Study On Synthesis And Corrosion Inhibition Performance Of Sulfur And Nitrogen Heterocyclic Compounds

The sulfur compounds in oil products have strong metal corrosion,which not only reduces the quality of the oil,but also affects the performance of the oil.The active sulfur in the oil can erode the copper parts of the engine or the copper wire in the transformer,which brings many safety problems to the production and life.The corrosion inhibitor has the advantages of high efficiency,economy,environmental protection,simple operation,is widely used in metal protection.This paper focuses on the corrosion inhibition performance of several sulfur and nitrogen heterocyclic compounds on copper in oil under the action of elemental sulfur.1.The corrosion inhibition performance of 5-Mercapto-1-methyltetrazole and 1-[2-(Dimethylamino)ethyl]-1H-tetrazole-5-thiol for the copper was studied with the corrosion test,gravimetric method,electrochemical measurements and surface analysis experimental method and theoretical calculation method.The results showed that the addition of corrosion inhibitors can effectively inhibit the corrosion of copper and reduce the corrosion current density of the copper electrode,increase the reaction resistance of the electrode surface.The order of the corrosion inhibition efficiency was MTZ>MMT.The theoretical calculations show that the active site of MMT molecules located in the five membered ring of S and N atoms;but the MTZ molecules located in the branches of S and N atoms,and molecular dynamics simulations finally in a parallel way adsorption on Cu(111).2.The inhibitive performance for copper of 5-ethvlthio-1H-tetrazole,5-benzyl-1H-tetrazole and 5-phenyl-1H-tetrazole was evaluated by gravimetric method,electrochemical measurements and surface analysis experimental method and theoretical calculation method.The electrochemical measurements showed that the addition of three inhibitors can reduce the corrosion current density of the copper electrode and increase capacitance arc radius.According to the thermodynamic analysis,the adsorption behavior of the EHT,BHT and PHT on the copper surface was in line with the Langmuir adsorption model.The active sites located in the ring and the functional group attached the ring.The dynamic equilibrium configuration was EHT and BHT molecules parallel adsorbed on Cu(111)surface,while the PHT molecules were in a certain angle with the Cu(111)surface,and the N atoms in the ring preferentially adsorb on the surface of Cu(111).3.The corrosion inhibition efficiency of four thiadiazole compounds 2-mercapto-5-methyl-1,3,4thiadiazole,2-amino-5-methyl-1,3,4-thiadiazole,2-amino-5-mercapto-1,3,4-thiadiazole and 2-amino-1,3,4-thiadiazole was evaluated by electrochemical measurements and surface analysis and theoretical calculation method for copper strip.The experimental results show that the corrosion inhibitors molecules adsorbed on the copper surface successfully,and the adsorption accords with Langmuir adsorption isothermal equation,which belongs to the mixed adsorption based on chemical adsorption.The theoretical calculation results showed that the active site located in the thiazole ring and the S and N atoms attached the ring of the corrosion inhibitor molecules and the order of the adsorption energy of the four kinds of corrosion inhibitors was AMT>MMTD>MATD>ATD.