Kinetics of hemicellulose extraction during autohydrolysis of sugar maple wood

The aim of this work is to study the kinetics of hemicellulose hydrolysis during the hydrothermal pretreatment of sugar maple wood. To describe the concentrations of the residual xylan, xylooligomers, xylose and degradation product (furfural) obtained in the autohydrolysis of wood meal, a kinetic model assuming no diffusion limitations and based on first-order kinetics with Arrhenius-type temperature dependence of the reaction rate constants is developed. The model is validated with experimental data obtained in the autohydrolysis of sugar maple wood meal carried out under various pretreatment conditions of 145-185°C, reaction times 0-8 h, and a liquor to solid ratio 20 g/g, in a batch reactor.; To predict the yields of residual xylan, xylooligomers, and xylose obtained during autohydrolysis of wood chips, a mass transfer model based on first-order kinetics with Arrhenius-type temperature dependence of the rate coefficients is developed. The predicted compositions of the products at different temperatures are well described by the model. The proposed model is further validated against experimental data obtained with aspen chips at 160°C under similar reaction conditions as those used for the sugar maple chips. The model satisfactorily predicts the experimental data obtained with the aspen chips by using similar values of the regression parameters as obtained for the autohydrolysis of sugar maple chips at 160°C. The model can also predict the deacetylation of xylan and the formation of products (free acetyl groups and acetyl groups attached to xylooligomers) obtained during the autohydrolysis of sugar maple and aspen wood chips with fair accuracy.; The ability of the models to satisfactorily predict the empirically observed data in xylan hydrolysis and deacetylation in the autohydrolysis of sugar maple and aspen wood chips demonstrates the utility and applicability of the proposed theoretical framework to investigate hemicellulose hydrolysis of other lignocellulosic materials (LCM).; Keywords. hydrothermal processing; autohydrolysis; kinetics; mass transfer; modeling; hemicelluloses; xylan hydrolysis; xylose; xylooligomers; deacetylation...