Inhibition Performance of Imidazolines and Their Quaternary Ammonium Salts in Acidic Media

The inhibition performance of two imidazolines and their quaternary ammonium salts was studied by static weight loss method. The results showed that naphthene-base imidazoline(NI)and lauric acid imidazoline(YUC) had good inhibition efficiency on N80 steel in 15% HCl and 9% mud acid at 60 ℃. The inhibition efficiency increased with increasing the dosage of naphthene-base imidazoline quaternary ammonium salt(NIAS)and thiourea-base imidazoline quaternary ammonium salt(SUDEI), and reduced with increasing the concentration of HCl and mud acid. Increasing of temperature decreased remarkably the inhibition efficiency of NIAS, while it had little effect on the inhibition efficiency of SUDEI. NIAS and SUDEI had higher inhibition efficiency on A3 than on N80. SUDEI had higher efficiency of inhibition on N80 steel in acidification medium than NIAS. When the dosage of NIAS was 0.1%, the inhibition efficiency on N80 steel in 9% mud acid containing SUDEI at 60 ℃ was up to 98.50%, and corrosion rate was 1.39 g/m2·h, which can meet the demand of China Petroleum and Natural Gas industrial standard, while NIAS can not.