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Abstract: To analye the decomposition mechanism of nitroglycerin (NG) during storage in detail, the change in the concentrations of three kinds of gases, including CO, NO, NO2 released by NG decomposition at 55℃ and 60℃ was monitored by thermal decomposition experiment.The rate constants of four kinds of initial reactions including the hemolytic cleavage reaction of O-NO2 group, HONO elimination reaction, hydrogen abstraction reaction at α-position and hydrogen abstraction reaction at β-position at 20-60℃ were calculated by the density functional theory and canonical variational transition state theory. Results show that 90 days and 70 days respectively are two important time points at 55℃ and 60℃.With increasing the decomposition time gradually, the concentrations of CO and NO increase, but the concentration of NO2 increases first and then decreases. At 20-60℃, the rate constant of autocatalytic reaction of hydrogen abstraction at β-position is the fastest, which is 102-1011 times greater than those of the other three kinds of reactions and the rate of HONO elimination reaction is smallest which is 1/1011-1/105 times of the rate constants of the other three kinds of reactions. The rate of hydrogen abstraction reaction at α-position is about two orders of magnitude more than the rate of the hemolytic cleavage reaction of O—NO2 group. On basis of the double attribute of NO2 molecules as the decomposition reaction product and the reactants of catalytic reaction, taking NO2 gas concentration reaching the highest point in time as benchmark, the process of NG decomposition during storage can be divided into two stages. The hemolytic cleavage of O—NO2 is the main reaction channels of the first stage, and the rates of autocatalytic reaction of hydrogen abstraction at α=position and β-position increase with the NO2 concentration increasing. The autocatalytic reaction of hydrogen abstraction at β-position is main reaction channel of the second stage. The autocatalytic reaction of hydrogen abstraction at α-position is secondary reaction channel of the second stage. HONO elimination reaction has minimum effects to NG decomposition throughout the entire process.
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