Process safety evaluation of the synthesis of tert-butyl peracetate

Abstract

To explore the thermal hazard of tert-butyl peracetate (TBPA), various instruments were applied to investigate the synthesis and decomposition of TBPA. Reaction calorimeter (RC1e) was used to analyze the exothermic characteristics during synthesis of TBPA in acid and alkaline medium, respectively. The thermal parameters, such as adiabatic temperature rise (ΔTad,r) and maximum temperature of the synthesis reaction (MTSR), were calculated for assessing the thermal hazard of TBPA synthesis. Differential scanning calorimetry (DSC) and Phi-TEC II adiabatic calorimeter were used to understand thermal characteristics of TBPA decomposition. According to the exothermic curves from the interruption and rescanning experiments and isothermal experiments by DSC, TBPA decomposed following the nth-order law. Thermal parameters of TBPA decomposition at different heating rates were obtained from non-isothermal experiments and the corresponding apparent activation energy (Ea) was calculated by Kissinger method and Starink method. Phi-TEC II was, in turn, used to obtain the thermokinetic parameters of TBPA decomposition under adiabatic conditions. The thermokinetic parameters, such as Ea, the pre-exponential factor (A) and reaction order (n), were used to calculate the time to maximum rate under adiabatic conditions (TMRad) and TD24 (Temperature at which TMRad is 24.0 h). To further understand the decomposition process, thermal decomposition products were studied using gas chromatography/mass spectrometry (GC/MS). Then the reaction scheme of TBPA decomposition was proposed. The thermal hazard of TBPA synthesis was evaluated according to the risk matrix and the Stoessel criticality diagram. Results shows that compared to synthesis in acid medium, TBPA synthesis in alkaline medium was preferred. However, the operating conditions of synthesis also need to be redesigned to improve the process safety level. These studies were considered to have potential applications in inherently safer operating measures and safer storage and transportation.