Study On Optimization Of DINA Synthesis By Acetic Anhydride And Thermal Risk Assessment

N-Nitrodiethanolamine dinitrate(DINA)is a widely used energetic material and its synthesis methods include magnesium nitrate method and acetic anhydride method.The study of these two synthesis methods are important for the production of DINA.Most of the existing works reported takes the magnesium nitrate method to synthesis DINA,but this method is dangerous and prone to thermal runaway.In order to improve the thermal safety of DINA synthesis,this paper will explore the synthesis process of DINA by acetic anhydride,and carry out an in-depth study on the thermal risk of process.Firstly,the optimum process conditions for the synthesis of DINA by acetic anhydride were determined by small-scall test,reaction calorimetry,fourier transform infrared spectroscopy(FTIR),500 MHz solid nuclear magnetic resonance(NMR),high performance liquid chromatography(HPLC)and yield calculation:the reaction temperature is 5?,the raw material(an amine)and nitrating agent(fuming nitric acid)adopts the way of simultaneous feeding,the molar ratio of nitrating agent to raw material is 4.5:1,the molar ratio of solvent(acetic anhydride)to raw material is 6:1,and the mass ratio of catalyst(an amine hydrochloride)in raw material is 1:9.Next,differential scanning calorimeter(DSC),accelerating rate calorimeter(ARC),reaction calorimeter(RC1e),and AKTS(Advanced Kinetics and Technology Solutions)were used to test and analyze the thermal risk of DINA synthesis by acetic anhydride.Based on the test results,the thermal risk of DINA synthesis by acetic anhydride was evaluated.The specific results include:the materials initialy charged have no obvious exothermic phenomenon,and the heat released by the material systems after feeding and heating are around 850 J/g,the maximum temperature of systhesis reaction(MTSR)is 11.60?,the time to maximum rate under adiabatic condition is 24 hours the corresponding temperature(T_D24)is 61.90?.According to the risk matrix method,the risk level of thermal runaway of the target reaction is 2(conditional acceptance of risk),and the risk level of thermal runaway of the secondary decomposition reaction is 4(unacceptable risk).Based on the characteristic temperature classification method,the risk level of thermal runaway is 2(acceptable risk).Finally,the magnesium nitrate method and acetic anhydride method were compared in terms of thermal safety,synthesis cycle and yield,and the acetic anhydride process is considered to be relatively safe and efficient.The specific performance is as follows:a significant amount of unstable intermediates will accumulate in the synthesis of DINA by magnesium nitrate method and the reaction system is heterogeneous,while in the synthesis process by acetic anhydride mnethod,the intermediates can be rapidly converted into products,and the reaction process is homogeneous system.The acetic anhydride synthesis process has only one feeding process,while the magnesium nitrate method has three feeding process.The post-processing process of acetic anhydride method is simpler than that of magnesium nitrate method.The yield of the products obtained by acetic anhydride method is 95%,which is significantly higher than that by magnesium nitrate method(67.80%).