The Synthesis And Inhibition Property Evaluation Of Efficient Corrosion Inhibitor For The Overhead Circulating Reflux System Of Fractionation Tower

Imidazoline has been one of the most research prospects because it has advantages of good thermal stability,outstanding performance for corrosion inhibition and low toxicity.The study of imidazoline inhibitor for the corrosion of the overhead circulating reflux system of fractionation tower has not been covered so far at home and abroad.In this paper,different imidazoline amides were synthesized by different acids,amines and acetic anhydride according the principle of“Structure determines function”.Then the corrosion inhibitions of them were studied to select the preferable one for the corrosion of the overhead circulating reflux system of fractionation tower.Different imidazoline amides were synthesized by different acids,amines and acetic anhydride.The inhibition properties of them were inspected in the corrosion system of HCl/Cl^--phOH-H₂O and simulative oil.The results show that the inhibition efficiencies of imidazoline intermediates and amides increase as the acid side chain increases and the number of double bond in the range of C₁₂^C₁₈8 and that the inhibition efficiencies of the products decrease whose acid side chain contains benzene ring.The inhibition efficiency of OXA is higher than the OXM in the simulative oil corrosion system and the sequence of inhibition efficiencies is OXA>OYA>OZA in the corrosion system of HCl/Cl^--phOH-H₂O.The factors affecting the synthesis of the OXA were further inspected and the optimal synthesis conditions were getted.The validity of the structure of OXA was verified by IR,UV-vis,H¹-NMR,MS after separation and the thermal stability was proved by thermogravimetry.The affecting factors on inhibition propertry of OXA were studied in the corrosion system of HCl/Cl^--phOH-H₂O,such as the concentration of OXA,the concentration of ph OH,the concentration of HCl/Cl^-,the temperature of corrosion system and corrosion time.At the same time,the inhibition efficiencies of OXA in the corrosion system of HCl-phOH-H₂O,HCl-phOH-H₂S-H₂O,and HCl-phOH-（NH₄）₂S-simulative oil were inspected and the results showed that it is better than the inhibitors on sale.SGZ was selected as the mixture of OXA according the principle of synergistic effect.The inhibition efficiency of the mixture could reach 91.78%when the ratio of mass is 6:4.The storage period has no affection on the inhibition efficiency indicating that this inhibitor has preferable storage stability.The results of electrochemical measurements indicate that OXA is a mixed-type inhibitor and that the inhibition mechanism is“geometric blocking effect”.The adsorption of OXA on A3 mild steel includes chemisorption and slows down the rate of dissolve of A3 mild steel concluded from calculated values of kinetic parameters.OXA has a good performance on inhibiting A3 mild steel corrosion according to the SEM images and XRD results.