(484d) Enhanced Performance of Polymeric Amines Supported On Heteroatom-Incorporated Silica in CO2 Adsorption/Desorption

Silica-aminopolymer composites are promising materials that can be used to adsorb CO₂ from dilute gases, with the most commonly studied compositions being simulated flue gas from power plants (ca. 5-15% CO₂) and ambient air (ca. 400 ppm CO₂). The CO₂ adsorption characteristics of prototypical, class 1 [1] poly(ethyleneimine)-silica composite adsorbents are shown here to be significantly enhanced by altering the acid/base properties of the silica support via heteroatom incorporation into the silica matrix. [2] To demonstrate this, a series of poly(ethyleneimine)-impregnated mesoporous silica SBA-15 materials containing heteroatoms (Al, Ti, Zr, and Ce) in the silica matrix are prepared and characterized in adsorption experiments under conditions simulating flue gas (10% CO₂ in Ar) and ambient air (400 ppm CO₂ in Ar). The structure of the composite adsorbents, including local information concerning the state of the incorporated heteroatoms and the overall surface properties of the silicate supports, are investigated to develop a relationship between the adsorbent structure and CO₂ adsorption/desorption performance. The CO₂ adsorption/desorption kinetics are assessed by thermogravimetric analysis and in-situ FT-IR measurements. These combined results, coupled with data on adsorbent regenerability, demonstrate a stabilizing effect of the heteroatoms on the poly(ethyleneimine) contained within the support mesopores, enhancing adsorbent capacity, adsorption kinetics, regenerability, and stability of the supported aminopolymers over continued cycling. [3] It is suggested that the CO₂ adsorption performance of silica-aminopolymer composites may be further enhanced in future work by more precisely tuning the acid/base properties of the support, an approach that has not yet been widely exploited in the literature.

References

[1] P. Bollini, S. A. Didas, C. W. Jones, J. Mater. Chem. 2011, 21, 15100.

[2] Y. Kuwahara, D.-Y. Kang, J. R. Copeland, N. A. Brunelli, S. A. Didas, P. Bollini, C. Sievers, T. Kamegawa, H. Yamashita, C. W. Jones, J. Am. Chem. Soc. 2012, 134, 10757.

[3] Y. Kuwahara, D.-Y. Kang, J. R. Copeland, N. A. Brunelli, S. A. Didas, P. Bollini, C. Sievers, T. Kamegawa, H. Yamashita, C. W. Jones, Chem. Eur. J. 2012, 18, 16649.