In Situ Molecular Spectroscopic Evidence for CO2 Intercalation into Montmorillonite in Supercritical Carbon Dioxide

• DOI: 10.1021/la301136w
• Publication Date: 2012-04-26T00:21:09Z
• Authors: John S. Loring; Herbert T. Schaef; Romulus V. F. Turcu; Christopher J. Th...; Quin R. S. Miller; Paul F. Martin; Jianzhi Hu; David W. Hoyt; Odeta Qafoku; Eugene S. Ilton; Andrew R. Felmy; Kevin M. Rosso
• Keywords: Supercritical Carbon Dioxide; Anhydrous; Hectorite

The interaction of anhydrous supercritical CO(2) (scCO(2)) with both kaolinite and ~1W (i.e., close to but less than one layer hydration) calcium-saturated montmorillonite was investigated under conditions relevant geologic carbon sequestration (50 °C 90 bar). molecular environment probed in situ using a combination three novel high-pressure techniques: X-ray diffraction, magic angle spinning nuclear magnetic resonance spectroscopy, attenuated total reflection infrared spectroscopy. We report the first direct evidence that expansion scCO(2) is due migration into interlayer. Intercalated molecules are rotationally constrained do not appear react waters form bicarbonate or carbonic acid. In contrast, does intercalate kaolinite. findings show predicting seal integrity caprock will have complex dependence on clay mineralogy hydration state.