Patent ID: 8268121

Claim:
A method to remove lignin from biomass which comprises lignin containing plant material and to produce amino salt of lignin, amino-lignin-cellulose, amino lignin aldehyde resin, and carbohydrates comprising mixing, heating and reacting at ambient to elevated temperature, at ambient, or elevated or reduced pressure the following components: a) biomass, comprising lignin containing plant material, in the amount of 200 to 400 parts by weight; b) amino compound, selected from the group consisting of urea, guanidine, aminoguanidine, guanidine carbonate, urea guanidine condensates, urea polyamine condensates, urea-melamine condensates, urea-cyandiamide, urea-aminoguanidine condensate, urea cyanoguanidine condensate, and mixtures thereof, and urea combined with 50% by weight of thiourea, methyl urea, biuret, cyanuric acid, melamine dicyandiamide, melamine cyanurate and mixtures thereof, said amino compounds are utilized in the amount of 25-100 parts by weight; c) water, 1 to 500 parts by weight; components a, b and c are mixed, heated at ambient to elevated pressure for 1-24 hours and reacted to produce a mixture of water soluble aqueous amino salt of lignin and water soluble cellulose and non-water soluble amino-lignin-cellulose which are separated by pressing and filtering, then the following component d, e and f are added to the aqueous amino salt of lignin; d) aldehyde, in the amount of 1 to 3 moles of aldehyde to 1 mol of amino compound; e) catalyst, selected from the group consisting of sulfuric acid, hydrogen chloride, nitric acid, halogen acids, acidic compounds containing sulfur, sulphonic acid halides, acidic phosphorus containing compound, carboxylic acids, polycarboxylic acids, nitric acids and mixtures thereof in the amount of 0.1 to 100 parts by weight; f) filler, in the amount of 1-300 parts by weight; component d, e and f are mixed with the aqueous amino salt of lignin and adjusting the pH to 5 then agitated and heated up to 70 degrees C. for 0.5 to 60 minutes then heated up to 150 degrees C. till polymerization takes place thereby producing a thermosetting, brown, hard, fire resistant aldehyde-amino-lignin-cellulose material, then the non-water soluble amino-lignin-cellulose is dried and mixed with 70% sulfuric acid in the ratio of 2 to 3 parts by weigh of acid to 2 part by weight of non-water soluble amino-lignin-cellulose then heated at 50 degrees C. for 2-6 hours thereby producing a carbohydrates mixture which also contains sulfuric acid, amino sulfate and residual cellulose and lignin cellulose mixture, then the carbohydrates, amino salt of sulfuric acid and sulfuric acid are separated from the residual lignin cellulose and cellulose by pressing and filtering, then the acid and carbohydrates are separated by ion exchange and the solution of carbohydrates are neutralized by adding of calcium hydroxide.