Hydrotalcite material properties, specifically its CO{sub 2} reversibility, are critical to the performance of the proposed hydrotalcite-based membrane. In this report, we summarize the fundamental study we have performed using TGA, TGA/MS, and DRIFTS to quantify the degree of CO{sub 2} reversibility for the temperature range from 200 to 300 C. Results from these three separate studies consistently exhibit the CO{sub 2} reversibility. In addition, water effect appears negligible. Finally a high-pressure experimental study was performed to determine the reversibility under the actual operating condition. The results from this high-pressure (CO{sub 2}) study also demonstrate the CO{sub 2} reversibility. In the next quarter, we will continue the high-pressure experiment in the presence of high-pressure steam to quantify its effect under the actual WGS environment. The quantitative information obtained from this study will then be incorporated in a mathematical model describing the CO{sub 2} permeance as a function of the membrane layer thickness.

In this quarter, we have made progress in the three approaches selected for preparing CO{sub 2}-affinity membrane. A defect free nanoporous membrane was prepared via slip casting. This membrane will then be used for post treatment to seal the micropores to become a non-porous membrane with CO{sub 2} affinity. This post treatment study will be our focus in the next several quarters. Polymeric gel as a precursor was successfully prepared, which will be used for subsequent thin film deposition. Preparation of a defect-free thin film from this precursor will be our future focus using the sol-gel approach. Finally, the third approach, in-situ impregnation approach, was modified. Although we were able to deposit the precursor within the porous of the membrane, we have not been able to enhance the pH in-situ. Designing an unconventional approach to alternate the pH in-situ will be our focus of the next quarter.