58834-75-6

Basic information

• Product Name: VANADYLPYROPHOSPHATE
• Synonyms: VANADYLPYROPHOSPHATE
• CAS NO: 58834-75-6
• Molecular Formula: O9P2V2
• Molecular Weight: 0
• EINECS: 406-260-5
• Mol File: 58834-75-6.mol
• Article Data: 69

Chemical Properties

• Boiling Point: 360℃[at 101 325 Pa]
• Appearance: /
• Density: 1.767[at 20℃]
• Water Solubility: 12.25mg/L at 20℃
• CAS DataBase Reference: VANADYLPYROPHOSPHATE(CAS DataBase Reference)
• NIST Chemistry Reference: VANADYLPYROPHOSPHATE(58834-75-6)
• EPA Substance Registry System: VANADYLPYROPHOSPHATE(58834-75-6)

Safety Data

• Hazard Codes: Xi
• Statements: 36-43-52/53
• Safety Statements: 24-26-37-61
• Hazardous Substances Data: 58834-75-6(Hazardous Substances Data)

Usage

Flammability and Explosibility

Nonflammable

InChI:InChI=1/3H4O7P2.4V/c3*1-8(2,3)7-9(4,5)6;;;;/h3*(H2,1,2,3)(H2,4,5,6);;;;/q;;;4*+3/p-12

Upstream product

• 86119-84-8 phosphoric acid 
• 80937-33-3 oxygen 
• 12054-39-6 oxo orthohydrogenphosphato vanadium (IV) 

Relevant articles and documents

HREM microstructural studies on the effect of steam exposure and cation promoters on vanadium phosphorus oxides: New correlations with n-butane oxidation reaction chemistry

In situ environmental high-resolution electron microscopy (in situ EHREM) under different gaseous environments and ex situ HREM have been used to directly probe commercially important vanadyl pyrophosphate ((VO)2P2O7) cata

Novel preparation of vanadyl pyrophosphate for selective oxidation of n-butane utilizing intercalation and exfoliation

Intercalation-exfoliation of VOPO4·2H2O crystallites (20 (μm in size) in 2-butanol, followed by reduction with 2-butanol, brought about thin layers of precursor, VOHPO4·O-5H2O, with size of about 2 μm. The obtai

Microstructures of V-P-O catalysts derived from VOHPO4·0. 5H2O of different crystallite sizes

The influence of crystallite size of precursor VOHPO4·0. 5H2O on the microstructure of a resulting catalyst and selective oxidation of n-butane are investigated. Two kinds of VOHPO4·0. 5H2O, small crystallites (av. 1 μm × 110 nm) and large crystallites (av. 10 μm × 415 nm), were prepared by intercalation-exfoliation-reduction of VOPO4·2H2O in 2-butanol and the direct reduction of VOPO4·2H2O with 2-butanol, respectively. The small VOHPO4·0.5H 2O crystallites transformed into single-phase (VO)2P 2O7 of high specific surface area under the reaction conditions of 1.5% n-butane, 17% O2, and He (balance) at 663 K. In contrast, the catalyst formed from the large VOHPO4·0.5H 2O crystallites assumed the form of particles having a double-layered structure, consisting of peripheral (VO)2P2O7 and internal αII-VOPO4. As compared with the large (VO)2P2O7, the small (VO)2P 2O7 showed high selectivity to maleic anhydride (～78% at 663 K) and higher catalytic activity. Meanwhile, the catalyst with the double-layered structure exhibited moderate selectivity (～70%). Since (VO)2P2O7 is considered to be a selective phase for the selective oxidation of n-butane, the single-phase of (VO) 2P2O7 derived from the small-sized VOHPO 4·0.5H2O crystallites is considered a reason for the high selectivity to maleic anhydride.

The oxygen isotopic exchange reaction on vanadium oxide catalysts

The reactivity of lattice oxygen of vanadium oxide catalysts was studied with the oxygen isotopic exchange reaction. The reactivity of pure V2O5 is compared with the reactivity of Li0.33V2O5, V2

Permanent blockade of in situ-generated acid Bronsted sites of vanadyl pyrophosphate catalysts by pyridine during the partial oxidation of toluene

The permanent blockade of in situ-formed Bronsted-acid OH groups and an effective lowering of the catalyst acidity during the partial oxidation of toluene to benzaldehyde is demonstrated by an efficient method using a continuous dosing of pyridine to the feed that leads to drastically increased aldehyde selectivities.

The unexpected role of aldehydes and ketones in the standard preparation method for vanadium phosphate catalysts

Since vanadium phosphate compounds are widely used as heterogeneous catalysts for the production of maleic anhydride for n-butane partial oxidation, their preparation has been extensively studied. The potential role played by aldehyde or ketone by-products in the synthesis of such catalysts was investigated. VO(H2PO4)2 was formed as the exclusive product from the reaction of aldehydes or ketones (C4-C10) with V2O5 and H3PO4 whether aqueous (85%) or crystalline (100%) orthophosphoric acid was used. This observation was significant for the synthesis of the commercially important hemihydrate VOHPO4·0.5H2O precursor, which is typically synthesized from V2O5 and H3PO4 using an alcohol as the reducing agent, leading to the formation of aldehydes/ketones as by-products. The use of isobutanol containing a small amount of butanone for the reaction of V2O5 and H3PO4 (100%) proved that low levels of VO(H2PO4)2 could be formed along with VOHPO4·0.5H2O.

Effects of mechanochemical treatment to the vanadium phosphate catalysts derived from VOPO4·2H2O

Modification by using mechanochemical treatment of vanadium phosphate catalysts on the microstructure, morphology, oxygen nature and catalytic performance for n-butane oxidation is described and discussed. In this work, the precursor, VOHPO4·0.5H2O prepared by reduction of VOPO4·2H2O by isobutyl alcohol was subjected to a high energy planetary ball mill for 30, 60 and 120 min in ethanol. The ball milling process reduced the crystallite size of the catalysts and consequently increased their surface area. The morphologies of the milled catalysts are dependent on milling time. The highest reactivity and mobility of the lattice oxygen species has been achieved by the catalyst milled for 60 min with lower reduction peak temperature and higher amount of oxygen atoms removed. The oxygen species removed from the active V4+ phase was shown to be correlated with the rate of reaction. A good relationship was also found between the oxygen species associated with V5+ and maleic anhydride selectivity. However, a larger amount of this oxygen species will give a deleterious effect on the conversion rate. The present study demonstrate that the mechanochemical method (with an appropriate duration) effectively enhanced the catalytic activity by increasing the surface area and controlling the reactivity, and that the amount of oxygen species contributed to the partial oxidation of n-butane to maleic anhydride.

Selective oxidation of n-butane to maleic anhydride on vanadyl pyrophosphate: I. Influence of oxidation pretreatments on the catalytic performances

A pure and well-crystallized (VO)2P2O7 catalyst was oxidized under an oxygen flow at 500°C for different times up to 24 h. These samples were characterized by TGA-DTA, XRD, UV-VIS spectroscopy and 31P NMR. Their catalytic performances were compared in the selective oxidation of n-butane to maleic anhydride (MA) as a function of the time of oxidizing pretreatments. The sample oxidized for 1 h displayed an important increase in MA selectivity (from 52 to 84%), whereas the activity remained virtually nonaffected. These results have been discussed in relation with the development of a proper density of selective VV species associated with the creation of structural disorder in the pyrophosphate lattice.

Redox Interaction of Ammonia with (VO)2P2O7

The interaction of ammonia with (VO)2P2O7 prepared by calcination of the precursor compound VOHPO4*0.5H2O under nitrogen has been studied using temperature-programmed desorption of ammonia (TPDA), temperature-programmed reaction spectroscopy (TPRS), and IR and EPR spectroscopy.Mass-spectrometric detection was applied to observe possible ammonia decomposition or oxidation products.The investigation revealed that ammonia is not only adsorbed on but also reacts with (VO)2P2O7 in a redox process generating nitrogen, water and an amorphous V(III)-containing compound, the concentration of which could be directly determined by potentiometric titration.The high amount of V(III) found pointed towards reduction of V(IV) not only on the surface but also in deeper layers of the bulk.This was also confirmed by EPR spectroscopy.Furthermore, this reaction results in a change of the Broensted and Lewis acidity observed by IR spectroscopy.The concentration of the Broensted-acid OH groups was strongly enhanced by hydrolysis of P-O-P and/or V-O-P links by water formed during the redox reaction.The increased concentration of Lewis sites was caused by the removal of oxygen from surface vanadyl groups, probably creating additional coordinatively unsaturated sites.The influence of the observed redox reaction on the characterization of the acidity and the formation of VPO catalysts in the ammoxidation reaction are discussed.

Vanadyl hydrogenphosphate sesquihydrate as a precursor for preparation of (VO)2P2O7 and cobalt-incorporated catalysts

Vanadyl hydrogenphosphate sesquihydrate (VOHPO4 · 1.5H2O) was prepared by reduction of VOPO4 · 2H2O suspended in refluxed 1-butanol and activated at 480°C over 10 h on-stream to give (VO)2P2O7, which revealed high specific activity per unit surface area in the vapor-phase oxidation of n-butane. Cobalt-modified (VO)2P2O7 catalysts were prepared in the present work by intercalating sesquihydrate precursor with cobaltous acetate employing 1-butanol as solvent. The catalysts prepared from cobalt-intercalated precursor showed high specific activity, but both selectivities to maleic anhydride and surface area decreased with increasing cobalt-contents. Presumably, intercalated cobalt species retarded topotactic dehydration of layered precursor to afford crystalline active species (VO)2P2O7, leading to an increase in unfavorable combustion activity due to pentavalent β-VOPO4 species. The activity of catalysts prepared for reference by kneading vanadyl hydrogenphosphate hydrates with an additive Co2P2O7 was interpreted as the variation in surface area, and cobalt has none of positive effects in these catalysts. (C) 2000 Elsevier Science B.V.

Investigation of vanadium phosphorus oxide catalysts (VPO) during toluene ammoxidation: New mechanistic insights by in situ EPR

(VO)2P2O7, differently prepared (NH4)2(VO)3(P2O7) 2 samples and supported amorphous vanadium phosphorus oxide (VPO) catalysts were investigated during the ammoxidation of toluene using a self-constructed in situ EPR flow reactor in the X-band. For the unsupported catalysts, changes in the spin-spin exchange behaviour were analysed by calculating the quotient of the 4th and the square of the 2nd moment, 〈B4〉/〈B2〉2, of the absorption signal. The catalytic activity was found to increase with exchange efficiency, while isolated vanadyl centres, as present in the supported catalysts, do not obviously participate in the catalytic process. NH4+ containing catalysts can easily supply ammonia for N insertion into the hydrocarbon indicating that the latter does not react directly with NH3 molecules from the gas phase but with those activated by adsorption on the surface of the catalyst according to a Langmuir-Hinshelwood mechanism.

Preparation and characterization of lamellar vanadyl alkylphosphates as catalyst precursors for the selective oxidation of butane

Vanadyl alkylphosphates consisting of V4+ and P5+ were synthesized by the reaction of a solid mixture of V2O5 and V4O9 (2:3 in mol) with P2O5 in primary aliphatic (from C1 to C8), secondary aliphatic (C3 and C4), and alicyclic (C5) alcohols, and were characterized by means of elemental analysis, thermogravimetric analysis, X-ray diffraction, IR spectroscopy, and magnetic susceptibility. The chemical formulae of the products were determined to be VO(RO)x(HO)1-xPO3·(ROH)y (x = 0.5-0.7, y = 0.3-0.5 for primary aliphatic alcohols; x = 0.1-0.2, y = 0.4-0.9 for secondary aliphatic and alicyclic alcohols; and R = organic group). X-ray diffraction revealed that the compounds had a lamellar structure, where the organic groups existed as double layers with a tilt of about 56° against the basal plane. Magnetism and IR spectroscopy demonstrated that the construction of the basal planes in the vanadyl alkylphosphates was similar to that of VOHPO4 · 0.5H2O, which consists of V4+ dimers linked with PO4, except for vanadyl sec-butylphosphate, consisting of isolated V4+ monomers. Calcination of vanadyl methylphosphate and vanadyl cyclopentylphosphate brought about crystallites of (VO)2P2O7. These (VO)2P2O7 exhibited high selectivities to maleic anhydride (65-68%) for the selective oxidation of butane under a high concentration of butane (5.0%).

31 P-NMR Study of Low-Energy Spin Excitations in Spin Ladder (VO)2P2O4 and Spin Dimer VO(HPO4)0.5H2O Systems

Using 31P-nuclear magnetic resonance (NMR), low-energy spin excitations are investigated in both (VO)2P2O7 and VO(HPO4) 0.5H2O, in which V4+ (S = 1/2) ions take ladder and dimer (isolated pair) configurations, respectively. Temperature (T) dependences of Knight shift (K) and nuclear spin-lattice relaxation time (Ti) in the two compounds show a thermally activated behavior originating from the spin gap formation in the low energy spin excitation. The most distinct difference appears in the T-dependence of (T1TK)-1 at low temperature, i.e., the T-independent behavior in the dimer system and the large decrease below the order of the spin gap in the ladder system. These experimental results suggest that the spin gap A is independent of wave vector q in the case of the dimer system, while A depends on q for the spin ladder system. Resonance frequency dependence of T1 in the temperature regions of both T and T Δ is also discussed.

Selective oxidation of p-substituted toluenes to the corresponding benzaldehydes over (VO)2P2O7: An in situ FTIR and EPR study

The adsorption and oxidation of p-chlorotoluene (PCT), p-methoxytoluene (PMT), and toluene on vanadyl pyrophosphate catalyst (VPP) were studied by in situ FTIR and EPR spectroscopy. Various amounts of strongly adsorbed benzaldehydes and cyclic anhydride species were observed by FTIR in dependence on the different educts after oxidation experiments. The extent of spin-spin exchange pertubation and, thus, the loss of the EPR signal intensity caused by substrate adsorption and interaction is influenced by the nature of the aromatic compound. The strength of reactant and product adsorption on the catalyst surface was found to be an important selectivity-limiting factor in the aldehyde formation. The benzaldehyde adsorption is enhanced by additional interaction of the carbonyl group with Bronsted acid hydroxyl groups generated during oxidation reaction, which facilitates deeper oxidation. The co-adsorption of pyridine is one possibility to suppress the strong aldehyde adsorption and to improve the selectivities. Yields of benzaldehydes and selectivities at constant conversion increase in the order PMT toluene PCT. Strong product adsorption favoured by electron donating p-substituents causes total oxidation leading to lower aldehyde selectivities. Both, the acid/basic characters of the reactants and products and their steric properties play an important role for adsorption/desorption processes. (C) 2000 Elsevier Science B.V.

Application of vanadyl hydrogen phosphate/KIT-6 composites as a catalyst for dehydration of sucrose

In this research work, the synthesis of well-ordered mesoporous structure KIT-6 silica-supported vanadyl hydrogen phosphate hemihydrate (VHP/KIT-6) catalysts possessing varying surface area was carried out, followed by being utilized in the dehydration of sucrose to 5-hydroxymethylfurfural (5-HMF) as a solid acid catalyst. The fabrication of two different VHP/KIT-6 catalysts was conducted using the impregnation approach through V2O5 reduction in alcoholic media. Then, the catalytic behavior presented by the prepared VHP/KIT-6 samples was compared with unsupported VHP and unsupported vanadyl pyrophosphate (VPP), which was prepared through the calcination of VHP precursor at 400?°C for 24?h. The prepared catalysts were characterized by different analyses, including ICP-OES, BET, XRD, NH3-TPD analysis, FT-IR spectroscopy, as well as SEM and TEM techniques. Furthermore, important parameters, including the catalyst type and weight, sucrose amount, time, temperature, and the type of solvent on sucrose dehydration, were also studied. It was observed that the highest catalytic activity in the dehydration reaction (5-HMF yield: 67%, sucrose conversion: > 94%) could be provided by the catalyst possessing the highest surface area. Moreover, the catalyst reusability was examined for consecutive four times, based on which no considerable change in the catalytic activity was observed.

Vanadium phosphorus oxide catalyst modified by niobium doping for mild oxidation of n-butane to maleic anhydride

The interest of doping (VO)2P2O7 with Nb5+ ions was studied for n-butane oxidation to maleic anhydride. Niobium was solubilized as niobium (V) ethoxide into isobutanol and used as a reducing reagent to prepare the VOHPO4·0.5H2O precursor. Under n-butane fuel-lean oxidation conditions, the VNbPO precursor was activated at 20°C lower than for undoped vanadium phosphorus oxide (VPO) due to a modification of its morphology. The activated VNbPO catalyst was more disorganized than the activated VPO. It comprised more defects and concentrates niobium at the surface. NB acted an n-type dopant for the p-type (VO)2P2O7 semi-conductor. VNbPO catalyst was more oxidized, particularly at the surface. Doping with niobium created defects, responsible for C-H n-butane activation, which were associated with Lewis acid sites of low acidity. This was the reason for the enhancement of the n-butane conversion. Selectivity to maleic anhydride was not modified by Nb-doping while CO2/CO formation was increased due to the higher surface V5+/V4+ ratio.

Structural changes of surface layer of vanadyl pyrophosphate catalysts by oxidation-reduction and their relationships with selective oxidation of n-butane

The surface structure of vanadyl pyrophosphate ((VO)2P2O7) and its changes upon controlled oxidation and reduction have been investigated comprehensively by means of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), EXAFS, X-ray diffraction (XRD), transmission electron diffraction (TED), and 'micropulse' reaction of n-butane. Oxidation of a well-defined (VO)2P2O7 with O2 (1 atm) at 733 K formed 'X1 phase' as a thin surface overlayer on (VO)2P2O7, where X1 phase is a phase reported previously (Shimoda, T.; Okuhara, T.; Misono, M. Bull. Chem. Sec. Jpn. 1985, 58, 2163-2171) and similar to δ-VOPO4. By the repeated micropulse reactions of n-butane, the surface X1 phase was gradually reduced back to (VO)2P2O7, showing that reversible redox reactions between X1 phase and (VO)2P2O7 occur by the reactions with butane and oxygen. XRD, EXAFS, and TED demonstrated that X1 phase has a structure analogous to (VO)2P2O7, in both of which V-O-V pair sites exist. The micropulse reaction of n-butane with the surface XI phase produced maleic anhydride with a significantly higher selectivity (~ 40%) than that with β-VOPO4 (1 phase is the real active phase involved in the redox cycle for the oxidation of n-butane to maleic anhydride(VO)2P2O7.

Preparation of vanadium phosphate catalysts from VOPO4·2H2O: Effect of VOPO4·2H2O preparation on catalyst performance

The morphology and structure of vanadium phosphate catalysts prepared from VOPO4·2H2O obtained from different preparation methods was studied. The manner in which the initial VOPO4·2H2O was prepared could have s

Structure-activity relationships for Co- and Fe-promoted vanadium phosphorus oxide catalysts

The effect of Co and Fe doping on vanadium phosphate catalysts, prepared by the reaction of V2O5 and H3PO4 with isobutanol, for the oxidation of n-butane to maleic anhydride is described and discussed. At low levels, both Co and Fe dopants significantly enhance the selectivity and the intrinsic activity to maleic anhydride. A combination of powder X-ray diffraction, 31P NMR spin-echo mapping spectroscopy and transmission electron microscopy, together with catalyst test data, is utilised to analyse the origin of the effects of Co doping. Co appears to be essentially insoluble in crystalline (VO)2P2O7 and is preferentially distributed in and stabilises an amorphous VPO material. It is suggested that the origin of the promotional effect of Co is associated with its interaction with the disordered VPO phase. The same techniques have been used to analyse the Fe-doped catalyst, but at present it is not possible to be definitive concerning the specific location of the Fe-dopant within the phases present. Previous studies have indicated that Fe can form a solid solution within (VO)2P2O7 and therefore it is probable that the Fe may act as an electronic promoter for this phase. The role of Co, however, emphasises the importance of amorphous vanadium phosphate phases in the catalyst system.

Thermogravimetric analysis of vanadium phosphorus oxide catalysts doped with cobalt and iron

The transformation of VOHPO4·0.5H2O (VPO) precursor doped with cobalt or iron for n-butane oxidation to maleic anhydride was investigated by thermogravimetric analysis under air and nitrogen, with and without n-butane in the flow. While almost no effect was observed in nitrogen or air, a strong influence of the doping was observed when n-butane was added to the nitrogen or air. This resulted in a delay of the decomposition of the precursor and a further reoxidation of the VPO catalyst, particularly for doping with cobalt at low percentage (1%). This shows that doping can change the oxidation state of vanadium phosphorus oxide catalysts, which can explain differences in their catalytic performances and the favourable effect of doping by cobalt.

Hierarchical design of mixed metal oxides: Novel macroporous VPO phases

Macroporous vanadium-phosphorus-oxide phases (macro-VPO) displaying ordered 0.2-0.4 μm pores and unprecedented high surface areas (44-75 m2 g-1) have been synthesized using colloidal arrays of polystyrene spheres as a template.

Boosting hydrogen evolution activity of vanadyl pyrophosphate nanosheets for electrocatalytic overall water splitting

Herein, (VO)2P2O7 nanosheets function as a highly-active electrocatalyst for the hydrogen evolution reaction with an ultralow overpotential of 30 mV at 10 mA cm-2 in basic media, being close to Pt/C. Furthermore, as a bifunctional electrocatalyst, (VO)2P2O7 not only exhibits high activity but also good stability for overall water splitting.

Olefins from Natural Gas by Oxychlorination

Ethylene and propylene are the key building blocks of the chemical industry, but current processes are unable to close the growing gap between demand and manufacture. Reported herein is an exceptional europium oxychloride (EuOCl) catalyst for the selective (≥95 %) production of light olefins from ethane and propane by oxychlorination chemistry, thus achieving yields of ethylene (90 %) and propylene (40 %) unparalleled by any existing olefin production technology. Moreover, EuOCl is able to process mixtures of methane, ethane, and propane to produce the olefins, thereby reducing separation costs of the alkanes in natural gas. Finally, the EuOCl catalyst was supported on suitable carriers and evaluated in extrudate form, and preserves performance for >150 h under realistic process conditions.