(389b) Characterization and CO2 Sorption Properties of Materials for CCS Applications

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 NO_x 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_2­ 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.