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Computational Predictions of the The...

Lontchi, Eddy Mfopah,

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Computational Predictions of the Thermochemical Properties of Metal Oxides and Hydrolysis of Actinide Oxides /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Computational Predictions of the Thermochemical Properties of Metal Oxides and Hydrolysis of Actinide Oxides // Eddy Mfopah Lontchi.
Author:	Lontchi, Eddy Mfopah,
Description:	1 electronic resource (332 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-03, Section: B.
Contained By:	Dissertations Abstracts International86-03B.
Subject:	Chemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31300738
ISBN:	9798384071921

Computational Predictions of the Thermochemical Properties of Metal Oxides and Hydrolysis of Actinide Oxides /
Lontchi, Eddy Mfopah,

Computational Predictions of the Thermochemical Properties of Metal Oxides and Hydrolysis of Actinide Oxides /Eddy Mfopah Lontchi. - 1 electronic resource (332 pages)

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.

Actinide oxides play an important role in the energy sector in terms of fuels for nuclear power generation to reduce our carbon footprint and for fuel reprocessing and management of spent fuel. Pa and Group V transition metals share a similar pentavalent oxidation state, but Pa oxides with 5f valence orbitals are less explored than the transition metal oxides. The structures and thermochemical properties of various M2O5 (M = V, Nb, Ta, Pa) isomers were predicted together with single metal oxides, hydroxides, and fluorides using the Feller-Peterson-Dixon (FPD) approach at the coupled cluster CCSD(T)/CBS (complete basis set) level of calculation. The structure of Pa2O5 exhibits actinyl character dominated by the interaction of PaO2+ groups with a bridging O2-. The results provide insights into Pa being a transitional element between actinide character as found for U and transition metal character as found for Ac and Th. Hydrolysis reactions play an important role in processes across the nuclear enterprise and are important in the transformation of metal oxides to hydroxides. A detailed computational investigation was made to predict the hydrolysis of various high oxidation state actinide oxides (An = Th - Pu). Reaction coordinates were calculated based on geometries at the DFT/B3LYP level with additional energetics at the higher MP2, and/or CCSD(T) levels. Hydrolysis is initiated by the formation of a Lewis acid/base adduct with H2O adding to the actinide followed by proton transfer to an adjacent oxygen. The initial physisorption (physical adsorption) energy of H2O on the An was predicted to fall between −20 to −30 kcal/mol. The stability of the chemisorption (chemical adsorption) product varied across the actinide series and the structural conformation of the products. Thorium oxides (ThnO2n) (n = 1 - 6) were predicted to have a high propensity for hydrolysis, readily forming hydroxide products over hydrated complexes. The hydrolysis reactions of Pa monomer and dimers were also predicted to be exothermic. Hydrolysis reactions of U, Np, and Pu were predicted to be the least capable of achieving full hydrolysis.In addition, this dissertation covers studies of a fuel based on a blend of ammonia borane, methylamine borane, and methanol as an alternative to carbon-based fuel for use in high velocity combustion systems. The work describes experiments performed to test the spray characteristics, ignition delay, and ignition methods. Ignition and combustion of the fuel was performed using a combustion apparatus and the burns were characterized using high framerate imaging.

English

ISBN: 9798384071921Subjects--Topical Terms:

516420
Chemistry.
Subjects--Index Terms:

Actinide oxide

Computational Predictions of the Thermochemical Properties of Metal Oxides and Hydrolysis of Actinide Oxides /
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245 1 0 $a Computational Predictions of the Thermochemical Properties of Metal Oxides and Hydrolysis of Actinide Oxides / $c Eddy Mfopah Lontchi.
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500 $a Source: Dissertations Abstracts International, Volume: 86-03, Section: B.
500 $a Advisors: Dixon, David A.; Street, Shane C. Committee members: Bakker, Martin G.; Allred, Jared M.; Klein, Tonya M.
502 $b Ph.D. $c The University of Alabama $d 2024.
520 $a Actinide oxides play an important role in the energy sector in terms of fuels for nuclear power generation to reduce our carbon footprint and for fuel reprocessing and management of spent fuel. Pa and Group V transition metals share a similar pentavalent oxidation state, but Pa oxides with 5f valence orbitals are less explored than the transition metal oxides. The structures and thermochemical properties of various M2O5 (M = V, Nb, Ta, Pa) isomers were predicted together with single metal oxides, hydroxides, and fluorides using the Feller-Peterson-Dixon (FPD) approach at the coupled cluster CCSD(T)/CBS (complete basis set) level of calculation. The structure of Pa2O5 exhibits actinyl character dominated by the interaction of PaO2+ groups with a bridging O2-. The results provide insights into Pa being a transitional element between actinide character as found for U and transition metal character as found for Ac and Th. Hydrolysis reactions play an important role in processes across the nuclear enterprise and are important in the transformation of metal oxides to hydroxides. A detailed computational investigation was made to predict the hydrolysis of various high oxidation state actinide oxides (An = Th - Pu). Reaction coordinates were calculated based on geometries at the DFT/B3LYP level with additional energetics at the higher MP2, and/or CCSD(T) levels. Hydrolysis is initiated by the formation of a Lewis acid/base adduct with H2O adding to the actinide followed by proton transfer to an adjacent oxygen. The initial physisorption (physical adsorption) energy of H2O on the An was predicted to fall between −20 to −30 kcal/mol. The stability of the chemisorption (chemical adsorption) product varied across the actinide series and the structural conformation of the products. Thorium oxides (ThnO2n) (n = 1 - 6) were predicted to have a high propensity for hydrolysis, readily forming hydroxide products over hydrated complexes. The hydrolysis reactions of Pa monomer and dimers were also predicted to be exothermic. Hydrolysis reactions of U, Np, and Pu were predicted to be the least capable of achieving full hydrolysis.In addition, this dissertation covers studies of a fuel based on a blend of ammonia borane, methylamine borane, and methanol as an alternative to carbon-based fuel for use in high velocity combustion systems. The work describes experiments performed to test the spray characteristics, ignition delay, and ignition methods. Ignition and combustion of the fuel was performed using a combustion apparatus and the burns were characterized using high framerate imaging.
546 $a English
590 $a School code: 0004
650 4 $a Chemistry. $3 516420
650 4 $a Physical chemistry. $3 1981412
650 4 $a Computational chemistry. $3 3350019
653 $a Actinide oxide
653 $a Ammonia borane
653 $a Hydrolysis
653 $a Methylamine borane
653 $a Proton transfer
653 $a Transition metal oxides
690 $a 0485
690 $a 0494
690 $a 0219
710 2 $a The University of Alabama. $b Chemistry. $e degree granting institution. $3 3817163
720 1 $a Dixon, David A. $e degree supervisor.
720 1 $a Street, Shane C. $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 86-03B.
790 $a 0004
791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31300738