In Situ Molecular Spectroscopic Evidence for CO2 Intercalation into Montmorillonite in Supercritical Carbon Dioxide
The interaction of anhydrous supercritical CO2 (scCO2) with both kaolinite and ~1W (i.e. close to but less than one layer of hydration) calcium-saturated montmorillonite was investigated under conditions relevant to geologic carbon sequestration (50 °C and 90 bar). The CO2 molecular environment was probed in situ using a combination of three novel high-pressure techniques: X-ray diffraction, magic angle spinning nuclear magnetic resonance spectroscopy and attenuated total reflection infrared spectroscopy. We report the first direct evidence that the expansion of montmorillonite under scCO2 conditions is due to CO2 migration into the interlayer. Intercalated CO2 molecules are rotationally constrained and do not appear to react with waters to form bicarbonate or carbonic acid. In contrast, CO2 does not intercalate into kaolinite. The findings show that predicting the seal integrity of caprock will have complex dependence on clay mineralogy and hydration state.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1040958
- Report Number(s):
- PNNL-SA-86500; 47427; 39937
- Journal Information:
- Langmuir, 28(18):7125-7128, Journal Name: Langmuir, 28(18):7125-7128 Journal Issue: 18 Vol. 28; ISSN LANGD5; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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