Kinetics of γ-alumina chlorination by phosgene

The kinetics of the reaction between γ-Al₂O₃ and COCl₂ have been studied by isothermal TG measurements in the temperature range 585–1085 K. The influence of the partial pressure of COCl₂ on the reaction rate was investigated at 648, 673 and 698 K in the 10⁴–10⁵ Pa range, using N₂ as a diluting gas. The reaction seems to proceed in the chemical control region below 675 K. Above this temperature, however, diffusional processes and decomposition of COCl₂ are considered to affect the reaction rate. In the chemical control region an apparent order of reaction of 0.75 in respect of COCl₂ and an apparent activation energy of 128–135 kJ mole^?1 were found for the chlorination process.