2.3 Olefin sulfonate
Sodium olefin sulfonate is a type of sulfonate surfactant prepared by sulfonating olefins as raw materials with sulfur trioxide. According to the position of the double bond, it can be divided into a-alkenyl sulfonate (AOS) and Sodium internal olefin sulfonate (IOS).
2.3.1 a-alkenyl sulfonate （AOS）
AOS is a class of sulfonate surfactants obtained from a-olefins (commonly used C14~C18 olefins) through sulfonation, neutralization and hydrolysis. AOS is another type of large-scale surfactant produced after LAS and AES. AOS is actually a mixture of sodium alkenyl sulfonate (60%~70%), sodium hydroxyalkyl sulfonate (30%) and sodium disulfonate (0~10%). The product usually comes in two forms: 35 % Of liquid and 92% of powder.
High carbon chain AOS(C2024AOS) has good plugging ability in high temperature foam flooding, which makes it have good application prospects.
2.3.2 Sodium internal olefin sulfonate (IOS)
Internal olefin sulfonate (referred to as IOS) is a type of sulfonate surfactant obtained from internal olefin through sulfonation, neutralization and hydrolysis. The ratio of sodium hydroxy sulfonate to sodium alkenyl sulfonate in IOS products depends on whether or not aging occurs after sulfonation: if the internal olefin is directly neutralized after sulfonation without aging, the product contains about 90% hydroxy sulfonic acid Sodium and 10% sodium alkenyl sulfonate; if the internal olefin is neutralized after sulfonation and aging, the content of sodium hydroxysulfonate in the product will decrease, the content of sodium alkenyl sulfonate will increase, and free oil and inorganic salts The content also rises. In addition, the sulfonic acid group of IOS is located in the middle of the carbon chain, forming an internal olefin sulfonate with a “double hydrophobic tail chain” structure. IOS products are darker in color than AOS and are mainly used in some industrial fields.
2.4 Sodium fatty acid methyl ester sulfonate
Sodium fatty acid methyl sulfonate (MES) is usually a type of surfactant obtained from C16~18 fatty acid methyl ester through SO3 sulfonation, aging, re-esterification bleaching, and neutralization. The difference in production technology is mainly in bleaching and esterification. The sequence of chemical process can be attributed to acid bleaching, neutral bleaching and secondary bleaching technology. MES has good decontamination ability, calcium soap dispersing power is strong, and it is easy to biodegrade.