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- Author or Editor: Chi-Chang Liu x
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Abstract
The decomposition of organic peroxides by their relatively weak oxygen linkage and hydroperoxide radical in the presence of reaction solution is one of the thermal hazards for triggering a runaway reaction. Runaway incidents may occur in oxidation reactors, vacuum condensation reactors, tank lorries, or storage tanks. In NFPA 432 organic peroxides in NFPA 432 are classified as flammable. The exothermic behaviors of solid organic peroxides, dicumene peroxide, benzoyl peroxide, and lauroyl peroxide, were determined by differential scanning calorimetry (DSC), and vent sizing package 2 (VSP2). Relevant data detected by DSC provided thermal stability information, such as exothermic onset temperature (T 0), maximum heat-releasing peak (T max), and heat of decomposition (ΔH d). VSP2 was used to perform the bench scale situation for pushing the expected or unexpected reaction to undergo runaway reaction. Onset temperature, maximum pressure, self-heating rate ((dT dt −1)max), and pressure-release rate ((dP dt −1)max) were therefore obtained and explained. These results are essentially crucial in process design for an inherently safer approach.
Abstract
Activity concentrations using gamma-ray spectrometer and distributions of natural radionuclides in soil samples collected were investigated to assess the environmental radioactivity and characterization of radiological hazard. The average concentrations of 238U, 232Th series and 40K in the 5 cm depth soil were 22.53, 33.43 and 406.62 Bq kg−1, respectively, which was within world median ranges in the UNSCEAR 2000 report. The average absorbed dose rate estimated by soil activity and annual effective doses were 49.32 nGy h−1 and 60.48 μSv, respectively. Since the soil is an important building material, the mean radium equivalent activity (Ra eq), external (H ex) and internal (H in) hazard index using various models given in the literature for the study area were evaluated as 101.72 Bq kg−1, 0.27 and 0.34, respectively, which were below the recommended limits. The effects of pH value, conductivity, true density and textural properties of soil samples on the natural radionuclide levels were also studied. The application of cluster analysis (CA) and principal component analysis (PCA), coupled with Pearson correlation coefficient analysis, were utilized to analyze the data, identify and clarify the effects of physico-chemical properties on natural radioactivity levels. The CA and PCA results showed that the former method yielded three distinctive groups of the soil variables whereas the latter one yielded the number of variables into three factors with 87.5% variance explanation.
Abstract
SBA-15 materials were synthesized through the hydrothermal method. The SBA-15 prepared at the hydrothermal time of 24 h possessed a higher surface area and a good hexagonal structure, so it was used as the catalytic support in this experiment. The base metals (Cu, Co, Ni) coated on SBA-15 were prepared for toluene removal. The results revealed that the catalytic activity of Cu/SBA-15 for toluene removal was about 70% at 250 °C, which was the best among the three catalysts. The modification of Cu/SBA-15 by adding different transition metals (Ce, Co, Ni, Mn) to improve the removal efficiency of toluene and NO was also investigated in this study. The results indicate that the catalytic activity of Mn–Cu/SBA-15 for toluene removal was about 100% at 250 °C. The toluene as a reductant on the removal of NO was also determined. Furthermore, the catalytic activity of Mn–Cu/SBA-15 for NO removal can reach about 70% at 300 °C when toluene is used as reductant.
Abstract
Liquid organic peroxides have been broadly employed in the process industries such as tert-butyl peroxy-2-ethyl hexanoate (TBPO). This study investigated the thermokinetic parameters of TBPO, a typical liquid organic peroxide, by isothermal kinetic algorithms and non-isothermal kinetic algorithms with thermal activity monitor III, and differential scanning calorimetry, respectively. An attempt has been made to determine the thermokinetic parameters by simulation software, such as exothermic onset temperature (T 0), maximum temperature (T max), decomposition (ΔH d), activation energy (E a), self-accelerating decomposition temperature, and isothermal time to maximum rate (TMRiso). A liquid thermal explosion model was established for a reactor containing liquid organic peroxide of interest. From experimental results, liquid organic peroxides’ optimal conditions for avoiding a violent runaway reaction of storage and transportation were created.
Abstract
This study investigated the role played by green thermal analysis technology in promoting the use of resources, preventing pollution, reducing energy consumption and protecting the environment. The chemical tert-butyl peroxybenzoate (TBPB) has been widely employed in the petrifaction industries as an initiator of polymerization formation agent. This study established the thermokinetic parameters and thermal explosion hazard for a reactor containing TBPB via differential scanning calorimetry (DSC). To simulate thermokinetic parameters, a 5-ton barrel reactor of liquid thermal explosion model was created in this study. The approach was to develop a precise and effective procedure on thermal decomposition, runaway, and thermal hazard properties, such as activation energy (E a), control temperature (CT), critical temperature (TCR), emergency temperature (ET), heat of decomposition (∆H d), self-accelerating decomposition temperature (SADT), time to conversion limit (TCL), total energy release (TER), time to maximum rate under isothermal condition (TMR iso), etc. for a reactor containing TBPB. Experimental results established the features of thermal decomposition and huge size explosion hazard of TBPB that could be executed as a reduction of energy potential and storage conditions in view of loss prevention.
