Synthesis Of Bis-imidazoline Inhibitors For Anti-corrosion In CO2 And Study On Inhibitory Performance

The steel corrosion of carbon dioxide has caused huge loss in petroleum and natural gas industry world widely. The first-line task in the pipeline is to solve the problem of metal corrosion in carbon dioxide condition. The use of corrosion inhibitor is an effective way.Based on the characteristic of corrosion in carbon dioxide, in this article a kind of quaternary ammonium bis-imidazoline was synthesized with diamine, adiponitrile and benzyl chlorine. Through change the condition, found out the best one. Its structures were characterized by IR spectrum.Studied the inhibitory performance in simulating corrosion medium of oil and gas field by dynamic weight-loss experiment in 6Mpa with L80 and NT-80SS, change the inhibitor's concentration and the temperature. The result proved that quaternary ammonium bis-imidazoline put up a better inhibitory performance after 96h in experimentation condition. In 6Mpa, 50℃, after 96h with the concentration of 0.5%, the efficiency reached 60%. The more the inhibitor's concentration, the more the inhibitory performance. In 6Mpa, after 96h with the concentration of 0.5%, the efficiency minished with the temperature's augmentation. In 6Mpa, 50℃ with the concentration of 1.0%, at first the efficiency declined with the time increase, after a long corrosion time, the efficiency kept in a certain area.Studied the intramolecular synergistic inhibitive effect by dynamic weight-loss experiment between quaternary ammonium bis-imidazoline and thiourea. In 6Mpa,50 ℃, after 96h, when each of the concentration was 0.05%, the efficiency reached 90% for two materials. After the concentration was added, the efficiency has not marked increase.The dynamic weight-loss experiment and the SEM's observe proved that L80 had better anti-corrosion performance than NT-80SS. Through EDS and XRD, it proved that the corrosion product film is FeCO₃.Reviewed the effect of CO₂ corrosion when H₂S existed. The result proved that with H₂S and CO₂ coexistence the corrosion speed was much lower than only in CO₂ condition for L80 in 1.5Mpa, 90℃, after 96h.