Reactions of metal oxides with NO2(g) + O2(g)

Gimzewski, Edmund; HAWKINS, S. H.

doi:10.1016/0040-6031(86)85302-3

Cited by 7 publications

(4 citation statements)

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“…The test conditions listed in Table are based on reported literature transitions for the U–O system. The proportion of NO 2 (g)/O 2 (g) was selected from Collins et al The reaction of UO 2 in NO 2 /O 2 (g) has been shown to not proceed at temperatures up to 350 °C, so the initial oxidation step is chosen with temperatures ranging from 350 to 450 °C. Further oxidation of U 3 O 8 to UO 3 is reported to occur in temperatures ranging from 250 to 375 °C. , However, the transition from U 3 O 8 to UO 3 is reversible, with the potential to convert back to U 3 O 8 at temperatures as low as 400 °C .…”

Section: Methodsmentioning

confidence: 99%

“…One report uses thermogravimetric data to show that UO 3 reacts with NO 2 (g), and the authors suggest the product may be a uranyl nitrate phase. 14 However, no bulk phase analysis was performed to corroborate this conclusion. An instance of UO 3 reaction with nitric acid indicates the formation of uranyl nitrate, 17 as well.…”

Section: Introductionmentioning

confidence: 98%

“…The specific reaction of UO 3 under NO 2 (g) is not well documented. One report uses thermogravimetric data to show that UO 3 reacts with NO 2 (g), and the authors suggest the product may be a uranyl nitrate phase . However, no bulk phase analysis was performed to corroborate this conclusion.…”

Section: Introductionmentioning

confidence: 99%

“…The reaction of UO 2 with NO 2 was first studied by Katz and Gruen, 5 who noted that the reaction produced something similar to UO 3 or another intermediate oxide. Gimzewski et al 14 presented a conflicting result, with thermogravimetric data indicating that UO 2 did not react with the mixture of NO 2 /O 2 (g). An important conclusion from the original Katz and Gruen work is that NO 2 (g) may adsorb to the surface of UO 2 , 5 suggesting that this reaction is surface-area dependent.…”

Section: Introductionmentioning

confidence: 99%

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Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO₂ Voloxidation

Peruski,

Spano,

Vick

et al. 2024

ACS Omega

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Voloxidation is a potential alternative reprocessing scheme for spent nuclear fuel that uses gas−solid reactions to minimize aqueous wastes and to separate volatile fission products from the desired actinide phase. The process uses NO 2 (g) as an oxidant for uranium dioxide (UO 2 ) fuel, ideally producing soluble uranium powders which can then be processed for full recycle. To continue development of the process flowsheet for voloxidation, ongoing examination of the process chemistry and associated process materials is required: discrepancies in the proposed chemical reactions that occur when spent nuclear fuel is exposed to NO 2 (g) atmospheres must be addressed. The objective of this work is to analyze the intermediate solid phases produced during voloxidation to support verification of the proposed NO 2 (g) voloxidation reaction mechanisms. This objective was achieved through using (1) powder X-ray diffraction and Raman spectroscopy to identify bulk uranium phases and (2) scanning electron microscopy to describe the morphology and microstructure of the powders at each reaction stage. The initial oxidation of UO 2 under NO 2 (g) reactions produced ε-UO 3 . Further exposure to NO 2 (g) did not nitrate the solid to produce uranyl nitrate, as reported in some literature. However, after the powder was hydrated with steam and then further exposed to NO 2 (g), some traces of uranyl nitrate hexahydrate were found. The results of this study suggest that surface hydration of powders plays a vital role in uranyl nitrate formation under voloxidation conditions and raises questions about the kinetics of the oxide-to-nitrate voloxidation conversion process. Future chemical and engineering design decisions for the voloxidation process may benefit from an improved understanding of these chemical mechanisms.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO₂ Voloxidation

Peruski,

Spano,

Vick

et al. 2024

ACS Omega

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ChemInform Abstract: Reactions of Metal Oxides with NO₂ (g) + O₂ (g).

Gimzewski¹,

HAWKINS²

1986

Chemischer Informationsdienst

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Thermal analysis in reactive atmospheres

Gimzewski

1988

Journal of Thermal Analysis

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By using reactive atmospheres, the area of aplb]ication of thermal analysis is expanded considerably to cover many aspects of high temperature research into fuels, extractive metallurgy, materials and catalysts. This article reviews the design of apparatus and its application in kinetic and thermodynamic studies involving atmospheres such as H2, CO, N2, NH3, CO2, H20, SO2or3~ H2 S, $2. C12, HCI, F2 and HF at low or high pressures and as low pressure plasmas. Apart from gas-solid reactions, the important influence of a controlled product gas atmosphere on decomposition reactions is discussed also. Gas-solid adsorption and solubility studies are not included. John Wiley & Sons, Limited, ChichesterAkaddmiai Kiad6, Budapest GIMZEWSKI: ANALYSIS IN REACTIVE ATMOSPHERESTable I Areas of application of thermal analysis using reactive atmospheres ATMOSPHERE APPLICATIONS 02 H2, CO N2, NH3, NO2 C02 H20 802 or3 H2S 02, HCI etc F2, HF etc Plasmas Combustion, extractive metallurgy, oxidation stability tests, carbon analysis. Extractive metallurgy, coal hidrogenation, catalysts, materials science, hydrogen storage. Nitriding using N 2 or NH3, decomposition of catalysts, and propellants in NH3, extractive metallurgy using NO2.Exploitation and analysis of carbonate minerals, processing fuel gases, corrosion.Coal gasification, materials science, reversible dehydration reaction analysis of plaster.Cleaning combustion gases, extractive metallurgy.Cleaning fuel gases, corrosion.Extractive metallurgy, analysis of ceramics.Nuclear fuel processing. Materials science Experimental ApparatusThermal analysis has been performed in gases and vapours at low and high pressures and in low pressure plasmas. Plasmas and vapours pose specific problems discussed below, but otherwise the apparatus design is dictated by the corrosive nature of the atmosphere, its pressure and its flow arrangement. A flowing atmosphere is preferred at normal and high pressures to facilitate mass transfer but at low pressures the atmosphere is usually static. Below, corrosion problems are discussed for furnaces, thermocouples and thermobalances, and the difficulties in generating and using controlled atmospheres are considered separately for gases, vapours and plasmas.s ThermalAnal. 33, 1988

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Reactions of metal oxides with NO2(g) + O2(g)

Cited by 7 publications

References 6 publications

Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO₂ Voloxidation

Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO₂ Voloxidation

ChemInform Abstract: Reactions of Metal Oxides with NO₂ (g) + O₂ (g).

Thermal analysis in reactive atmospheres

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Reactions of metal oxides with NO2(g) + O2(g)

Cited by 7 publications

References 6 publications

Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO2 Voloxidation

Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO2 Voloxidation

ChemInform Abstract: Reactions of Metal Oxides with NO2 (g) + O2 (g).

Thermal analysis in reactive atmospheres

Contact Info

Product

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Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO₂ Voloxidation

Elucidating the Composition and Structure of Uranium Oxide Powders Produced via NO₂ Voloxidation

ChemInform Abstract: Reactions of Metal Oxides with NO₂ (g) + O₂ (g).