The present invention relates to novel lignin-derived compounds and compositions comprising the same and their use as redox flow battery electrolytes. The invention further provides a method for preparing said compounds and compositions as well as a redox flow battery comprising said compounds and compositions. Additionally, an assembly for carrying out the inventive method is provided.

The present invention relates to fractions of high purity lignin which are thermally stable, and to methods of producing said fractions from lignocellulosic material.

The invention concerns a method for treatment of a stream of mixed compounds (4a) obtained from a process (3) comprising decomposition and/or conversion of a wood or pulp material, the method comprising: feeding the stream (4a-4e) through a processing arrangement (2) comprising one or more treatment units (10, 20, 30, 40, 50) arranged to separate at least a first compound from other compounds in the stream and form a first product flow (4f) containing the first compound, wherein the one or more treatment units comprises at least a first primary separation unit (20) arranged to separate one or more compounds other than the first compound from the stream; and feeding the compounds separated from the first compound in the first primary separation unit (20) to a first auxiliary separation unit (21) so as to separate a second compound from at least one of the other compounds separated from the first compound in the first primary separation unit (20) and thereby increase the purity of said second compound and form a second product flow (22, 23) in the form of a purified second compound and/or a purified derivative of the second compound, wherein the second compound is dimethyl sulfide (DMS, CH3—S—CH3), methyl mercaptan (CH3—S—H) or acetone (CH3—CO—CH3).

Methods of dewatering viscous materials are provided. The method comprises contacting the viscous material with pressurized carbon dioxide at a temperature and for a time wherein at least a fraction of water is expressed from the viscous material. Then the pressure is released, and the water expressed from the viscous material is removed to yield a dewatered product. Exemplary viscous materials that can be dewatered by the method include black liquor from wood pulping operations, wet lignin, wet super water absorbent polymers and sugar solutions. The pressurized carbon dioxide is present in subcritical or supercritical form. The method provides dewatering at reduced cost.

A low energy production process for producing paper pulp from lignocellulosic biomass, the process comprising the following successive steps: a) extracting lignins and hemicellulose from lignocellulosic biomass by putting at least one solid lignocellulosic raw material in the presence of a mixture, composed only of water and of formic acid, at atmospheric pressure and under controlled conditions of reaction temperature between ambient temperature and the reflux temperature of the mixture at atmospheric pressure, preferably between 80° C. and 100° C., with a weight ratio of the at least one solid lignocellulosic raw material/liquid mixture comprised between 1/1 and 1/15, and for a determined period of time of reaction; and b) separating, at atmospheric pressure and at the reaction temperature, a solid fraction, constituting raw paper pulp, from an organic phase containing in solution at least the starting formic acid and water mixture, solubilized monomeric and polymeric sugars, lignins.

The invention relates to a method and a system for adjusting S/Na-balance of a pulp mill, wherein an aqueous pulp mill liquor containing sulphides is diverted into a bioreactor and oxidized by means of sulphur-oxidizing microbes, thereby producing an aqueous suspension from which elemental sulphur can be separated as a precipitate and the residual solution may be directed to causticizing. Optionally, prior to oxidation in the bioreactor, the aqueous pulp mill liquor may be first stripped to obtain a gas stream containing H2S which is then scrubbed with a scrubbing solution to obtain an aqueous spent scrubbing solution containing sulphides, in which case the residual solution can be used to replenish the scrubbing solution.

Methods and systems for preparing agricultural residue or other agricultural feedstock for use as a pulp. The method includes providing non-wood agricultural residue (e.g., corn stover) or other agricultural feedstock that includes agricultural fibers, chemically pulping the agricultural fibers in a preliminary alkaline chemical pulping process at a low consistency and at a low temperature to produce partially pulped agricultural fibers, such step including separating lignin and hemicellulose from the partially pulped agricultural fibers, introducing the partially pulped agricultural fibers into a first reactor, wherein the first reactor operates at a low temperature of less than 100° C. (e.g., 65° C.), introducing the agricultural fibers from the first reactor into a second reactor, where the second reactor operates at a low temperature, of less than 100° C. (e.g., 94-96° C.), the second reactor operating at a higher temperature than the first reactor, to produce pulped agricultural fibers.

The present invention relates to a method for preparing monomers via depolymerisation from lignocellulose-containing biomass.

The method is for separation of lignin from original black liquor (BL.sub.IN) that has a first precipitation stage (PR) for precipitation of lignin by a first acidification using acidifier AC.sub.1, preferably using 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 our metals from the lignin followed by dewatering and obtaining a clean lignin product LP. The process further is improved by intensified hydrolysis of lignin cake such that most of the carbohydrates are broken down to dissolvable monomers that could be separated from the lignin in the filtrate from a filtering stage subsequent to the hydrolysis. The improved hydrolysis could reduce as much as 90% of the carbohydrate content using a moderately increased temperature and increased charge of acidifier while avoiding any larger lignin yield losses.

Provided is an unique, efficient and cost-effective process for the recovery of acid from acid-rich solutions. The process of the subject matter utilizes a strong oxidizer, such as Caro's acid, to disintegrate or render insoluble organic or inorganic materials such as carbohydrates and complexes thereof contained in acid-rich solutions, to make efficient and simple the separation and recovery of the acid solution. The acid recovered thus obtained is free of organic matter, and containing nearly all of the acid originally contained in the acid-rich solution.