CO2 interaction with geomaterials.

Conference · Wed Sep 01 00:00:00 EDT 2010

OSTI ID:1027024

Guthrie, George D ^[1]; Al-Saidi, Wissam A ^[2]; Jordan, Kenneth D ^[2]; Romanov, Vyacheslav N ^[1]; Lopano, Christina L ^[1]; Myshakin, Eugene M ^[3]; Hur, Tae Bong ^[2]; Warzinski, Robert P ^[1]; Lynn, Ronald J ^[3]; Howard, Bret H ^[1]; Cygan, Randall Timothy

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1. U.S. Department of Energy, Pittsburgh, PA
2. University of Pittsburgh, Pittsburgh, PA
3. URS Corporation, Pittsburgh, PA

This work compares the sorption and swelling processes associated with CO2-coal and CO2-clay interactions. We investigated the mechanisms of interaction related to CO2 adsortion in micropores, intercalation into sub-micropores, dissolution in solid matrix, the role of water, and the associated changes in reservoir permeability, for applications in CO2 sequestration and enhanced coal bed methane recovery. The structural changes caused by CO2 have been investigated. A high-pressure micro-dilatometer was equipped to investigate the effect of CO2 pressure on the thermoplastic properties of coal. Using an identical dilatometer, Rashid Khan (1985) performed experiments with CO2 that revealed a dramatic reduction in the softening temperature of coal when exposed to high-pressure CO2. A set of experiments was designed for -20+45-mesh samples of Argonne Premium Pocahontas No.3 coal, which is similar in proximate and ultimate analysis to the Lower Kittanning seam coal that Khan used in his experiments. No dramatic decrease in coal softening temperature has been observed in high-pressure CO2 that would corroborate the prior work of Khan. Thus, conventional polymer (or 'geopolymer') theories may not be directly applicable to CO2 interaction with coals. Clays are similar to coals in that they represent abundant geomaterials with well-developed microporous structure. We evaluated the CO2 sequestration potential of clays relative to coals and investigated the factors that affect the sorption capacity, rates, and permanence of CO2 trapping. For the geomaterials comparison studies, we used source clay samples from The Clay Minerals Society. Preliminary results showed that expandable clays have CO2 sorption capacities comparable to those of coal. We analyzed sorption isotherms, XRD, DRIFTS (infrared reflectance spectra at non-ambient conditions), and TGA-MS (thermal gravimetric analysis) data to compare the effects of various factors on CO2 trapping. In montmorillonite, CO2 molecules may remain trapped for several months following several hours of exposure to high pressure (supercritical conditions), high temperature (above boiling point of water) or both. Such trapping is well preserved in either inert gas or the ambient environment and appears to eventually result in carbonate formation. We performed computer simulations of CO2 interaction with free cations (normal modes of CO2 and Na+CO2 were calculated using B3LYP / aug-cc-pVDZ and MP2 / aug-cc-pVDZ methods) and with clay structures containing interlayer cations (MD simulations with Clayff potentials for clay and a modified CO2 potential). Additionally, interaction of CO2 with hydrated Na-montmorillonite was studied using density functional theory with dispersion corrections. The sorption energies and the swelling behavior were investigated. Preliminary modeling results and experimental observations indicate that the presence of water molecules in the interlayer region is necessary for intercalation of CO2. Our preliminary conclusion is that CO2 molecules may intercalate into interlayer region of swelling clay and stay there via coordination to the interlayer cations.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1027024
• Report Number(s): SAND2010-6210C; TRN: US201121%%234
• Resource Relation: Conference: Proposed for presentation at the 2010 American Geophysical Union Fall Meeting held December 13-17, 2010 in San Francisco, CA.
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
03 NATURAL GAS
BOILING POINTS
CATIONS
CLATHRATES
CLAYS
COAL
COMPUTERIZED SIMULATION
GEOCHEMISTRY
GEOPHYSICS
GRAVIMETRIC ANALYSIS
ISOTHERMS
METHANE
MINERALOGY
MONTMORILLONITE
PERMEABILITY
PETROLOGY
POLYMERS
SORPTION
SPECTRA
SWELLING
THERMODYNAMICS
THERMOPLASTICS
TRAPPING
X-RAY DIFFRACTION