The thermal behavior and kinetic parameters of the major exothermic decomposition reaction of the title compound in a temperature-programmed mode were studied by means of TG-DTG and DSC. The critical temperature of th...The thermal behavior and kinetic parameters of the major exothermic decomposition reaction of the title compound in a temperature-programmed mode were studied by means of TG-DTG and DSC. The critical temperature of thermal explosion was calculated. The effect of the title compound on the combustion characteristic of composition modifier double base propellant containing RDX was explored with a strand burner. The results show that the kinetic model function in differential forms, the apparent activation energy(E a) and the pre-exponential factor(A) of the major exothermic decomposition reaction are 3(1-α)[-ln(1-α)] 2/3, 190.56 kJ/mol and 10 13.39 s -1, respectively. The critical temperature of thermal explosion of the compound is 353.08 ℃. The kinetic equation of the major exothermic decomposition process of the title compound at 0.1 MPa could be expressed as dα/dT=10 14.65(1-α)[-ln(1-α)] 2/3 e -2.2920×104/T. As an auxiliary catalyzer, the title compound can help the main catalyzer of lead salt of 4-hydroxy-3,5-dinitropyridine to accelerate the burning rate and reduce the pressure exponent of RDX-CMDB propellant.展开更多
Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390°C. The correspond...Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390°C. The corresponding densities of the solvent are 0.25–1.26 g/cm3 and 0.21–1.03 g/cm3 for sulfolane and 1,4-dioxane, respectively. As a result, in both solvents, more than 90% of cellulose is found to be decomposed to the solvent-soluble portion in which levoglucosan is the main component with the highest yield of about 35% on original cellulose basis. The decomposition rate to levoglucosan is, however, faster in sulfolane than in 1,4-dioxane, while levoglucosan is more stable in 1,4-dioxane. In addition, its yield is found to be solvent-density dependent to be highest around 0.4–0.5 g/cm3 for both solvents. To elucidate these decomposition behaviors, the results obtained in this study with aprotic solvents are compared with protic solvents such as water and methanol in previous works.展开更多
Zhijin phosphorus ore is a moderate and low-grade phosphorus rare-earth ore contained in mines. The separation and extraction of associated rare earth are important research topics. In this study, the migration behavi...Zhijin phosphorus ore is a moderate and low-grade phosphorus rare-earth ore contained in mines. The separation and extraction of associated rare earth are important research topics. In this study, the migration behavior of rare earth during the thermal decomposition of Zhijin phosphorus ore and the separation and extraction of rare earth in phosphorus slag are discussed systematically. During the thermal decomposition process of phosphorus ore, almost all of the associated rare earth enters into the phosphorus slag phase but does not enter into the ferrophosphorus or gas phases. Amorphous calcium metasilicate and calcium fluosilicate are major components of phosphorus slag, and rare earth mainly exists as a calsil solid solution. Hydrochloric acid was used for acidolysis of the phosphorous slag. Under the following conditions, 96% of the rare earth in the phosphorous slag can be dissolved in the acidolysis solution： acid excess coefficient of 1.5, reaction time of 50 min and reaction temperature of 50℃. The rare earth in the acidolysis solution was separated and recycled using oxalic acid as a precipitator and NaOH as a pH modifier. At pH of 1.7, rare-earth-enriched matter with rare-earth content of 2.1 wt% was obtained, and the recovery of the rare earth was 88%.展开更多
文摘The thermal behavior and kinetic parameters of the major exothermic decomposition reaction of the title compound in a temperature-programmed mode were studied by means of TG-DTG and DSC. The critical temperature of thermal explosion was calculated. The effect of the title compound on the combustion characteristic of composition modifier double base propellant containing RDX was explored with a strand burner. The results show that the kinetic model function in differential forms, the apparent activation energy(E a) and the pre-exponential factor(A) of the major exothermic decomposition reaction are 3(1-α)[-ln(1-α)] 2/3, 190.56 kJ/mol and 10 13.39 s -1, respectively. The critical temperature of thermal explosion of the compound is 353.08 ℃. The kinetic equation of the major exothermic decomposition process of the title compound at 0.1 MPa could be expressed as dα/dT=10 14.65(1-α)[-ln(1-α)] 2/3 e -2.2920×104/T. As an auxiliary catalyzer, the title compound can help the main catalyzer of lead salt of 4-hydroxy-3,5-dinitropyridine to accelerate the burning rate and reduce the pressure exponent of RDX-CMDB propellant.
基金the National Natural Science Foundation of China (Grant No. 90610035)
文摘Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390°C. The corresponding densities of the solvent are 0.25–1.26 g/cm3 and 0.21–1.03 g/cm3 for sulfolane and 1,4-dioxane, respectively. As a result, in both solvents, more than 90% of cellulose is found to be decomposed to the solvent-soluble portion in which levoglucosan is the main component with the highest yield of about 35% on original cellulose basis. The decomposition rate to levoglucosan is, however, faster in sulfolane than in 1,4-dioxane, while levoglucosan is more stable in 1,4-dioxane. In addition, its yield is found to be solvent-density dependent to be highest around 0.4–0.5 g/cm3 for both solvents. To elucidate these decomposition behaviors, the results obtained in this study with aprotic solvents are compared with protic solvents such as water and methanol in previous works.
基金Project supported by Key Industrial Engineering Project of Guizhou Province([2013]3041)High-level Talent Project of Guizhou Province(TZJF-2011-54)Guizhou Science and Technology Support Plan Project([2017]2892)
文摘Zhijin phosphorus ore is a moderate and low-grade phosphorus rare-earth ore contained in mines. The separation and extraction of associated rare earth are important research topics. In this study, the migration behavior of rare earth during the thermal decomposition of Zhijin phosphorus ore and the separation and extraction of rare earth in phosphorus slag are discussed systematically. During the thermal decomposition process of phosphorus ore, almost all of the associated rare earth enters into the phosphorus slag phase but does not enter into the ferrophosphorus or gas phases. Amorphous calcium metasilicate and calcium fluosilicate are major components of phosphorus slag, and rare earth mainly exists as a calsil solid solution. Hydrochloric acid was used for acidolysis of the phosphorous slag. Under the following conditions, 96% of the rare earth in the phosphorous slag can be dissolved in the acidolysis solution： acid excess coefficient of 1.5, reaction time of 50 min and reaction temperature of 50℃. The rare earth in the acidolysis solution was separated and recycled using oxalic acid as a precipitator and NaOH as a pH modifier. At pH of 1.7, rare-earth-enriched matter with rare-earth content of 2.1 wt% was obtained, and the recovery of the rare earth was 88%.
