Comparison of four pre-treatment methods

Plant biomass can be used for production of future fuels and chemicals. Lignocellulosic raw materials may serve as an abundant resource for these products. The challenges associated arise from the recalcitrant nature of lignocellulosics, where cellulose and hemicelluloses are tightly coupled with lignin making the structure of plant cell walls difficult to loosen for further utilization of the biomass components.

Pretreatment of lignocellulosics is a key for future biorefineries and utilization of the main components. A variety of pretreatment methods have been developed during the past decades but only a few ones have reached the commercialization phase. In the future biorefineries utilization of the all major components in lignocellulose (cellulose, hemicelluloses and lignin) to value added products is of utmost importance to make the process sustainable and profitable. Therefore pretreatment methods allowing fractionation of the main components in a polymeric form are highly interesting.

We have systematically compared four pretreatment methods based on steam explosion, super-heated steam, alkaline oxidation and organosolv, with respect to their technical feasibility and economic aspects in case of three distinct raw materials: spruce, beech and straw. Technical sugars were produced from the carbohydrate fraction and the characteristics of lignin were determined. The paper will discuss the results of this comparison, including also the results of a light techno-economic assessment.