THE ROLE OF PREHYDROLYSIS IN REFINING LIGNOCELLULOSIC BIOMASS

The paper investigates the effects of mild acidic treatment, i.e. preh ydrolysis, on the main components of lignocellulosic materials, and ba sed on that, discusses the potential role of prehydrolysis for biomass refining, defined as the systematic fractionation of its main compone nts to a number of high-value intermediates, which could be used by va rious downstream industries, like oil refinery products. Prehydrolysis was shown to very effectively fractionate hemicelluloses, since more than 90% of this component can be easily saccharified, mostly in monos accharide form. Under the optimal conditions for hemicellulose fractio nation, both cellulose and lignin undergo significant depolymerization ; a limited part of their depolymerized oligomers is soluble in the pr ehydrolysate, whereas considerably more could become solubilized ill s ubsequent treatment steps, e.g., in alkaline conditions - for cellulos e - or by extraction with organic solvents - for lignin. All major asp ects of prehydrolysis can he adequately described by a relatively simp le reaction engineering model, based on tile concept of ''reaction fac tor'' which permits to optimize the incorporation of a prehydrolytic s tage in a biomass refinery.