Effect of Structural Changes on Corrosion Inhibition Behavior of Synthesized N2O4 Imine Compounds for Steel Pipelines in Oil and Gas Wells

The inhibition properties of synthesized imine compounds N,Nʹ-bis(2,4-dihydroxyhydroxybenzaldehyde)-1,3-Propandiimine, N, N′-bis(2,4-dihydroxypropiophenone)-2,2-dimethylpropandiimine, N,Nʹ-bis(2,4-dihydroxyacetophenone)-1,3-Propandiimine has been investigated for API-5L-X65 steel corrosion in hydrochloric acid by scanning electron microscopy, potentiodynamic polarization and impedance spectroscopy. Aqueous hydrochloric acid was applied to simulate the oil and gas well acidizing fluid. Potentiodynamic polarization studies indicated that compounds retard both the anodic and cathodic reactions through adsorption and blocking the active corrosion sites. The inhibition efficiency increased with inhibitor concentration. Electrochemical impedance spectroscopy data were studied by equivalent circuit and showed that with increasing inhibitor concentration, the resistance of charge transfer enhanced and the capacitance of double layer reduced. The measured data proposed that the inhibition efficacy was increased for inhibitor in the absence of alkyl addition. The geometrical steric hindrance offered by the alkyl groups in the imine compounds plays an important role in its corrosion inhibition properties. Scanning electron microscopy was used to study the steel surface with and without inhibitors.