Determination of the kinetic parameters of fast exothermal reactions using a novel microreactor-based calorimeter

Making chemical processes safe requires a thorough knowledge of the kinetic and thermal parameters of the chemical reactions involved. The aim of this work was to develop a calorimetric method particularly adapted to the study of fast exothermal reactions. The proposed system combines a microreactor with a commercially available microcalorimeter. The microreactor was inserted into the cavity of the commercial calorimeter and the thermal efficiency of the system was optimized. The flow in the reaction channel of the microreactor was found to be purely laminar and the mixing time corresponded to the time for radial diffusion. Due to the small size of the channels, the mixing time was found to be adequate and not limiting for the characterization of fast reactions. First, a model reaction was studied in order to validate the results obtained with the microsystem and to avoid the risk of systematic errors. In a second stage, a previously unknown fast exothermal reaction was characterized. The heat flows measured during the reaction reached 160 000 W kg(-1) but the conditions, however, remained completely isothermal. The global kinetics of this reaction as well as its activation energy were determined. (c) 2005 Elsevier B.V. All rights reserved.