Thermochemical pretreatment of lignocellulose to enhance methane fermentation. II. Evaluation and application of pretreatment model

A model was developed and evaluated as a tool for predicting the formation of soluble products from staged thermochemical treatment of lignocellulosic materials under acidic conditions typical of autohydrolysis. The model was used to predict the general trend of hemi‐cellulose and cellulose hydrolysis between pH 2 and 4 and temperatures of 170–230°C, and results were compared with experimental data. When the model was evaluated for this range of temperatures and pH values, results indicated: (1) a relatively low temperature (175°C) during the first stage allows hydrolysis of the hemi‐cellulose polysaccharides without significant mono‐saccharide decomposition, (2) subsequent stages at higher temperatures (equal or greater than 200°C) are needed for significant cellulose hydrolysis, but glucose decomposition will also occur, and, (3) a pH in the range of 2–2.5 will enhance polysaccharide hydrolysis while limiting monosaccharide decomposition. The model's predictions, indicating that the formation of biodegradable products could be optimized using Pretreatments at pH 2–2.5 for the pH range evaluated, were confirmed in experiments with white fir as a representative lig nocellulose.