Abstract
Abrupt rise in a corrosion rate has been observed when the concentration of NH4HS reached a certain value suggesting that a change in the corrosion mechanism is taking place. In order to elucidate the reason for accelerated metal loss under highly concentrated solutions, corrosion tests were executed in medium and high concentrated solutions at a static condition. Though significant corrosion observed in rich solutions is often ascribed to formation of the iron complex, its presence has not been proved. In the current work, the aggressive environment was successfully generated in a laboratory and the identification of corrosion products, namely ammine complexes of ferrous ion ([Fe(NH3)x]2+), was achieved using XANES spectrum technique by using synchrotron radiation facility.
In this paper, the results of laboratory corrosion tests in concentrated NH4HS solutions were reported, and the corrosion mechanism due to NH4HS, which is one of the largest threats in Hydrodesulfurization units, shall be discussed.