Synthesis And Performance Study Of Carboxylic Imidazoline Corrosion Inhibitor

At present,secondary and tertiary oil recovery are used more popular in oil production,which resulting in a lot of oilfield sewage.In order to save costs and reduce the waste of water resources,rejection water is used many times for oil production.The composition of oilfield sewage is complex and high salinity,dissolved oxygen and acid gases such as H₂S,CO₂,will cause serious corrosion for oil production equipment and pipeline and exacerbate economic losses of oilfield exploitation.The way of adding drugs is adopted to solve the corrosion problem of oilfield sewage.As one of the most widely used green corrosion inhibitors,most of imidazoline are poor solubillity in water.Therefore,we synthesized water-soluble and green environmental imidazoline containing carboxyl omoiety which is on the basis of alkyl imidazoline,Firstly,take different carbon atoms for fatty acids?oleic acid,palmitic acid,dodelic acid,decoic acidoctylic acid and pentanoic acid?react with diethylenetriamine to synthesize imidazoline derivatives which were reacted with acrylic acid to obtain inhibitors which can dissolve in the water.The separation and purification of carboxylic Imidazoline by the way of column chromatography with the eluent?n-butyl alcohol:glacial acetic acid:water?,The structure of purified WMB3,XMB4,GMB2,YuMB4,ZMB4 and YoMB3 wered etermined by FT-IR,¹H-NMR and elemental analyzer.The corrosion inhibitive performance of the pure carboxylic imidazolines for A3 were evaluated by static weight loss measurement in the simulate oilfield sewage?50??;The control variable method was adopted to explore the corrosion performance of oleic imidazoline under the circumstance of the the molar ratio of acrylic acid and alkyl imidazoline,the number of carbon atoms in alkyl chain,evaluate time.The results showed that the molar ratio of acrylic and acid alkyl imidazoline was 1:6,the solubility and corrosion inhibition efficiency of products was best;the length of alkyl chain was from 9 to 11,the corrosion performance of carboxylic imidazoline was best;When the dosage of corrosion inhibition was 10 mg·L^-1,the results indicated that the corrosion rate and inhibitive efficiency of carboxylic imidazoline reached 99.30%and 0.0015 mm·a^-1respectively.In a neutral medium,the corrosion perfoumance of carboxylic imidazoline was better than in acidic and alkaline conditions;When evaluatied time was 7 days,the corrosion effect carboxylic imidazoline was slow released to get best;Under the condition of dissolved oxygen,corrosion inhibition efficiency of carboxylic imidazoline was lower than anaerobic condition.The inhibition mechanisms of the carboxylic imidazoline were studied by EIS,polarization curve,electron microscope scanning and EDAX energy spectrum analysis.The results indicated that the carboxylic imidazoline was a mixed type inhibitor,which could effectively inhibit the corrosion in simulated oilfield sewage by forming protective layer on the surface of A3 steel;Adsorption of carboxylic imidazoline on the steel surface obeyed Langmuir adsorption isotherm model and the type of adsorption was physical and chemical adsorption.