Solid acids as catalysts for the conversion of d-xylose, xylan and lignocellulosics into furfural in ionic liquid

With the aim to develop an ecologically viable catalytic pathway for furfural production without the use of inorganic acids, H3PW12O40, Amberlyst-5 and NKC-9 (macroporous styrene-based sulfonic acid resin) were used as catalysts for producing furfural from xylose, xylan and lignocellulosic biomass in [BMIM]Cl under microwave irradiation at atmospheric pressure. A surprisingly high furfural yield of 93.7% from xylan was obtained by H3PW12O40 at 160 °C in 10 min. The degradation of furfural affected by single addition of [BMIM]Cl and solid acids was also investigated. The IL could be easily recycled and reused with stable solvent capacity for multiple runs (5×) after the product furfural was extracted with ethyl acetate.