(348f) Reactive Distillation Process for the Production of Furfural from Xylose Using Solid Acid Catalysts

There is growing interest in the production of chemicals and fuels from renewably sourced feedstocks due to rising petroleum prices, limited availability, and increasing consciousness of customers about environmentally-friendly processes. Furthermore, fossil fuels used to manufacture chemicals and fuels have an increased environmental footprint relative to renewable feedstocks. The overall concept of converting biomass into chemicals provides several advantages to make processes inherently safer and more sustainable.

Furfural, an intermediate derived from the hemicellulose portion of lignocellulosic biomass, is considered as one of the key renewably sourced feedstocks for products that can compete with petroleum-based chemicals [1]. Furfural currently has numerous commercial applications, including the manufacture of furfuryl alcohol, but the availability of commercial quantities of economically-priced furfural could lead to an expansion to other products and markets. The current commercial furfural manufacturing processes use corn cob and bagasse with ~50% molar yield [2]. Based on this low yield and other drawbacks of the current technology, we undertook a research endeavor to develop a novel process using reactive distillation with solid acid catalysts to convert xylose into furfural.

A comprehensive experimental study was carried out using synthetic xylose feeds containing a mixture of pure xylose, water, and sulfolane as a solvent. A number of different solid acid catalysts were tested in a reactive distillation process for their ability to produce furfural from xylose. The reactive distillation process provides a unique advantage of immediate separation of furfural from the reaction zone as it is formed, thus minimizing the formation of undesired by-products (e.g., humins) from subsequent furfural reactions. During this process, the aqueous feed was introduced at the top of the column, and xylose was dehydrated to furfural which was co-distilled with water out of the top of the column. The high-boiling sulfolane, with dissolved humins, was drained through the bottom of the column. Among various catalysts screened, the zeolite H-mordenite (Si/Al = 10) gave the highest furfural yield of about 80%. 

This study was further extended to using authentic aqueous process feeds containing C5-sugars. Salts present in these feeds resulted in significant catalyst deactivation. We present a systematic study to show how we resolved this problem, which resulted in extended catalyst lifetime and furfural yield, similar to that obtained with synthetic xylose feeds.

References

[1]        J.J. Bozell, G.R. Petersen, Green Chemistry 12 (2010) 539-554.

[2]        R. Karinen, K. Vilonen, M. Niemelä, ChemSusChem 4 (2011) 1002-1016.