Microwave-assisted dehydration of D-xylose into furfural by diluted inexpensive inorganic salts solution in a biphasic system

• Microwave activation for the dehydration of D-xylose to furfural.
• FeCl3 as metal chloride is an efficient acid catalyst for the synthesis of furfural.
• The presence of NaCl in a biphasic system water-CPME is the best media.
• The reusability of the catalyst was efficient during four cycles.
• Application to L-arabinose and xylan gave the furfural in good yields.

Production of furfural from biomass using less corrosive acids and minimizing the formation of undesired by-products is great challenge. Dehydration of D-xylose to furfural was carried out under microwave irradiation in biphasic system consisting of CPME and aqueous inorganic salts solution. Best conditions of dehydration of D-xylose using FeCl3 were investigated by varying temperature, reaction time, pentose loading and influence of NaCl. Highest furfural yield of 74% was achieved at 170 °C for 20 min in presence of 10 mol% of iron chloride and 100 mol% of sodium chloride in water-CPME, 1:3, v/v. Addition of NaCl was found to increase the catalytic activity of FeCl3 and allowed to reduce the amounts of FeCl3 used from 20 mol% to 10 mol%. This approach was tested with success starting from L-arabinose and xylan, a pentose-rich polysaccharide.

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