Thermal instability is a loss of thermal control which liberates high amount of energy and pressure. An incident took place during drying of an intermediate having amino alcohol functional group in agitated nutsche filter dryer at plant scale. During our investigation using advanced reactive system screening tool (ARSST), thermal decomposition was observed. Onset temperature of decomposition (To) is at 85 °C, adiabatic temperature rise due to decomposition (ΔTad) is 215 °C, maximum temperature attained due to decomposition (Tmax) is 300 °C, maximum self-heat rate (dT/dt)max is 6,215 °C min?1, and maximum rate of pressure rise (dP/dt)max is 1,442 psi min?1 obtained from ARSST experiments. TD24 value is 75 °C which was estimated experimentally. The correlations of these results were utilized to identify the root cause of this incident and necessary control measures were taken accordingly. 相似文献
The thermal decomposition behaviors of 2,4,6-Trinitrotoluene (TNT) and 1-methoxy-2,4-dinitro-benzene (DNAN) were studied by using a NETSCH company accelerating rate calorimetry. Hazard indicators such as onset temperature, adiabatic temperature rise, initial self-heat temperature, maximum self-heating rate, and time-to-maximum temperature rise rate have been determined directly. The kinetic parameters, such as the activation energy (Ea) and the pre-exponential factor (A) were studied from the measured self-heating rate data by assuming order reaction. 相似文献
The oxidative addition of CH3I to planar rhodium(I) complex [Rh(TFA)(PPh3)2] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh3)2(CH3)(CH3CN)][BPh4] (1), or neutral, cis-[Rh(TFA)(PPh3)2(CH3)(I)] (4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH3 and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh3)2(CH3)(NH3)][BPh4] (2) and cis-[Rh(TFA)(PPh3)2(CH3)(Py)][BPh4] (3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh3)2(CH3)(I)] (5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh3)2(CH3)(CH3CN)][BPh4] in acetone at −15 °C. Complexes 1-5 were characterized by elemental analysis, 31P{1H}, 1H and 19F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1-5 and related complexes are discussed from the viewpoint of their isomerism. 相似文献
In this study, the thermal hazard features of various lithium-ion batteries, such as LiCoO2 and LiFePO4, were assessed properly by calorimetric techniques. Vent sizing package 2 (VSP2), an adiabatic calorimeter, was used to measure the thermal hazards and runaway characteristics of the 18650 lithium-ion batteries under an adiabatic condition. The thermal behaviors of the lithium-ion batteries were obtained at normal and abnormal conditions in this study. The critical parameters for thermal hazardous behavior of lithium-ion batteries were obtained including the exothermic onset temperature (T0), heat of decomposition (ΔH), maximum temperature (Tmax), maximum pressure (Pmax), self-heating rate (dT/dt), and pressure rise rate (dP/dt). Therefore, the result indicates the thermal runaway situation of the lithium-ion battery with different materials and voltages in view the of TNT-equivalent method by VSP2. The hazard gets greater with higher voltage. Without the consideration of other anti-pressure measurements, different voltages involving 3.3, 3.6, 3.7, and 4.2 V are evaluated to 0.11, 0.23, 0.88, and 1.77 g of TNT. Further estimation of thermal runaway reaction and decomposition reaction of lithium-ion battery can also be confirmed by VSP2. It shows that the battery of a fully charged state is more dangerous than that of a storage state. The technique results showed that VSP2 can be used to strictly evaluate thermal runaway reaction and thermal decomposition behaviors of lithium-ion batteries. The loss prevention and thermal hazard assessment are very important for development of electric vehicles as well as other appliances in the future. Therefore, our results could be applied to define important safety indices of lithium-ion batteries for safety concerns. 相似文献
The temperature dependence of unimolecular rate constant are reported for the one-electron reduction of various Co(III) and Cr(III) reactants attached to mercury or silver surfaces via either thiocyanate or various thiophenecarboxylate ligands. Combining the “ideal” activation enthalpies obtained at a constant electrode potential using a non-isothermal cell arrangement with the corresponding activation entropies estimated from reaction entropy data enables values of the unimolecular frequency factor, Aet, for the elementary electron-transfer step to be evaluated. Values of Aet close to 1013 s?1 were obtained in this manner for the thiocyanate-bridged reactions at mercury, indicating that the electronic transmission coefficient, κel, approaches unity, i.e. the reactions are adiabatic. Although a comparable value of Aet was obtained for Co(III) reduction via a thiophenecarboxylate bridge featuring uninterrupted conjugation, substantially smaller Aet values were observed with bridges containing one or more saturated carbon atoms, suggesting that κel?1 under the latter conditions. 相似文献
Heat capacities of perfluoro-N-(4-methylcyclohexyl)piperidine (PMCP) have been measured by low-temperature adiabatic calorimetry. The purity of the compound, its triple-point temperature, and its enthalpy and entropy of fusion have been determined. The saturated vapor pressure was determined by comparative ebulliometry as a function of temperature in the 6.2–101.6 kPa pressure range and 374.2–460.9 K temperature range. The calorimetric enthalpy of vaporization at T = 298.15 K has been measured. The following thermodynamic properties were calculated for PMCP: normal boiling temperature, enthalpy of vaporization ΔvapHm0(T) as a function of temperature, and critical parameters. The enthalpies of vaporization at 298.15 K obtained experimentally and by calculation methods match within their error limits, which validates their adequacy and the adequacy of the ΔvapHm0 = f(T) equation as an extrapolation. 相似文献
The synthesis and characterization of the trifluoroacetic acid (H-TFA) derivatives of a series of alkaline earth congeners was undertaken through the dissolution of the alkaline earth (AE) metal in H-TFA. After drying, the resulting reaction powders were independently crystallized from Lewis basic solvents [pyridine (py) or tetrahydrofuran (THF)] as diverse AE-TFA derivatives. For the smallest cation, an octahedrally bound monomer Mg(TFA)2(py)4 (1) was isolated, wherein the TFA ligands were all terminally (TFA) bound. The remaining compounds were found to adopt polymeric structures with: only bridging (μ-TFA) ligands for {[Ca2(μ-TFA)3(THF)4](μ-TFA)}n (2); a mixture of μ-TFA and chelating bridging (μc-TFA) ligands in {[(μ-TFA)2Sr(μc-TFA)][H-py]py}n (3); and only μc-TFA ligands for {[Ba(μc-TFA)2(μc-TFA)(py)][H-py]}n (4) structure. The later two structures were solved with a pyridinium salt located in the lattice. The trend observed for the TFA ligand was that as the cation increases in size, the ligands transform from bridging to chelating bridging due to the increased coordination sphere of the metals. Elemental analyses, solid-state, and solution multinuclear NMR, and FTIR data confirm the bulk powders were consistent with the X-ray structures. 相似文献
The low-temperature heat capacities of berberine hydrochloride were measured over the temperature range from 78 to 350 K by an adiabatic calorimeter. The thermodynamic functions HT ? H298.15 and ST ? S298.15 were derived from the heat capacity data. The results showed that the structure of berberine hydrochloride was stable over the temperature range from 78 to 350 K. The thermal stability of the compound was further tested by DSC and TG measurements. The results were in agreement with those obtained from adiabatic calorimetry experiment. The standard molar enthalpy of formation in the crystalline state of berberine hydrochloride was obtained from the standard molar energies of combustion in oxygen at T = 298.15 K, measured by a rotating-bomb combustion calorimeter. 相似文献
The adiabatic rotational state method is used to investigate the rotational state dependence of the rate coefficients for ion-polar molecule reactions in the very low temperature regime characteristic of interstellar molecular clouds. Results obtained for the systems H3++HCl and H3++HCN indicate that all the methods based on the adiabatic separation of the rotational and radial motion of the collision complex — adiabatic capture centrifugal sudden approximation (ACCSA), statistical adiabatic channel model, classical adiabatic invariance method — agree very satisfactorily in the low temperature limit. Discrepancies observed between some of the published data would appear to arise from numerical inaccuracies rather than from any defect of the theory. 相似文献
The thermal decomposition behavior of composite modified double-base propellant containing hexanitrohexaazaisowurtzitane (CL-20/CMDB propellant) was studied by microcalorimetry. The kinetic and thermodynamic parameters were obtained from the analysis of the heat flow curves. The effect of different proportion of CL-20 to the thermal decomposition behavior, kinetics, and thermal hazard was investigated at the same time. The critical temperature of thermal explosion (Tb), the self acceleration decomposition temperature (TSADT), and the adiabatic decomposition temperature rise (??Tad) were calculated to evaluate the thermal hazard of the CL-20/CMDB propellant. It shows that the CMDB propellant with 38% CL-20 has relative lower values of E and lgA, and with 18% CL-20 has the highest potential hazard. 相似文献
The photodissociation dynamics of the lowest reaction channel on the electronic ground state potential surface of propynal (HCCCHO) and butynal (H3CCCCHO), RCCCHO → RCCH+CO, with a dissociation rate constant kdiss(E), has been examined. Based on previous calculations, the geometry and the force constants of propynal's transition state were calculated at the CI(DZ+P) level and the energy profile along the reaction path determined. The barrier height of propynal is predicted to be 69.9 kcal/mol thus lying significantly below the S1 zero-point level at 74.8 kcal/mol. With these data and the RRKM method, the unimolecular dissociation rate constant kdiss(E) was obtained. For butynal the same parameters were calculated using the less extensive SCF method. Furthermore, MC SCF CI calculations with a DZ+P basis set were used to examine the radical dissociation reaction HCCCHO → on the T1 potential surface. The barrier height is predicted to be 37.0 kcal/mol (without zero-point correction). These findings are discussed in the light of recent experimental results of propynal and butynal obtained in the bulk phase and in the supersonic free jet. 相似文献
The temperature dependence of the heat capacity of a first-generation liquid crystal carbosilane dendrimer with methoxyphenyl benzoate end groups is studied for the first time in the region of 6–370 K by means of precision adiabatic vacuum calorimetry. Physical transformations are observed in this interval of temperatures, and their standard thermodynamic characteristics are determined and discussed. Standard thermodynamic functions Cp°(T), H°(T) ? H°(0), S°(T) ? S°(0), and G°(T) ? H°(0) are calculated from the obtained experimental data for the region of Т → 0 to 370 K. The standard entropy of formation of the dendrimer in the partially crystalline state at Т = 298.15 K is calculated, and the standard entropy of the hypothetic reaction of its synthesis at this temperature is estimated. The thermodynamic properties of the studied dendrimer are compared to those of second- and fourth-generation liquid crystal carbosilane dendrimers with the same end groups studied earlier. 相似文献
The cure kinetics for two-component silicone rubber formed by addition reaction was studied by the rheological method. The influence of reaction temperature (T) on the cure kinetics was explored in detail. It was observed that the data of gel time (tgel, i.e. the time when the reaction reaches the gel point) or a specific reaction time (tnc) (defined as the reaction time before which time the influence of confinement of network on the diffusion of reaction components can be neglected) versus T obey certain functional relationship, which was well explained by the cure kinetics model of thermoset network. The cure kinetics for the two-component silicone rubber can be well fitted by the Kamal-Sourour(autocatalyst) reaction model rather than Kissinger model. When the reaction time was before or equal to tnc, the reaction order obtained by the Kamal-Sourour reaction model was 2, which was consistent with the reaction order inferred from the two components chemical reaction when the diffusion of reaction components was not influenced by the formed cross-linked polymer network. When the reaction time was larger than tnc, such as to the end of reaction (te), the influence of confinement of network on the diffusion of reaction components cannot be neglected, and the reaction order obtained by the Kamal-Sourour reaction model was larger than 2. It was concluded that the confinement effect of network had a greater influence on the cure kinetics of the silicone rubber. The reaction rate constants (kr) under different temperatures were also determined by Kamal-Sourour reaction model. The activation energy (E) for the two-component silicone rubber was also calculated from the results of lntgel, lntnc, and lnkr versus 1/T, respectively. The three values of E were close, which indicated that above analyses were self-consistent. 相似文献
The mechanism of the reaction of the ammonia nucleophilic addition to nitriles RC≡N, both free and activated in the platinum complex trans-[PtCl2(N≡CCH3)2], was studied in detail by theoretical quantumchemical methods. The reaction resulting in the formation of free or coordinated amidines proceeds through consecutive formation of an orientation complex, a six-membered cyclic transition state, and a final reaction product, in which an amidine is in the E-configuration. Water containing in a solvent plays a role of a promoter of this process. The activation effect is interpreted from the viewpoint of both kinetic and thermodynamic factors. It was shown that the mechanism of the reaction product E-Z-isomerization includes the deprotonation of the amino-group nitrogen atom, the change of the coordinated ligand conformation, and the protonation of the nitrogen atom. 相似文献
The temperature dependence of the heat capacity of triphenylantimony dibenzoate Ph3Sb(OC(O)Ph)2 is studied in the range of 6–480 K by means of precision adiabatic vacuum calorimetry and differential scanning calorimetry. The melting of the compound is observed in this temperature range, and its standard thermodynamic characteristics are identified and analyzed. Ph3Sb(OC(O)Ph)2 is obtained in a metastable amorphous state in a calorimeter. The standard thermodynamic functions of Ph3Sb(OC(O)Ph)2 in the crystalline and liquid states are calculated from the obtained experimental data: Cp°(T), H°(T)–H°(0), S°(T), and G°(T)–H°(0) for the region from T → 0 to 480 K. The standard entropy of formation of the compound in the crystalline state at T = 298.15 K is determined. Multifractal processing of the low-temperature (T < 50 K) heat capacity of the compound is performed. It is concluded that the structure of the compound has a planar chain topology. 相似文献
Polymer-supported N-benzyloxy-2-nitrobenzenesulfonamides 1 were N-alkylated using three different routes: via Fukuyama reaction with alcohols, by N-alkylation with alkylbromides, and by Michael addition reaction with α,β-unsaturated carbonyl compounds. The N-alkylated products prepared on the linker 1b were obtained in excellent purity and yield. The 2-nitrobenzenesulfonyl (Nos) group was cleaved under mild conditions to yield polymer-supported N-alkylated benzyloxyamines. Acylation by carboxylic acids and cleavage with TFA yielded N-alkyl hydroxamic acids. 相似文献
H2 S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment.However,undesirable results such as large formation of SO2 and catalyst deactivation inevitably occur,due to the temperature rise of fixed reaction bed caused by the exothermic reaction.Catalyst with high activity in wide operating temperature window,especially in high temperature range,is urgently needed.In this... 相似文献
Values of the adiabatic and isothermal compressibility, κS and κT, of some 80 molten salts at the corresponding temperature of T = 1.1Tm (Tm is the melting point) are obtained from literature data either directly or re-calculated here. For some of the series of salts: alkali metal halides and nitrates, divalent metal halides, and alkali metal sulfates and carbonates the κT values are inversely proportional to the corresponding cohesive energy densities ced (internal energies per unit volume, separately for each class of compounds). The ced values for 1:2 and 2:1 salts not previously evaluated are presented here too. 相似文献
A set of experiments was conducted in an HEL thermal screening unit with synthetic mixtures of raw materials in various proportions
to evaluate the potential thermal hazards at normal and offset process conditions for nitration of symmetrical trichlorobenzene
(TCB). The experiments were carried out in the adiabatic condition. The onset temperatures of the exotherms along with maximum
temperature and pressure rise data for the desired and undesirable reactions were obtained. In the presence of excess nitric
acid and oleum, the reaction shows a severe thermal runaway at the onset temperature of 138°C with a rapid rise in temperature
and pressure leading to a potential explosion.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
The temperature dependences of the heat capacities of titanium di-and tetrachloride were studied by vacuum adiabatic calorimetry. The parameters of fusion (Ttr, ΔtrH, and ΔtrS) were determined for TiCl4. The thermodynamic functions of the substances were calculated over the temperature range 10–300 K. The results obtained were compared with literature data. 相似文献