Methods and devices for processing lignocellulosic biomass with recovery purified lignin and purified wax fractions.

Abstract

Where hydrothermal pretreatment of lignocellulosic feedstocks is conducted so as to avoid agitation, melted lignin microdroplets remain very small in size, typically <3 μm. Carrying a net negative surface charge at neutral pH, the solidified microdroplets can be recovered from biogas digestate or process effluents from other biological conversion systems as a liquid fraction following solid/liquid separation to remove fibers, silicates and other suspended solids. This liquid suspension can be concentrated and used directly in chemical and thermochemical conversion systems with or without catalysts. Alternatively, the lignin microparticles can be flocculated and collected as a purified solid fraction. The solids can be solubilized in NaOH at room temperature as wet filter cake and used for base catalysed depolymerization or as fundamental reagent in production of phenolic resins, binder and dispersants. At least with straw and grass feedstocks, the lignin microparticles also include wax content which can be recovered separately.

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