Adsorption of Polyfunctional Molecules Onto Zeolites for the Development of Biorefinery Separation Processes

Thursday, November 11, 2010: 12:30 PM
251 A Room (Salt Palace Convention Center)
Elizabeth E. Mallon, Aditya Bhan and Michael Tsapatsis, Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN

Adsorption isotherms have been developed for oxygenates with different carbon number and functionality on zeolites that vary in pore size and connectivity (FER, MWW, MFI, BEA, MOR, FAU) as well as on ordered microporous/mesoporous materials (MCM-36, 3DOm, and SBA-15) using liquid chromatography. Henry's constants (Kads) increases exponentially with carbon number for C2-C6 diol and triol adsorption on MFI, BEA, and MWW indicating that dispersion forces are critical for polyol adsorption; this conclusion is supported by the observation that Kads for propylene glycol adsorption decreases with increasing zeolite pore size and that propylene glycol preferentially adsorbs in the micropores of MCM-36 and 3DOm. It is also shown that the chemical composition of the zeolite only has a marginal effect on propylene glycol adsorption, which again demonstrates that confinement of the adsorbate in the zeolite pore is the major contributor to the energy of adsorption. Overall, initial correlations for oxygenate adsorption in zeolites are presented in this study which will have an impact on the separation and catalytic conversion of oxygenates in the processing of biomass to chemicals and fuels.

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