烷醇酰胺磷酸酯表面活性剂的缓蚀性能

以十四酸、十六酸和硬脂酸为原料与二乙醇胺反应合成了脂肪酸烷醇酰胺,经磷酸化反应及醇胺中和反应后制备了3种脂肪酸烷醇酰胺磷酸酯盐表面活性剂。测试了产物的组成及表面活性,电化学法和失重法考察了产物在矿化水中的防腐性能并与其他缓蚀剂进行了对比。结果表明,脂肪酸碳数为C14、C16、C18的磷酸酯盐(C14N、C16N和C18N)的临界胶团浓度(cmc)分别为50～30mg/L,对应于cmc的表面张力(γcmc)分别为27.31,24.57和27.65mN/m;电化学法和失重法均表明随着脂肪酸碳数的增加,缓蚀性能先增加后降低。C16N具有较好的缓蚀性能,C14N次之,C18N最差。在模拟盐水中加入100mg/L的产物C16N时,极化缓蚀率可以达到71.7%,50℃、4d时失重法平均腐蚀速率为0.0716mm/a,满足油田注入水腐蚀速率要求。从分子结构讨论了产物缓蚀机理。

PERFORMANCE STUDY OF A SERIES OF FATTY ACID DIETHANOLAMINE PHOSPHATE AS CORROSION INHIBITORS

A series of anionic surfactants with different carbon number of fatty acid diethanolamide phosphate were prepared from fatty acids(myristic acid,hexadecanoic acid and stearic acid),diethanolamine,phosphorous pentoxide and diethanolamine through acylating,phosphating and neutralizing reactions.Their surface activity was determined with different concentrations of products,and their inhibition efficiency against corrosion of carbon steel A3 in synthetic brine were investigated by weight loss measurement and polarization curves method.The experimental results showed that cmc of myristic acid diethanolamide phosphate(C14N),hexadecanoic acid diethanolamide phosphate(C16N) and stearic acid diethanolamide phosphate(C18N) are 50,50 and 30 mg/L,respectively,and their γcmcs were between 25-29 mN/m.The results showed that C16N had a great corrosion inhibition,with the inhibition efficiency by polarization curve being 71.7% at the amount of 100 mg/L,and the corrosion rate by static weight loss being 0.071 6 mm/a at 50 ℃ within 4 d with the simulated water,which meets the requirement of for the injection water in oilfield.The corrosion inhibition mechanism was discussed based on the molecular structure.