264899 Characterization and CO2 Sorption Properties of Materials for CCS Applications

Tuesday, October 30, 2012
Hall B (Convention Center )
Jiajun He, Erik C. Rupp and Jennifer Wilcox, Department of Energy Resources Engineering, Stanford University, Stanford, CA

Carbon capture and sequestration (CCS) has become an important option for mitigating CO2 emission and global climate change by capturing CO2 from large point sources and sequestering it underground. However, the feasibility of CCS is mainly limited by the high cost of carbon capture, and to be more specific, the significant energy requirements during the regeneration of aqueous amine solutions. To overcome this limitation, micro and mesoporous sorbents have become promising candidates. A considerable variety of sorbent materials have been investigated for the application of CO2 capture, including metal organic frameworks, zeolites, carbon nanotubes and mesoporous silicas, including SBA-15 and MCM-41. However, the CO2 sorption capacity and kinetics under realistic flue gas conditions remain unclear. In this study, a variety of potential sorbents are investigated by several characterization techniques to gain insights into the relationship between sorbent properties and adsorption performance under flue gas conditions.

Breakthrough experiments are performed in a temperature-controlled packed-bed reactor with small amounts of sorbent (<250 mg). Experiments are performed with a resolution of 0.1 mmol CO2 per gram of sorbent using an Extrel MAX300-LG quadrupole mass spectrometer downstream of the packed bed.  The inlet gas is either a mixed gas (CO­2, N2 and H2O) for testing under ideal conditions or a simulated flue gas created by burning methane in air, with potential contaminants such as SO2, HCl and NOx doped in at part per million levels post-combustion. The breakthrough experiments provide an understanding of CO2 uptake, sorbent repeatability and impact of flue gas contaminants on capture. In addition, a Quantachrome Autosorb iQ2 automated gas sorption analyzeris used to determine surface area, pore volume and pore size distribution of the testedCO2 sorbents.

The sequestration of captured CO2 is the other key aspect of CCS. Enhanced natural gas production in gas shale formations using captured CO may help offset the costs associated with CCS. The composition of gas shale (primarily clay minerals with small amounts of kerogen) has non-negligible effects on the interaction of a particular shale and injected CO2, which may affect the extent of sequestration and enhanced gas recovery. In this study, we investigate the compositions of various shale formations, including the Barnett, Eagle Ford, Haynesville and Fort St. John formations. X-ray photoelectron microscopy is used to analyze the atomic composition of the samples while Fourier transform infrared spectroscopy is utilized for the characterization of functional compounds in the samples. Knowledge of the physical and chemical properties of these materials will provide insight into the surface-CO2 interactions that take place in these systems.

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