Search Results

You are looking at 1 - 10 of 54 items for :

  • "thermokinetic parameters" x
  • All content x
Clear All

Abstract  

Information about the kinetics and thermal decomposition of hydrogen peroxide (H2O2) has been required for safety reasons, due to its broad applications in many chemical industries. To determine the inherent hazards during H2O2 manufacturing, transportation, disposal, usage, and so on, this study deliberately selected various H2O2 concentrations and analyzed them by differential scanning calorimetry (DSC). In addition, thermokinetic parameters were not only established for each of these reactions, but also aimed at comprehensive, kinetic models with various tests conducted at different heating rates. To build up a comprehensive kinetic model, various tests were conducted by heating rates of 1, 2, 4, 10C min–1, respectively. According to dynamic DSC tests, the experimental curves show that H2O2 decomposition has one exothermic peak and may start to decompose under 47–81C. The total heat of decomposition is about 192–1079 J g–1. Not only can these results prevent accidents caused by H2O2 during storage and transportation, but also assess its inherent hazards and thereby design procedures for emergency response while runaway reactions occurring.

Restricted access

by the National Fire Protection Association (NFPA) [ 7 ]. We investigated the thermokinetic parameters for CHP, DTBP, and TBPB by differential scanning calorimetry (DSC) [ 8 ]. The activation energy ( E a ) for CHP, DTBP, and TBPB at different

Restricted access

examined using a thermal dynamic calorimeter (differential scanning calorimetry, DSC) and isothermal microcalorimeter (thermal activity monitor III, TAM III) to evaluate basic exothermic decomposition and various thermokinetic parameters. Furthermore

Restricted access

Abstract  

Information about the kinetics and thermal decomposition of dicumyl peroxide (DCPO) is required for safety concerns, due to its wide applications and accident cases. To understand the inherent hazards during DCPO manufacturing, we selected various concentrations in different stages and analyzed them by differential scanning calorimetry (DSC). We evaluated thermokinetic parameters to set up a simple, but comprehensive kinetic model, with various tests conducted at heating rates of 2, 4, 6 and 10C min-1 . Subsequently, we established a more efficient, resource-effective, and cost-effective model of safety evaluation for DCPO with different concentrations, according to thermokinetic parameters, such as activation energy E a is 125.35 kJ mol-1 , frequency factor k 0 is 3.12410 12 s-1 , reaction order n is 0.9 and heat of decomposition ΔH is 750.52 J g-1 for DCPO 99 mass%.

Restricted access

Abstract  

Many concerns over unsafe or unknown properties of multi-walled carbon nanotubes (MWNTs) have been raised. The thermal characteristics regarding stability would represent potential hazards during the production or utilization stage and could be determined by calorimetric tests for various thermokinetic parameters. Differential scanning calorimetry (DSC) was employed to evaluate the thermokinetic parameters for MWNTs at various compositions. Thermoanalytical curves showed that the average heat of decomposition (ΔH d) of the MWNTs samples in a manufacturing process was about 31,723 J g−1, by identifying them as an inherently hazardous material. In this study, significant thermal analysis appeared in the presence of sulfuric acid (H2SO4). From the DSC experiments, the purification process of MWNTs could induce an unexpected reaction in the condition of batch addition with reactants of H2SO4. The results can be applied for designing emergency relief system and emergency rescue strategies during a perturbed situation or accident.

Restricted access

Abstract  

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.

Restricted access

Abstract  

Organic peroxides (OPs) have caused many momentous explosions and runaway reactions, resulting from thermal instability, chemical pollutants, and even mechanical shock. In Taiwan, dicumyl peroxide (DCPO), due to its unstable reactive nature, has caused two thermal explosions and runaway reaction incidents in the manufacturing process. To evaluate thermal hazards of DCPO in a batch reactor, we studied thermokinetic parameters, such as heat of decomposition (†H d), exothermic onset temperature (T 0), maximum temperature rise ((dT/dt)max), maximum pressure rise ((dP/dt)max), self-heating rate (dT/dt), etc., via differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2).

Restricted access

Abstract  

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.

Restricted access

are not well understood. Due to the hazardous consequences of decomposition of BTBPC and its extensive use in the industry, we made efforts to understand the runaway reaction phenomena by evaluating the thermokinetic parameters. In this study

Restricted access

study was applied to simulate 0.5-L and 25-kg containers with the aim of developing a reliable procedure to replace the complex method for evaluating the thermokinetic parameters and predicting the thermal hazard of LOPs. The model may be applied to the

Restricted access