Continuous sulfonation of hexadecylbenzene in a microreactor

Abstract

Heavy alkyl benzene sulfonates are inexpensive surfactants that are extensively used as oil-displacing agents during tertiary oil recovery. Among these, C16–18 heavy alkyl benzene sulfonates possess an excellent ability to reduce the oil-water interface tension. In this study, hexadecylbenzene sulfonic acid (HBSA) was synthesised in a continuous stirred-tank microreactor using a continuous method with 1,2-dichloroethane (EDC) dilution. Post-sulfonation liquid SO3 solution was used as a sulfonating agent for hexadecylbenzene (HDB). The effects of reaction conditions, such as the SO3:HDB molar ratio, sulfonation temperature and sulfonation agent concentration, on the yield and purity of the product were investigated. Optimisation of the reaction process yielded high-quality HBSA samples with a purity exceeding 99 wt%. The continuous sulfonation process significantly enhanced the production and efficiency in the case of a considerably short residence time (10 s) in the reactor, without the need for aging. The results of this study demonstrate significant potential for application in industrial production.

Keywords

• microreactor
• sulfonation
• hexadecylbenzene sulfonic acid
• liquid sulfur trioxide
• surfactants