Preparation of Methyl Ester Sulfonates Based on Sulfonation in a Falling Film Microreactor from Hydrogenated Palm Oil Methyl Esters with Gaseous SO3

Abstract

Fatty acid methyl ester sulfonate (MES) is an environmentally friendly anionic surfactant. It contains RCH(CO2Me)SO3Na (α-MES) as the active component and RCH(CO2Na)SO3Na (the disodium salt) whose content must be lower than 5%. In this paper, MES was prepared first in a falling film microreactor (FFMR) by sulfonation of hydrogenated palm oil methyl ester (ME) with SO3 diluted with N2, followed by aging in a tubular reactor and subsequent bleaching and neutralization with NaOH. The influences of the ME flow rate, the channel size, the N2 flow rate, the SO3-to-ME molar ratio, and the sulfonation temperature in the sulfonation step, as well as the influences of the SO3-to-ME molar ratio, the aging residence time, and the aging temperature in the aging step, were all examined. The results indicated that the ME flow rate had no evident influence on the ME conversion and the α-MES concentration both without overflow and with overflow. In the sulfonation step, the disodium salt (disalt) concentration increased w...