Mannich Base as Corrosion Inhibitors for N80 Steel in a CO₂ Saturated Solution Containing 3 wt % NaCl.

Mingjin Tang,Luoping Fu,Bo Zeng,Jianbo Li,Jie Lv,Zhida Li

doi:10.3390/ma12030449

Mingjin Tang, Luoping Fu + Show 4 more

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https://doi.org/10.3390/ma12030449

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Abstract

In this paper, a corrosion inhibitor containing nitrogen atoms and a conjugated π bond was synthesised, and its final product synthesised by the optimal conditions of the orthogonal test results is named multi-mannich base (MBT). The corrosion inhibition effect on the N80 steel sheet of the corrosion inhibitor was evaluated in a CO2 saturated solution containing 3 wt % NaCl; the corrosion rate was 0.0446 mm/a and the corrosion inhibition rate was 90.4%. Through electrochemical and adsorption theory study, MBT is a mixed corrosion inhibitor that mainly shows cathode suppression capacity. The adsorption of MBT on the surface of the steel sheet follows the Langmuir adsorption isotherm; it can be spontaneously adsorbed on the surface of the N80 steel sheet, which has a good corrosion inhibition effect. The surface of the N80 steel sheet was microscopically characterised by atomic force microscope (AFM). It can be seen from the results that the N80 steel sheet with MBT added is significantly different from the blank control group; the surface of the steel sheet is relatively smooth, indicating that MBT forms an effective protective film on the surface of N80 steel, which inhibits the steel sheet.

Highlights

To improve oil and gas recovery, CO2 injection is used in the exploitation of oil, natural gas, coalbed methane and shale gas [1]
Combined with infrared radiation spectroscopy (IR) characterisation, characterisation, the results indicate that MBT is the target product of synthesis
As evidenced by polarisation curve analysis, MBT is a mixed type corrosion inhibitor mainly used for suppressing the cathode

Summary

Introduction

To improve oil and gas recovery, CO2 injection is used in the exploitation of oil, natural gas, coalbed methane and shale gas [1]. The most common and effective way to control corrosion is to use chemical additives that reduce corrosion at very small dosages [7,8]. Various corrosion inhibitors have been successfully applied to the industry, and the corrosion has been controlled obviously and effectively [9,10]. Phosphorus-containing corrosion inhibitors have excellent corrosion inhibition properties. They have some fatal defects; for example, phosphorus compounds are difficult to degrade in water and usually lead to eutrophication. The widespread use of this chemical may cause oxygen deficiency in the water, which leads to the death of aquatic organisms [12]. In the last few years, the industry has required the effectiveness of chemical compounds and their safety [13]. Finding an alternative solution, namely the effective control of corrosion

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