(89b) Improvements in Steam Pretreatment of Lignocellulosic Biomass, for Bioethanol Production, Using New/Combination of Catalysts
Reducing the production costs of ethanol from lignocellulosic material is essential in enabling its commercialization. A process based on enzymatic hydrolysis and fermentation is today regarded as the most promising alternative in converting the biomass to ethanol with high yields and low production cost. However, to reach high yields and high ethanol concentration, cellulosic biomass must be pretreated. This is a crucial step to increase the enzymatic digestibility of biomass and has a key role in the ethanol production cost. Dilute acid pretreatment, using SO2, has been shown to be a leading pretreatment process that is currently under commercial development for conversion of forest and agricultural residues to ethanol. Increased recovery of hemicellulose sugars, improved enzymatic hydrolysis of the solid residue and higher ethanol yields are some certain advantages of the dilute-acid pretreatments. However, handling high acidity of the pretreated material, difficulty in recovery/degradation of the catalyst, corrosion of the reaction vessels, and formation of the inhibitory compounds to fermentation organisms are some of the drawbacks of the dilute acid processes. Utilization of an organic-acid as the impregnating catalyst instead, would results in a waste stream that is biodegradable and could be used for production of biogas by anaerobic digestion. The latter could also be used to improve the storage of biomass, like ensiling. This study deals with the influence of utilization of organic-acids, as impregnating and preservative catalyst, on the sugar yield from the pretreatment.