Development of Methods for Synthesis of Quality Hydrolyzates Based on the Integration of Catalytic Processes of Peroxide Delignification and Acid Hydrolysis of Birchwood

Abstract

The traditional processes of catalytic acid hydrolysis of wood are low effective due to the low quality of the formed glucose solutions contaminated with admixtures that inhibit fermentation of glucose to ethanol. This is a particularly acute problem in hydrolysis of birchwood containing hemicelluloses in large proportions. In the present paper, quality glucose solutions are suggested to produce via sulfuric acid hydrolysis (80 % H 2 SO 4 , 25 °C) of cellulose products formed during catalytic peroxide delignification of birchwood. The composition of the cellulose products are established to affect considerably the content of glucose, xylose and admixtures (furfural, 5-hydroxymethylfurfural, levulinic acid) in glucose, which inhibit enzymatic synthesis of bioethanol. High yields of glucose (80.4–83.5 wt %) are achieved with cellulose products prepared by integrated processes of sulfuric acid hydrolysis of birchwood hemicelluloses and peroxide delignification of pre-hydrolyzed wood in the presence of catalysts 2 % H 2 SO 4 and 1 % TiO 2 . Concentrations of inhibitors of enzymatic processes are lower of the admissible levels in these hydrolyzates. The hydrolyzates with the maximal glucose content (86.4–88.5 wt %) and minimal concentration of inhibiting impurities are prepared by acid hydrolysis of cellulose products treated with 18 % NaOH. The hydrolyzate composition was studied using gas chromatography, HELC, chromatomass spectroscopy. IRS, XPS and chemical techniques were used for characterization of cellulose products.