Identification of Thermal Decomposition Products and Reactions for Liquid Ammonium Nitrate on the Basis of Ab Initio Calculation

Yu Ichiro Izato, Mitsuo Koshi, Atsumi Miyake

Abstract

This work analyzed the thermal decomposition of ammonium nitrate (AN) in the liquid phase, using computations based on quantum mechanics to confirm the identity of the products observed in past experimental studies. During these ab initio calculations, the CBS-QB3//ωB97XD/6–311++G(d,p) method was employed. It was found that one of the most reasonable reaction pathways is HNO3 + NH4 + → NH3NO2 + + H2O followed by NH3NO2 + + NO3 → NH2NO2 + HNO3. In the case in which HNO3 accumulates in the molten AN, alternate reactions producing NH2NO2 are HNO3 + HNO3 → N2O5 + H2O and subsequently N2O5 + NH4 + → NH2NO2 + H2O. In both scenarios, HNO3 plays the role of a catalyst and the overall reaction can be written as NH4 + + NO3 (AN) → NH2NO2 + H2O. Although the unimolecular decomposition of NH2NO2 is thermodynamically unfavorable, water and bases both promote the decomposition of this molecule to N2O and H2O. Thus AN thermal decomposition in the liquid phase can be summarized as NH4 + + NO3 (AN) → N2O + 2H2O.

Original languageEnglish
Pages (from-to)83-99
Number of pages17
JournalInternational Journal of Chemical Kinetics
Volume49
Issue number2
DOIs
StatePublished - 2017 Feb 1

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Ammonium Compounds
Nitrates
Hot Temperature
Water

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

Identification of Thermal Decomposition Products and Reactions for Liquid Ammonium Nitrate on the Basis of Ab Initio Calculation. / Izato, Yu Ichiro; Koshi, Mitsuo; Miyake, Atsumi.

In: International Journal of Chemical Kinetics, Vol. 49, No. 2, 01.02.2017, p. 83-99.

Research output: Contribution to journalArticle

Izato, Yu Ichiro; Koshi, Mitsuo; Miyake, Atsumi / Identification of Thermal Decomposition Products and Reactions for Liquid Ammonium Nitrate on the Basis of Ab Initio Calculation.

In: International Journal of Chemical Kinetics, Vol. 49, No. 2, 01.02.2017, p. 83-99.

Research output: Contribution to journalArticle

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AB - This work analyzed the thermal decomposition of ammonium nitrate (AN) in the liquid phase, using computations based on quantum mechanics to confirm the identity of the products observed in past experimental studies. During these ab initio calculations, the CBS-QB3//ωB97XD/6–311++G(d,p) method was employed. It was found that one of the most reasonable reaction pathways is HNO3 + NH4 + → NH3NO2 + + H2O followed by NH3NO2 + + NO3 – → NH2NO2 + HNO3. In the case in which HNO3 accumulates in the molten AN, alternate reactions producing NH2NO2 are HNO3 + HNO3 → N2O5 + H2O and subsequently N2O5 + NH4 + → NH2NO2 + H2O. In both scenarios, HNO3 plays the role of a catalyst and the overall reaction can be written as NH4 + + NO3 – (AN) → NH2NO2 + H2O. Although the unimolecular decomposition of NH2NO2 is thermodynamically unfavorable, water and bases both promote the decomposition of this molecule to N2O and H2O. Thus AN thermal decomposition in the liquid phase can be summarized as NH4 + + NO3 – (AN) → N2O + 2H2O.

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