation of the M1 phase with an interesting open structure and high catalytic activity.…”

Section: Microwave-assisted Strategiesmentioning

confidence: 99%

Oxide Nanomaterials: Synthetic Developments, Mechanistic Studies, and Technological Innovations

et al. 2010

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Oxide nanomaterials are indispensable for nanotechnological innovations, because they combine an infinite variety of structural motifs and properties with manifold morphological features. Given that new oxide materials are almost reported on a daily basis, considerable synthetic and technological work remains to be done to fully exploit this ever increasing family of compounds for innovative nano-applications. This calls for reliable and scalable preparative approaches to oxide nanomaterials and their development remains a challenge for many complex nanostructured oxides. Oxide nanomaterials with special physicochemical features and unusual morphologies are still difficult to access by classic synthetic pathways. The limitless options for creating nano-oxide building blocks open up new technological perspectives with the potential to revolutionize areas ranging from data processing to biocatalysis. Oxide nanotechnology of the 21st century thus needs a strong interplay of preparative creativity, analytical skills, and new ideas for synergistic implementations.

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“…[142] Die Partikelgröße wurde dabei durch Verwendung von 1,4-Butandiol gesteuert, das durch Oberflächenstabilisierung das Teilchenwachstum beschränkt und Agglomerationsphänomene verhindert. Auch das Mo-V-Te-Nb-O-Oxidsystem [68] wurde nicht nur mit Hydrothermal-und Spraytrocknungsmethoden [143] erschlossen, sondern auch mit Mikrowellenstrahlung als Heizquelle. [144] Diese Strategie führte schließlich zur Bildung der M1-Phase dieses Systems mit einem interessanten offenen Strukturmotiv und hoher katalytischer Aktivität.…”

Section: Mikrowellensynthesenunclassified

Oxidische Nanomaterialien: Von der Synthese über den Mechanismus zur technologischen Innovation

et al. 2010

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Oxidische Nanomaterialien verbinden eine einzigartige und unerschöpfliche Vielfalt struktureller Motive und Eigenschaften mit einer großen Bandbreite morphologischer Variationen – dies macht sie unverzichtbar für nanotechnologische Innovationen. Die Familie der Oxidmaterialien ist in einem stetigen Wachstum begriffen, und somit liegt eine beträchtliche präparative und technologische Arbeit vor uns, um diese Fülle von Komponenten für neuartige Anwendungen auf der Nanoskala zu erschließen. Dies erfordert die Entwicklung zuverlässiger und skalierbarer Präparationsstrategien, die aber besonders für nanostrukturierte Oxide mit komplexer Zusammensetzung eine Herausforderung sind. Mit ihrem anspruchsvollen physikochemischen Hintergrund eröffnen die bislang eingeführten Methoden den Weg zu nanoskaligen Oxiden verschiedenartiger Morphologie, die auf konventionelle Weise nur schwer erhältlich sind. Die vielfältigen modularen Optionen nanoskaliger Oxide als neue Bausteine können revolutionäre Entwicklungen vorantreiben, von der Datenverarbeitung bis hin zur Biokatalyse. Um diese Wechselwirkungen entsprechend zu nutzen, bedarf die Oxid‐Nanotechnologie des 21. Jahrhunderts einer starken Kombination aus präparativer Kreativität, analytischen Instrumentarien und neuen Anwendungsideen.

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

Cited by 65 publications

References 43 publications

Synthesis of MoVTeNb Oxide Catalysts with Tunable Particle Dimensions

Synthesis of MoVTeNb Oxide Catalysts with Tunable Particle Dimensions

Oxide Nanomaterials: Synthetic Developments, Mechanistic Studies, and Technological Innovations

Oxidische Nanomaterialien: Von der Synthese über den Mechanismus zur technologischen Innovation

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