HEMICELLULOSE EXTRACTION-KRAFT PULPING FOR BIOETHANOL PRODUCTION

The pulp and paper industry provides an opportunity to expand the range of the products that are manufactured to an Integrated Forest Biorefinery, thus improving the utilization of the woody biomass. During kraft pulping, hemicelluloses are degraded into low molecular weight saccharinic acids and end up in the black liquor together with degraded lignin. To recover energy, black liquors are concentrated and burned. As the heating value of hemicelluloses is considerably lower than that of lignin, extracting the hemicelluloses before the pulping stage for generation of high value products has the potential to improve overall economics. The combination of hemicelluloses extraction with chemical pulping processes is one approach to generate a sugar feedstock amenable to biochemical transformation to fuels, especially when the raw material is Pinus radiata, which is difficult to pretreat by other methods. Two treatments, diluted acid (1% H₂SO₄, 170°C, 25 min) and saturated vapor (190°C, 28 min) were applied to P. radiata wood chips prior the cooking stage (170°C, AA 16-18 and H-factor 600-1200). Approximately 53% and 56% of original hemicelluloses amount in wood was disassembled and recovered in acid solutions and saturated vapor, respectively. Lignin removal increased with increasing active alkali and H-factor, leading delignification grade above 30% for DA and 47% for pretreatment from SV. P. radiata pulp digestibility was evaluated by enzymatic hydrolysis with cellulases. All pulps obtained presented low glucan to glucose conversion, reaching values between 36 and 53%, probably due to new structure features of the pretreatment material.

 Acknowledgements: Project FONDECYT 1130693.