Alkylaromatics in Detergents Manufacture: Modeling and Optimizing Linear Alkylbenzene Sulfonation

摘要

Linear alkylbenzene sulfonic acid (ASA) is the main ingredient of many commercial formulations for industrial and domestic synthetic detergents. The current industrial ASA production method includes sulfonation of linear alkylbenzene (LAB) with sulfur trioxide in tubular falling-film reactors. The present study investigates the influence of light alkylaromatics on the efficiency of ASA production. After dealkylation and polymerization, these aromatic compounds form viscous components in the sulfonation reactor. This increases the organic liquid viscosity and disrupts the uniformity of sulfonation. We present the results of IR analysis of the LAB and ASA samples, which indicate that the viscous components are sulfones that are part of the unsulfonated matter. With due consideration of the sulfonation process reaction network, we developed a mathematical model for a sulfonation reactor considering the alkylaromatics content in the feed flow and its effect on the reaction rates. The results allowed the improvement of sulfonation process in terms of increasing the number of days between the reactor washings. The sulfur flow rate increased from 371.7 to 380.9 kg h(-1) at the end of this period for the aromatics content in LAB of 4 wt.% and from 372.1 to 380.1 kg h(-1) for aromatics content in LAB of 6 wt.%. The proposed modifications of the process modes can increase the SO3 conversion up to 98%.