Optimization of Cellulignin Production from Sugarcane Bagasse Autohydrolysis for Advanced Biofuels

Optimization procedures such as experimental designs (DOE) improve pretreatment efficiency, and chemical characterization of the starting material becomes necessary to assess the efficiency. Hydrothermal pretreatment (HTP), also called auto-hydrolysis (AH), is one of the most economically interesting pretreatments since only water work as reactant. AH pretreatment optimization can reach a liquor rich in monosaccharide units at the same time that a low content of toxic compounds to biological processes (i.e., 2-furfuraldeído (FUR) e 5-hidroximetil-2-furfuraldeído (HMF). Early, AH pretreatment variables temperature (T), time (t), solid-liquid ratio (SLR) and stirring (RPM) were studied by a 24 factorial design. A new HPLC analytical method for quantifying acids that can be formed during AH (i.e., formic, acetic, glucuronic and levulinic acids) has been developed using Bio-Rad Aminex HPX-37H column in a Shimadzu Prominence HPLC. In general, the most significant factors were T and t; higher levels of T improved hemicellulose depolymerization whereas lower levels of t disfavoured pentoses degradation to FUR. At 220 ºC, 60 min, 20 % of SCB and 60 rpm it was possible to achieve a yield of 109.84 g kg-1 of pentoses (i.e., xylose and arabinose) with only 14.42 g kg-1 of FUR. Under these same conditions, the acid content in the liquor was 15.1 g kg-1, 12.2 g kg-1, 39.8 g kg-1 and 55.5 g kg-1 for glucuronic, formic, acetic and levulinic acids, respectively.