Thermal decomposition on Aceox® BTBPC mixed with hydrochloric acid

Abstract

1,1-Bis(tert-butylperoxy)cyclohexane (BTBPC) has two active O-O peroxide groups and is usually used as an initiator in a chemical process. However, it also easily accelerates decomposition in the presence of certain catalysts. This paper discusses the runaway reactions of BTBPC alone or mixed with various concentrations of hydrochloric acid (HCl, 1.0, 2.0, 4.0, and 8.0 N). Essential thermokinetic parameters, including apparent exothermic onset temperature (T o ), peak temperature (T p ), apparent activation energy (E a ), heat of decomposition (DH d ), and rate constant (k), were evaluated by differential scanning calorimetry under the heating rates of 1.0, 2.0, 4.0, and 8.0°C min -1 . A kinetics-based curve fitting method was employed to appraise the possible kinetic models and their thermokinetic parameters at 4.0°C min -1 heating rate. All the BTBPC HCl mixtures have two exothermic peaks, but BTBPC alone and BTBPC mixed with 1.0 N HCl have just only one. 4.0 N HCl mixture has two endothermic peaks. T o of the first peak in 8.0 N HCl mixtures is shifted to lower temperatures, 46.1°C. The model of BTBPC is a single-stage reaction; however, BTBPC mixed with 1.0 or 2.0 N HCl is a two-stage decomposition reaction. Moreover, 4.0 or 8.0 N HCl mixture is three-and five-stage decomposition reaction, respectively. As more concentrated HCl is being mixed, kinetic models become more complex.Keywords 1,1-Bis(tert-butylperoxy)cyclohexane (BTBPC) Á Curve fitting method Á DSC Á Hydrochloric acid (HCl) Á Kinetic models List of symbols 2E a Apparent activation energy of reaction (kJ mol -1 ) DH max Maximum heat release (kJ kg -1 min -1 , or W g -1 ) DH d Heat of decomposition (kJ kg -1 ) DH p Heat release of peak (kJ kg -1 ) DH t Total heat release (kJ kg -1 ) kReaction rate constant (s -1 ) k o Pre-exponential factor in the Arrhenius equationMass of reactant (g) N Normality of hydrochloric acid (HCl) (eq mol -1 ) nOrder of reaction (dimensionless) n i Reaction order of ith stage (dimensionless) R Ideal gas constant (8.314 J mol -1 K -1 ) rReaction rate (g s -1 ) r rctn Reaction rate for the reactant in each stage of reaction (g s -1 )