Solvothermal synthesis of vanadium phosphates in the form of xerogels, aerogels and mesostructures

Sydorchuk, V.; Zazhigalov, V. A.; Khalameida, S.; Diyuk, O. A.; Skubiszewska–Zięba, J.; Лебода, Р.; Кузнецова, Л. С.

doi:10.1016/j.materresbull.2010.06.010

Cited by 14 publications

(5 citation statements)

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“…Other mechanisms associated with crystallization processes, which often cause an increase in specific surface area and pore volume [20], do not take place under these conditions for amorphous silica and zirconium phosphate. These methods of modification have also shown their efficiency in regulating the physicochemical characteristics of vanadium phosphates [25,26] and titanium phosphate [27] as well as zirconium dioxide [28]. Preliminary results were also obtained for tin phosphate precipitated in strongly acid medium and then modified through hydrothermal and microwave treatments [29].…”

Section: Introductionmentioning

confidence: 98%

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

Sydorchuk¹,

Khalameida²,

Charmas

et al. 2021

J Sol-Gel Sci Technol

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Micro-mesoporous tin phosphate is prepared via precipitation under acid medium with subsequent modification using hydrothermal, microwave, and mechanochemical treatments (HTT, MWT, and MChT, respectively). The structure of the initial and modified samples is studied using nitrogen adsorption-desorption, DTA-TG and XRD analysis, FTIR spectroscopy, and SEM. Selected samples are tested as catalysts in aldol condensation of formaldehyde with acetic acid and in photocatalytic degradation of safranin T under visible irradiation. It is established that modification, primarily under hydrothermal conditions, results in the formation of mesoporous or meso-macroporous structure which is more accessible for the reagents molecules and more resistant to sintering and coking at higher temperature. Maximum effect is obtained in the case of modification of wet gel. Catalytic performance of the tested samples in aldol condensation is primarily determined by the parameters of their porous structure. The acquisition of photocatalytic activity is due to the narrowing of the band gap as a result of modification.

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Section: Introductionmentioning

confidence: 98%

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

Sydorchuk¹,

Khalameida²,

Charmas

et al. 2021

J Sol-Gel Sci Technol

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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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“…Knowing the nature of intermediates and how and when they react is crucial for extending this synthesis method to other MAX phases and even to compounds beyond this class of materials. Vanadium phosphate solution chemistry proves to be very complicated because vanadium has many stable oxidation states. − Therefore, it is imperative that a variety of analytical techniques are utilized to elucidate chemical and structural information.…”

Section: Introductionmentioning

confidence: 99%

In-Depth Analysis of the Species and Transformations during Sol Gel-Assisted V₂PC Synthesis

Sinclair,

Flores,

Brugh

et al. 2024

Inorg. Chem.

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The sol−gel reaction mechanism of 211 MAX phases has proven to be very complex when identifying the intermediate species, chemical processes, and conversions that occur from a mixture of metal salts and gelling agent into a crystalline ternary carbide. With mostly qualitative results in the literature (Cr 2 GaC, Cr 2 GeC, and V 2 GeC), additional analytical techniques, including thermal analysis, powder diffraction, total scattering, and various spectroscopic methods, are necessary to unravel the identity of the chemical compounds and transformations during the reaction. Here, we demonstrate the combination of these techniques to understand the details of the sol−gel synthesis of MAX phase V 2 PC. The metal phosphate complexes, as well as amorphous/nanocrystalline vanadium phosphate species (V in different oxidation states), are identified at all stages of the reaction and a full schematic of the reaction process is suggested. The early amorphous vanadium species undergo multiple changes of oxidation states while organic species decompose releasing a variety of small molecule gases. Amorphous oxides, analogous to [NH 4 ][VO 2 ][HPO 4 ], V 2 PO 4 O, and VO 2 P 2 O 7 are identified in the dried gel obtained during the early stages of the heating process (300 and 600 °C), respectively. They are carbothermally reduced starting at 900 °C and subsequently react to crystalline V 2 PC with the excess carbon in the reaction mixture. Through CHN analysis, we obtain an estimate of left-over amorphous carbon in the product which will guide future efforts of minimizing the amount of carbon in sol gel-produced MAX phases which is important for subsequent property studies.

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Solvothermal synthesis of vanadium phosphates in the form of xerogels, aerogels and mesostructures

Cited by 14 publications

References 32 publications

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

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

In-Depth Analysis of the Species and Transformations during Sol Gel-Assisted V₂PC Synthesis

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Solvothermal synthesis of vanadium phosphates in the form of xerogels, aerogels and mesostructures

Cited by 14 publications

References 32 publications

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

Influence of hydrothermal, microwave and mechanochemical treatment of tin phosphate on porous structure and catalytic properties

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

In-Depth Analysis of the Species and Transformations during Sol Gel-Assisted V2PC Synthesis

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In-Depth Analysis of the Species and Transformations during Sol Gel-Assisted V₂PC Synthesis