OPTIMAL DEGREE OF BACKMIXING IN AUTOCATALYTIC REACTIONS - A CASE-STUDY - CHLORINATION OF DODECANOIC ACID

The kinetic parameters of the autocatalytic chlorination of dodecanoic acid to monochlorododecanoic acid were determined from experimental d ata obtained in a laboratory scale semibatch reactor operating at 130- degrees-C. The kinetic model was based on a reaction mechanism involvi ng the acid catalyzed enolization of the reaction intermediate and chl orination of the enolic intermediate as rate controlling steps. The ef fect of the degree of backmixing on the reactor performance was studie d using the complete backmixing, plug flow, recycled plug flow and axi al dispersion models. The model equations were presented and solved an alytically (the plug flow, recycling and backmixing models) and numeri cally (the axial dispersion model) at different operating conditions. It was shown that at high conversions of dodecanoic acid there exists an optimal degree of backmixing-an optimal recycle ratio and an optima l Peclet number-giving the lowest reactor space time. The optimal degr ee of backmixing was shown to be close to the conditions of complete b ackmixing. In carrying out the chlorination reaction continuously the backmixing conditions are preferred to the plug flow conditions.