Solid adsorbents for carbon dioxide capture have many benefits over traditional liquid amine absorbents, such as low volatility, lower corrosivity, and greener operation requirements. However, these materials can also suffer from lower capacities for multi-cycle use, with any sorbents showing either low capacity that is consistent over multiple cycles or high initial capacities that degrade very quickly upon cyclic use. 1,2
One-way to improve the performance of solid adsorbents it to post-synthetically modify them with amine groups through either physical impregnation or covalent grafting. This modification has tradeoffs and will often slow adsorption kinetics due to the blocking of diffusion channels with loaded amine groups. 3
Previously we studied the sorption kinetics of 1-dimensial pore structures, determining that excessive amine loading can degrade the carbon capture performance of functionalized adsorbents. We have begun investigating the functionalization of materials with 2-dimensional pore structures using Ti-MCM-36 in order to figure out the relations of the pore structure of support materials and the adsorption kinetics of supported amine adsorbents. Ti-MCM-36 is a derivative of the well-known pillared zeolitic material, MCM-36, that consists of silicate layers pillared with TiO2
columns. We have shown that Ti-MCM-36 has a higher affinity for CO2
adsorption than Si-MCM-36, with high capacities despite lower surface areas. In this work, we have attempted to further improve the materials by the introduction of TEPA (tetraethylenepentamine).
(1) Andirova, D.; Cogswell, C. F.; Lei, Y.; Choi, S. Effect of the Structural Constituents of Metal Organic Frameworks on Carbon Dioxide Capture. Microporous Mesoporous Mater. 2016, 219, 276–305.
(2) Andirova, D.; Lei, Y.; Zhao, X.; Choi, S. Functionalization of Metal-Organic Frameworks for Enhanced Stability under Humid Carbon Dioxide Capture Conditions. ChemSusChem 2015, 8, 3405–3409.
(3) Cogswell, C. F.; Jiang, H.; Ramberger, J.; Accetta, D.; Willey, R. J.; Choi, S. Effect of Pore Structure on CO Adsorption Characteristics of Aminopolymer Impregnated MCM-36. Langmuir 2015, 31, 4534–4541.