Rendering lignin separable from cellulose and hemicellulose - by plasticising lignocellulosic material and extruding from pressure vessel

摘要

Lignin is rendered separable from cellulose and hemicellulose in lignocellulosic material(s) by (a) packing (I) in a divided form in a pressure vessel having a closed extrusion die outlet; (b) rapidly filling the pressure vessel with steam of >=500 p.s.i. to bring (I) to a temp. of 185-240 degrees C. in 60 secs. to plasticise (I); and as soon as (I) is in the plasticised condition, opening the extrusion die outlet and instantly extruding (I) from the pressure vessel through the outlet to atmosphere so that the material issues in particulate form with lignin rendered separable from the cellulose and hemicellulose. Esp. (I) in the pressure vessel is brought to a temp. of 234 degrees C. in 45 secs. The lignin may be solvent extracted from the treated material, thermally plasticised and extruded as filaments. The lignin filaments can be carbonised to form carbon fibres useful, e.g. in air and water filtration.