In Situ Infrared Spectroscopic Study of Brucite Carbonation in Dry to Water-Saturated Supercritical Carbon Dioxide

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• 作者：John S. Loring ; Christopher J. Thompson ; Changyong Zhang ; Zheming Wang ; Herbert T. Schaef ; Kevin M. Rosso
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：May 17, 2012
• 年：2012
• 卷：116
• 期：19
• 页码：4768-4777
• 全文大小：590K
• 年卷期：v.116,no.19(May 17, 2012)
• ISSN：1520-5215

文摘

In geologic carbon sequestration, whereas part of the injected carbon dioxide will dissolve into host brine, some will remain as neat to water saturated supercritical CO₂ (scCO₂) near the well bore and at the caprock, especially in the short term life cycle of the sequestration site. Little is known about the reactivity of minerals with scCO₂ containing variable concentrations of water. In this study, we used high-pressure infrared spectroscopy to examine the carbonation of brucite (Mg(OH)₂) in situ over a 24 h reaction period with scCO₂ containing water concentrations between 0% and 100% saturation, at temperatures of 35, 50, and 70 掳C, and at a pressure of 100 bar. Little or no detectable carbonation was observed when brucite was reacted with neat scCO₂. Higher water concentrations and higher temperatures led to greater brucite carbonation rates and larger extents of conversion to magnesium carbonate products. The only observed carbonation product at 35 掳C was nesquehonite (MgCO₃路3H₂O). Mixtures of nesquehonite and magnesite (MgCO₃) were detected at 50 掳C, but magnesite was more prevalent with increasing water concentration. Both an amorphous hydrated magnesium carbonate solid and magnesite were detected at 70 掳C, but magnesite predominated with increasing water concentration. The identity of the magnesium carbonate products appears strongly linked to magnesium water exchange kinetics through temperature and water availability effects.