Influence of Ammonium Ion on Nitrolysis of 3,7-Dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane(DPT)

Based on the two mechanisms of 3, 7-dinitro-1, 3, 5, 7-tetraazabicyclo[3,3,1] nonane (DPT) nitrolysis via HNO3-NH4NO3 or HNO3, the effects of NH4+ in nitrolysis of DPT were studied by experiment and theoretical calculation. The effect of NH4+ on the yield of HMX was studied with adding the ammonium salts including (NH4)2HPO4, (NH4)2SO4 and CH3COONH4 to nitrate solution system. Results show that the above-mentioned ammonium salts can improve the yield of HMX to 41.5%, 37.4% and 20.7%, respectively. Their function is similar to NH4NO3. In different nitric acid-ammonium salt systems, when the molar ratio of NH4+ and DPT is close to 10, the yield of HMX reaches a maximum value of 56.3%, 52.2% and 35.5%, respectively. Results of the nitrolysis of DPT in nitric acid-ammonium salt systems and nitric acid-nitrate system are compared, finding that NH4+ plays a dominant role in improving the yield of HMX. The reaction mechanism of NH4+ in the nitrolysis process of DPT is theoretically explained by the density functional theory (DFT), deriving that the activation energy of DPT nitrolysis in HNO3/NH4+ is 133.95 kJ·mol-1, lower than 376.73 kJ·mol-1 in HNO3.