A new zwitterionic surfactant with high interfacial activity and high salt tolerance derived from methyl oleate through an eco‐friendly aryl‐introducing method

Abstract

AbstractSurfactants, that can reduce the interfacial tension between crude oil and formation water to ultra‐low, are needed in tertiary oil recovery. A bio‐based zwitterionic surfactant, N‐phenylpropanaldehyde epoxy acetal octadecanoicamido propyl‐N, N‐dimethyl hydroxy sulfonate (PADS), was derived from methyl oleate. In the process of synthesizing PADS, a new reactive site was introduced by epoxidizing methyl oleate and then the benzene ring was introduced by acetalization, which was a greener new method of introducing benzene ring into hydrophobic chains of surfactants. PADS was identified by ESI‐MS and NMR, and its interfacial activity was measured by interfacial tensiometer. The results showed that PADS possessed excellent interfacial activity and potential for low‐dose application. Under alkali‐free conditions, it could reduce the interfacial tension between crude oil and simulated formation water to ultra‐low in a wide concentration range (0.005–3 g/L). In addition, although the NaCl concentration was 230 g/L in the system, PADS still had good interfacial activity and could maintain ultra‐low oil–water interfacial tension. The protocol of epoxidation and acetalization provides a new feasible path to preparing bio‐based surfactants with high interfacial activity.