Synthesis And Performance Study Of Imidazoline Corrosion Inhibitor Used In Oilfield Sewage

With the exploitation of oil,the amount of oil wastewater emissions is more and more.The composition of oilfield sewage is complex and high salinity.They will cause serious corrosion for pipeline and equipment and even affect the normal production of oil field.So the oilfield sewage resulting in corrosion is not to be taken lightly.As one of the most widely used inhibitor,most of imidazoline are poor solubility in water and not easy to apply in oilfield sewage system.Therefore,we synthesized good water-soluble imidazoline containing carboxyl moiety.The imidazoline derivatives containing carboxyl moiety was prepared through condensation reaction using oleic acid?diethylenetriamine and acrylic acid as materials.Withing temperature is 50?,corrosive medium is simulate wastewater,pH is 7.0,anaerobic and evaluation time is 5 days,the corrosion inhibitive performances of different structure of imidazoline containing carboxyl moiety were investigated by static weight loss measurement.When the dosage of corrosion inhibition was 20 mg·L^-1,the results indicated that the corrosion rate and inhibitive efficiency of YM4313 reached 0.0109 mm·a^-1 and87.06%respectively;The corrosion rate and inhibitive efficiency of YM5413 reached0.0101 mm·a^-1 and 87.93%respectively;YM5422 and YM6522 have similar corrosion inhibition efficiency and the corrosion rate are more than 89%.The above corrosion inhibition are up to the standard of oilfield(less than 0.076 mm·a^-1).In order to further study the corrosion mechanism of imidazoline containing carboxyl moiety,the molecular formula of YM4313 was determined as C₃₁H₅₅N₃O₆ by High Performance Liquid Chromatography-High Resolution Mass Spectromettry?HPLC-HRMS?.Using eluent?n-butyl alcohol:glacial acetic acid:water=6:1:1.5?,YM4313 was purified.The structure of purified YM4313 was determined by ¹H-NMR,elemental analyzer and FT-IR.Water-soluble performance and corrosion inhibitive performance of the pure YM4313 were evaluated by static weight loss measurement.The results indicated that the purified YM4313 water-soluble is good and the corrosion rate was 90.52%.The inhibition mechanisms of the purified YM4313 were studied by EIS,polarization curve,electron microscope scanning and EDAX energy spectrum analysis.The results indicated that the purified YM4313 was a mixed type inhibitor,which could effectively inhibit the corrosion in simulated wastewater by forming protective layer on the surface of A3 steel;Adsorption of purified YM4313 on the steel surface obeyed Langmuir adsorption isotherm model and the type of adsorption is physical and chemical adsorption.Finally,simulation data got from the calculation of dynamics simulation.The results indicated that adsorption energy of single molecule of YM4313 is 1134.90 kJ·mol^-1,more than water molecule is 24.42 kJ·mol^-1.Providing the basis of outstanding corrosion inhibition,single molecule of YM4313 adsorbed parallel in the surface of the steel.