Use of Aqueous Solutions to Simulate Supercritical CO₂Corrosion

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.