The complexes of synthetic and petroleum acids N-derivatives as steel acidic corrosion inhibitors

Abstract

Oxy- and petroleum acids were synthesized by liquid-phase oxidation of naphthen-paraffin concentrate, separated from diesel fraction of Azerbaijani oils mixture with atmospheric oxygen in the presence of heterogeneous catalytic systems. As the catalyst aluminum nano-oxide modified by Cr ,Co, Mn transition metals was used. The oxidation was carried out in reactor of bubble type in the interval of temperature 135…140 ºС during 5 h. Their imidazoline derivatives were obtained by the use of the synthesized acids and polyamines, and the complexes were prepared on the basis of them and aliphatic monobasic acids (formic and acetic) at equal molar ratio. Their influence was studied on the kinetics of the corrosion process of C1018 steel samples in 1% solution of NaCl, saturated by CO2 at 50 °С. The complexes were tested as inhibitors of carbon dioxide corrosion at concentration of 25 and 50 ppm in 20 h. According to obtained data, the usage of different concentrations of complexes decreases corrosion rate and metal loss (up to 9…10 times). The values of surface coverage (θ) and the extent of inhibition efficiency (IE, %) of corrosion process of steel example in CO2-medium in presence of prepared complexes were calculated. IR spectra of surface layer of used electrodes were recorded before and after adding prepared complexes into corrosion medium. As a result of the studies it was determined, that the obtained complexes had high prospects for use (protection degree 97…98%) as CO2-corrosion inhibitors in suppressing of carbon dioxide corrosion of steel equipment.