(318b) Pervaporation-Assisted Catalytic Conversion of Xylose to Furfural

Furfural produced from the biomass-derived xylose may serve as a platform molecule for sustainable fuel production. The Brønsted acid-catalyzed dehydration of xylose to furfural is plagued by side reactions that form a set of soluble and insoluble degradation products, collectively known as humins, which reduce the yield of furfural. The formation of humins can be minimized by removal of furfural, either by steam stripping or by liquid-liquid extraction (LLE). However, both these techniques are very costly. The goal of this study was to demonstrate the feasibility of using pervaporation, a membrane process, to remove furfural as it is produced. A laboratory-scale reactor/membrane system was designed, built, and tested for this purpose and its performance for furfural production was compared with that achieved by carrying out the reaction with and without furfural extraction by LLE. Furfural production assisted by pervaporation or LLE produced comparable amounts of furfural, and more than could be achieved by reaction without extraction. Our results showed that under our experimental conditions, pervaporation extracted a smaller fraction of the furfural produced than did LLE (72% vs 89%), but pervaporation produced a permeate phase with a furfural concentration 10 times greater than that present in the extractant phase obtained by LLE. It is noted that further improvement in the separation of furfural from the aqueous phase where it is produced can be achieved by operating the membrane at the reaction temperature and using a thinner pervaporation membrane. A 3-fold membrane-thickness reduction was simulated using MATLAB and was shown to increase the extracted fraction of furfural produced to 90% while maintaining the same furfural concentration in the permeate. An analogous change in LLE (i.e. increasing the organic:aqueous volume ratio) would increase the extracted fraction of furfural produced at the cost of diluting the furfural concentration in the extractant phase.