Study On The Adsorption Behavior Of Mannich Corrosion Inhibitors At High Temperature

In this paper,based on the investigation of domestic and foreign literatures,the Mannich base inhibitors were selected by molecular dynamics principle,and the theoretical selected inhibitors were synthesized and characterized in laboratory.The inhibition performance of two Mannich base inhibitors was analyzed by weight loss method,while the inhibition mechanism was studied by polarization curve and AC impedance test.Based on the density functional theory?DFT?,the molecular frontier orbitals and reactivity were calculated and analyzed,and the adsorption mechanism between the Mannich base inhibitor and the iron surface was studied on the atomic scale.The results show that:In the equilibrium configuration of molecular dynamics simulation,ZJ-1 and ZJ-2inhibitor molecules have more negative adsorption energy,higher molecular reaction activity,more stable adsorption with Fe surface,and tend to selfassemble into film on Fe?001?crystal surface.The bond length of Fe-O and Fe-N formed by the two molecules on the surface of Fe is smaller,the bond with the metal surface is closer,and the adsorption performance is better.Therefore,ZJ-1 and ZJ-2 have good corrosion inhibition on Fe?001?surface.ZJ-1 and ZJ-2 Mannich base corrosion inhibitors synthesized in the laboratory have good corrosion inhibition effect on P110 steel by CO₂,and the best concentration is 100 mg/L and150 mg/L respectively.The inhibition performance of ZJ-1 is better.At lower temperature,the inhibition efficiency is as high as 90.94%;at higher temperature,the molecular adsorption of inhibitor is reduces,as well as the reduced inhibition efficiency.But the inhibition efficiency of ZJ-1 remains at 72.59%when the temperature reaches to 120?,which still has higher adsorption and inhibition performance.Both ZJ-1 and ZJ-2 are mixed corrosion inhibitors which mainly inhibit anode reaction,and the mechanism of action is geometric covering effect.The frontier orbitals of ZJ-1 and ZJ-2 inhibitors are distributed on the aromatic ring and active atom.The O17 and N7 atoms in the molecule are both electrophilic and nucleophilic active centers.Quantum chemical calculations show that the two inhibitors have two nucleophilic sites,three electrophilic sites and one electrophilic site.