Electrochemical system to study corrosion of metals in supercritical CO₂ fluids

The sequestration of CO₂ is an important technology to be promptly developed if fossil fuels are continued to be used and CO₂ emission to the atmosphere is to be reduced. Low alloy carbon steel pipelines are being considered to transport the supercritical CO₂ from power plants to underground sequestration sites. However, the CO₂ stream will not be pure and dry, but will contain a number of corrosive contaminants. We have developed an experimental system that allows the use of a number of in-situ electrochemical techniques, such as electrochemical impedance spectroscopy, linear sweep voltammetry, and cyclic voltammetry, at elevated temperature and pressure. These methods are used to measure the parameters of the real time corrosion process without removing the sample from the system. This paper describes the design of the apparatus and presents the results of our first measurements of corrosion of carbon steel in supercritical CO₂ doped with H₂O at 50 °C and 15 MPa. The first conductivity measurements in the dry and water-saturated supercritical CO₂ fluid are also presented in this paper.