Kinetics and Hazards of 4-Vinylbenzyl Chloride Storage and Thermal Decomposition of Di-4-methylbenzoyl Peroxide by DSC and TAM

Abstract

Thermal hazard assessments in process industries often require calorimetry and kinetic modeling. These techniques are illustrated using examples of inhibited 4-vinylbenzyl chloride (VBC) self-polymerization and di-4-methylbenzoyl peroxide (MeBPO) thermal stability. The polymerization kinetics of inhibited VBC were studied using isothermal and non-isothermal calorimetry. A thermokinetic model was developed using calorimetry data and this model was coupled with a heat balance to predict the consequence of a commonly encountered plant scenario, loss of active cooling to a storage tank. Isothermal differential scanning calorimetry (DSC) and microcalorimetry (using a TAM IV microcalorimeter) were also applied to analyze the thermal decomposition of MeBPO desensitized with silicone oil (50% w/w). The thermokinetic parameters and thermal stability were evaluated. MeBPO decomposes in two exothermic reactions, and the total heat of decomposition was determined to be 658.8 J/g of sample. The thermal decomposition of MeBPO was described by a model of two parallel reactions, the first leading to 4,4′dimethylbiphenyl and the second to p-methylbenzyl p-toluate. The results can be applied for emergency relief system design and for emergency rescue strategies during an upset or accident.

Process Safety in the Pharmaceutical Industry─Part II: Process Safety Labs and Instruments Used in Process Safety Labs for Thermal Hazards

“…This includes starting materials, intermediates, reactants, catalysts, and wastes; (b) the reaction at the desired process temperature; and (c) materials and reaction mixtures under the worst-case scenarios (e.g., undesired decomposition if the temperature control of an equipment malfunctions). There are several illustrations available in the literature where calorimetries helped PSLs in the chemical and pharmaceutical industries to successfully identify potential hazards and subsequently develop strategies to mitigate those risks. − For example, potential process safety hazards of 45 common peptide coupling reagents were studied using DSC (differential scanning calorimetry) and ARC (accelerating rate calorimetry), where these instruments helped scientists identify thermally unstable coupling reagents …”