Study of the Corrosion Rate of Three Contactors Materials Using the Electrochemical Technique of Tafel

Abstract

The main objective of this project was to study the corrosion rate of three different structured packing materials, a metallic, one polymeric and the other one ceramic, which will be in contact with an aqueous solution of MEA (monoethanolamine) to 30% and sour gases in a countercurrent absorption column. The materials were studied in two electrochemical cells: the first one in the presence of an aqueous solution of 1N sulfuric acid, and the second in the aqueous solution of MEA 30%, the study was done using the Tafel extrapolation methods and resistance to the polarization to measure the corrosion current (I Corr), and determine the corrosion rates of the three materials structured packings. The standard procedure used was according to ASTM G59-91, following the technique ININ No. P. SC (Cl) -06, the following results were found: in the presence of 1N sulfuric acid solution the metallic material presented a rate of 7.8 x 10-4 corrosion mpy (miles per year), the polymeric material submitted a corrosion rate of 2.82 x 10-4 mpy, and the ceramic material presented a corrosion rate of 1.03 x 101 mpy. With the aqueous solution of MEA at 30% in weight, and the sour gases the results were as follows: the metallic material presented a corrosion rate of 6.42 x 10-2 mpy, the polymeric material submitted a corrosion rate of 1.48 x 10-1 mpy and the ceramic material presented a corrosion rate of 5.6 x 10-1 mpy. These results provide a basis for predicting the lifetime of the three materials, as well as chemical resistance in the absorption column. Finally, we examined the morphology of the etched surface by scanning electron microscopy and found that in the metallic material was formed a layer of Cr2O3, which is helping the passivating material to further protect the acid attacks, the polymer material has a surface smoother after the attack and in the ceramic is observed pores larger than those observed in the material before the attack.