Synthesis of a Hydroxyl-Containing Corrosion Inhibitor and Its Inhibitory Performance on N80 Steel in Hydrochloric Acid Solution

In the process of petroleum exploitation, in order to effectively inhibit the corrosion damage of acid to metal equipment. Mannich base corrosion inhibitors are generally added to inhibit the corrosion damage of acid. In order to enhance the solubility of Mannich base corrosion inhibitor. This paper intends to introduce hydrophilic groups to enhance the solubility of the Mannich base corrosion inhibitor. In this paper, two efficient corrosion inhibitors 3-(2-hydroxyethylamino)-1-phenylpropan-1-one (MY1) and 3-(2-aminoethylamino)-1-phenylpropan-1-one (MY2), were synthesized based on the Mannich reaction, using formaldehyde, acetophenone and ethanolamine/ethylenediamine as reaction raw materials. The corrosion inhibition performance of the inhibitor on N80 steel in 15% (mass fraction) hydrochloric acid solution was studied by means of the static weight loss method, electrochemical test and optical contact angle analysis. It could be seen from the static weight loss method that the corrosion rate in the hydrochloric acid solution before and after adding 0.7% (mass fraction) corrosion inhibitor concentration decreased from 129.39 g·m−2·h−1 to 1.45 g·m−2·h−1 and 2.79 g·m−2·h−1, respectively. The corrosion inhibition rate could reach 98%, indicating that both inhibitors had good corrosion inhibition performance, and the corrosion inhibition effect of MY1 was better than that of MY2. It was found from the electrochemical tests that the two inhibitors were mixed corrosion inhibitors mainly inhibiting the anodic reaction, and both inhibitors belonged to spontaneous adsorption, and their adsorption behaviors followed the Langmuir adsorption isotherm. In addition, the surface of N80 steel was characterized by SEM, EDS elemental mapping and contact angle measurement. The results show that a dense hydrophobic film is formed on the surface of the steel sheet after the addition of a corrosion inhibitor, which prevents corrosion.