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Route for the synthesis of furfural from xylan

Commercial chemicals were of reagent grade or better, and were used without further purification. Reactions were performed in glass vessels heated in a temperature-controlled oil bath with magnetic stirring. [EMIM]Cl (99.5%) was from Solvent-Innovation (Cologne, Germany). Birchwood xylan (X0502, 98% xylose residues, ca. 95% dry solids) and beechwood xylan (X4252, 95% xylose residues, ca. 95% dry solids) were from Aldrich Chemical (Milwaukee, WI). Oat hull xylan (X0011, 70.2% xylose residues, ca. 95% dry solids) was from TCI (Tokyo, Japan). Milled and sieved corn stover (ca. 95% dry solids) was generously provided by B. E. Dale and co-workers (Michigan State University),[] and was passed through a 40-mesh screen prior to use.

Synthesis of Furfural from Xylose and Xylan - DeepDyve
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We attempted to address this problem by using acid for xylan saccharification prior to furfural synthesis. To do so, we treated xylan with HCl at 140°C prior to addition of the chromium catalyst and reaction at 120°C (). This process enabled furfural yields similar to those obtained at 140 °C. Use of HCl during the solubilization step was essential for furfural production, though HCl alone did not result in yields as high as those obtained with both chromium and HCl. The effects of other additives such as LiCl, LiBr, and ionic liquids were modest. These data suggest that pretreatment of xylan to form xylose improves furfural yields. We anticipate that improved methods for xylan depolymerization under our reaction conditions would provide higher furfural yields at lower temperatures. Using HCl in water/ionic liquid mixtures, we have demonstrated that 77% of birch xylan can be hydrolyzed to xylose.[] The major side products observed by HPLC analysis are furfural and species with retention times characteristic of carboyhydrate oligomers. Both xylose and xylose oligomers are possible intermediates on the route from xylan to furfural. Combining this hydrolysis process with chromium catalysts could enable the efficient transformation of xylan into furfural.

for the synthesis of furfural from xylose, xylan and ..

Synthesis of Furfural from Xylose by Heterogeneous …
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An environmentally benign processing approach for furfural production from xylose and xylan under verymild conditions (353-373 K) was developed with the addition of metal chlorides in ChCl-oxalic acid (a deep eutectic solvent (DES)) synthesized from cheap and renewable starting materials). ChCl-oxalic acid acted as both a Brønsted acid catalyst and a reaction medium in this catalytic route. In addition, a biphasic system with methyl isobutyl ketone as an extracting reagent (DES/MIBK) to further increase furfural yield was also proposed. This processing approach for producing furfural eliminated the large energy consumption for high pressure saturated steam and the generation of acidic effluent, which was very difficult to handle. The whole catalytic system was more environmentally friendly compared with the commercial process for furfural production.

In conclusion, renewable fuels and chemicals such as pentose-derived furfural can reduce the dependence of humanity on fossil resources. Although furfural is produced industrially by using high temperatures and strong acid catalysts, we have found that chromium halide catalysts enable furfural synthesis from xylose in N,N-dimethylacetamide and ionic liquids at moderate temperatures. Mechanistic investigations suggest that these catalysts isomerize xylose into xylulose, a reactive ketose intermediate that dehydrates readily into furfural. We have also demonstrated the transformation of xylan into furfural under similar conditions. Our chromium-based process offers an advantageous route from pentoses and pentosans to renewable furfural-derived fuels and chemicals.

Conversion of xylose and xylan into furfural in …

Acid-catalyzed conversion of xylose, xylan and straw into furfural …
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Rising fossil energy prices and environmental preservation call for alternative sources of energy, such as renewable fuels based on biomass.[] Biofuels could reduce carbon dioxide emissions and decrease fuel prices, particularly if derived from nonfood biomass resources such as agricultural, forest, and landfill wastes. Hemicellulose, a mixture of polysaccharides containing xylose, arabinose, glucose, galactose, mannose, and other sugars, is typically the second-most-abundant component of biomass, after cellulose.[] In grasses and hardwoods, xylan, a polymer of xylose, is often the primary hemicellulose. As a result, xylan conversion is critical for utilization of important biomass feedstocks such as bagasse, corn stover, Miscanthus, switchgrass, and poplar.

Zhang, L., Yu, H., Wang, P., and Li, Y. (2014). “Production of furfural from xylose, xylan, and corncob in gamma-valerolactone using FeCl3•6H2O as catalyst,” Bioresour. Technol. 151, 355-360.

Acid-catalyzed conversion of xylose, xylan and straw into furfural by microwave-assisted reaction
Photo provided by Flickr
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