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Tetraethylenepentamine (TEPA) modified silica aerogel CO 2 adsorbents were prepared by two methods: evaporative precipitation and wet-impregnation. The distribution of amine on the support and CO 2 adsorption performance of these sorbents were studied by nitrogen porosimetry, thermogravimetric analysis, transmission electron microscopy, and CO 2 gravimetric adsorption analysis to understand the synthesis-structure-CO 2 adsorption property relationships of the silica aerogel supported amine sorbents. The sorbents prepared by evaporative precipitation showed slightly better distributions of TEPA and adsorption performance relative to the wet impregnated analogues. The enhancements observed, however, were unexpectedly small suggesting that the two methods of amine immobilization result in similar TEPA distributions. It appears that the thermodynamic limitation toward lowering the free energy of the system is causing the TEPA to consolidate inside the aerogel network, suggesting that methods of impregnation are of little influence on amine distribution within the pore network of the support.

The hydrophobic silica aerogel Cabot Nanogel TLD302 was evaluated as an adsorbent for recovering 2–5 carbon n-alcohols from aqueous solutions. Whereas intraparticle transport limitations restricted adsorption under dilute conditions, at higher concentrations, improved surface wetting resulted in facile “pore intrusion” and ∼5-fold increases in adsorption capacity for all alcohols. To promote surface wetting and pore intrusion at lower concentrations, partial oxidation of TLD302 was performed by heat treatment to create a series of novel aerogel materials with tunable surface hydrophobicities. An optimum surface oxidation state was found to exist wherein pore intrusion under dilute conditions was achieved while still balancing high adsorption affinity. Lastly, the optimized aerogel adsorbent was used to recover n-butanol from a Clostridium acetobutylicum ATCC 824 fermentation broth. Relative to model solutions, no loss of adsorption affinity or capacity was observed, indicating that competitive coadsorption by other media components was not a performance-limiting factor.