The properties of supercritical carbon dioxide (scCO2) have made it attractive in numerous industries and in a variety of applications [1-3]. The need for compatibility of materials with scCO2 has been identified as a stumbling block for even wider application in industry [4-6]. An expanded understanding of the corrosion characteristics of engineering alloys in scCO2 with various impurities will provide necessary information for increased utilization.
Experimental:
Experiments were conducted in an autoclave, lined with Teflon. The autoclave is capable of maintaining a temperature of up to 423K (150˚C). Materials studied include austenitic steels as well as nickel based alloys. Environment included scCO2, as well as scCO2 with impurities. The surface of the samples were characterized after exposure to scCO2 using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy.
Results:
Figure 1 shows Raman spectra obtained from Inconel 625 and stainless steel 316 exposed to scCO2. Only Inconel 625 has detectable Raman modes after exposure to scCO2 with saturated water vapor at 80°C. The corrosion performance of Inconel 625 and stainless steel 316 are observed with respect to their surface chemistry.
Figure 1: Raman spectra for both the austenitic steel SS316 and nickel based alloy I625 exposed to 80°C SCO2 with saturated water vapor. Spectra collected with 532nm laser.
Acknowledgements: This study was supported by the Department of Energy, under Contract DE-NE0008236, and Nuclear Regulatory Commission (NRC) under award NRC-HQ-11-G-38-0039.
References:
[1] A.P. Sánchez-Camargo, J.A. Mendiola, E. Ibáñez, M. Herrero, Supercritical Fluid Extraction, Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, Elsevier, 2014.
[2] H. Taher, S. Al-Zuhair, A.H. Al-Marzouqi, Y. Haik, M. Farid, Biochemical Engineering Journal 90 (2014) 103-113.
[3] K.M. Krupka, K.J. Cantrell, B.P. McGrail, Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review, Pacific Northwest National Laboratory, 2010.
[4] X. Han, M. Poliakoff, Chemical Society Reviews 41 (2012) 1428-1436.
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[6] O. Yevtushenko, Water Impact on Corrosion Resistance of Pipeline Steels in Circulating Supercritical CO2 with SO2- and NO2- Impurities.