Digestion of cellulosic biomass solids may be complicated by release of lignin therefrom. Methods and systems for processing a reaction product containing lignin-derived products, such as phenolics, can comprise hydrotreating the reaction product to convert the lignin-derived products to desired higher molecular weight compounds. The methods can further include separating the higher molecular weight compounds from unconverted products, such as unconverted phenolics, and recycling the unconverted phenolics for use as at least a portion of the digestion solvent and for further conversion to desired higher molecular weight compounds with additional hydrotreatment. The methods and systems can further include generating hydrogen with the further hydrotreatment.

A process for recovery of lignin from black liquor that contains either soluble or dispersed lignin by generating a “liquid lignin” at high yield is disclosed. Soluble lignin at a high pH is precipitated by reducing the pH of the black liquor stream by countercurrent reaction with carbon dioxide, at elevated temperature and pressure, creating a dense liquid-lignin phase and a light lignin-depleted phase. The dense lignin-rich phase is separated and washed countercurrently with a non-sulfur containing acid, such as acetic acid or formic acid, to displace metal cations from the lignin, creating a low-salt lignin, which is then formed into a low-dust, high-bulk density lignin fuel pellet. If desired, an oxidation step may be used to eliminate odor for lignins having high value green chemistry applications.

A process for preparing lactic acid and/or a lactate salt via the fermentation of carbohydrates obtained from lignocellulosic material. In particular the process includes: a) treating a lignocellulosic material with an alkaline agent including a caustic magnesium salt in the presence of water to provide a treated aqueous lignocellulosic material; b) saccharifying the treated aqueous lignocellulosic material in the presence of a hydrolytic enzyme to provide a saccharified aqueous lignocellulosic material including fermentable carbohydrates and a solid lignocellulosic fraction; c) fermenting the fermentable carbohydrates in the saccharified aqueous lignocellulosic material by way of lactic acid producing microorganism in the presence of an alkaline agent including a caustic magnesium salt to provide an aqueous fermentation broth including a magnesium lactate; and d) isolating lactic acid and/or lactate salt from the fermentation broth; wherein the saccharification step b) and the fermentation step c) are performed as two separate steps.

The invention herein disclosed and claimed is a process for refining fiber from lignocellulosic biomass. The process provides refined fiber and agriculturally amenable co-products, with a virtually waste-free systems design.

Digestion of cellulosic biomass solids may be complicated by release of lignin therefrom. Methods and systems for processing a reaction product containing lignin-derived products, such as phenolics, can comprise hydrotreating the reaction product to convert the lignin-derived products to desired higher molecular weight compounds. The methods can further include separating the higher molecular weight compounds from unconverted products, such as unconverted phenolics, and recycling the unconverted phenolics for use as at least a portion of the digestion solvent and for further conversion to desired higher molecular weight compounds with additional hydrotreatment.

Lignin has a weight average molecular weight of at least 6,000 daltons and comprising (a) from 2% to 10% of a low molecular component having a weight average molecular weight (M.sub.w) of from 300 to 1500 daltons, and (b) from 10% to 50% of a high molecular weight component having a weight average molecular weight (M.sub.w) of at least 10,000 daltons; and exhibiting a T.sub.g of from 100° C. to 130° C. when measured by differential scanning calorimetry.

The invention is directed to compositions and processes concerning efficient downstream processing of products derived from organic acids pretreatment of plant materials.

The method is for separation of lignin from original black liquor (BL.sub.IN) that has a first precipitation phase (PR1/PR2) for precipitation of lignin by a first acidification using acidifier, CO.sub.2, at alkaline conditions, then separating a lignin cake with subsequent suspension of the lignin cake in a strong acid in order to leach out metals from the lignin followed by dewatering and obtaining a clean lignin product LP. Lignin germ particles (LG) are added to the original black liquor in the first precipitation stage, preferably between two phases in said precipitation stage, in order to increase lignin particle growth on such lignin germ particles instead of spontaneous nucleation of lignin particles in said original black liquor. This results in improved filterability in subsequent dewatering and lignin cake formation and hence an increased lignin yield.

Methods of fractionating lignocellulosic biomass using maleic acids are provided. Also provided are methods of forming lignin particles, furans, sugars, and/or lignocellulosic micro- and nanofibrils from the liquid and solid fractions produced by fractionation process. The fractionation can be carried out at low temperatures with short reaction times to carboxylate and dissolve lignin with a low degree of condensation.

A method of depolymerising a lignin includes oxidising the lignin to provide an oxidised lignin wherein benzylic —OH of β-O-4 linkages have been converted to carbonyl. The oxidised lignin is depolymerised with a metal selected from the group consisting of zinc, magnesium, aluminium and titanium or mixtures thereof, in the presence of an ammonium salt or carbon dioxide. Also described are methods for manufacturing phenolic products from lignin and a method for the cleavage of a β-O-4 linkage in a substrate.