Corrosion and Pitting Behavior of Carbon Steel in Simulated Fuel Grade Ethanol Under Variations in Ethanol Chemistry

The role of ethanol chemistry, such as water, acetic acid, chloride, and oxygen level, in corrosion and pitting behaviour of carbon steel  was investigated in simulated fuel-grade ethanol (SFGE). In the absence of the supporting electrolyte, the issue of IR drop and its effect on the electrochemical testing in SFGE are discussed in detail. A modified cell geometry enabled us to conduct the electrochemical measurement in the ethanolic solutions with low-conductivity. Weight loss, as well as the pit density and pit size, are studied along with the related electrochemical data. Results have shown that the water in the SFGE strongly influences the surface film stability and interface electrochemistry in ethanolic environments. The increase in the water concentration induces pitting and metal loss. Dissolved chlorides and higher acidity promote the pit initiation and growth. Alkaline condition inhibits both localized and uniform corrosion. Corrosion products and relevant cathodic reaction are also briefly discussed.