MICROWAVE-ASSISTED HYDROLYSIS OF GIANT REED HEMICELLULOSE IN THE PRESENCE OF AMBERLYST-70 AS HETEROGENEOUS CATALYST

Lignocellulosic biomass conversion to sugars represents the basis of future biorefineries, because sugars can be converted to valuable products through chemical or fermentative routes. In order to guarantee a sustainable bio-based economy, a multi-stage fractionation/conversion of biomass feedstock should be developed, in this way maximizing sugars recovery and minimizing the formation of by-products. Under this perspective, the present work is focused on the investigation and optimization of the hydrolysis of giant reed (Arundo donax L.) hemicellulose fraction to xylose in the presence of an acid heterogeneous catalyst, the resin Amberlyst-70, under microwave irradiation. In fact, xylose is precursor of several products, such as xylitol, furans and five carbon alcohols. The influence of the main reaction parameters, such as temperature, catalyst and biomass amounts, on reducing sugars yield was investigated. The quantitative conversion of hemicellulose into xylose equal to 96.3 mol% was achieved at 160 °C for 20 min, employing the ratio Amberlyst-70/biomass of 0.2 wt/wt, adopting the initial biomass concentration of 200 g/L. The obtained results confirm the feasibility of Amberlyst-70 as solid acid catalyst in an alternative smart strategy for the biomass hydrolysis, leading to the complete recovery of xylose.