Kinetic modelling and improvement of the ageing step of industrial alkylbenzene sulfonation process

Abstract

The article describes the developed concept of a new, improved method of carrying out the alkylbenzene sulfonic acid (LABSA) ageing process in an industrial scale plant. Experimental studies of the new method of ageing step, confirming our expectations in terms of its high effectiveness, were preceded by the development of a mathematical model of the process, the high adequacy of which was verified in industrial realities.The improvement of the subject ageing step consists in replacing the conventional continuous process with a semi-batch one, carried out in a system of two swinging stirred tank reactors. In each of the swinging reactors, the reaction is performed in two stages: in the first stage, during the filling of the reactor tank, which runs under the continuous, unsteady regime, and in the second stage, starting to run after completing filling the reactor, undergoing in the batch process regime. In order to ensure entire plant throughput continuity, the work of both swinging reactors is time phase-shifted.The proposed solution was implemented on an industrial scale, within a real, licensed 24 000 t p.a. LABSA plant, achieving a 25–30% increase in the LAB to LABSA conversion rate. Above 98% of LABSA content and less than 0.3% of unreacted LAB were obtained in the final product, while maintaining a low value of the Klett colour index, not exceeding 20 units.Apart from the series of standard product quality indicators, particular attention was paid to the concentration of sulfones in the final product, the value of which did not increase in relation to the conventional process.