The chemistry of catalysts based on vanadium-phosphorus oxides

Centi, Gabriele; Manenti, I.; Riva, A.; Trifirò, F.

doi:10.1016/0166-9834(84)80062-7

Cited by 46 publications

(13 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, an excess of P principally affects the rate of hydrocarbon activation. Similar results are obtained in the oxidation of 1-butene [5,13,16].…”

Section: Relationship Between Redox Properties and Catalytic Propertiessupporting

confidence: 86%

See 1 more Smart Citation

Structure and reactivity of vanadium-phosphorus oxides

Cavani

Centi

Trifirò

et al. 1985

Journal of Thermal Analysis

Self Cite

View full text Add to dashboard Cite

The contribution of thermal methods of analysis to the study of the structure and reactivity of vanadium-phosphorus oxides is examined. In particular, data are reported on the solid-state reaction VOHPO4. 89 H20 for VOHPO4. 89 prepared in different ways, on the redox properties of oxidation and reduction of vanadium for catalysts prepared with different P : V atomic ratios in the range 0.9-1.3, and on the surface properties determined by TPD of catalysts with different P : V ratios. The relationship between these properties and the catalytic properties in the selective oxidation of n-butane and but-l-ene is discussed.Vanadium-phosphorus mixed oxides comprise a very interesting catalytic system for selective oxidation and ammoxidation reactions; these catalysts not only give high yields, but are also able to promote the selective oxidation of different reactants, such as paraffins (n-butane), olefins (but-l-ene and butadiene) and alkylaromatics (toluene derivatives) [1,2]. In all cases the active phase is a pyrophosphate of vanadium(IV) [3-811 (VO)2P207 is formed by dehydration of VOHPO4 " 89 that can be prepared in different ways [3,6,8,[9][10][11][12]. However, although the structure is always similar, the catalytic activities of pure (VO)2P207 phases prepared by different methods differ considerably in particular in selective nbutane oxidation [3, 11-14]. This suggests that the activity of these catalysts must be attributed not only to the presence of a particular crystalline compound, but also to the specific nature of that phase, i.e. to the presence of deformations in the crystalline structure.Since the reaction forming (VO)2P207 from VOHPO4-89 is a topotactic one [11,12,15], analysis of the transformation can give useful information on the specific nature of the active phase. Therefore, thermal methods of analysis of the solid-state reaction are particularly useful, because they are very sensitive to modifications in the transformation mechanism. Another peculiarity of these oxides is the possibility of varying the P : V atomic ratio within the range 0.9-1.3 without apparent modification of the (VO)2P207 structure, even though there is a drastic change of the catalytic activity [13,16]. Moreover, the content of phosphorus in the catalyst also affects the redox John Wiley & Sons, Limited, Chichester Akad~miai Kiad6, Budapest

show abstract

“…However, an excess of P principally affects the rate of hydrocarbon activation. Similar results are obtained in the oxidation of 1-butene [5,13,16].…”

Section: Relationship Between Redox Properties and Catalytic Propertiessupporting

confidence: 86%

“…VOHPO4" 89 can be obtained by different methods: (i) in aqueous medium by precipitation [4,5,20]: VzO5 reduction with 37% HC1, addition of o-H3PO 4, concentration of the solution and addition of water;…”

Section: Influence Of the Methods Of Preparation On The Solid-state Rementioning

confidence: 99%

Structure and reactivity of vanadium-phosphorus oxides

Cavani

Centi

Trifirò

et al. 1985

Journal of Thermal Analysis

Self Cite

View full text Add to dashboard Cite

show abstract

“…Chemical analysis using ICP showed that the P/V ratio for VPD and VPDMn are similar and confirmed the presence of Mn with a Mn/V atomic ratio of 0.010. These values fall in the optimal atomic ratio of P/V in the range of 1.0-1.2 for producing (VO) 2 P 2 O 7 phases [12][13][14]. The average oxidation number and the percentage of V 4+ and V 5+ oxidation state is shown in Table 2.…”

Section: Resultsmentioning

confidence: 99%

Physico-chemicals and catalytic properties of manganese-promoted vanadium phosphate (VPO) catalyst

Taufiq‐Yap

Goh

Kamiya

2007

React Kinet Catal Lett

View full text Add to dashboard Cite

The addition of 1% Mn promoter to vanadium phosphate catalyst led to doubling of the specific surface area from 20.3 (unpromoted) to 39.4 m 2 g -1 . The XRD pattern of the Mn-promoted catalyst gave only the characteristics of the (VO) 2 P 2 O 7 phase, indicating that the Mn was incorporated into the crystal lattice of the catalyst. The Mn-promoted catalyst was also twice as active in removing the total amount of oxygen. However, since the only oxygen species related to V 4+ being removed and no oxygen species associated with V 5+ was observed, the nbutane conversion was not much improved as compared to the unpromoted counterpart. A necessary amount and distribution of the V 5+ phase in a well crystalline V 4+ phase is essential in order to enhance the catalytic performance in the mild oxidation of n-butane to maleic anhydride.

show abstract

“…The lack of a better and in‐depth understanding of the related catalytic chemistry, including the crystalline phase transition analysis ((VO) 2 P 2 O 7 VOPO 4 ) and specific catalytic mechanism, is a major obstacle to achieve further catalyst development in such aldol condensations. The VPOs exhibit peculiar properties , including the nature of the active sites, the preferred composition of the catalyst, and the role of the V 5+ and V 4+ phases. However, the research of the catalytic mechanism remains to be subject to debate and a fascinating topic for study , .…”

Section: Introductionmentioning

confidence: 99%

Enhanced Catalytic Activity with Oxygen for Methyl Acrylate Production via Cross‐Aldol Condensation Reaction

Zuo

Wang

et al. 2018

Chem Eng & Technol

View full text Add to dashboard Cite

An innovative technology for the production of methyl acrylate via vapor-phase cross-aldol condensation is described. Catalytic process intensification was realized through the enhanced catalytic activity with oxygen by catalyst design and adjustment of active sites. Crystal phases with different V valences in vanadium phosphate catalysts were controllably synthesized in the presence of oxygen. Donating electron and withdrawing electron sites arose when oxygen moved from one crystalline phase to another, just for the a-H removal of methyl acetate and formaldehyde protonation. The reaction pathway and transition states were confirmed via molecular simulation with quantum chemistry theory. The catalytic activity was evaluated in a fixed-bed reactor by adjusting the percentage of oxygen in the carrier gas. Finally, the mechanism of a-H removal of methyl acetate through the activated oxygen was clarified.

show abstract

The chemistry of catalysts based on vanadium-phosphorus oxides

Cited by 46 publications

References 9 publications

Structure and reactivity of vanadium-phosphorus oxides

Structure and reactivity of vanadium-phosphorus oxides

Physico-chemicals and catalytic properties of manganese-promoted vanadium phosphate (VPO) catalyst

Enhanced Catalytic Activity with Oxygen for Methyl Acrylate Production via Cross‐Aldol Condensation Reaction

Contact Info

Product

Resources

About