Kinetics for the sulfuric acid-catalyzed reactions of ethylene oxide with water and ethylene glycols

Abstract

Adiabatic calorimeter experiments have quantified the sulfuric acid-catalyzed reaction of ethylene oxide (EO) with water to form ethylene glycol (EG) and higher glycols. Conditions were selected relevant to industrial safety, such as a scenario of reverse flow of acid from a scrubber to an EO tank. Concentrations of 25–95 wt% EO with acidified water of pH 3.0 down to pH –0.7 were examined. In some experiments, EG was also added to the mix. The best fit apparent reaction rate expression exhibits a 1.5 order in EO concentration, third order in water concentration, nearly first order in acid concentration, and an activation energy of 76,500 kJ/kmol. The reaction model provides an adequate fit of adiabatic self-heat rate versus temperature, pressure rate versus temperature, pressure versus time, and temperature versus time data for a large number of APTAC (Automatic Pressure Tracking Adiabatic Calorimeter) experiments. The model builds on one previously developed for the neutral reactions of EO with water and EGs. A case study involving a sulfuric acid-contaminated EO railcar is presented. The reaction model can help quantify the behavior of EO contaminated with sulfuric acid solution below about 120°C. Above this temperature, other reaction pathways not characterized in this study become more prominent.