(634c) Correlations for Adsorption of Oxygenates Onto Zeolites From Aqueous Solutions
Henry’s constants (Kads) for the adsorption of C2-C6 polyfunctional molecules from aqueous solutions onto H-ZSM-5 (MFI), FAU, BEA, and ITQ-1 (MWW) were obtained at 278 K and compared with the octanol-water partition coefficients, Kow, computed using the ClogP group contribution method. It was found that a linear correlation exists between Kads and Kow for these four zeolite frameworks which allows for the facile and accurate prediction of Kads of molecules with varying functionality onto zeolite adsorbents. Decoupling of water-adsorbate and Kads does not significantly perturb the correlation; this observation in conjunction with the result that the slope of the Kads-Kow correlation increases with a decrease in zeolite pore size indicates that confinement in the zeolite pore is a critical driving force for adsorption. Exceptions to the linear correlation established include 1,2,4-butanetriol and 1,2,6-hexanetriol on H-ZSM-5 as well as all adsorbates on the small pore zeolite FER which highlights the critical role of size selectivity for the adsorption of oxygen-containing molecules onto zeolites. These results enable the prediction of separation selectivities of biomass-derived chemicals on zeolite adsorbents.