Biomass delignification

Abstract

A method for substantially removing constituents of a lignocellulosic biomass into separate streams, where said method comprises the following steps:Step 1: providing said lignocellulosic biomass comprising: cellulose; hemicellulose; and lignin;Step 2: exposing the lignocellulosic biomass to a delignification step performed at a temperature below 55° C. using a modified Caro's acid and generating a reaction mixture, said delignification step is carried out for a first period of time sufficient to dissolve enough of the lignin present in said lignocellulosic biomass to obtain a kappa number for the remaining solids of less than 10;Step 4: recovering, from the reaction mixture, a liquid stream comprising depolymerized lignin constituents and said remaining solids comprising cellulose and hemicellulose and having a lignin content of less than 1.5% lignin;Step 5: exposing said remaining solids to a caustic composition at a low temperature, (preferably below 60° C.), to generate a caustic mixture comprising said caustic composition, hemicellulose and cellulose;Step 6: allowing sufficient time for at least 85% of the remaining hemicellulose present to be dissolved by said caustic composition, and wherein exposure to said caustic composition yields a final solids portion;Step 6: optionally, separating said dissolved hemicellulose from said final solids portion; andStep 7: optionally, recovering said final solid portion; andStep 8: recovering said hemicellulose from said dissolved hemicellulose, wherein said hemicellulose recovered constitutes over 85% of the hemicellulose present in said remaining solids portion and is mainly in a polysaccharide form.

1 . A method for substantially removing constituents of a lignocellulosic biomass into separate streams, where said method comprises the following steps:
 Step 1: providing said lignocellulosic biomass comprising: cellulose; hemicellulose; and lignin;   Step 2: exposing the lignocellulosic biomass to a delignification step performed at a temperature below 55° C. using a modified Caro's acid and generating a reaction mixture, wherein said modified Caro's acid is selected from the group consisting of:
 composition A; composition B; composition C; composition D; 
 composition E; composition F; composition G; composition H; composition I; and composition J; 
   
       wherein said composition A comprises:
 sulfuric acid; 
 a compound comprising an amine moiety and a sulfonic acid moiety; and 
 a peroxide; and wherein sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1; 
 
       wherein said composition B comprises:
 sulfuric acid; 
 a compound comprising an amine moiety; 
 a compound comprising a sulfonic acid moiety; and 
 a peroxide; wherein sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1:1:1; 
 
       wherein said composition C comprises:
 an alkylsulfonic acid; and 
 a peroxide; wherein said alkylsulfonic acid and said peroxide are present in a molar ratio of no less than 1:1; 
 
       wherein said composition D comprises:
 sulfuric acid; 
 a heterocyclic compound; and 
 peroxide; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition E comprises:
 sulfuric acid; 
 a modifying agent comprising a compound containing an amine group; and 
 a peroxide; and wherein sulfuric acid and said compound containing an amine group; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition F comprises:
 sulfuric acid; 
 a modifying agent comprising an alkanesulfonic acid and 
 a peroxide; and wherein sulfuric acid and said alkanesulfonic acid are present in a molar ratio of no less than 1:1; 
 
       wherein said composition G comprises:
 sulfuric acid; 
 a substituted aromatic compound; and 
 a peroxide; and wherein sulfuric acid and said substituted aromatic compound; 
 are present in a molar ratio of no less than 1:1; 
 
       wherein said composition H comprises:
 sulfuric acid; 
 a modifying agent comprising an arylsulfonic acid; 
 a peroxide; and 
 optionally, a compound containing an amine group; wherein sulfuric acid and said a arylsulfonic acid; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition I comprises:
 sulfuric acid; 
 a heterocyclic compound; 
 an alkanesulfonic acid and 
 a peroxide; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition J comprises:
 sulfuric acid; 
 a carbonyl-containing nitrogenous base compound; and 
 a peroxide; and wherein sulfuric acid and said a carbonyl-containing nitrogenous base compound; are present in a molar ratio of no less than 1:1; 
 said delignification step is carried out for a first period of time sufficient to dissolve enough of the lignin present in said lignocellulosic biomass to obtain a kappa number for the remaining solids of less than 10; 
 Step 4: recovering, from the reaction mixture, a liquid stream comprising depolymerized lignin constituents and said remaining solids comprising cellulose and hemicellulose and having a lignin content of less than 1.5% lignin; 
 Step 5: exposing said remaining solids to a caustic composition at a low temperature, (preferably below 60° C.), to generate a caustic mixture comprising said caustic composition, hemicellulose and cellulose; 
 Step 6: allowing sufficient time for at least 85% of the remaining hemicellulose present to be dissolved by said caustic composition, and wherein exposure to said caustic composition yields a final solids portion; 
 Step 6: optionally, separating said dissolved hemicellulose from said final solids portion; and 
 Step 7: optionally, recovering said final solid portion; and 
 Step 8: recovering said hemicellulose from said dissolved hemicellulose, wherein said hemicellulose recovered constitutes over 85% of the hemicellulose present in said remaining solids portion and is mainly in a polysaccharide form. 
 
     
     
         2 . The method according to  claim 1 , wherein said modified Caro's acid composition is composition A. 
     
     
         3 . The method according to  claim 1 , wherein said modified Caro's acid composition is composition B. 
     
     
         4 . The method according to  claim 1 , wherein said modified Caro's acid composition is composition C. 
     
     
         5 . A method for the delignification by exposure to a modified Caro's acid of a lignocellulosic biomass and separation of said lignocellulosic biomass constituents into separate streams and recovery of hemicellulose in a polysaccharide form, said method comprising the steps of:
 providing a vessel;   providing a biomass feedstock comprising lignin, hemicellulose and cellulose fibers into said vessel;   providing a modified Caro's acid comprising the following:
 a sulfuric acid component; 
 a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; taurates; aminoalkylsulfonic acids where the alkyl is selected from the group consisting of C 1 -C 5  linear alkyl and C 3 -C 5  branched alkyl; 
 a peroxide component; 
   exposing said lignocellulosic biomass to said modified Caro's acid;   allowing said modified Caro's acid to come into contact with said lignocellulosic biomass for a period of time sufficient to a delignification reaction to occur and yielding a remaining solids portion comprising cellulose and hemicellulose and having a lignin content of less than 1.5% lignin;   separating a resulting liquid portion mainly comprising dissolved lignin from said remaining solids portion comprising mainly cellulose and hemicellulose:   treating said remaining solids portion by exposing such to a caustic composition for a period of time sufficient to solubilize over 90 wt % of remaining hemicellulose into a caustic liquid phase;   separating said caustic liquid phase comprising said dissolved hemicellulose in a polysaccharide form from a final solid portion comprising mainly cellulose.   
     
     
         6 . The method according to  claim 5 , wherein the removal of hemicellulose from hemicellulose-containing caustic solution comprises an addition of a solvent, such as ethanol, to said caustic liquid phase to precipitate said hemicellulose from said caustic alkali solution and a removal of the resulting precipitated hemicellulose from the caustic solution. 
     
     
         7 . A method for the recovery of hemicellulose in its polysaccharide form from a delignification of a lignocellulosic biomass by exposure to a modified Caro's acid, said process comprises the steps of:
 providing a vessel;   providing a biomass feedstock comprising lignin, hemicellulose and cellulose fibers into said vessel;   providing a modified Caro's acid, wherein the acid concentration in said modified Caro's acid is less than 40%;   exposing said lignocellulosic biomass to said modified Caro's acid to create a reaction mixture;   allowing said modified Caro's acid to come into contact with said lignocellulosic biomass for a period of time sufficient to perform a delignification reaction which yields a liquid portion and a remaining solids portion comprising hemicellulose and cellulose, said remaining solid portion having a kappa number of less than 10;   separating the resulting liquid portion from said remaining solid portion, said liquid portion comprising depolymerized lignin;   treating said remaining solid portion with a caustic composition for a period of time sufficient to solubilize over 90 wt % of remaining hemicellulose into a caustic liquid phase;   separating said caustic liquid phase comprising said dissolved hemicellulose from a final solid portion comprising a high purity cellulose; and   recovering said hemicellulose from said dissolved hemicellulose, wherein said hemicellulose recovered constitutes over 85% of the hemicellulose present in said remaining solid portion and is mainly in a polysaccharide form.   
     
     
         8 . A method according to  claim 7 , where said modified Caro's acid is selected from the group consisting of: composition A; composition B; composition C; composition D; composition E; composition F; composition G; composition H; composition I; and composition J; 
       wherein said composition A comprises:
 sulfuric acid; 
 a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; taurates; aminoalkylsulfonic acids where the alkyl is selected from the group consisting of C 1 -C 5  linear alkyl and C 3 -C 5  branched alkyl; 
 and 
 a peroxide; and wherein sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no less than 1:1:1; 
 
       wherein said composition B comprises:
 sulfuric acid; 
 a compound comprising an amine moiety; 
 a compound comprising a sulfonic acid moiety; and 
 a peroxide; wherein sulfuric acid and said a compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio of no less than 1:1:1; 
 
       wherein said composition C comprises:
 an alkylsulfonic acid; and 
 a peroxide; wherein said alkylsulfonic acid and said peroxide are present in a molar ratio of no less than 1:1; 
 
       wherein said composition D comprises:
 sulfuric acid; 
 a heterocyclic compound; and 
 a peroxide; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition E comprises:
 sulfuric acid; 
 a modifying agent comprising a compound containing an amine group; and 
 a peroxide; and wherein sulfuric acid and said compound containing an amine group; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition F comprises:
 sulfuric acid; 
 a modifying agent comprising an alkanesulfonic acid and 
 a peroxide; and wherein sulfuric acid and said alkanesulfonic acid are present in a molar ratio of no less than 1:1; 
 
       wherein said composition G comprises:
 sulfuric acid; 
 a substituted aromatic compound; and 
 a peroxide; and wherein sulfuric acid and said substituted aromatic compound; 
 are present in a molar ratio of no less than 1:1; 
 
       wherein said composition H comprises:
 sulfuric acid; 
 a modifying agent comprising an arylsulfonic acid; 
 a peroxide; and 
 optionally, a compound containing an amine group; wherein sulfuric acid and said a arylsulfonic acid; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition I comprises:
 sulfuric acid; 
 a heterocyclic compound; 
 an alkanesulfonic acid and 
 a peroxide; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1; 
 
       wherein said composition J comprises:
 sulfuric acid; 
 a carbonyl-containing nitrogenous base compound; and 
 a peroxide; and 
 
       wherein sulfuric acid and said a carbonyl-containing nitrogenous base compound; are present in a molar ratio of no less than 1:1; and 
       wherein the acid concentration in said modified Caro's acid is less than 40%. 
     
     
         9 . A method according to  claim 7 , where said lignocellulosic biomass is in chips of up to 5 cm in size. 
     
     
         10 . A method according to  claim 7 , where said lignocellulosic biomass is in chips of up to 3 cm in size. 
     
     
         11 . A method according to  claim 7 , where said lignocellulosic biomass is in chips ranging between 1 and 2 cm in size.