Thermal Behavior,Nonisothermal Decomposition Reaction Kinetics of Mixed Ester Double-base Gun Propellants

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.

Thermal Behavior, Non-isothermal Decomposition Reaction Kinetics of Copper(Ⅱ) Salt of 4-Hydroxy-3,5-dinitropyridine and Its Application in Propellant

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.

Decomposition reaction kinetics of Baotou RE concentrate with concentrated sulfuric acid at low temperature

Baotou RE concentrate was decomposed with concentrated sulfuric acid by controlling the roasting temperature below 500℃.Thermogravimetry-differential thermal analysis（TG-DTA） and chemical analytical methods were used to study the thermal decomposition process and the thermal decomposition effect.The Freeman-Carroll method was applied to analyze the TG-DTA curves.The activation energy, reaction order, and reaction frequency factor at different stages were calculated.The Satava method was used to deduce the reaction mechanism and the relative reaction rate during the thermal decomposition process.

Catalytic Reaction Kinetics of Propylene Dimerization to 4-Methyl-1-Pentene Using Cu-K/K_(2)CO_(3) Solid Base Catalyst

The catalysis technology of propylene dimerization to form 4-methyl-1-pentene(4MP1)using a Cu-K/K_(2)CO_(3) solid base catalyst is a well-known heterogeneous catalytic reaction.In this study,the intrinsic kinetics of propylene dimerization were studied in a fixed-bed continuous reactor.Internal and external diffusion during the dimerization reaction experiments were eliminated by adjusting the flow rate of the carrier gas and the particle size of the catalyst support.Then,the concentration changes of each substance at the outlet of the catalyst bed under different residence times were investigated.Moreover,the suitable reaction kinetics equations was derived using the Langmuir Hinshelwood-Hougen-Watson kinetic model.Finally,the activation energy for each reaction involved in the dimerization reaction was calculated.The activation energies of 4MP1,branched by-products,and 1-hexene were 115.0,150.8,and 177.4 kJ/mol,respectively.The effect of process conditions on propylene dimerization with solid base catalysts was studied through kinetic model simulation.By comparing the theoretical values obtained from the simulation with the experimental results,the applicability and accuracy of the kinetic model were verified.

Non-isothermal kinetics of the first-stage decomposition reaction of the complex of samarium p-methoxybenzoate with 1,10-phenanthroline

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.

“Buckets effect”in the kinetics of electrocatalytic reactions

In this study,we systematically investigated the effect of proton concentration on the kinetics of the oxygen reduction reaction(ORR)on Pt(111)in acidic solutions.Experimental results demonstrate a rectangular hyperbolic relationship,i.e.,the ORR current excluding the effect of other variables increases with proton concentration and then tends to a constant value.We consider that this is caused by the limitation of ORR kinetics by the trace oxygen concentration in the solution,which determines the upper limit of ORR kinetics.A model of effective concentration is further proposed for rectangular hyperbolic relationships:when the reactant concentration is high enough to reach a critical saturation concentration,the effective reactant concentration will become a constant value.This could be due to the limited concentration of a certain reactant for reactions involving more than one reactant or the limited number of active sites available on the catalyst.Our study provides new insights into the kinetics of electrocatalytic reactions,and it is important for the proper evaluation of catalyst activity and the study of structureperformance relationships.

Thermal Decomposition Reaction Kinetics Model of Powdered Bastnaesite

The thermal decomposition procedure of powdered bastnaesite from Mianning was investigated, and TG DTA curves of bastnaesite were tested in atmosphere. According to the model provided by Criado, the kinetics data were calculated and treated with thermal analysis techniques, and kinetics curves of thermal decomposition reaction of powdered bastnaesite were drawn. Comparing these curves with the standard curves and combining with the previous research results of kinetics parameter calculation, the results confirmed that the reaction mechanism was nucleation and nuclei growth, and its differential and integral forms of reaction kinetics model can be expressed as: f(α)=(1-α) and g(α) =-ln(1- α ) respectively.

Mitigated reaction kinetics between lithium metal anodes and electrolytes by alloying lithium metal with low-content magnesium

Lithium(Li)metal is regarded as a promising anode candidate for high-energy-density rechargeable batteries.Nevertheless,Li metal is highly reactive against electrolytes,leading to rapid decay of active Li metal reservoir.Here,alloying Li metal with low-content magnesium(Mg)is proposed to mitigate the reaction kinetics between Li metal anodes and electrolytes.Mg atoms enter the lattice of Li atoms,forming solid solution due to the low amount(5 wt%)of Mg.Mg atoms mainly concentrate near the surface of Mg-alloyed Li metal anodes.The reactivity of Mg-alloyed Li metal is mitigated kinetically,which results from the electron transfer from Li to Mg atoms due to the electronegativity difference.Based on quantitative experimental analysis,the consumption rate of active Li and electrolytes is decreased by using Mgalloyed Li metal anodes,which increases the cycle life of Li metal batteries under demanding conditions.Further,a pouch cell(1.25 Ah)with Mg-alloyed Li metal anodes delivers an energy density of 340 Wh kg^(-1)and a cycle life of 100 cycles.This work inspires the strategy of modifying Li metal anodes to kinetically mitigate the side reactions with electrolytes.

Study on thermal decomposition kinetics of azobenzene-4,4′-dicarboxylic acid by using compensation parameter method and nonlinear fitting evaluation

Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent performance.With large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite important.Thus,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were investigated.Experiments were conducted by using a SENSYS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA decomposition.The results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks fall.The amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition progress.Applying the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.

Copper Indium Sulfide Enables Li-CO_(2)Batteries with Boosted Reaction Kinetics and Cycling Stability

High energy density Li-CO_(2)batteries have attracted much attention owing to the"two birds with one stone"feature in fixing greenhouse gas CO_(2)and providing renewable energy.However,poor reversibility of the discharge product Li_(2)CO_(3)is one of the main problems that limit its application,resulting in poor cycling stability and severe polarization.Herein,copper indium sulfide(CIS),a semiconducting non-precious metal sulfide,is fabricated as cathode catalysts for high-performance Li-CO_(2)batteries.Combined with the synergistic effect of bimetallic valence bonding and coordinated electron transfer,Li-CO_(2)batteries using CIS cathodes exhibit high full specific discharge capacity,excellent rate capability and cycle stability,namely it delivers a high specific full discharge capacity of 8878μAh cm^(-2),runs steadily from 10 to 100μA cm^(-2),and performs a stable long-term cycling behavior(>1050 h)under a high energy efficiency of 84%and a low charge voltage of approximately 3.4 V at 20μA cm^(-2)within 100μAh cm^(-2).In addition,a flexible Li-CO_(2)pouch cell is constructed to reveal the potential of employing CIS to fabricate flexible high energy storage devices in practical applications.This work shows a promising development pathway toward next-generation sustainable energy storage devices.

Kinetics and Mechanism of Exothermic First-stage Decomposition Reaction of 2,6-Bis(2,2,2-trinitroethyl)glycoluril

The thermal behavior, mechanism and kinetic parameters of the exothermic first-stage decomposition of the title compound in a temperature-programmed mode were investigated by means of DSC, TG-DTG and IR. The reaction mechanism was proposed. The kinetic model function in differential form, apparent activation energy(\%E\%\-a) and pre-exponential factor(\%A\%) of this reaction are (3/2)(1-\%α\%)\[-ln(1-\%α\%)\]\+\{1/3\}, 185\^52 kJ/mol and 10\+\{17\^78\} s\+\{-1\}, respectively. The critical temperature of the thermal explosion of the compound is 201\^30 ℃. The values of Δ\%S\%\+≠, Δ\%H\%\+≠ and Δ\%G\%\+≠ of this reaction are 72\^46 J/(mol· K), 175\^1 kJ/mol and 141\^50 kJ/mol, respectively.

Study on the catalytic degradation of sodium lignosulfonate to aromatic aldehydes over nano-CuO:Process optimization and reaction kinetics

As one of the few renewable aromatic resources,the research of depolymerization of lignin into highvalue chemicals has attracted extensive attention in recent years.Catalytic wet aerobic oxidation(CWAO)is an effective technology to convert lignin like sodium lignosulfonate(SL),a lignin derivative,into aromatic aldehydes such as vanillin and syringaldehyde.However,how to improve the yield of aromatic aldehyde and conversion efficiency is still a challenge,and many operating conditions that significantly affect the yield of these aromatic compounds have rarely been investigated systematically.In this work,we adopted the stirred tank reactor(STR)for the CWAO process with nano-CuO as catalyst to achieve the conversion of SL into vanillin and syringaldehyde.The effect of operating conditions including reaction time,oxygen partial pressure,reaction temperature,SL concentration,rotational speed,catalyst amount,and NaOH concentration on the yield of single phenolic compound was systematically investigated.The results revealed that all these operating conditions exhibit a significant effect on the aromatic aldehyde yield.Therefore,they should be regulated in an optimal value to obtain high yield of these aldehydes.More importantly,the reaction kinetics of the lignin oxidation was explored.This work could provide basic data for the optimization and design of industrial operation of lignin oxidation.

Thermal Decomposition and Kinetics of Rigid Polyurethane Foams Derived from Sugarcane Bagasse

Rigid polyurethane foams were fabricated with five kinds of liquefied sugarcane bagasse polyols （LBP）. The foams derived from sugarcane bagasse were investigated by thermogravimetric analysis （TGA）, and the thermal degradation data were analyzed using the Coast-Redfern method and Ozawa method to obtain the reaction order and activation energy. The results indicate that the sugarcane bagasse-foams exhibit an excellent heat-resistant property, whereas their pyrolysis procedures are quite complicated. The reaction as first order only takes place from 250 to 400 ℃, and the pyrolysis activation energies vary from 20 to 140 kJ/mol during the whole pyrolysis process.

Thermal Decomposition Kinetics and Mechanism of Tb(Ⅲ) m-Methylbenzoate Complex with 1,10-Phenanthroline in Static Air Atmosphere

The thermal behavior of [Tb_2( m -MBA)_6(phen)_2](H_2O)_2( m -MBA=C_8H_7O_2, methoxybenzoate; phen=C_ 12 H_8N_2, 1,10-phenanthroline) in static air atmosphere was investigated by means of TG-DTG and DTA methods. The thermal decomposition of the title compound takes place mainly in two steps. The intermediate and the residue for each decomposition were identified by the TG curve. By the kinetic method of processing thermal analysis data put forward by Malek et al ., it is defined that the kinetics model for the first-step thermal decomposition is SB( m,n ).

Non-isothermal Decomposition Mechanism and Kinetics of LiClO_4 in Nitrogen

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.

Thermal Decomposition Mechanism and Non Isothermal Kinetics of Complex of [La_2(P-MBA)_6(PHEN)_2]2H_2O

The complex of [La 2(P MBA) 6(PHEN) 2]2H 2O (P MBA: p methylbenzoate and PHEN: 1,10 phenanthroline) was prepared and characterized by elemental analysis and IR spectroscopy. The thermal behavior of [La 2(P MBA) 6(PHEN) 2]2H 2O in dynamic nitrogen atmosphere was investigated by TG DTG techniques. The results show that the thermal decomposition process of the [La 2(P MBA) 6(PHEN) 2]2H 2O occurs in five steps. The empirical kinetic model for the first step thermal decomposition obtained by Malek method is SB(m,n). The activation energy E and the pre exponential factor lnA for this step reaction are 76.4 kJ·mol -1 and 24.92, respectively.

Study on Non-Isothermal Decomposition Kinetics of Ephedrini Hydrochloridum

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.

STUDY ON THERMAL DECOMPOSITION KINETICS OF URUSHIOL METAL CHELATE POLYMERS

The thermal decomposition kinetics of urushiol-Cu, urushiol-Nd and urushiol-Ti chelatepolymers has been studied by non-isothermal thermogravimetry. The results suggest that thethermal decomposition kinetics of three chelate polymers are all of first order. Their averageactivation energy values of the thermal decomposition calculated by Ozawa-(I) method are 110,79, 136. 98 and 163. 64 kJ mol^(-1) respectively, which increase linearly with the metal valence of themetal chelate polymers