Performance Evaluation And Theoretical Research Of Pyrothiazole Corrosion Inhibitors

Corrosion inhibitors are widely used in various industries of social production,especially in oil exploration,production and well acidizing.Among them,organic corrosion inhibitor has become the most commonly used corrosion inhibitor because of its good corrosion performance and high economic benefits.The molecular structure of organic heterocyclic compounds contains heteroatoms with high electronegativity,such as N、O、S、P,which can provide lone pair electrons and form coordination bonds on the metal surface,so that the compound molecules can be well adsorbed on the metal surface and achieve good corrosion inhibition effect.N 、 S atoms are kinds of heteroatom commonly used in organic heterocyclic corrosion inhibitors.Because of its low toxicity,good adsorption effect,film-forming property and large coverage area,these heterocyclic compounds are widely used in metal corrosion protection.The main work of this paper includes the following two aspects:1.Synthesis,corrosion inhibition and theoretical study of pyridyldithiazoles.In this paper,three kinds of pyridyldithiazoles were synthesized by the reaction of three kinds of pyridyldehyde and dithiocarbamide in N、N-dimethylformamide at 150 ℃,and their molecular structures were determined by NMR and IR.Then the weight-loss experiments and electrochemical tests were carried out on three kinds of inhibitors.The results showed that pyridinedithiazole compounds were good mixed inhibitors,and the inhibition efficiency increased with the increase of inhibitor concentration.Among them,2-Py TT has the best inhibition effect,and the highest inhibition efficiency can reach97.96%;The adsorption isotherm model shows that the adsorption process of inhibitor molecules on carbon steel surface is spontaneous,including chemical and physical adsorption;The results of quantum chemical calculation shows that there are many active adsorption sites on the metal surface of carbon steel,which are distributed in pyridine ring and thiazole ring;It is also shown that the inhibitor molecules have higher adsorption strength and better adsorption stability on the surface of carbon steel.2.Synthesis,corrosion inhibition and theoretical study of imidazoledithiazoles.In this paper,two imidazoledithiazoles were synthesized by the reaction of two imidazole formaldehyde and dithiocarbamide in N、N-dimethylformamide at 150 ℃,and their molecular structures were determined by a series of spectral tests.The weight-loss and electrochemical tests of the two inhibitors showed that imidazoledithiazole compounds were good mixed inhibitors,and the inhibition efficiency increased with the increase of inhibitor concentration.The performance of 2-Im TT and 4-Im TT are similar,and the inhibition efficiency of both of them is over 96.00%.The results of thermodynamics show that the adsorption law of imidazoledithiazole inhibitors on the surface of carbon steel follows the Langmuir adsorption isotherm,and the adsorption process is spontaneous,mainly physical adsorption.The results of quantum chemical calculation show that there are many active adsorption sites on the metal surface of carbon steel,which are all over imidazole ring and thiazole ring;At the same time,it shows that the inhibitor molecules have good adsorption strength and stability on the surface of carbon steel.In this paper,five kinds of dithiazole compounds were studied in electrochemistry,thermodynamics,quantum chemistry and so on.The results show that the heterocyclic compounds can be used as corrosion inhibitors of carbon steel in hydrochloric acid solution.It can be used for acidizing and other operations in practical application and has good corrosion inhibition effect.