Efficient continuous synthesis of long-chain alkylbenzenes catalyzed by ionic liquids in microreaction systems

Abstract

Alkylbenzene (LAB) is an important benzene derivative that can be used as a raw material for high-performance anionic surfactants such as alkylbenzene sulfonates (LAS) to meet the new requirements for surfactants in many fields. LAB can be synthesized through Friedel-Crafts reaction in the presence of acidic catalysts as alkylating agents, which is commonly used in the production of fine chemicals. In this work, a novel and efficient continuous flow micro reaction system was introduced to enhance the production of long-chain alkylbenzene catalyzed by [(CH3)3NH][Al2Cl7] ionic liquid. The optimal conditions were investigated for the synthesis of long-chain alkylbenzenes with the 1-tetradecene and mixing α-alkenes of C14-C16 from Fischer-Tropsch process. The results showed that the yield of benzene alkylation can achieve 99 % under the optimal process conditions which the reaction tube length was 2000 mm, the reaction temperature was 30 ℃, the catalyst dosage was 0.30 mL/min and the molar ratio of aluminum chloride to trimethylamine hydrochloride was 2:1. In addition, α-alkenes with C14-C16 lead to deactivation of the ionic liquids catalyst easier because of transfer of AlCl3 from the ionic liquid to the organic phase compared to the pure 1-tetradecene as an alkylating agent. Continuous synthesis of the long-chain alkylbenzenes catalyzed by ionic liquids can achieve in the microchannel reaction system by controlling the flow patterns.