Structure and Inhibition of the Indolizine Derivative: New Concept of High-Efficient Corrosion Inhibitors for Acidizing

Among the numerous corrosion inhibitors for acidizing, the propargyl alcohol, with great expense and high toxicity, is often added as an important synergistic component. In this work, novel indolizine derivative high-effective inhibitor for acidizing was introduced. The indolizine derivative could exhibit an excellent protection performance at a much lower concentration without the synergism of the poisonous propargyl alcohol. The two inhibitive indolizine derivatives in this paper were synthesized easily from Benzyl Quinolinium Chloride (BQC, known as the a commonly used key component of acidizing inhibitor) via 1,3-dipolar cycloaddition reaction. The indolizine derivatives were purified by the column chromatography and the structure were characterized by NMR and elementary analysis etc. The inhibition performance of the BQC, propargyl alcohol and the indolizine derivatives in 15 wt.% HCl and 20 wt.% HCl for N80 steel was investigated by weight loss test and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The conclusion obtained from the electrochemical tests is in accordance with the results of gravimetric test. It is amazing to notice that the derivative could exhibit a much better anti-corrosion performance than its precursor BQC and propargyl alcohol in the abserence of the poisonous propargyl alcohol. Compared with BQC, the active adsorption sites are reinforced and strengthed in indolizine derivatives, and therefore, the inhibitor would fasten the steel surface more stronger. The firmly adsorbed inhibitors would prohibit the steel from the contact of acid. Indolizine derivative is presented as a new concept of effective acidizing inhibitor for the first time in this paper. It may offer a new method for the corrosion prevention in acidification engineering.