Solid acid catalyzed dehydration of xylose to obtain furfural

Recent years have witnessed much activity to upgrade sugars contained in side-streams from the pulp and paper industry into ethanol and other value-added chemicals. An interesting catalytic route, namely the dehydration of sugars to furans, is considered one of the most promising routes for the production of platform chemicals and fuels. Furans such as furfural are highlighted in the “Top 10 + 4” by the United States Department of Energy list as the most rewarding bio-based platform molecules (1).
The current furfural production uses mineral acids at approx. 200 °C, providing around 50 mol% yield. These mineral acids possess several drawbacks, e.g., high toxicity, corrosiveness, difficult recovery and large salt waste after work-up. The purpose of this study is to replace the mineral acid with solid acid catalysts. This approach may offer several advantages over current processes in the conversion of pentosan derivatives e.g. xylose into furfural: high yields, facile separation and reusability of the catalyst. In the present study, different solid acid catalysts developed for this purpose (sulfated zirconia, alumina and Al-MCM-41), as well as commercial polymers have been tested to find a selective and stable catalyst.
The results of this work could be used to produce platform chemicals from sugar-based side-streams in the forestry industry, in particular from the pre-hydrolysate liquor for dissolving pulp. These obtained value-added products have applications in a wide range of industrial branches (biofuel, pharmaceutical, agrochemical, petrochemical and chemical industry, among others).