(35e) Fabricating Polyurethane/Zeolite Mixed Matrix Membranes for Pervaporation of Dilute Aqueous Organic Solvents

Acetone, butanol, and ethanol (ABE) are excellent alternative renewable liquid fuels that have the potential to partially supplement fossil fuels. Currently bioconversion of biomass is the leading technology for the production of renewable ABE. After a series of mechanical and chemical pretreatments, biomass liquor is enzymatically hydrolyzed to release monomeric sugars. The biomass hydrolysate is then forwarded to the fermentation unit for the conversion of monomeric sugars to ABE. The the final product is more than 95 wt.% water and less than 5% ABE. Water content should be reduced to less than 2 wt.%. Currently, the leading technology for concentration of organics in the fermentation broth is distillation.

The successful deployment of economically feasible renewable ABE is highly dependent on a cascade of thoroughly engineered unit operations. Phase-changing separations are known to be energy-intensive, and replacing such separation could lead to energy savings of up to one order of magnitude. Here we present our recent work on fabricating mixed matrix membranes with commercial Thermoplastic Polyurethane (TPU, Texin DP7-1199) and the high-silica ZSM-5 zeolites. To date, polyurethane has not been well evaluated for pervaporation applications. A significant advantage of polyurethane over polydimethylsiloxane (PDMS) membranes is that it does not require crosslinking. Our results show that mixed matrix of polyurethane-zeolite membranes are more permeable than PDMS mixed matrix membrane. Easier processing and higher fluxes are promising for future manufacturing.