The thermal decomposition behavior and nonisothermal reaction kinetics of the double-base gun propellants containing the mixed ester of triethyleneglycol dinitrate（TEGDN） and nitroglycerin（NG） were investigated by...The thermal decomposition behavior and nonisothermal reaction kinetics of the double-base gun propellants containing the mixed ester of triethyleneglycol dinitrate（TEGDN） and nitroglycerin（NG） were investigated by thermogravimetry（TG） and differential thermogravimetry（DTG）, and differential scanning calorimetry（DSC） under the high-pressure dynamic ambience. The results show that the thermal decomposition processes of the mixed nitric ester gun propellants have two mass-loss stages. Nitric ester evaporates and decomposes in the first stage, and nitrocellulose and centralite II（C2） decompose in the second stage. The mass loss, the DTG peak points, and the terminated temperatures of the two stages are changeable with the difference of the mass ratio of TEGDN to NG. There is only one obvious exothermic peak in the DSC curves under the different pressures. With the increase in the furnace pressure, the peak temperature decreases, and the decomposition heat increases. With the increase in the content of TEGDN, the decomposition heat decreases at 0.1 MPa and rises at high pressure. The variety of mass ratio of TEGDN to NG makes few effect on the exothermic peak temperatures in the DSC curves at different pressures. The kinetic equation of the main exothermal decomposition reaction of the gun propellant TG0601 was determined as： dα/dt=1021.59（1-α）3e-2.60×104/T. The reaction mechanism of the process can be classified as chemical reaction. The critical temperatures of the thermal explosion（Tbe and Tbp） obtained from the onset temperature（Te） and the peak temperature（Tp） are 456.46 and 473.40 K, respectively. ΔS≠, ΔH≠, and ΔG≠ of the decomposition reaction are 163.57 J·mol^-1·K^-1, 209.54 kJ·mol^-1, and 133.55 kJ·mol^-1, respectively.展开更多
The thermal decomposition of Zn-MPA complex was investigated under microwave irradiation. ZnO and ZnS nanocrystals could be obtained by decomposing Zn-MPA（3-mercaptopropionic acid） complex under different reaction c...The thermal decomposition of Zn-MPA complex was investigated under microwave irradiation. ZnO and ZnS nanocrystals could be obtained by decomposing Zn-MPA（3-mercaptopropionic acid） complex under different reaction conditions. It was found that both the pH value of the solution and the molar ratio of Zn2＋ and MPA can play an important role in the formation of ZnO and ZnS nanocrystals. MPA mainly acts as an S source or as a complexing agent. This study provides a new route for the controllable preparation of semiconductor nanocrystals.展开更多
The possible excited state decomposition reactions (dehydrogensulfidation, dehydration, and dehydrogenation) of the four tautomers of monothioformic acid have been investigated by ab initio methods with 6-31G** basis ...The possible excited state decomposition reactions (dehydrogensulfidation, dehydration, and dehydrogenation) of the four tautomers of monothioformic acid have been investigated by ab initio methods with 6-31G** basis sets at the CIS level. The activation energies of the four excited state reactions are 42.57, 42.49, 56.90, 47.73 kcal/mol, and are respectively lower than that of the ground states by 24.52, 24.98, 27.28, and 21.10 kcal/mol.展开更多
We compute the thermodynamic and the kinetic properties for the reaction: HCOCN→HCH+CO using the statistical theory and the transition-state theory.The equi- librium constants and the rate coefficients of this reacti...We compute the thermodynamic and the kinetic properties for the reaction: HCOCN→HCH+CO using the statistical theory and the transition-state theory.The equi- librium constants and the rate coefficients of this reaction are also reported here,and the half lives of formyl cyanide at different temperatures are first estimated in this work.展开更多
This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical reactions.The model simulates two-phase flow,heat,and mass transfer processes in a pyrolysi...This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical reactions.The model simulates two-phase flow,heat,and mass transfer processes in a pyrolysis furnace to improve the decomposition rate of magnesium nitrate.The performance of multi-nozzle and single-nozzle injection methods was evaluated,and the effects of primary and secondary nozzle flow ratios,velocity ratios,and secondary nozzle inclination angles on the decomposition rate were investigated.Results indicate that multi-nozzle injection has a higher conversion efficiency and decomposition rate than single-nozzle injection,with a 10.3%higher conversion rate under the design parameters.The decomposition rate is primarily dependent on the average residence time of particles,which can be increased by decreasing flow rate and velocity ratios and increasing the inclination angle of secondary nozzles.The optimal parameters are injection flow ratio of 40%,injection velocity ratio of 0.6,and secondary nozzle inclination of 30°,corresponding to a maximum decomposition rate of 99.33%.展开更多
Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion resu...Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion result was relatively high. It reached 80% for CCl4 and 97% for CHCl3. Using atmospheric air as the carrier gas, the plasma reaction occurred at exothermic reaction and the main products were CO2, CO, and Cl2. Transformation into CCl4 was also detected for CHCl3 decomposition reaction. The conversion of CCh and CHCl3 were increased with the increasing applied frequency and decreasing total gas flow rate.展开更多
The reaction mechanisms of intermolecular cleavage reaction of N-（2-hydroxyphenyl）-phthalamic acid were studied via the density functional theory（DFT）. All geometries of the reactant, transition states, and produc...The reaction mechanisms of intermolecular cleavage reaction of N-（2-hydroxyphenyl）-phthalamic acid were studied via the density functional theory（DFT）. All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G（d, p） level. Vibration analysis was carried out to confirm its identity as transitions＇ structure, and the intrinsic reaction coordinate method（IRC） was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other.展开更多
The microcosmic reaction mechanism of the thermal decomposition of potassium nitroformate（KNF） has been investigated by density functional theory within the generalized gradient approximation. The geometric structur...The microcosmic reaction mechanism of the thermal decomposition of potassium nitroformate（KNF） has been investigated by density functional theory within the generalized gradient approximation. The geometric structures of reactants, intermediates, transition states, and products are fully optimized. The frequency analysis approves the authenticity of intermediates and transition states. Our results show that there are four feasible reaction pathways. The main pathway of the reaction is KNF → B1 → TSB1 → B2 → TSB2 → B3 → TSB3 → B4 → KNO2 ＋ NO2 ＋ NO ＋ CO, and the energy barrier of the rate-limiting step is 216.30 k J·mol^-1. The dominant products predicted theoretically are KNO2, NO2, NO, and CO, which is in agreement with the experiment.展开更多
Structural stability in terms of the decomposition temperature in LiMn_(2)O_(4) was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn_(2)O_(4) was found to have structural ...Structural stability in terms of the decomposition temperature in LiMn_(2)O_(4) was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn_(2)O_(4) was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn_(2)O_(4) varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn_(2)O_(4) materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.展开更多
The thermal behavior, nonisothermal decomposition reaction kinetics and specific heat capacity of nitrate glycerol ether cellulose（NGEC） were determined by thermogravimetric analysis（TGA）, differential scanning ca...The thermal behavior, nonisothermal decomposition reaction kinetics and specific heat capacity of nitrate glycerol ether cellulose（NGEC） were determined by thermogravimetric analysis（TGA）, differential scanning calori- metry（DSC） and microcalorimetry. The apparent activity energy（Ea）, reaction mechanism function, quadratic equa- tion of specific heat capacity（Cp） with temperature were obtained. The kinetic parameters of the decomposition reac- tion are Ea=170.2 kJ/mol and lg（A/s^-l）=16.3. The kinetic equation isf（α）=（4/3）（1-α）[-ln（1-α）]^1/4. The specific heat capacity equation is Cp=1.285-6.276×10^-3T＋1.581×10^-5T^2（283 K〈T〈353 K）. With these parameters, the thermal safety properties of NGEC were studied, such as the self-accelerating decomposition temperature（TSADT）, critical temperature of thermal explosion（Tb） and adiabatic time-to-explosion（tTlad）. The results of the thermal safety evalua- tion of NGEC are： TSADV=459.6 K, Tb=492.8 K, tTlad=0.8 S.展开更多
基金the National Natural Science Foundation of China(No.20573098)the Foundation of Key Laboratory of Science and Technology for National Defence of Propellant and Explosive of China(No.9140C3503020605).
文摘The thermal decomposition behavior and nonisothermal reaction kinetics of the double-base gun propellants containing the mixed ester of triethyleneglycol dinitrate（TEGDN） and nitroglycerin（NG） were investigated by thermogravimetry（TG） and differential thermogravimetry（DTG）, and differential scanning calorimetry（DSC） under the high-pressure dynamic ambience. The results show that the thermal decomposition processes of the mixed nitric ester gun propellants have two mass-loss stages. Nitric ester evaporates and decomposes in the first stage, and nitrocellulose and centralite II（C2） decompose in the second stage. The mass loss, the DTG peak points, and the terminated temperatures of the two stages are changeable with the difference of the mass ratio of TEGDN to NG. There is only one obvious exothermic peak in the DSC curves under the different pressures. With the increase in the furnace pressure, the peak temperature decreases, and the decomposition heat increases. With the increase in the content of TEGDN, the decomposition heat decreases at 0.1 MPa and rises at high pressure. The variety of mass ratio of TEGDN to NG makes few effect on the exothermic peak temperatures in the DSC curves at different pressures. The kinetic equation of the main exothermal decomposition reaction of the gun propellant TG0601 was determined as： dα/dt=1021.59（1-α）3e-2.60×104/T. The reaction mechanism of the process can be classified as chemical reaction. The critical temperatures of the thermal explosion（Tbe and Tbp） obtained from the onset temperature（Te） and the peak temperature（Tp） are 456.46 and 473.40 K, respectively. ΔS≠, ΔH≠, and ΔG≠ of the decomposition reaction are 163.57 J·mol^-1·K^-1, 209.54 kJ·mol^-1, and 133.55 kJ·mol^-1, respectively.
基金the National Natural Science Foundation of China(Nos.50602019 and 50572031)the Key Project of Min-istry of Education, China
文摘The thermal decomposition of Zn-MPA complex was investigated under microwave irradiation. ZnO and ZnS nanocrystals could be obtained by decomposing Zn-MPA（3-mercaptopropionic acid） complex under different reaction conditions. It was found that both the pH value of the solution and the molar ratio of Zn2＋ and MPA can play an important role in the formation of ZnO and ZnS nanocrystals. MPA mainly acts as an S source or as a complexing agent. This study provides a new route for the controllable preparation of semiconductor nanocrystals.
文摘The possible excited state decomposition reactions (dehydrogensulfidation, dehydration, and dehydrogenation) of the four tautomers of monothioformic acid have been investigated by ab initio methods with 6-31G** basis sets at the CIS level. The activation energies of the four excited state reactions are 42.57, 42.49, 56.90, 47.73 kcal/mol, and are respectively lower than that of the ground states by 24.52, 24.98, 27.28, and 21.10 kcal/mol.
文摘We compute the thermodynamic and the kinetic properties for the reaction: HCOCN→HCH+CO using the statistical theory and the transition-state theory.The equi- librium constants and the rate coefficients of this reaction are also reported here,and the half lives of formyl cyanide at different temperatures are first estimated in this work.
基金the financial support for this work provided by the National Key R&D Program of China‘Technologies and Integrated Application of Magnesite Waste Utilization for High-Valued Chemicals and Materials’(2020YFC1909303)。
文摘This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical reactions.The model simulates two-phase flow,heat,and mass transfer processes in a pyrolysis furnace to improve the decomposition rate of magnesium nitrate.The performance of multi-nozzle and single-nozzle injection methods was evaluated,and the effects of primary and secondary nozzle flow ratios,velocity ratios,and secondary nozzle inclination angles on the decomposition rate were investigated.Results indicate that multi-nozzle injection has a higher conversion efficiency and decomposition rate than single-nozzle injection,with a 10.3%higher conversion rate under the design parameters.The decomposition rate is primarily dependent on the average residence time of particles,which can be increased by decreasing flow rate and velocity ratios and increasing the inclination angle of secondary nozzles.The optimal parameters are injection flow ratio of 40%,injection velocity ratio of 0.6,and secondary nozzle inclination of 30°,corresponding to a maximum decomposition rate of 99.33%.
文摘Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion result was relatively high. It reached 80% for CCl4 and 97% for CHCl3. Using atmospheric air as the carrier gas, the plasma reaction occurred at exothermic reaction and the main products were CO2, CO, and Cl2. Transformation into CCl4 was also detected for CHCl3 decomposition reaction. The conversion of CCh and CHCl3 were increased with the increasing applied frequency and decreasing total gas flow rate.
基金Supported by the National Natural Science Foundation of China(No.20672104)
文摘The reaction mechanisms of intermolecular cleavage reaction of N-（2-hydroxyphenyl）-phthalamic acid were studied via the density functional theory（DFT）. All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G（d, p） level. Vibration analysis was carried out to confirm its identity as transitions＇ structure, and the intrinsic reaction coordinate method（IRC） was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other.
基金supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJ131318,KJ1401227,KJ15012002)the Fuling Science and Technology Commission(FLKJ2015ABA1042)the Project of Chongqing Key Laboratory of Inorganic Special Functional Materials(KFKT201506)
文摘The microcosmic reaction mechanism of the thermal decomposition of potassium nitroformate（KNF） has been investigated by density functional theory within the generalized gradient approximation. The geometric structures of reactants, intermediates, transition states, and products are fully optimized. The frequency analysis approves the authenticity of intermediates and transition states. Our results show that there are four feasible reaction pathways. The main pathway of the reaction is KNF → B1 → TSB1 → B2 → TSB2 → B3 → TSB3 → B4 → KNO2 ＋ NO2 ＋ NO ＋ CO, and the energy barrier of the rate-limiting step is 216.30 k J·mol^-1. The dominant products predicted theoretically are KNO2, NO2, NO, and CO, which is in agreement with the experiment.
基金by the National Natural Science Foundation of China(Grant No.12074273)the Doctoral Research Fund of Southwest University of Science and Technology(Grant No.20zx7136).
文摘Structural stability in terms of the decomposition temperature in LiMn_(2)O_(4) was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn_(2)O_(4) was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn_(2)O_(4) varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn_(2)O_(4) materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.
基金Supported by the Foundation of National Key Laboratory of Science and Technology on Combustion and Explosion of China(No.9140C3503011004)
文摘The thermal behavior, nonisothermal decomposition reaction kinetics and specific heat capacity of nitrate glycerol ether cellulose（NGEC） were determined by thermogravimetric analysis（TGA）, differential scanning calori- metry（DSC） and microcalorimetry. The apparent activity energy（Ea）, reaction mechanism function, quadratic equa- tion of specific heat capacity（Cp） with temperature were obtained. The kinetic parameters of the decomposition reac- tion are Ea=170.2 kJ/mol and lg（A/s^-l）=16.3. The kinetic equation isf（α）=（4/3）（1-α）[-ln（1-α）]^1/4. The specific heat capacity equation is Cp=1.285-6.276×10^-3T＋1.581×10^-5T^2（283 K〈T〈353 K）. With these parameters, the thermal safety properties of NGEC were studied, such as the self-accelerating decomposition temperature（TSADT）, critical temperature of thermal explosion（Tb） and adiabatic time-to-explosion（tTlad）. The results of the thermal safety evalua- tion of NGEC are： TSADV=459.6 K, Tb=492.8 K, tTlad=0.8 S.
