(634c) Correlations for Adsorption of Oxygenates Onto Zeolites From Aqueous Solutions

Henry’s constants (K_ads) 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, K_ow, computed using the ClogP group contribution method. It was found that a linear correlation exists between K_ads and K_ow for these four zeolite frameworks which allows for the facile and accurate prediction of K_ads of molecules with varying functionality onto zeolite adsorbents. Decoupling of water-adsorbate and K_ads does not significantly perturb the correlation; this observation in conjunction with the result that the slope of the K_ads-K_ow 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.