ReaxFF-Based Molecular Dynamics Study of the Mechanism of the Reaction of N2O4 with H2O

Y Guo and G Tian and XL Chang and ZM Tang and ZY Huang and DJ Liu and XZ Yang, ACS OMEGA, 9, 18893-18900 (2024).

DOI: 10.1021/acsomega.3c08695

During long-term storage of the liquid propellant N2O4, it absorbs H2O to form the N2O4(H2O)(n) system, and this in turn generates HNO3, HNO2, and other substances in the storage tank because of corrosion, which seriously affects the performance of weaponry. In this work, we carried out computational simulations of N2O4 with different masses of water based on ReaxFF, analyzed the reaction intermediates and products, and investigated the mechanism of the reaction of N2O4 with H2O and of N2O4(H2O)(n). The results show that the reaction product omega(HNO3+HNO2) undergoes a rapid growth in the early stage of the reaction and then tends toward dynamic equilibrium; the potential energy of the system decreases with the increase of omega(H2O), the reaction rate increases, and the rate of decomposition of HNO2 to form HNO3 increases. When omega(H2O) is 0.2 or 1.0%, the intermediate products are N2O4H2O or N2O4(H2O)(2), respectively, and the reaction proceeds along two paths; when omega(H2O) >= 2.0%, N2O4(H2O)(3) appears as the intermediate product, HNO3 and HNO2 are directly produced in one step, and a stable current loop can be formed within the whole system.

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