TKX-50热分解氮气形成机理的分子动力学模拟

Molecular Simulation on the Nitrogen Generation in Thermal Decomposition of TKX-50

为研究新型富氮含能化合物5,5'-联四唑-1,1'-二氧二羟铵(TKX-50)高能钝感背后的微观机制,采用从头算分子动力学方法模拟了TKX-50在不同压力及温度下的分解过程,通过分析主要产物N_2的生成路径,揭示了TKX-50热分解随温度与压力变化的规律。模拟显示TKX-50分解的主要产物为H_2O和N_2。其中N_2存在三条主要的生成路径,两条来源于唑环环裂过程,另一条与铵盐和唑环的相互作用相关联。唑环环裂直接生成N2的过程受温度影响较大,温度越高,断裂速度越快,对压力不敏感。铵盐与唑环相互作用生成N_2的过程则依赖于扩散,扩散速率与温度呈正相关,与压力呈负相关。三条反应路径的共同作用使得TKX-50的反应速率宏观上呈现随温度升高而升高,随压力升高而下降的趋势。

Recently, a new nitrogen-rich compound, dihydroxylanmonium 5,5′-bistetrazole-1,1′-diolate（TKX-50） was synthesized. It possesses low impact sensitivity and a high energy content, and is readily synthetized. We use ab initio molecular dynamics method to simulate the decomposition process of TKX-50 under various pressure and temperature. The formation mechanism of the main product N2 is then analyzed. There are three main paths for the N2 generation： two paths are derived from the break of the tetrazole ring and the remaining is related to the interaction between the ammonium ion and the triazole ring. The rate of the N2 generation is affected by the temperature and pressure. That is, the higher the temperature, the lower the pressure, and the faster the reaction rate. The N2 generation rate by the intermolecular interactions between the ammonium ion and ammonium ring depends on diffusion, because the diffusion rate is observed positively correlated with temperature while negatively with pressure. The reaction rate of the TKX-50 thus increases with temperature increasing and pressure decreasing.