The thermal decomposition processes of ephedrini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar method, Coats-Redfera method, and Ozawa method, is put forward...The thermal decomposition processes of ephedrini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar method, Coats-Redfera method, and Ozawa method, is put forward for determining kinetic model under non-isothermal conditions. By applying the combined method, it is determined that the thermal decomposition of ephedrini hydrochloridum is subjected to cylindrical symmetric diffusion. And the reaction function isƒ(α)=2(1-α)?, apparent activation energy (115.26±3.55) kJ·mol−1, pre-exponential factor 4.62×108 s−1. Results show that the combined method is feasible and simple.展开更多
The thermal decomposition of Tb_2(O-MBA)_6(PHEN)_2 (O-MBA: o-methylbenzoate;PHEN: 1,10-phenanthroline) and its kinetics were studied under the non-isothermal condition bythermogravimetry-derivative thermogravimetry (T...The thermal decomposition of Tb_2(O-MBA)_6(PHEN)_2 (O-MBA: o-methylbenzoate;PHEN: 1,10-phenanthroline) and its kinetics were studied under the non-isothermal condition bythermogravimetry-derivative thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtainedfrom analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method.The most probable mechanism function was suggested by comparing the kinetic parameters. The kineticequation for the first stage can be expressed as dα/dt = Aexp(-E/RT)·3(1 - α)^(2/3). Thelifetime equation at mass loss of 10% was deduced as lnτ= -28.7429 + 19797.795/T by isothermalthermogravimetric analysis.展开更多
In recent years, there has been considerable inte- rest in complexes formed by lanthanide cations and va-rious benzoate derivatives^[1-4], due to their potential application in areas, such as extraction, separation, g...In recent years, there has been considerable inte- rest in complexes formed by lanthanide cations and va-rious benzoate derivatives^[1-4], due to their potential application in areas, such as extraction, separation, germicide preparation, catalysis, luminescence, and functional material preparation^[5]. As a continuation of the study on lanthanide carboxylate^[6-13], samarium complexes with m-methylbenzoic acid or o-methoxy- benzoic acid and 1,10-phenanthroline were synthesized and characterized by elemental analysis and IR spec- trometry. The thermal decomposition mechanisms of the two complexes were derived and the corresponding non- isothermal kinetics was studied using the Achar diffe- rential method^[14], the MKN integral method^[15], the non-linear isoconversional integral ( NL-INT), and dif-ferential(NL-DIF) method^[16,17]. The information of the thermodynamic properties of the complex is impor- tant to characterize and understand the properties of the coordination compound, which could eventually be use-ful in determining their potential application.展开更多
The thermal behavior and non-isothermal decomposition kinetics of 1-amino-1-hydrazino-2,2-dinitro-ethylene potassium salt[K(AHDNE)] were studied under the non-isothermal conditions by different scanning calorimeter...The thermal behavior and non-isothermal decomposition kinetics of 1-amino-1-hydrazino-2,2-dinitro-ethylene potassium salt[K(AHDNE)] were studied under the non-isothermal conditions by different scanning calorimeter(DSC) method. The thermal behavior of K(AHDNE) presents three exothermic decomposition processes. The kinetic equation of the first thermal decomposition reaction obtained is dα/dT=(1019.63/β)3(1-α)[-ln(1-α)]2/3exp(-1.862× 105/RT). The self-accelerating decomposition temperature(TSADT) and critical temperature of thermal explosion(Tb) of K(AHDNE) are 162.5 and 171.4 °C, respectively. K(AHDNE) has higher thermal stability than AHDNE.展开更多
The thermal decomposition kinetics of high iron gibbsite ore was investigated under non-isothermal conditions.Popescu method was applied to analyzing the thermal decomposition mechanism.The results show that the most ...The thermal decomposition kinetics of high iron gibbsite ore was investigated under non-isothermal conditions.Popescu method was applied to analyzing the thermal decomposition mechanism.The results show that the most probable thermal decomposition mechanism is the three-dimensional diffusion model of Jander equation,and the mechanism code is D3.The activation energy and pre-exponential factor for thermal decomposition of high iron gibbsite ore calculated by the Popescu method are 75.36 kJ/mol and 1.51×10-5 s-(-1),respectively.The correctness of the obtained mechanism function is validated by the activation energy acquired by the iso-conversional method.Popescu method is a rational and reliable method for the analysis of the thermal decomposition mechanism of high iron gibbsite ore.展开更多
The thermal behavior and non-isothermal decomposition kinetics of [Cu(en)2H2O](FOX-7)2·H2O (en=ethylenediamine) were studied with DSC and TG-DTG methods.The kinetic equation of the exothermal process is dα...The thermal behavior and non-isothermal decomposition kinetics of [Cu(en)2H2O](FOX-7)2·H2O (en=ethylenediamine) were studied with DSC and TG-DTG methods.The kinetic equation of the exothermal process is dα/dt=(10^17.92/β)4α^3/4exp(-1.688×10^5/RT).The self-accelerating decomposition temperature and critical temperature of the thermal explosion are 163.3 and 174.8 ℃,respectively.The specific heat capacity of [Cu(en)2H2O](FOX-7)2·H2O was determined with a micro-DSC method,with a molar heat capacity of 661.6 J·mol^-1·K^-1 at 25 ℃.Adiabatic time-to-explosion was also estimated as 23.2 s.[Cu(en)2H2O](FOX-7)2·H2O is less sensitive.展开更多
Experiments on thermal decomposition of nano-sized calcium carbonate were carried out in a thermo-gravimetric analyzer under non-isothermal condition of different heating rates (5 to 20K·min-1). The Coats and Red...Experiments on thermal decomposition of nano-sized calcium carbonate were carried out in a thermo-gravimetric analyzer under non-isothermal condition of different heating rates (5 to 20K·min-1). The Coats and Redfern's equation was used to determine the apparent activation energy and the pre-exponential factors. The mechanism of thermal decomposition was evaluated using the master plots, Coats and Redfern's equation and the kinetic compensation law. It was found that the thermal decomposition property of nano-sized calcium carbonate was different from that of bulk calcite. Nano-sized calcium carbonate began to decompose at 640℃, which was 180℃lower than the reported value for calcite. The experimental results of kinetics were compatible with the mechanism of one-dimensional phase boundary movement. The apparent activation energy of nano-sized calcium carbonate was estimated to be 151kJ·mol-1 while the literature value for normal calcite was approximately 200kJ·mol-1. The order of magnitude of pre-exponential factors was estimated to be 10~9 s-1.展开更多
The non-isothermal decomposition kinetics of LiClO4 in flow N2 atmosphere was studied. TG-DTA curves show that the decomposition proceeded through two well-defined steps below 900℃, and the mass loss was in agreement...The non-isothermal decomposition kinetics of LiClO4 in flow N2 atmosphere was studied. TG-DTA curves show that the decomposition proceeded through two well-defined steps below 900℃, and the mass loss was in agreement with the theoretical value. XRD profile demonstrates that the product of the thermal decomposition at 500℃ is LiCI. For the decomposition kinetics study, the activation energies calculated with the Friedman method were considered as the initial values for non-linear regression and were used for verifying the correctness of the fired models. The decomposition process was fitted by a two-step consecutive reaction: extended Prout-Tompkins equation[Bna, f(α) is (1-α)^nα^α] followed by a lth order reaction(F1). The activation energies were (215.6±0.2) and (251.6±3.6) kJ/mol, respectively. The exponentials n and a for Bna reaction were (0.25±0.05) and (0.795±0.005), respectively. The reaction types and activation energies were in agreement with those obtained from the isothermal method, but the exponentials were optimized for better firing and prediction.展开更多
The thermal decomposition reaction of Eu-2(p-MBA)(6)(PHEN)(2) (p-MBA=CH3C6H4COO, methylbenzoate; PHEN=C12H8N2, 1,10-phenanthroline) was studied in a static atmosphere using TG-DTG method. The thermal decomposition pro...The thermal decomposition reaction of Eu-2(p-MBA)(6)(PHEN)(2) (p-MBA=CH3C6H4COO, methylbenzoate; PHEN=C12H8N2, 1,10-phenanthroline) was studied in a static atmosphere using TG-DTG method. The thermal decomposition process of the complex was determined and its kinetics was investigated. Kinetic parameters were obtained from the analysis of TG-DTG curves by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism functions of the thermal decomposition reaction for the first stage are: f(alpha) =(1-alpha)(2), g(alpha) = (1-alpha)(-1)-1. The activation energy for the first stage is 255.18 kJ/mol, the entropy of activation DeltaS is 227.32 J/mol and the Gibbs free energy of activation DeltaG is 128.04 W/mol.展开更多
The polyoxometalate complex (CPFX-HCl)(4)H5BW12O40-12H(2)O was prepared in aqueous solution for the first time, and characterized by elemental analysis, IR spectrum, and TG-DTG. The TG-DTG curves showed that its therm...The polyoxometalate complex (CPFX-HCl)(4)H5BW12O40-12H(2)O was prepared in aqueous solution for the first time, and characterized by elemental analysis, IR spectrum, and TG-DTG. The TG-DTG curves showed that its thermal decomposition was a four-step process consisting of the simultaneous collapse of Keggin anion. The intermediate and residue of the decomposition were identified by mean of TG-DTG, IR, and XRD technique. The non-isothermal kinetic data were analyzed by the Achar method and Coats-Redfern method. The apparent activation energy (E) and the pre-exponential factor (In A) of each decomposition were obtained. The most probable thermal decomposition reaction mechanisms were proposed by comparison of the kinetic parameters. The kinetic equation for both the second stage and the third stage can be expressed as d alpha/dt = Ae(-E/RT) -(1 - alpha)(2), and the fourth stage d alpha/dt = Ae(-E/RT) -(1 - alpha). And their mathematic expressions of the kinetic compensation effects of thermal decomposition reaction were also determined.展开更多
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
The thermal decomposition of the strontium chloride hexahydrate and its kinetics were studied under non isothermal condition in nitrogen by thermogravimetric and derivative thermogravimetric techniques. The intermedi...The thermal decomposition of the strontium chloride hexahydrate and its kinetics were studied under non isothermal condition in nitrogen by thermogravimetric and derivative thermogravimetric techniques. The intermediate and residue for each decomposition were identified from TG curve. The non isothermal kinetic data were analyzed by the Achar method and the Coats Redfern method. The possible reaction mechanisms were suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as d α /d t = A exp(- E/RT)(1-α ), the second stage, d α /d t = A exp(- E/RT)3(1-α ) 2/3 , and the third stage, d α /d t = A exp(- E/RT)3/2(1-α ) 2/3 [1-(1- α ) 1/3 ] -1 . Mathematic expressions of the kinetic compensation effects of each stage of the thermal decomposition reaction were also obtained.展开更多
The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the...The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the complex has been stUdied from the TG-DTGcurves by means of the Achar et al. and Coats-Redfern methods,the most probab1e kinetic equation canbe expressed as dofdtrAe -E / RT * l /(2Q).The corresponding kinetic compensation effect expressions arefound to be lnuA=0. 1794E+0. 1689.The non-isothermal thermal decomposition process of the complex isone-dimensional diffusion.But electrochemical studies of the complex(Cu2L'2)from cyclic voltamrnetriccurves by means of powder microelectrodes technique'',shows one two-electron irreversible process.展开更多
The complex of [Sm(p-MOBA)3phen]2 (p-MOBA, p-methoxybenzoate; phen,1 10-phenanthroline) was prepared and characterized by elemental analysis, IR, and UV spectroscopy. The thermal decomposition of the [Sm(p-MOBA)...The complex of [Sm(p-MOBA)3phen]2 (p-MOBA, p-methoxybenzoate; phen,1 10-phenanthroline) was prepared and characterized by elemental analysis, IR, and UV spectroscopy. The thermal decomposition of the [Sm(p-MOBA)sphen]2 complex and its kinetics were studied under a static air atmosphere by TG-DTG methods. The intermediate and residue for each decomposition stage were identified from the TG curve. The kinetic parameters and mecha- nisms of the first decomposition stage were obtained from the analysis of the TG-DTG curves by a new method of processing the data of thermal analysis kinetics. The lifetime equation at a mass loss of 10% was deduced as lnr= - 30.6795 + 21034.56/Tby isothermal thermogravimelric analysis.展开更多
The non-isothermal decomposition reaction of Nd[(C_5H_ 10NS_2)_3(C_ 12H_8N_2)] were carried out by means of TG-DTG and the thermal decomposition mechanism, and the associated kinetics was investigated. The kinetic par...The non-isothermal decomposition reaction of Nd[(C_5H_ 10NS_2)_3(C_ 12H_8N_2)] were carried out by means of TG-DTG and the thermal decomposition mechanism, and the associated kinetics was investigated. The kinetic parameters are obtained from an analysis of the TG-DTG curves at different heating rate by integral and differential methods. The most probable kinetic model function of the decomposition reaction is Maple Power of n=3/2, f(α)=2/3α -1/2 and the apparent activation energy E is 116.67 kJ·mol -1 and the pre-exponential factor lg[A/s -1] is 7.6891.展开更多
The salicylaldehyde salicylhydrazone and its complex of Er(Ⅲ) were synthesized. The formulae K·4H_2O(HL=[C_(14)H_(10)N_2O_3]^(2-), the bivalent form of the salicylaldehyde salicylhydrazone) were determined by el...The salicylaldehyde salicylhydrazone and its complex of Er(Ⅲ) were synthesized. The formulae K·4H_2O(HL=[C_(14)H_(10)N_2O_3]^(2-), the bivalent form of the salicylaldehyde salicylhydrazone) were determined by elemental analysis and EDTA volumetric analysis. Molar conductance, IR, UV and X-ray power diffraction were carried out for the characterizations of the complex and the ligand. There are two stable five-numbered and six-numbered circles in the complex. The thermal decompositions of the ligand and the complex with the kinetic study are carried out by non-isothermal thermogravimetry. The stages of the decompositions were identified by TG-DTG curve. The non-isothermal kinetic data were analyzed by means of integral and differential methods. The possible reaction mechanism and the kinetic equation were investigated by the corresponding kinetic parameters.The activation energy value of the main step decomposition are also calculated by Kissinger′s method and Ozawa′s method.展开更多
The thermal decomposition process of LiHC2O4·H2O from 30 to 600 ℃ was investigated by the thermogravimetric and differential scanning calorimetry (TG-DSC). The phases decomposited at different temperature were c...The thermal decomposition process of LiHC2O4·H2O from 30 to 600 ℃ was investigated by the thermogravimetric and differential scanning calorimetry (TG-DSC). The phases decomposited at different temperature were characterized by X-ray diffraction (XRD), which indicated the decompositions at 150, 170, and 420℃, relating to LiHC2O4, Li2C2O4, Li2C2O4, and Li2CO3, respectively. Reaction mechanisms in the whole sintering process were determined, and the model fitting kinetic approaches were applied to data for non-isothermal thermal decomposition of LiHC2O4?H2O; finally, the kinetic parameters of each reaction were also calculated herein.展开更多
The thermal decomposition of a new antitumor agent,4-{5-[3,4-dimethyl-5-(3,4,5-trimethoxyphenyl)thiophen-2-yl]-2-methoxyphenyl}morpholine was studied by Differential Scanning Calorimetry(DSC)and Thermogravimetry(TG)/D...The thermal decomposition of a new antitumor agent,4-{5-[3,4-dimethyl-5-(3,4,5-trimethoxyphenyl)thiophen-2-yl]-2-methoxyphenyl}morpholine was studied by Differential Scanning Calorimetry(DSC)and Thermogravimetry(TG)/Derivative Thermogravimetry(DTG)methods at a flow rate of nitrogen gas of 120 mL/min,The kinetic parameters were obtained from the analysis of the corresponding curves by Kissinger's method,Ozawa's method and the integral method,The results indicate that the apparent activation energy and pre-exponential constants of the decomposition reaction are 106.67 kJ/mol and 10^6.19s^(-1),respectively.展开更多
Polystyrene/iron-nickel (PS/FeNi3) nanocomposites were synthesized via an in-situ polymerization route and characterized by XRD,SEM and FTIR. FeNi3 nanoparticles were characterized by TEM and XRD. The pure FeNi3 nan...Polystyrene/iron-nickel (PS/FeNi3) nanocomposites were synthesized via an in-situ polymerization route and characterized by XRD,SEM and FTIR. FeNi3 nanoparticles were characterized by TEM and XRD. The pure FeNi3 nanoparticles (100~125 nm) were highly clustered and percolated through the PS matrix. When the content of FeNi3 nanoparticles reached 5 wt%,an interaction between FeNi3 nanoparticles and PS matrix was observed. The thermal decomposition behavior of PS/FeNi3 nanocomposites was investigated by thermal analysis. The activation energies (E) and pre-exponential factors (lnA) were calculated by using Archar method. The results show that the thermal decomposition of pure PS is a one-dimensional diffusion mechanism. A three-dimensional diffusion mechanism appears when FeNi3 nanoparticles incorporate. The E of PS/FeNi3 nanocomposites with different FeNi3 contents is 217.5,225.3,180.6 and 73.0 kJ·mol-1,and the corresponding lnA is 35.6,34.9,27.5 and 10.4 S-1,respectively.展开更多
基金the Foundation of the Science and Technology Committee of Hubei Province(2001ABA009)
文摘The thermal decomposition processes of ephedrini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar method, Coats-Redfera method, and Ozawa method, is put forward for determining kinetic model under non-isothermal conditions. By applying the combined method, it is determined that the thermal decomposition of ephedrini hydrochloridum is subjected to cylindrical symmetric diffusion. And the reaction function isƒ(α)=2(1-α)?, apparent activation energy (115.26±3.55) kJ·mol−1, pre-exponential factor 4.62×108 s−1. Results show that the combined method is feasible and simple.
基金This project was financially supported by the Natural Science Foundation of Hebei Province (Nos. 202140 and 203148) Hebei Education Department (No. 2001121)
文摘The thermal decomposition of Tb_2(O-MBA)_6(PHEN)_2 (O-MBA: o-methylbenzoate;PHEN: 1,10-phenanthroline) and its kinetics were studied under the non-isothermal condition bythermogravimetry-derivative thermogravimetry (TG-DTG) techniques. Kinetic parameters were obtainedfrom analysis of TG-DTG curves by the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method.The most probable mechanism function was suggested by comparing the kinetic parameters. The kineticequation for the first stage can be expressed as dα/dt = Aexp(-E/RT)·3(1 - α)^(2/3). Thelifetime equation at mass loss of 10% was deduced as lnτ= -28.7429 + 19797.795/T by isothermalthermogravimetric analysis.
基金Supported by the Natural Science Foundation of Hebei Province,China(No.B2007000237)Department of Education of He-bei Pro-vince,China(No.2004325)Hebei Normal University,China(Nos.L2006Z06and L2005Y12).
文摘In recent years, there has been considerable inte- rest in complexes formed by lanthanide cations and va-rious benzoate derivatives^[1-4], due to their potential application in areas, such as extraction, separation, germicide preparation, catalysis, luminescence, and functional material preparation^[5]. As a continuation of the study on lanthanide carboxylate^[6-13], samarium complexes with m-methylbenzoic acid or o-methoxy- benzoic acid and 1,10-phenanthroline were synthesized and characterized by elemental analysis and IR spec- trometry. The thermal decomposition mechanisms of the two complexes were derived and the corresponding non- isothermal kinetics was studied using the Achar diffe- rential method^[14], the MKN integral method^[15], the non-linear isoconversional integral ( NL-INT), and dif-ferential(NL-DIF) method^[16,17]. The information of the thermodynamic properties of the complex is impor- tant to characterize and understand the properties of the coordination compound, which could eventually be use-ful in determining their potential application.
基金Supported by the National Natural Science Foundation of China(No.20803058)the Shaanxi Provincial Science Program Foundation, China(No.2011kjxx31)the Education Committee Foundation of Shaanxi Province, China(Nos.2010JK881,12JK0636)
文摘The thermal behavior and non-isothermal decomposition kinetics of 1-amino-1-hydrazino-2,2-dinitro-ethylene potassium salt[K(AHDNE)] were studied under the non-isothermal conditions by different scanning calorimeter(DSC) method. The thermal behavior of K(AHDNE) presents three exothermic decomposition processes. The kinetic equation of the first thermal decomposition reaction obtained is dα/dT=(1019.63/β)3(1-α)[-ln(1-α)]2/3exp(-1.862× 105/RT). The self-accelerating decomposition temperature(TSADT) and critical temperature of thermal explosion(Tb) of K(AHDNE) are 162.5 and 171.4 °C, respectively. K(AHDNE) has higher thermal stability than AHDNE.
基金Project(51374058)supported by the National Natural Science Foundation of China
文摘The thermal decomposition kinetics of high iron gibbsite ore was investigated under non-isothermal conditions.Popescu method was applied to analyzing the thermal decomposition mechanism.The results show that the most probable thermal decomposition mechanism is the three-dimensional diffusion model of Jander equation,and the mechanism code is D3.The activation energy and pre-exponential factor for thermal decomposition of high iron gibbsite ore calculated by the Popescu method are 75.36 kJ/mol and 1.51×10-5 s-(-1),respectively.The correctness of the obtained mechanism function is validated by the activation energy acquired by the iso-conversional method.Popescu method is a rational and reliable method for the analysis of the thermal decomposition mechanism of high iron gibbsite ore.
基金Supported by the National Natural Science Foundation of China(Nos. 21241003, 20803058), the Science and Technology Research and Development Program of Shaanxi Province, China(No.2013K02-25) and the Education Committee Foundation of Shaanxi Province, China(No.2013JK0697).
文摘The thermal behavior and non-isothermal decomposition kinetics of [Cu(en)2H2O](FOX-7)2·H2O (en=ethylenediamine) were studied with DSC and TG-DTG methods.The kinetic equation of the exothermal process is dα/dt=(10^17.92/β)4α^3/4exp(-1.688×10^5/RT).The self-accelerating decomposition temperature and critical temperature of the thermal explosion are 163.3 and 174.8 ℃,respectively.The specific heat capacity of [Cu(en)2H2O](FOX-7)2·H2O was determined with a micro-DSC method,with a molar heat capacity of 661.6 J·mol^-1·K^-1 at 25 ℃.Adiabatic time-to-explosion was also estimated as 23.2 s.[Cu(en)2H2O](FOX-7)2·H2O is less sensitive.
基金Supported by the Key Research of Science & Technology of Education(No.0202)and the Fundamental Research Plan of HuoYingdong(No.81063).
文摘Experiments on thermal decomposition of nano-sized calcium carbonate were carried out in a thermo-gravimetric analyzer under non-isothermal condition of different heating rates (5 to 20K·min-1). The Coats and Redfern's equation was used to determine the apparent activation energy and the pre-exponential factors. The mechanism of thermal decomposition was evaluated using the master plots, Coats and Redfern's equation and the kinetic compensation law. It was found that the thermal decomposition property of nano-sized calcium carbonate was different from that of bulk calcite. Nano-sized calcium carbonate began to decompose at 640℃, which was 180℃lower than the reported value for calcite. The experimental results of kinetics were compatible with the mechanism of one-dimensional phase boundary movement. The apparent activation energy of nano-sized calcium carbonate was estimated to be 151kJ·mol-1 while the literature value for normal calcite was approximately 200kJ·mol-1. The order of magnitude of pre-exponential factors was estimated to be 10~9 s-1.
基金Supported by the National Natural Science Foundation of China(No.20071026)
文摘The non-isothermal decomposition kinetics of LiClO4 in flow N2 atmosphere was studied. TG-DTA curves show that the decomposition proceeded through two well-defined steps below 900℃, and the mass loss was in agreement with the theoretical value. XRD profile demonstrates that the product of the thermal decomposition at 500℃ is LiCI. For the decomposition kinetics study, the activation energies calculated with the Friedman method were considered as the initial values for non-linear regression and were used for verifying the correctness of the fired models. The decomposition process was fitted by a two-step consecutive reaction: extended Prout-Tompkins equation[Bna, f(α) is (1-α)^nα^α] followed by a lth order reaction(F1). The activation energies were (215.6±0.2) and (251.6±3.6) kJ/mol, respectively. The exponentials n and a for Bna reaction were (0.25±0.05) and (0.795±0.005), respectively. The reaction types and activation energies were in agreement with those obtained from the isothermal method, but the exponentials were optimized for better firing and prediction.
基金This project was financially supported by the Education Department of Hebei Province.]
文摘The thermal decomposition reaction of Eu-2(p-MBA)(6)(PHEN)(2) (p-MBA=CH3C6H4COO, methylbenzoate; PHEN=C12H8N2, 1,10-phenanthroline) was studied in a static atmosphere using TG-DTG method. The thermal decomposition process of the complex was determined and its kinetics was investigated. Kinetic parameters were obtained from the analysis of TG-DTG curves by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The most probable mechanism functions of the thermal decomposition reaction for the first stage are: f(alpha) =(1-alpha)(2), g(alpha) = (1-alpha)(-1)-1. The activation energy for the first stage is 255.18 kJ/mol, the entropy of activation DeltaS is 227.32 J/mol and the Gibbs free energy of activation DeltaG is 128.04 W/mol.
文摘The polyoxometalate complex (CPFX-HCl)(4)H5BW12O40-12H(2)O was prepared in aqueous solution for the first time, and characterized by elemental analysis, IR spectrum, and TG-DTG. The TG-DTG curves showed that its thermal decomposition was a four-step process consisting of the simultaneous collapse of Keggin anion. The intermediate and residue of the decomposition were identified by mean of TG-DTG, IR, and XRD technique. The non-isothermal kinetic data were analyzed by the Achar method and Coats-Redfern method. The apparent activation energy (E) and the pre-exponential factor (In A) of each decomposition were obtained. The most probable thermal decomposition reaction mechanisms were proposed by comparison of the kinetic parameters. The kinetic equation for both the second stage and the third stage can be expressed as d alpha/dt = Ae(-E/RT) -(1 - alpha)(2), and the fourth stage d alpha/dt = Ae(-E/RT) -(1 - alpha). And their mathematic expressions of the kinetic compensation effects of thermal decomposition reaction were also determined.
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.
文摘The thermal decomposition of the strontium chloride hexahydrate and its kinetics were studied under non isothermal condition in nitrogen by thermogravimetric and derivative thermogravimetric techniques. The intermediate and residue for each decomposition were identified from TG curve. The non isothermal kinetic data were analyzed by the Achar method and the Coats Redfern method. The possible reaction mechanisms were suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as d α /d t = A exp(- E/RT)(1-α ), the second stage, d α /d t = A exp(- E/RT)3(1-α ) 2/3 , and the third stage, d α /d t = A exp(- E/RT)3/2(1-α ) 2/3 [1-(1- α ) 1/3 ] -1 . Mathematic expressions of the kinetic compensation effects of each stage of the thermal decomposition reaction were also obtained.
文摘The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the complex has been stUdied from the TG-DTGcurves by means of the Achar et al. and Coats-Redfern methods,the most probab1e kinetic equation canbe expressed as dofdtrAe -E / RT * l /(2Q).The corresponding kinetic compensation effect expressions arefound to be lnuA=0. 1794E+0. 1689.The non-isothermal thermal decomposition process of the complex isone-dimensional diffusion.But electrochemical studies of the complex(Cu2L'2)from cyclic voltamrnetriccurves by means of powder microelectrodes technique'',shows one two-electron irreversible process.
基金the Natural Science Foundation of Hebei Province (No. B2007000237)Hebei Education Department (No. 2004325)Hebei Normal University (No. L2006Z06, No. L2005Y12).
文摘The complex of [Sm(p-MOBA)3phen]2 (p-MOBA, p-methoxybenzoate; phen,1 10-phenanthroline) was prepared and characterized by elemental analysis, IR, and UV spectroscopy. The thermal decomposition of the [Sm(p-MOBA)sphen]2 complex and its kinetics were studied under a static air atmosphere by TG-DTG methods. The intermediate and residue for each decomposition stage were identified from the TG curve. The kinetic parameters and mecha- nisms of the first decomposition stage were obtained from the analysis of the TG-DTG curves by a new method of processing the data of thermal analysis kinetics. The lifetime equation at a mass loss of 10% was deduced as lnr= - 30.6795 + 21034.56/Tby isothermal thermogravimelric analysis.
文摘The non-isothermal decomposition reaction of Nd[(C_5H_ 10NS_2)_3(C_ 12H_8N_2)] were carried out by means of TG-DTG and the thermal decomposition mechanism, and the associated kinetics was investigated. The kinetic parameters are obtained from an analysis of the TG-DTG curves at different heating rate by integral and differential methods. The most probable kinetic model function of the decomposition reaction is Maple Power of n=3/2, f(α)=2/3α -1/2 and the apparent activation energy E is 116.67 kJ·mol -1 and the pre-exponential factor lg[A/s -1] is 7.6891.
文摘The salicylaldehyde salicylhydrazone and its complex of Er(Ⅲ) were synthesized. The formulae K·4H_2O(HL=[C_(14)H_(10)N_2O_3]^(2-), the bivalent form of the salicylaldehyde salicylhydrazone) were determined by elemental analysis and EDTA volumetric analysis. Molar conductance, IR, UV and X-ray power diffraction were carried out for the characterizations of the complex and the ligand. There are two stable five-numbered and six-numbered circles in the complex. The thermal decompositions of the ligand and the complex with the kinetic study are carried out by non-isothermal thermogravimetry. The stages of the decompositions were identified by TG-DTG curve. The non-isothermal kinetic data were analyzed by means of integral and differential methods. The possible reaction mechanism and the kinetic equation were investigated by the corresponding kinetic parameters.The activation energy value of the main step decomposition are also calculated by Kissinger′s method and Ozawa′s method.
基金financially supported by the National"863"Program of China(No.2009AA03Z226)Project on the Integration of Industry,Education and Research of Guangdong Province(No.2011A090200012)the Fundamental Research Funds for the Central Universities(No.FRF-MP-12-005B)
文摘The thermal decomposition process of LiHC2O4·H2O from 30 to 600 ℃ was investigated by the thermogravimetric and differential scanning calorimetry (TG-DSC). The phases decomposited at different temperature were characterized by X-ray diffraction (XRD), which indicated the decompositions at 150, 170, and 420℃, relating to LiHC2O4, Li2C2O4, Li2C2O4, and Li2CO3, respectively. Reaction mechanisms in the whole sintering process were determined, and the model fitting kinetic approaches were applied to data for non-isothermal thermal decomposition of LiHC2O4?H2O; finally, the kinetic parameters of each reaction were also calculated herein.
基金SUPPORTED BY THE NATIONAL YOUNG SCHOLAR AWARD OF NSFC(NO.30125043).
文摘The thermal decomposition of a new antitumor agent,4-{5-[3,4-dimethyl-5-(3,4,5-trimethoxyphenyl)thiophen-2-yl]-2-methoxyphenyl}morpholine was studied by Differential Scanning Calorimetry(DSC)and Thermogravimetry(TG)/Derivative Thermogravimetry(DTG)methods at a flow rate of nitrogen gas of 120 mL/min,The kinetic parameters were obtained from the analysis of the corresponding curves by Kissinger's method,Ozawa's method and the integral method,The results indicate that the apparent activation energy and pre-exponential constants of the decomposition reaction are 106.67 kJ/mol and 10^6.19s^(-1),respectively.
基金supported by the National Natural Foundation of China (No. 10476024)
文摘Polystyrene/iron-nickel (PS/FeNi3) nanocomposites were synthesized via an in-situ polymerization route and characterized by XRD,SEM and FTIR. FeNi3 nanoparticles were characterized by TEM and XRD. The pure FeNi3 nanoparticles (100~125 nm) were highly clustered and percolated through the PS matrix. When the content of FeNi3 nanoparticles reached 5 wt%,an interaction between FeNi3 nanoparticles and PS matrix was observed. The thermal decomposition behavior of PS/FeNi3 nanocomposites was investigated by thermal analysis. The activation energies (E) and pre-exponential factors (lnA) were calculated by using Archar method. The results show that the thermal decomposition of pure PS is a one-dimensional diffusion mechanism. A three-dimensional diffusion mechanism appears when FeNi3 nanoparticles incorporate. The E of PS/FeNi3 nanocomposites with different FeNi3 contents is 217.5,225.3,180.6 and 73.0 kJ·mol-1,and the corresponding lnA is 35.6,34.9,27.5 and 10.4 S-1,respectively.