Synthesis and Characterization of Niobium and Tungsten Substituted VOPO4

Roy, Subrata Chandra; Yeasmin, Lilufer; Rahman, Mahmadur

doi:10.3329/jbas.v43i1.42231

Cited by 2 publications

(1 citation statement)

References 19 publications

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“…Single-phase bulk phosphates like α II -V V OPO 4 and β-V V OPO 4 show a significantly lower yield in n -butane oxidation compared to the VPP catalyst. , Eichelbaum et al carried out near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) on VPP, which showed the presence of V 4+ and V 5+ on the surface with an average oxidation state of +4.3 . Starting from crystalline α II -VOPO 4 and β-VOPO 4 , a substitution of the V 5+ sites with V 4+ /W 6+ in (V 1- x W x )OPO 4 synthesized by solution combustion synthesis (SCS) results in a slight reduction of the V oxidation state, as well as an increased MAN selectivity of up to S MAN = 30%. , The (V 1- x W x )OPO 4 solid solution demonstrated the potential for accessing new bulk catalysts in the family of orthophosphates by incorporating two transition metals or even more elements, for example, in quinary systems (V, Nb, W), with a potential impact on the catalytic behavior of the host material. A promotional effect of transition metals introduced into VPOs is described in the literature in many facets comprising, for example, Co, Cr, Fe, Ga, Mo, Nb, Sm, or even Au. ,− …”

Section: Introductionmentioning

confidence: 99%

Niobium Insertion into α_II-VOPO₄: Tuning the Catalytic Properties for Selective Oxidation

et al. 2023

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A holistic understanding of the key catalytic features of vanadyl(IV) pyrophosphate enabling high maleic anhydride (MAN) yields in n-butane oxidation has fostered a debate which has continued since the finding of the catalyst. Under reaction conditions, vanadium(V) orthophosphate structure fragments were detected on the surface of the catalyst. However, single-phase αII- and β-VVOPO4 reveal a much lower catalytic performance. This study shows that introducing Nb into αII-VOPO4 forming a solid solution (V1-x Nb x )OPO4 yields a bulk material with tunable catalytic properties. Selectivities of S MAN = 48% at a conversion of X n‑butane = 30% on (V0.1Nb0.9)OPO4 are shown to be related to the isolation of surface V-sites, which surpass known VOPO4 catalysts by far. A boost in the overall n-butane consumption and MAN selectivity under alkane-rich feed conditions is shown to be another characteristic of (V1-x Nb x )OPO4, leading to a highly increased MAN productivity. XPS studies reveal that a progressive replacement of V by Nb induces a reduction of the averaged oxidation state of near-surface V from +4.7 to +4.3, a finding that correlates linearly with an elevated MAN selectivity. This study experimentally confirms site isolation and electronic environment of the near-surface V-species as the key catalytic properties, from which catalyst design rules are derived to optimize partial oxidation reactions.

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Section: Introductionmentioning

confidence: 99%

Niobium Insertion into α_II-VOPO₄: Tuning the Catalytic Properties for Selective Oxidation

et al. 2023

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Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

Chernova

Hidalgo

Kaplan

et al. 2020

Advanced Energy Materials

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Vanadyl phosphates comprise a class of multielectron cathode materials capable of cycling two Li+, about 1.66 Na+, and some K+ ions per redox center. In this review, structures, thermodynamic stabilities, and ion diffusion kinetics of various AxVOPO4 (A = Li, Na, K, NH4) polymorphs are discussed. Both the experimental data and first‐principle calculations indicate kinetic limitations for alkali metal ions cycling, especially between for 0 ≤ x ≤ 1, and metastability of phases with x > 1. This creates challenges for multiple‐ion cycling, as the slow kinetics call for nanosized particles, which being metastable and reactive with organic electrolytes are prone to side reactions. Thus, various synthesis approaches, surface coating, and transition metal ion substitution strategies are discussed here as possible ways to stabilize AxVOPO4 structures and improve alkali metal ion diffusion. The role of advanced characterization techniques, such as X‐ray absorption spectroscopy, diffraction, pair distribution function analysis and 7Li and 31P NMR, in understanding the reaction mechanism from both structural and electronic points of view is emphasized.

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Synthesis and Characterization of Niobium and Tungsten Substituted VOPO4

Cited by 2 publications

References 19 publications

Niobium Insertion into α_II-VOPO₄: Tuning the Catalytic Properties for Selective Oxidation

Niobium Insertion into α_II-VOPO₄: Tuning the Catalytic Properties for Selective Oxidation

Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

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Synthesis and Characterization of Niobium and Tungsten Substituted VOPO4

Cited by 2 publications

References 19 publications

Niobium Insertion into αII-VOPO4: Tuning the Catalytic Properties for Selective Oxidation

Niobium Insertion into αII-VOPO4: Tuning the Catalytic Properties for Selective Oxidation

Vanadyl Phosphates AxVOPO4 (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

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Niobium Insertion into α_II-VOPO₄: Tuning the Catalytic Properties for Selective Oxidation

Niobium Insertion into α_II-VOPO₄: Tuning the Catalytic Properties for Selective Oxidation

Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries