272454 Nano-Confined CO2 Sorbents for High-Efficiency CO2-Capture

Monday, October 29, 2012: 1:20 PM
324 (Convention Center )
David Palm, Chemical Engineering Department, University of Pittsburgh, Pittsburgh, PA, Karen J. Uffalussy, Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA, Robert M. Enick, Department of Chemical and petroleum Engineering, University of Pittsburgh, Pittsburgh, PA; Chemical and Petroleum Engineering Department, University of Pittsburgh, Pittsburgh, PA and Götz Veser, Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA

CO2 capture and sequestration are among the prime challenges of our time, as the need to reduce atmospheric concentrations of this greenhouse gas has become evident.  Among the most mature CO2 capture technologies are liquid amine-based processes; however, even these applications are hampered by high cost and large energy penalty. Grafting or supporting liquid amines on solid supports offers a promising avenue to overcome some of these limitations. In particular, embedding amines into microporous solids constitutes a simple, flexible approach.

In the present project, we are investigating the application of this embedding approach to a novel class of CO2 sorbents, so-called phase-change sorbent materials. An aminosilicone sorbent (“GAP-0”) that has recently shown great promise as a CO2 sorbent due to its high sorbent capacity and its ability to change from a liquid to a solid upon CO2 sorption, was chosen as a model compound and embedded into porous silica shells. The resulting material has the advantage of a well-defined particle size, suppressed agglomeration, and fast CO2 transport. Furthermore, on a fundamental level, the impact of nanoconfinement on phase transitions of materials is poorly understood to-date and the present system poses a well-defined model system for such studies.

 GAP-0 was loaded into silica “nanobubbles” with ~30 nm diameter via a straight-forward wet impregnation method. The walls of these nanobubbles are ~10 nm thick and highly porous with average pore diameters of ~8Å. After characterization of the material, the CO2 adsorption capability of the sorbent was studied via Thermo-Gravimetric Analysis (TGA) during cyclic CO2 uptake and release over a temperature range between 45-90oC.

Results to-date show that nanoencapsulated GAP-0 does indeed adsorb and desorb CO2 effectively. However, the GAP-0 compound exhibited unexpected volatility over the temperature range of the experiments, leading to a loss of sorbent material over time. These losses were reduced via optimization of uptake and release conditions (time, temperature), but multi-cycle experiments still showed continual loss of CO2 sorption capacity. Current work is extending the demonstrated approach onto other aminosilicone-based phase-change sorbent materials.

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