Determination of kinetic parameters of dehydrochlorination of dichloropropanol in a microreactor

The reaction kinetics of dehydrochlorination of dichloropropanol (including 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol) is investigated with a microchemical system, which is constructed with a micromixer, a micro-tube and a microneutralizer. The reaction starts up by mixing dichloropropanol solution and sodium hydroxide solution in the micromixer, proceeds in the following micro-tube for a residence time strictly controlled to several seconds, and quenches in the microneutralizer. The results show that 2,3-dichloro-1-propanol is much less reactive than 1,3-dichloro-2-propanol. Rate constants of the dehydrochlorination reaction (2,3-dichloro-1-propanol) are determined in the temperature range of 50-80 degrees C. The reaction kinetics is found to be first order with respect to hydroxyl ion concentration and second order to dichloropropanol concentration. The activation energy is 150 (+/- 10) kJ mol(-1) and the pre-exponential factor is 1.61 x 10(25). Compared with earlier reports on the kinetics of this reaction, this microchemical system provides information much closer to what the intrinsic kinetics determines, showing distinct values for reaction mechanism understanding and process intensification in further work. (C) 2012 Elsevier B.V. All rights reserved.