Use of Aqueous Solutions to Simulate Supercritical CO₂ Corrosion

Capturing and storage of anthropogenic carbon dioxide (CO₂) requires the transport of CO₂ with varying combinations of impurities depending on the capture technology and source. Traditional pipelines are not designed for the transport of such relatively low-purity CO₂; in fact, initial research indicates that a low-purity CO₂ environment poses a significant durability risk to conventional (gas) pipelines. The presence of water in a supercritical CO₂ stream will lead to acidic conditions via the formation of carbonic acid (H₂CO₃). In this work, a round robin of experiments has been executed in aqueous solutions where CO₂ has been added to water to form H₂CO₃ in situ, along with testing in sulfuric acid (H₂SO₄) that was found to simulate the impact of H₂CO₃ upon steel. The role of Cl⁻, NO₃⁻, and SO₄²⁻ impurities was also investigated. Conclusions have been drawn from electrochemical, weight-loss, and optical profilometry results, with future work outlined. While not a replacement to supercritical CO₂ experiments, we see that there is significant merit in such high throughput tests to form an initial understanding, which can be subsequently benchmarked by supercritical CO₂ tests.