There is a desire to use biomass to replace oil as the feedstock for modern chemicals and products. In this regard, polymers represent an attractive class of potential biobased materials. In this study, we seek to create tunable polymers using 5-hydroxymethylfurfural (HMF) as a renewable platform chemical. The properties of the final polymer can be tuned by modifying the side-chain of the monomer, which is added by the etherification of HMF, and the R-group is carried through the subsequent reactions. In this study, several different catalysts were evaluated for their activity for this etherification reaction, including: Hydrotalcite, H-BEA and H-ZSM-5 Zeolites, WO3, Amberlyst-15, and γ-Al2O3. These catalysts were chosen to evaluate a variety of active sites and pore structures. We have also evaluated the interplay of R-group identity and active site structure on the etherification kinetics. Catalysts possessing Brønsted acid sites (i.e., H-ZSM-5 and H-BEA Zeolites, and Amberlyst-15) showed the highest selectivities to the ether product. Catalysts possessing either base sites (e.g., hydrotalcite) or Lewis acid sites (e.g., WO3 and γ-Al2O3) were an order of magnitude less active and selective than those possessing Brønsted sites. The improved selectivity observed for H-BEA-Zeolite, compared with Amberlyst-15, is hypothesized to be due to the ability of the zeolite to stabilize reaction intermediates.1 When the rate of production of the ether product was evaluated for BEA Zeolite and Amberlyst-15 it was found that although the consumption rates were comparable, the ether production rate depends on catalyst identity. Increasing the size of the alcohol (e.g., butanol or phenol vs. ethanol) decreases the production rates, and the rate of production of all ether products is higher for H-BEA Zeolite for all alcohols tested. Based on these results, we hypothesize that the structure of H-BEA Zeolite leads to improved activity for etherification. We suggest that Brønsted acidity is needed for etherification, and catalyst morphology may also be significant.

Functionalization of 5-hydroxymethylfurfural by selective etherification

253rd National Meeting (2017)

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