Thermal Risk Assessment On Oxidation Process Of 3,4-Dia Minofurazan

Furazan energetic materials are one of the widely used high energy density materials with excellent performance.Most of the furazan energetic compounds are synthesized by oxidizing3,4-dia minofurazan(DAF).3-a mino-4-nitrosofurazan(ANSF)as an important intermediate compound for furazan energetic derivatives,is synthesized by oxidizing DAF with hydrogen peroxide in an organic solvent.At present,scholars at home and abroad focus on the research of the properties and thermal safety of furazan materials mainly.However,there are few studies on the thermal risks about their synthesis process.But the thermal risk of the process during oxidizing DAF is generally high.Therefore,it is necessary to study the thermal hazards during the synthesis.The thermal stability of DAF,oxidant materials,products mixture and ANSF was studied by differential scanning calorimeter(DSC)and adiabatic accelerated calorimeter(ARC).The result shows that DAF is thermal stable relatively,but autocatalytic.The hydrogen peroxide mixed with sodium tungstate decomposes even at room temperature with autocatalytic behavior.The oxidant mixture has poor thermal stability.The onset temperature(T_onset)of the products mixture is low,the thermal stability of aqueous phase is weaker than that of organic phase.Thermal decomposition of ANSF is autocatalytic,strong exothermic with low T_onset,large amount of specific heat release and gas.The thermal decomposition kinetics of DAF and ANSF were calculated by model fitting method.The apparent activation energy of DAF for the two-step reaction is 181.97 k J·mol^-1and 168.77 k J·mol^-1,respectively.The apparent activation energy of two-step decomposition of ANSF was 114.75 k J·mol^-1 and 109.02 k J·mol^-1.The reaction calorimeter was applied to study the exothermic behavior of DAF oxidation process under different conditions.The result reveals that different solvent amounts and stirring speed are almost of no influence on the exothermic rate of the reaction.The effect on the thermal parameters Cp and U of the system is apparent.The exothermic behavior of the reaction at different process temperatures were studied.It is found that the temperature has an effect on the exothermic rate obviously.High temperatures is beneficial for improving the reaction rate.The oxidation reaction of DAF is generally moderate exothermic.The thermal risk of the DAF oxidation process was assessed by a risk matrix and the reaction criticality classes of scenario obtained by combining the four temperature levels.By the risk matrix,the thermal risk rank of desired reaction and secondary decomposition reaction is 2 and 4 respectively.Due to the poor thermal stability of the oxidant materials,the criticality index of desired reaction is class 5 by criticality classes of scenario.Besides,if a thermal runaway occurs at a 2000 kg production scale,the severity of vapor release and gas release are both medium by the severity criterion which takes into account the effects of gas and vapor release.In this paper,the thermal risk during synthesis of ANSF is studied,the main risk factors in the oxidation process are clarified,which has certain guiding significance for recognition of the thermal risk when oxidizing DAF to synthesize other furazan energetic materials.