Synthesis and characterization of new VPO catalysts for partial n-Butane oxidation to maleic anhydride

Batis, Narjès Harrouch

doi:10.1016/0021-9517(91)90081-e

Cited by 113 publications

(14 citation statements)

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“…This result suggests that the active layer offering the best selectivity towards MA is d-VOPO 4 , and that with both catalysts the latter is formed by the oxidation of VPP at high temperature, especially in the presence of steam, whereas at intermediate temperature it is formed only in P/V1.2, and in the presence of steam. This also agrees with indications in the literature concerning the role of d-VOPO 4 in n-butane oxidation; [55][56][57] it cannot be ruled out, however, that in the presence of hydrocarbon the V V phosphate is readily reduced back to VPP and that, under a reactive atmosphere, the surface of the catalyst is reduced on average, if the re-oxidation of V is the rate-limiting step of the reaction.…”

Section: Discussionsupporting

confidence: 91%

Surface Dynamics of A Vanadyl Pyrophosphate Catalyst for n‐Butane Oxidation to Maleic Anhydride: An In Situ Raman and Reactivity Study of the Effect of the P/V Atomic Ratio

Cavani

Luciani

Esposti

et al. 2010

Chemistry A European J

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This work focused on investigating the effect of the P/V atomic ratio in vanadyl pyrophosphate, catalyst for n-butane oxidation to maleic anhydride, on the nature of the catalytically active phase. Structural transformations occurring on the catalyst surface were investigated by means of in situ Raman spectroscopy in a non-reactive atmosphere, as well as by means of steady-state and non-steady-state reactivity tests, in response to changes in the reaction temperature. It was found that the nature of the catalyst surface is affected by the P/V atomic ratio even in the case of small changes in this parameter. With the catalyst having P/V equal to the stoichiometric value, a surface layer made of alpha(Iota)-VOPO(4) developed in the temperature interval 340-400 degrees C in the presence of air; this catalyst gave a very low selectivity to maleic anhydride in the intermediate T range (340-400 degrees C). However, at 400-440 degrees C delta-VOPO(4) overlayers formed; at these conditions, the catalyst was moderately active but selective to maleic anhydride. With the catalyst containing a slight excess of P, the ratio offering the optimal catalytic performance, delta-VOPO(4) was the prevailing species over the entire temperature range investigated (340-440 degrees C). Analogies and differences between the two samples were also confirmed by reactivity tests carried out after in situ removal and reintegration of P. These facts explain why the industrial catalyst for n-butane oxidation holds a slight excess of P; they also explain discrepancies registered in the literature about the nature of the active layer in vanadyl pyrophosphate.

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Section: Discussionsupporting

confidence: 91%

Surface Dynamics of A Vanadyl Pyrophosphate Catalyst for n‐Butane Oxidation to Maleic Anhydride: An In Situ Raman and Reactivity Study of the Effect of the P/V Atomic Ratio

Cavani

Luciani

Esposti

et al. 2010

Chemistry A European J

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“…In the preparation of the cobalt hydroxyapatite, Co(NO 3 ) 2 ·6H 2 O (Merck KGa, Darmstadt, Germany) was used. The method of preparation of VPO has been extensively reported in literature 3,6,8,9,28 . In a modified method for preparing VPO, a mixture containing V 2 O 5 (5.00 g) (BDH, Poole, England) and H 3 PO 4 (30 mL, 85 wt.…”

Section: Preparation Of Catalystsmentioning

confidence: 99%

“…The similar trend in conversion is due to a similar reduction pattern observed in TPR and the difference in the selectivity is related to the Ca/P and Co/P ratios. Also, phosphorus stabilizes the active +4 valence state of vanadium and influences its oxidation properties 3,5,9 . In the supported VPO catalysts, phosphorus is present in the hydroxyapatite and VPO and there is a substantial increase in the amount of phosphorus at higher VPO loadings.…”

Section: Catalytic Testingmentioning

confidence: 99%

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Partial oxidation of n-pentane over vanadium phosphorus oxide supported on hydroxyapatites

Singh

2016

S.Afr.j.chem.

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The selective oxidation of n-pentane to value-added products, maleic anhydride or phthallic anhydride by vanadium phosphorus oxide loaded on hydroxyapatites as catalysts and oxygen as oxidant was investigated. Hydroxyapatite (HAp) and cobalthydroxyapatite (Co-HAp) were prepared by the co-precipitation method and VPO with varying weight percentages (2.5-15.0 %) were loaded on the hydroxyapatite supports by the wet impregnation technique. The catalyst materials were characterized by surface area measurements, elemental analysis, powder X-ray diffraction (XRD), infrared spectroscopy (IR) and temperatureprogrammed reduction (TPR). VPO is present in two phases, viz. (VO) 2 P 2 O 7 and VOPO 4 . With increase in the VPO loading on the hydroxyapatites, the (VO) 2 P 2 O 7 phase also increased. From catalytic results, a conversion of 75 % of n-pentane and selectivity towards maleic anhydride, about 50 % and phthalic anhydride, about 25 %, were consistently achieved with loadings of 5.0 and 7.5 wt. % VPO at 360°C for GHSVs of 1900 and 2300 h -1 . Under optimum conditions, product yields of up to 40 % maleic anhydride and 20 % phthalic anhydride were obtained. It is proposed that the products formed through the diene intermediate. KEYWORDSSelective oxidation, n-pentane, vanadium phosphorus oxide, hydroxyapatite, maleic anhydride, phthalic anhydride.

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“…The most interesting of these materials is considered to be vanadyl pyrophosphate (VO) 2 P 2 O 7 , which is derived from a stable precursor material, i.e., vanadyl hydrogen phosphate hemihydrate, VOHPO 4 ·0.5H 2 O, via a topotactic transformation [3]. Hence, the preparation route and precursor morphology is of importance in determining the eventual catalyst morphology [4][5][6][7][8][9][10][11][12][13][14], and the performance following in situ activation in n-butane/air to form the final catalyst [4,5].…”

Section: Introductionmentioning

confidence: 99%

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

Rownaghi

Taufiq‐Yap

Rezaei

2009

Chemical Engineering Journal

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a b s t r a c tIn this paper, we have developed a simple, low-cost, template-free and surfactant-free solvothermal process for synthesis of vanadyl hydrogen phosphate hemihydrate (VOHPO 4 ·0.5H 2 O) with well defined crystal size. The synthesis was performed by reaction of VPO 4 ·2H 2 O with an aliphatic alcohol (isobutyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol or 1-decanol). This afforded well crystallized VOHPO 4 ·0.5H 2 O by solvothermal methods at 120 • C temperature. This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO 4 ·0.5H 2 O) when compared to conventional hydrothermal synthesis methods. By varying the reducing agent, the solvothermal evolution process from layered tetragonal phase VOPO 4 ·2H 2 O to orthorhombic phase VOHPO 4 ·0.5H 2 O was observed. It was found that the length of carbon chain in an alcohol in the solvothermal condition had a great impact on chemical and physical properties of resulting catalysts. Interestingly, there was no trace of VO(H 2 PO 4 ) 2 an impurity noted to be readily formed under solvothermal preparation condition. Therefore, this study introduces a more facile synthetic pathway to V(III) compounds. In addition, the microwave-synthesized catalysts exhibited some properties superior to those of conventionally synthesized catalyst such as better stability, crystallinity, and catalytic activity in the production of maleic anhydride. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), N 2 physisorption, temperature programmed reduction (H 2 -TPR) and scanning electron microscopy (SEM). The XRD pattern of the active catalyst prepared by this solvothermal method confirmed the presence of smaller crystal size (between 6 and 13 nm along 0 2 0 planes) of vanadium phosphate catalyst with higher specific surface area. Finally, the yield of maleic anhydride was significantly increased from 29% for conventional catalyst to 44% for the new solvothermal catalyst.Crown

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Synthesis and characterization of new VPO catalysts for partial n-Butane oxidation to maleic anhydride

Cited by 113 publications

References 14 publications

Surface Dynamics of A Vanadyl Pyrophosphate Catalyst for n‐Butane Oxidation to Maleic Anhydride: An In Situ Raman and Reactivity Study of the Effect of the P/V Atomic Ratio

Surface Dynamics of A Vanadyl Pyrophosphate Catalyst for n‐Butane Oxidation to Maleic Anhydride: An In Situ Raman and Reactivity Study of the Effect of the P/V Atomic Ratio

Partial oxidation of n-pentane over vanadium phosphorus oxide supported on hydroxyapatites

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

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