Apparent autocatalysis due to liquefaction: thermal decomposition of ammonium 3,4,5-trinitropyrazolate

Apparent autocatalysis due to liquefaction: thermal decomposition of ammonium 3,4,5-trinitropyrazolate Full article

Journal

Physical Chemistry Chemical Physics
ISSN: 1463-9076 , E-ISSN: 1463-9084

Output data

Year: 2021, Volume: 23, Number: 20, Pages: 11797-11806 Pages count : 10 DOI: 10.1039/d1cp01530c

Authors

Muravyev Nikita V. ¹ , Monogarov Konstantin A. ¹ , Dalinger Igor L. ² , Koga Nobuyoshi ³ , Pivkina Alla N. ¹

Affiliations

1	N.N. Semenov Federal Research Center for Chemical Physic, Russian Academy of Sciences, 4 Kosygina Str., Moscow 119991, Russia
2	N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Ave., Moscow 119991, Russia
3	Department of Science Education, Division of Educational Sciences, Graduate School of Humanities and Social Sciences, Hiroshima University, 1-1-1 Kagamiyama, Higashi-Hiroshima 739-8524, Japan

Thermal decomposition of solids is often accompanied by autocatalysis, one of the possible causes of which is the formation of a liquid phase. The kinetic model considering the liquefaction of solid reactants under isothermal conditions was proposed by Bawn in the 1950s. The present study reports the application of the Bawn model to the thermolysis of 3,4,5-trinitropyrazole ammonium salt (ATNP) under nonisothermal conditions. The thermal decomposition of ATNP is comprised of low-temperature and high-temperature stages. The low-temperature stage exhibits two distinct exothermic peaks in differential scanning calorimetry (DSC), fitted by two consecutive autocatalytic reactions with a model-fitting kinetic analysis. The liquefaction of the solid reactant during the first reaction is directly observed, giving mechanistic evidence for the Bawn model. We have expressed the Bawn model by a combination of two extended Prout–Tompkins (ePT) equations with the activation energy for the leading liquid-state reaction of Ea = 140.6 ± 0.3 kJ mol−1. The release of ammonia is detected from the beginning, suggesting that the thermal dissociation of ATNP to 3,4,5-trinitropyrazole is an initiation reaction of the thermal decomposition. We proposed ATNP liquefication, leading to the apparent autocatalytic behavior of the first global decomposition reaction, is caused by the eutectic formation between ATNP and 3,4,5-trinitropyrazole, as it was confirmed by DSC analysis of the artificial mixture. The presented approach of the combination of ePT formalism with a Bawn model is generally applicable to a broader range of thermal processes accompanied by liquid phase formation and apparent acceleration.

Muravyev N.V. , Monogarov K.A. , Dalinger I.L. , Koga N. , Pivkina A.N.
Apparent autocatalysis due to liquefaction: thermal decomposition of ammonium 3,4,5-trinitropyrazolate
Physical Chemistry Chemical Physics. 2021. V.23. N20. P.11797-11806. DOI: 10.1039/d1cp01530c WOS Scopus OpenAlex

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