Countercurrent Process for Lignin Separation from Biomass Matrix

79276S Solid/liquid (S/L) separation is a challenging unit operation in all envisioned biomass conversion processes. The slurries encountered are non-Newtonian in nature due to the presence of soluble and insoluble solids (sugar, ash, and lignin based components), with the fine particle size causing difficulty in separation. This project will devise a scheme that obviates the very need for some of solid/liquid separation steps and to render the rest more pliable. In the proposed process, the solid/liquid separations occur in situ and at operating temperature, thereby yielding two liquor streams (one containing mostly pentose sugars and one containing mostly lignin) and a solid cellulose stream from a single piece of equipment, i.e., a twin-screw extruder. In Phase I, a twin-screw extruder apparatus will be used to demonstrate the concept of a continuous multi-stage reactive separation using wheat straw. Liquid streams from hemicellulose hydrolysis (first stage) and from ethanol delignification (second stage) will be generated and separated from solids in situ. These streams and the cellulose stream will be evaluated in the context of a potentially economical process. Commercial Applications and Other Benefits as Described by awardee: The reactive fractionation process separates cellulose fibers from the other constituents of lignocellulosic biomass. The end products should find use in the manufacture of paper, plastics, ethanol, and other chemicals. The purified cellulose could be used as a pulp or pulp substitute in the pulp and paper industry, or alternatively, it could be hydrolyzed to produce gluclose for producing different chemicals including ethanol. Other potential benefits include improved biorefining economics and the production of a purer lignin product, which could be used as a binder in asphalt and as a resin for manufacture of a variety of plastic products without environmental problems.