Vanadium phosphates on mesoporous supports: model catalysts for solid-state NMR studies of the selective oxidation of n-butane

Frey, Jörg; Ooi, Yean Sang; Thomas, Bejoy; Marthala, V. R. Reddy; Bressel, Arne; Schölkopf, Thomas; Schleid, Thomas; Hunger, Michael

doi:10.1016/j.ssnmr.2009.02.005

Cited by 11 publications

(6 citation statements)

References 26 publications

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“…These peaks gradually vanished over the reaction time and were almost not detectable in the 40 h sample. Similarly, the strong signals located around δ = 0 ppm in the 31 P, which are characteristic to the V 5+ states in VOPO4 phases 36,37 were substantially reduced over time. Nevertheless, NMR spectra demonstrated the presence of small amount of V +5 even after 40 h on stream.…”

Section: Resultsmentioning

confidence: 88%

Catalyst design for natural-gas upgrading through oxybromination chemistry

et al. 2016

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Natural gas contains large volumes of light alkanes, and its abundant reserves make it an appealing feedstock for value-added chemicals and fuels. However, selectively activating the C-H bonds in these useful hydrocarbons is one of the greatest challenges in catalysis. Here we report an attractive oxybromination method for the one-step functionalization of methane under mild conditions that integrates gas-phase alkane bromination with heterogeneously catalysed HBr oxidation, a step that is usually executed separately. Catalyst-design strategies to provide optimal synergy between these two processes are discussed. Among many investigated material families, vanadium phosphate (VPO) is identified as the best oxybromination catalyst, as it provides selectivity for CH3Br up to 95% and stable operation for over 100 hours on stream. The outstanding performance of VPO is rationalized by its high activity in HBr oxidation and low propensity for methane and bromomethane oxidation. Data on the oxybromination of ethane and propane over VPO suggest that the reaction network for higher alkanes is more complex.

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Section: Resultsmentioning

confidence: 88%

Catalyst design for natural-gas upgrading through oxybromination chemistry

et al. 2016

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“…According to 29 Si MAS NMR studies of siliceous SBA-15 materials, ca. 50% of the silicon atoms exist as Q 3 species and only 5-8% as Q 2 species [99,151,152]. The 1 H MAS NMR spectra of siliceous MCM-41 and SBA-1 materials, recorded in the dehydrated state, consist of a non-symmetric signal at d 1H ¼ 1.3-2.2 ppm due to terminal SiOH groups with a low-field shoulder at d 1H ¼ 2.5-3.5 ppm caused by geminal and hydrogenbonded SiOH groups [89,152].…”

Section: Acid Sites On Mesoporous Materialsmentioning

confidence: 99%

“…50% of the silicon atoms exist as Q 3 species and only 5-8% as Q 2 species [99,151,152]. The 1 H MAS NMR spectra of siliceous MCM-41 and SBA-1 materials, recorded in the dehydrated state, consist of a non-symmetric signal at d 1H ¼ 1.3-2.2 ppm due to terminal SiOH groups with a low-field shoulder at d 1H ¼ 2.5-3.5 ppm caused by geminal and hydrogenbonded SiOH groups [89,152]. Incorporation of aluminum atoms into the amorphous framework of mesoporous MCM-41 and SBA-15 materials does not change the 1 H MAS NMR characteristics of these materials in a significant manner [89].…”

Section: Acid Sites On Mesoporous Materialsmentioning

confidence: 99%

Solid-state nuclear magnetic resonance investigations of the nature, property, and activity of acid sites on solid catalysts

Jiang

Huang

Dai

et al. 2011

Solid State Nuclear Magnetic Resonance

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226

325

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“…Although the selective oxidation of n-butane to maleic anhydride (MA) has been one of the most studied topics in the field of catalytic selective oxidation starting from the 1980s, [1][2][3][4][5] the number of papers published yearly on this topic remains quite remarkable. Over the past few years, research in this field has been mainly focused on a deeper understanding of the nature of the active layer which develops on the surface of the V/P/O catalyst, whose bulk is made up of vanadyl pyrophosphate (VO) 2 P 2 O 7 (VPP), 29,30 on the development of new methods for the preparation of the catalyst precursor 22,23,26,27 and on the role of promoters, the proper selection of which is still considered to be the most efficient way for improving the catalytic behavior. [32][33][34][35][36][37] The never-ending interest in this reaction is also expected to continue to grow, because of the even greater availability of the starting raw material and, in general, of light alkanes, due to the exploitation of shale gas deposits.…”

Section: Introductionmentioning

confidence: 99%

An investigation on surface reactivity of Nb-doped vanadyl pyrophosphate catalysts by reactivity experiments and in situ Raman spectroscopy

Caldarelli

Bañares

Cortelli

et al. 2014

Catal. Sci. Technol.

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The effect of Nb when used as a promoter for vanadyl pyrophosphate, the catalyst for the oxidation of n-butane to maleic anhydride, was investigated. By means of both reactivity experiments and in situ Raman spectroscopy, it was found that the promoting effect shown by Nb occurred already for a very low amount of it, i.e., for a V/Nb atomic ratio as high as 150. The main role of Nb was to accelerate the formation of a limited amount of δ-VOPO 4 on the surface of vanadyl pyrophosphate, by prompting the oxidation of V 4+ into V 5+ under reaction conditions. On the other hand, the presence of Nb concentrations higher than the optimal amount led to the generation of an undesired excess quantity of VOPO 4 and the formation of α II -VOPO 4 , as well as having a detrimental effect on the catalytic behavior. ExperimentalCatalysts were prepared by means of the organic route described in previous references. 29,30 The Nb-doped V/P/O were prepared by adding the desired amount of Nb 5+ ammonium oxalate hydrate (Sigma-Aldrich) to the slurry containing V 2 O 5 , H 3 PO 4 and isobutanol, which are the raw materials for the synthesis of the catalyst precursor. V/P/O samples with

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Vanadium phosphates on mesoporous supports: model catalysts for solid-state NMR studies of the selective oxidation of n-butane

Cited by 11 publications

References 26 publications

Catalyst design for natural-gas upgrading through oxybromination chemistry

Catalyst design for natural-gas upgrading through oxybromination chemistry

Solid-state nuclear magnetic resonance investigations of the nature, property, and activity of acid sites on solid catalysts

An investigation on surface reactivity of Nb-doped vanadyl pyrophosphate catalysts by reactivity experiments and in situ Raman spectroscopy

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