Sulfonation of 1,4-diaminoanthraquinone leuco by chlorosulfonic acid: kinetics and process intensification

The work herein employed a rotating packed bed (RPB) to intensify the sulfonation process of 1,4-diaminoanthraquinone leuco (DL) in an attempt to improve the yield of the product 1,4-diaminoanthra quinone-2-sulfonic acid (DSA). First, the effects of operating conditions in a stirred tank reactor (STR), including stirring speed, chlorosulfonic acid/DL molar ratio (eta), solvent/DL mass ratio (zeta), reaction temperature and dropping speed of chlorosulfonic acid, on the yield of DSA were investigated. The yield of DSA can reach 87.34% under the optimal operating conditions: stirring speed of 500 r center dot min(-1), eta of 4.5, zeta of 7, reaction temperature of 150 degrees C, dropping speed of 0.61 ml center dot min(-1). In addition, the kinetics of the sulfonation process via the shrinking core model revealed that the reaction is controlled by diffusion via a product layer under the reaction temperature of 140 degrees C. Furthermore, the RPB was employed to intensify the mass transfer between liquid and solid phases during the sulfonation reaction process. The results showed that the DSA yield of 92.69% obtained by RPB was 5.35% higher than that by STR, indicating that RPB can significantly intensify the mass transfer in the liquid-solid phase sulfonation reaction process. (c) 2022 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.