ZHANG Chen-feng,HU Jun-ying,ZHONG Xian-kang,ZHENG Zi-qi,GENG Shuai.Bis-imidazoline Compound as a Corrosion Inhibitor in CO2/O2 Environment and Its Synergistic Effect with 2-mercaptoethanol[J],49(11):66-74
Bis-imidazoline Compound as a Corrosion Inhibitor in CO2/O2 Environment and Its Synergistic Effect with 2-mercaptoethanol
Received:July 27, 2020  Revised:September 07, 2020
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DOI:10.16490/j.cnki.issn.1001-3660.2020.11.008
KeyWord:corrosion inhibitor  imidazoline  electrochemical test  compound  quantum chemical calculation  O2 corrosion  CO2 corrosion
              
AuthorInstitution
ZHANG Chen-feng School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu , China
HU Jun-ying School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu , China;State Key Laboratory of Reservoir Geology and Development Engineering Southwest Petroleum University, Chengdu , China
ZHONG Xian-kang School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu , China;State Key Laboratory of Reservoir Geology and Development Engineering Southwest Petroleum University, Chengdu , China
ZHENG Zi-qi School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu , China
GENG Shuai School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu , China
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Abstract:
      To explore the corrosion inhibition performance of bis-imidazoline (PMA) and 2-mercaptoethanol (MAT) in a CO2/O2 environment, infrared spectroscopy, weight loss method, electrochemical measurement technology (impedance spectroscopy and polarization curve) and scanning electron microscope were used to evaluate the inhibition behavior of PMA and MAT on the corrosion of carbon steel. Through quantum chemical calculations and molecular dynamics simulation, the active sites of PMA and MAT are analyzed. The results show that the maximum corrosion inhibition rate is 66.47% when PMA is 100 mg/L in a CO2/O2 environment. As the concentration of MAT increases, the corrosion rate decreases, and the corrosion inhibition efficiency increases. MAT with a concentration of 40 mg/L shows the best corrosion inhibition rate (70.38%), and the electrochemical results are consistent with the weight loss results. Electrochemical tests show that PMA is a mixed corrosion inhibitor, after the addition of MAT, the corrosion inhibition efficiency increases. In the presence of the combined PMA and MAT inhibitor, the corrosion of carbon steel is mainly controlled by the charge transfer process. From the SEM image, corrosion is obviously suppressed after adding PMA and MAT inhibitor. Combined with quantum chemical calculations and molecular dynamics simulation, the active sites of PMA are on the imidazoline rings, while the active sites of MAT are mainly on the sulfur atoms. The corrosion inhibition mechanism is due to that protective film first formed on the surface of the carbon steel, however, the protective film may have defects. After adding MAT, its smaller molecular size can fill the defects in the film, and the active site S atoms are adsorbed on the metal surface to make the film more compact and thus increasing the inhibition efficiency. Due to its strong adsorption capacity and hydrophobic properties, PMA has a good corrosion inhibition effect in CO2/O2 environment, and has a good synergistic effect with 2-mercaptoethanol, which can more effectively inhibit the corrosion process.
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