Computational study of the catalytic synthesis of 5‐nitro‐1,2,4‐triazol‐3‐one

In this study, 5‐nitro‐1,2,4‐triazol‐3‐one (NTO) was theoretically synthesized from urea via chlorination followed by amination, formylation, and nitration under aqueous and gaseous environments based on experience of experimental methods, and metal chlorides and metal oxides were used as catalysts to promote reaction. Reaction routes closely related to experimental processes were successfully constructed, and the corresponding energy barriers were estimated for each elementary reaction. Reaction conditions distinct from those reported in the literature (including the adoption of aluminum chloride, ferric chloride, aluminum oxide, ferrous oxide, and chromium oxide catalysts, the use of nitric acid and dinitrogen pentoxide as nitration agents, and adjustment of the reaction temperature) were used in corresponding reaction systems, and the modeling results suggested that ferric chloride is a good catalyst for the chlorination reaction, ferrous oxide is suitable for catalyzing amination, formylation, and nitration, and nitric acid is the better agent for nitration. Estimates of the comparable energy barriers for each reaction stage were considered to imply more feasible pathways for NTO synthesis. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Thermal runaway hazards of <Emphasis Type="Italic">tert</Emphasis>-butyl hydroperoxide by calorimetric studies

Thermal runaway reactions associated with exothermic behaviors of tert-butyl hydroperoxide (TBHP) solutions and TBHP reacting with alkaline contaminants were studied. A differential scanning calorimetry (DSC) was used to characterize these inherent behaviors of TBHP solutions with KOH, NaOH, LiOH and NH₄OH. The exothermic peak in thermal curves of TBHP solutions with different alkali were detected by DSC thermal analysis. By thermal analysis, we compared various heats of decomposition of TBHP solutions with alkaline impurities, and determined the incompatible hazards of various TBHP solutions with alkaline contaminants. Comparing with TBHP in various diluents, the adiabatic runaway reaction via vent sizing package 2 (VSP2) indicated that aqueous TBHP intrinsically possesses the phenomena of thermal explosion with dramatic self-reactive rate and pressure rise under adiabatic conditions. Many commercial organic peroxides may have different hazard behaviors. Therefore, using thermal method to classify the hazards is an important subject.     

Thermal properties of hydrazine in nitric acid solution

Since some combustible, oxidative and reductive chemicals are used in the extracting process in the nuclear reprocessing plant the process has potential hazards of a fire and explosion due to the undesired reaction. In this study to obtain a better understanding of the thermal properties of hydrazine in nitric acid solution which is used for preventing the oxidation of extracted plutonium, thermal analysis was carried out for the mixtures in various conditions. From the results of DSC it was revealed that the vessel material has an influence on the thermal decomposition of hydrazine. It was also found that hydrazine reacted with nitric acid in an autocatalytic manner, and concentration of nitric acid has a strong influence on the thermal hazard of hydrazine and nitric acid mixtures.     

Identificaiton of potential thermal runaways using small scale thermal analytical techniques

With industry's focus on the early identification of potential thermal runaways in chemical processes, it is important that these potential thermal hazards be identified early in a process' development. Thermal runaways can be initiated in several ways: through an uncontrolled heat of reaction, the initiation of an exothermic decomposition/oxidation, or a combination of these two. It is therefore critical that information on exothermic decomposition/oxidation and heat of reaction be easily obtainable using small scale laboratory reactions.A small scale thermal hazards identification program, using process samples from a 200 ml reaction and small scale thermal analytical techniques, identifies potential thermal runaways rapidly. The small scale thermal hazards identification program utilizes three small scale thermal analytical techniques developed at the Merck Research Laboratories. These include the use of specially designed DSC reusable metal crucibles to identify closed system exothermic activity in process samples, the Small Scale Isothermal Age Technique to accurately determine exothermic onset temperatures and Syringe Injection calorimetry to determine heat of reactions which occur at room temperature.     

Solid-liquid equilibrium diagrams of common ion binary salt hydrate mixtures involving nitrates and chlorides of magnesium, cobalt, nickel, manganese, and iron(III)

The solid-liquid equilibrium diagrams of binary mixtures involving magnesium nitrate hexahydrate with cobalt nitrate hexahydrate, nickel nitrate hexahydrate (partly), manganese nitrate tetrahydrate, and iron(III) nitrate nonahydrate and of magnesium chloride hexahydrate with cobalt and nickel chlorides hexahydrates and manganese chloride tetrahydrate, and the of two manganese salts were determined. Those diagrams that showed a simple eutectic were fitted by the Ott equation and where the required BET parameters were available, the magnesium salt rich parts of the liquidus were modeled by means of this method.     

Reaction hazard analysis for cumene hydroperoxide with sodium hydroxide or sulfuric acid

Organic peroxides (OPs) are very susceptible to thermal sources, chemical pollutants or even mechanical shock. Over the years, they have caused many serious explosions. Cumene hydroperoxide (CHP) is widely employed to produce phenol and dicumyl peroxide (DCPO) in the manufacturing process. Differential scanning calorimetry (DSC) and thermal activity monitor (TAM) were employed to determine the potential thermal hazards and thermokinetic parameters (such as exothermic onset temperature (T ₀), maximum temperature (T _max), and enthalpy (ΔH)) of CHP mixed with sodium hydroxide (NaOH) and sulfuric acid (H₂SO₄). High performance liquid chromatography (HPLC) was used to analyze the concentration vs. time of CHP.When CHP is mixed with NaOH, the T ₀ is induced earlier and reactions become more intricate than the pure CHP solution. CHP added to NaOH or H₂SO₄ is more dangerous than pure CHP alone. Depending on the operating conditions, NaOH and H₂SO₄ are the incompatible chemicals for CHP.     

Reactive incompatibility of cumene hydroperoxide mixedwith alkaline solutions

Cumene hydroperoxide (CHP) is classified as a flammable hazard in NFPA 43B. Fires or explosions induced by thermal hazards ascribed to the unstable hydroperoxyl or peroxyl groups are often reported. This sequence studies is aimed at the decomposition phenomena associated with the reactive and incompatible characteristics of CHP mixed with alkaline solutions. Various alkalines were used for comparing the relative impact of bases and effects on concentrations. Exothermic onset temperatures and heats of decomposition of these incompatible mixtures were performed by differential scanning calorimetry (DSC). Comparisons of exothermic onset temperature, peak power, heat of decomposition, etc., were assessed to verify the severity of incompatible hazards in these systems. When mixed with a small amount of the hydroxides (in the production or storage of CHP), CHP will be more labile or unstable because of lower exothermic temperature. In addition, to elucidate the final products and propose mechanisms of the reaction of CHP mixed with alkaline solution, the analytical results were carried out by GC/MS and IR. The exhibited reactivity was complicated and significantly affected by the alkaline solutions. The reaction schemes have been proposed in this study. These results are especially important in process safety design for producing CHP and its related compounds, such as phenol, α-cumyl alcohol (CA), acetophenone (AP), and dicumyl peroxide (DCPO).     

Disintegration of pellets in ocean water

The problem of fixation of water pollutants, e. g., nuclear fission and corrosion products is concerned not only with the chemical and physical properties of these materials but also with the type of their dispersal in open waters under natural turbulent conditions. The delivery of a scavenging system into a required depth was the objective of this study. Pellets disintegrating at such a rate as to deliver the required uniform concentration of reacting chemicals into the contaminated body of water were developed. Attempts were made to depart from an empirical approach and to investigate formation and properties of pellets through systematic studies. Parameters investigated were particle size of pelleted chemicals, pelleting pressure and temperature, and age of pellets. Chemicals used were potassium permanganate; ferrous sulfate, anhydrous and heptahydrate; and ferrous chloride, dihydrate and tetrahydrate. The use of pelleted materials for removal of industrial nuclear waste products from water is feasible under emergency and under normal conditions using pellets designed for the specific conditions.     

SYNTESIS OF THE COMPLEXES OF MACROPOROUS SULFONATED RESINS WITH FERRIC CHLORIDE AND THEIR CATALYTIC BEHAVIOR FOR SETERIFICATION OF ACETIC ACID WITH BUTANOL

The complex resins prepared from macroporous sulfonated resin D72(H^+ form) with ferric chloride or ferric chloride hexahydrate have both sites of Bronsted acid and Lewis acid.In the catalysis of exterification of acetic acid with butanol the complex resins show to have much higher catalytic activity than that of its matrix.a conventional sulfonated cation exchange resin D72.     

Hazard evaluation for redox system of cumene hydroperoxide mixed with inorganic alkaline solutions

In petrochemistry, dicumyl peroxide (DCPO) is used in various resins for improving physical properties, which was produced by cumene hydroperoxide (CHP) with oxidization reaction, redox reaction, and dehydration reaction. The reactant, CHP, is a typical organic hydroperoxide and has been intrinsically unstable and reactive due to its bivalent -O-O- structure which can be broken readily with bond-dissociation energy. This sequence on sensitive study aimed at the thermal hazard evaluation for the reactive and incompatible characteristics of CHP mixed with various inorganic alkaline solutions. Differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2) were used to analyze the thermal hazards and runaway reaction of redox system, such as decomposition of CHP in cumene solution and CHP react with inorganic alkaline solutions, exothermic onset temperature, peak power, heat of decomposition of dynamic scanning tests, adiabatic self-heating rate, pressure rise rate, maximum temperature, maximum pressure of reaction system, etc. The results of the tests have proven helpful in establishing safe handling, storage, transportation, and disposal guidelines.     

Thermal hazard evaluation of lauroyl peroxide mixed with nitric acid

Many thermal runaway incidents have been caused by organic peroxides due to the peroxy group, -O-O-, which is essentially unstable and active. Lauroyl peroxide (LPO) is also sensitive to thermal sources and is incompatible with many materials, such as acids, bases, metals, and ions. From the thermal decomposition reaction of various concentrations of nitric acid (HNO3) (from lower to higher concentrations) with LPO, experimental data were obtained as to its exothermic onset temperature (T0), heat of decomposition (ΔHd), isothermal time to maximum rate (TMRiso), and other safety parameters exclusively for loss prevention of runaway reactions and thermal explosions. As a novel finding, LPO mixed with HNO3 can produce the detonation product of 1-nitrododecane. We used differential scanning calorimetry (DSC), thermal activity monitor III (TAM III), and gas chromatography/mass spectrometer (GC/MS) analyses of the reactivity for LPO and itself mixed with HNO3 to corroborate the decomposition reactions and reaction mechanisms in these investigations.     

Effects of cumene hydroperoxide on phenol and acetone manufacturing by DSC and VSP2

Cumene hydroperoxide (CHP) being catalyzed by acid is one of the crucial processes for producing phenol and acetone globally. However, it is thermally unstable to the runaway reaction readily. In this study, various concentrations of phenol and acetone were added into CHP for determination of thermal hazards. Differential scanning calorimetry (DSC) tests were used to obtain the parameters of exothermic behaviors under dynamic screening. The parameters included exothermic onset temperature (T ₀), heat of decomposition (ΔH _d), and exothermic peak temperature (T _p). Vent sizing package 2 (VSP2) was employed to receive the maximum pressure (P _max), the maximum temperature (T _max), the self-heating rate (dT/dt), maximum pressure rise rate ((dP/dt)_max), and adiabatic time to maximum rate ((TMR)_ad) under the worst case. Finally, a procedure for predicting thermal hazard data was developed. The results revealed that phenol and acetone sharply caused a exothermic reaction of CHP. As a result, phenol and acetone are important indicators that may cause a thermal hazard in the manufacturing process.     

Kinetic investigation of redox reaction between vitamin C and ferric chloride hexahydrate in acidic medium

The kinetics of the reaction between vitamin C (l-ascorbic acid) and ferric chloride hexahydrate was investigated in acidic medium at pH 3 spectrophotometrically. The order of the reaction was established by applying different methods, such as initial rate method, integration method and half-life method. The results obtained from each method were correlated with each other and consistency in all methods was observed. The order of the reaction with respect to each reactant was found first and the overall second order was recommended for the reaction.     

Reaction hazard analysis for the thermal decomposition of cumene hydroperoxide in the presence of sodium hydroxide

Organic peroxides have caused many serious explosions and fires that were promoted by thermal instability, chemical pollutants, and even mechanical shock. Cumene hydroperoxide (CHP) has been employed in polymerization and for producing phenol and dicumyl peroxide (DCPO). Differential scanning calorimetry (DSC) has been used to assess the thermal hazards associated with CHP contacting sodium hydroxide (NaOH). Thermokinetic parameters, such as exothermic onset temperature (T ₀), peak temperature (T _max), and enthalpy (ΔH) were obtained. Experimental data were obtained using DSC and curve fitting using thermal safety software (TSS) was employed to obtain the kinetic parameters. Isothermal microcalorimetry (thermal activity monitor, TAM) was used to investigate the thermal hazards associated with storing of CHP and CHP mixed with NaOH under isothermal conditions. TAM showed that in the temperature range from 70 to 90°C an autocatalytic reaction occurs. This was apparent in the thermal curves. Depending on the operating conditions, NaOH may be one of the chemicals or catalysts incompatible with CHP. When CHP was mixed with NaOH, the T ₀ is lower and reactions become more complex than those associated with assessment of the decomposition of the pure peroxide. The data by curve fitting indicated that the activation energy (E _a) for the induced decomposition is smaller than that for decomposition of CHP in the absence of hydroxide.     

Thermokinetic model simulations for methyl ethyl ketone peroxide contaminated with H2SO4 OR NaOH by DSC and VSP2

In this study, a mixture of methyl ethyl ketone peroxide (MEKPO) with various contaminants, such as H₂SO₄ and NaOH, was prepared in order to elucidate the cause of these accidents and the results of upset conditions. Thermokinetic parameters were acquired by both differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). In addition, we simulated the thermokinetic parameters and created kinetic models for the specific contaminants. The results indicate that the thermal hazard of MEKPO is less than that of the mixed MEKPO with the above-mentioned contaminants. Consequently, the evaluated parameters could be used to prevent any unexpected exothermic runaway reaction or to alleviate hazards to an acceptable extent, if such a reaction occurs.     

Thermal characteristics of mixtures of cyclonite and nitroglycerine or diazidonitrazapentane

The thermal characteristics of mixtures of cyclonite (RDX) and nitroglycerine (NG) and of RDX and diazidonitrazapentane (DIANP) were studied. The thermal decomposition processes of NG and RDX are not synchronous with those of RDX/NG mixtures. The DSC curves show two obviously exothermic peaks, one at 203°C for NG and other at 240°C for RDX. However, there is only a single exothermic peak in the DSC curves of RDX/DIANP mixtures within certain ratio limits, due to the coincidence of the exothermic decomposition peaks for both RDX and DIANP and their mutual dissolution. The effects of the different thermal characteristics of different explosives on the combustion performance are also discussed.     

Thermal hazards evaluation of cumene hydroperoxide mixed with its derivatives

Over 90% of the cumene hydroperoxide (CHP) produced in the world is applied in the production of phenol and acetone. The additional applications were used as a catalyst, a curing agent, and as an initiator for polymerization. Many previous studies from open literature have verified and employed various aspects of the thermal decomposition and thermokinetics of CHP reactions. An isothermal microcalorimeter (thermal activity monitor III, TAM III), and a thermal dynamic calorimetry (differential scanning calorimetry, DSC) were used to resolve the exothermic behaviors, such as exothermic onset temperature (T ₀), heat power, heat of decomposition (ΔH _d), self-heating rate, peak temperature of reaction system, time to maximum rate (TMR), etc. Furthermore, Fourier transform infrared (FT-IR) spectrometry was used to analyze the CHP products with its derivatives at 150 °C. This study will assess and validate the thermal hazards of CHP and incompatible reactions of CHP mixed with its derivatives, such as acetonphenone (AP), and dimethylphenyl carbinol (DMPC), that are essential to process safety design.     

Thermal hazards evaluation for sym-TCB nitration reaction using thermal screening unit (TSU)

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.     

Incompatible reaction for (3-4-epoxycyclohexane) methyl-3′-4′-epoxycyclohexyl-carboxylate (EEC) by calorimetric technology and theoretical kinetic model

(3-4-Epoxycyclohexane) methyl-3′-4′-epoxycyclohexyl-carboxylate (EEC) is a typical epoxy resin (EP). In Asia, due to the unstable reactive natures of EP, various thermal hazard and runaway reaction incidents have been occasioned by EP in the manufacturing process, such as fire, explosion, and toxic release, resulting in loss of life as well financial catastrophes and social outcries. Certain catalysis substances, H₂SO₄, acetic acid, or NaOH, may accelerate the reaction or curing rate for EP. However, an incompatible reaction with these chemical substances may induce a thermal hazard, causing a runaway excursion during the last stage. We employed thermogravimetry (TG) to obtain thermal stability parameters under non-isothermal conditions to evaluate the runaway reactions for EEC. The experimental data were compared with kinetics-based curve fitting to assess thermally hazardous phenomena by optimizing curve fitting on the kinetic parameters. The aim of this study was to estimate the incompatible hazards for EEC, provide thermal hazard information in order to determine the optimum operation conditions, and diminish the likelihood of fire and explosion accidents incurred by EP.     

Thermal Decomposition Behavior and Non-isothermal Decomposition Reaction of Copper（ll） Salt of 4-Hydroxy-3,5-dinitropyridine Oxide and Its Application in Solid Rocket Propellant

The thermal decomposition behavior and kinetic parameters of the exothermic decomposition reactions of the title compound in a temperature‐programmed mode have been investigated by means of DSC, TG‐DTG and lower rate Thermolysis/FTIR. The possible reaction mechanism was proposed. The critical temperature of thermal explosion was calculated. The influence of the title compound on the combustion characteristic of composite modified double base propellant containing RDX has been explored with the strand burner. The results show that the kinetic model function in differential form, apparent activation energy E_a and pre‐exponential factor A of the major exothermic decomposition reaction are 1‐a,207.98 kJ*mol^?1 and 10^15.64 s^?1, respectively. The critical temperature of thermal explosion of the compound is 312.87 C. The kinetic equation of the major exothermic decomposition process of the title compound at 0.1 MPa could be expressed as: dα/dT=10^16.42 (1–α)e‐2.502×10⁴/T As an auxiliary catalyst, the title compound can help the main catalyst lead salt of 4‐hydroxy‐3,5dinitropyridine oxide to enhance the burning rate and reduce the pressure exponent of RDX‐CMDB propellant.