Structure and properties of PVMo11O40 heteropolyoxomolybdate supported on silica SBA-15 as selective oxidation catalyst

Ressler, Thorsten; Dorn, U.; Walter, Anke; Schwarz, Stephan; Hahn, Alexander

doi:10.1016/j.jcat.2010.07.001

Cited by 32 publications

(18 citation statements)

References 28 publications

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“…The hydrated 11-molybdo-1-vanadophosphoric heteropolyacid (H4PMo11VO40·xH2O) was synthesized according to a method described previously in the literature [2]. The number of crystal water molecules was calculated from TGA results (vide infra), which suggested that eight molecules of water were incorporated in the secondary structure (H4PMo11VO40·8H2O).…”

Section: Materials Synthesesmentioning

confidence: 99%

“…Keggin-type heteropolyacid and their salts exhibit excellent performance in several catalytic reactions like oxidation, ammoxidation [1,2], oxidative dehydrogenation [3,4] and dehydration [5,6]. More particularly, vanado-molybdo-phosphoric acid (H4PMo11VO40) is a promising bi-functional catalyst for the direct oxidation of isobutane (IBAN) into methacrylic acid (MAA) because of its acidic and redox chemical properties [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

et al. 2015

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When using heteropolycompounds in the selective oxidation of isobutane to methacrolein and methacrylic acid, both the keeping of the primary structure (Keggin units) and the presence of acidic sites are necessary to obtain the desired products. The structural evolution of supported (NH4)3HPMo11VO40 (APMV) catalysts under preliminary thermal oxidizing and reducing treatments was investigated. Various techniques, such as TGA/DTG (Thermo-Gravimetric Analysis/Derivative Thermo-Gravimetry), H2-TPR (Temperature Programed Reduction), in situ XRD (X-Ray Diffraction) and XPS (X-ray Photoelectron Spectroscopy), were applied. It was clearly evidenced that the thermal stability and the reducibility of the Keggin units are improved by supporting 40% APMV active phase on Cs3PMo12O40 (CPM). The partial degradation of APMV takes place depending on temperature and reaction conditions. The decomposition of ammonium cations (releasing NH3) leads to the formation of vacancies favoring cationic exchanges between vanadium coming from the active phase and cesium coming from the support. In addition, the vanadium expelled from the ) to activate isobutane. The increase in reducibility of the supported catalyst is assumed to improve the catalytic performance in comparison with those of unsupported APMV.

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Section: Materials Synthesesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

et al. 2015

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“…Supporting the heteropolyacids on porous solids with high specific surface area may improve their catalytic performance in various liquid-solid and gas-solid heterogeneous reactions. A lot of studies have been pub- * corresponding author; e-mail: boudjemaa.souhila@gmail.com lished on the immobilization of heteropolyacids on various supports including silica, alumina, titania, and zeolites [6][7][8][9][10]. Among them, clay minerals have been also explored as the supports for heteropolyacids.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Cyclohexene with H₂O_{_2} Catalyzed by Vanadium Based Polyoxometalates Doped Modified Clays as Green Catalysts

2017

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The catalytic performance of supported heteropolyacids in various liquid-solid and gas-solid heterogeneous reactions may be affected by the choice of support and/or the method of heteropolyacid deposition. Vanadium substituted polyphosphomolybdate with the Keggin structure H4[PVMo11O40]·13H2O (PVMo) was dispersed throughout acid activated bentonite (clay from Hammam Boughrara, Maghnia, Algeria). A series of catalysts were prepared via modified impregnation. Modified preparation method employed ultrasonication as a means of the dispersion homogenization, followed by freeze-drying. The catalysts were characterized by the Brunauer-Emmett-Teller, the Fourier transform infrared, and 31 P solid-state magic angle spinning-NMR spectroscopy. The catalytic performance of PVMo/Hmont was evaluated in the oxidation of cyclohexene. Intact Keggin anions were preserved on Hmont after deposition aided by ultrasonication. The obtained results showed that a better catalytic activity can be obtained with PVMo/bentonite (98% of conversion and 89% of cyclohexene oxide), by drop addition of H2O2, for 3 h.

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“…[6,19] )i nt he range between 2.5 and 3.8 w as previously reported for PVMo 11 and PVMo 11 -SBA-15. [18] Eventually,t he Mo and VK -edge FT(c(k)·k 3 )c onfirmed that the Keggini on structure motif was maintained upon supportingP V 2 Mo 10 on SBA-15. The Vand Mo K-edge X-ray absorption near-edge structure (XANES) spectra of the as-prepared PV 2 Mo 10 -SBA-15 and activated PV 2 Mo 10 -SBA-15 after thermal treatment in 5% propene and 5% oxygen in He at 723 Ka re shown in Figure 3.…”

mentioning

confidence: 95%

“…[22,23] The evolution of the normalized pre-edge peak height together with the ion currents of H 2 O, CO, CO 2 ,a crolein, and acetone during the oxidation of propene is shown in Figure 5b )o factivated PV 2 Mo 10 -SBA-15 exhibited features similart ot hat of previously reported dehydrated molybdenum oxidesa nd HPOMs supported on SBA-15. [18,23] For am ore detailed analysis, hexagonal MoO 3 was used as astructuralmodel.Theoretical X-ray absorption fine structure (XAFS) phases and amplitudes were calculated for MoÀOa nd MoÀMo distances and used fore xtended X- Hence, isolated tetrahedral [MoO 4 ]u nits can be excluded as major molybdenum oxide species. [24] Linear combinations of the XANES spectra of Na 2 The evolution of the average local structure aroundVc enters in the supported catalysts and reference materials differed from that aroundM oc enters.…”

mentioning

confidence: 99%

Role of Vanadium and Phosphorus in Substituted Keggin‐Type Heteropolyoxo Molybdates Supported on Silica SBA‐15 in Selective Propene Oxidation

2015

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Vanadium‐containing Keggin‐type heteropolyoxo molybdate ([PV2Mo10O40]5−) was supported on silica SBA‐15 (denoted as PV2Mo10‐SBA‐15). The structural evolution and catalytic activity of PV2Mo10‐SBA‐15 and a suitable reference V2Mo10Ox‐SBA‐15 were investigated under selective propene oxidation conditions by using in situ X‐ray absorption spectroscopy. 31P MAS NMR measurements of supported PV2Mo10‐SBA‐15 and reference H3PO4‐SBA‐15 were performed after the catalytic reaction. PV2Mo10‐SBA‐15 formed a mixture of mainly tetrahedral [MoOx] and [VOx] units during thermal treatment under propene oxidation conditions. Changes in the average local structure around V centers coincided with the changes in the average local structure around Mo centers and the onset of catalytic activity. In addition, mainly tetrahedral [MoOx] and [VOx] units seemed to be in close proximity and interacted under catalytic conditions. Conversely, in the reference material V2Mo10Ox‐SBA‐15 synthesized with individual V and Mo source precursors, Mo and V centers appeared to be more separated from each other. The structural environment of P in PV2Mo10‐SBA‐15 under catalytic conditions corresponded to a mixture of various species. P was connected to both the support material SBA‐15 via POSi bonds and [MoOx] or [VOx] units. Apparently, the proximity of V and Mo in Keggin precursors was a prerequisite for obtaining (Mo,V) oxide species on the support material.

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Structure and properties of PVMo11O40 heteropolyoxomolybdate supported on silica SBA-15 as selective oxidation catalyst

Cited by 32 publications

References 28 publications

Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

Oxidation of Cyclohexene with H₂O_{_2} Catalyzed by Vanadium Based Polyoxometalates Doped Modified Clays as Green Catalysts

Role of Vanadium and Phosphorus in Substituted Keggin‐Type Heteropolyoxo Molybdates Supported on Silica SBA‐15 in Selective Propene Oxidation

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Structure and properties of PVMo11O40 heteropolyoxomolybdate supported on silica SBA-15 as selective oxidation catalyst

Cited by 32 publications

References 28 publications

Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

Structural Evolution under Reaction Conditions of Supported (NH4)3HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

Oxidation of Cyclohexene with H2O_2 Catalyzed by Vanadium Based Polyoxometalates Doped Modified Clays as Green Catalysts

Role of Vanadium and Phosphorus in Substituted Keggin‐Type Heteropolyoxo Molybdates Supported on Silica SBA‐15 in Selective Propene Oxidation

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Oxidation of Cyclohexene with H₂O_{_2} Catalyzed by Vanadium Based Polyoxometalates Doped Modified Clays as Green Catalysts