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; 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.

Claims

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.sub.1-C.sub.5 linear alkyl and C.sub.3-C.sub.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.sub.1-C.sub.5 linear alkyl and C.sub.3-C.sub.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.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0174] Features and advantages of embodiments of the present application will become apparent from the following detailed description and the appended figures, in which:

[0175] FIG. 1 is a FTIR spectra of the resulting cellulose obtained using the process according to a preferred embodiment of the present invention and a comparative FTIR spectra of Avicel, a commercially available cellulose.

DETAILED DESCRIPTION OF THE INVENTION

[0176] The delignification of biomass according to conventional approaches, such a kraft pulping, yields a pulp which is still high in lignin and hemicellulose.

[0177] The most common process for pulp delignification is the kraft process. In the kraft process, wood chips are converted to wood pulp. The multi-step kraft process consists of a first step where wood chips are impregnated with a chemical solution. This is done by wetting wood chips and pre-heating them with steam. This swells the wood chips and expels the air present in them and replaces the air with the liquid. Then the chips are saturated with a black liquor and a white liquor. The black liquor is a resulting product from the kraft process. It contains water, lignin residues, hemicellulose, and inorganic chemicals. White liquor is a strong alkaline solution comprising sodium hydroxide and sodium sulfide. Once the wood chips have been soaked in the different solutions, they undergo cooking. To achieve delignification in the wood chips, the cooking is carried out for a few hours at temperatures reaching up to 176 C. At these temperatures, the lignin and hemicellulose degrade to yield water soluble fragments. The remaining cellulosic fibers are collected and washed after the cooking step.

[0178] Biofuel production is another potential application for the kraft process. One of the current drawbacks of biofuel production is that it requires the use of plant parts (such as seeds) in order to transform carbohydrates into fuel in a reasonably efficient process. The carbohydrates could be obtained from cellulosic fibers, by using non-food grade biomass in the kraft process. However, the energy intensive nature of the kraft process for delignification as well as the low delignification efficiencies make this a less commercially viable option. In order to build a plant based chemical resource cycle, there is a great need for energy efficient processes which can utilize plant-based feedstocks that don't compete with human food production.

[0179] While the kraft pulping process is the most widely used chemical pulping process in the world, it is extremely energy intensive and has other drawbacks, for example, substantial odours emitted around pulp producing plants.

[0180] The applicant has a patented delignification process which produces a bio-crude feedstock that is substantially free of cellulose derivatives and hence its composition is enhanced compared to pyrolysis bio-crude. According to a preferred embodiment of the present invention, this bio-crude feedstock can be achieved by performing a delignification reaction using a modified Caro's acid composition selected from the group consisting of composition A; composition B and Composition C; [0181] wherein said composition A comprises: [0182] sulfuric acid in an amount ranging from 20 to 40 wt % of the total weight of the composition; [0183] a compound comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds; and [0184] a peroxide; [0185] wherein said composition B comprises: [0186] an alkylsulfonic acid; and [0187] a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt % of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt % of the total weight of the composition; [0188] wherein said composition C comprises: [0189] sulfuric acid; [0190] a compound comprising an amine moiety; [0191] a compound comprising a sulfonic acid moiety; and [0192] a peroxide.

[0193] According to preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,678) comprises: sulfuric acid; a heterocyclic compound; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1. Preferably, the sulfuric acid and said heterocyclic compound are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 16:1 to 5:1. Preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 12:1 to 6:1. Also preferably, said heterocyclic compound has a molecular weight below 300 g/mol. Also preferably, said heterocyclic compound has a molecular weight below 150 g/mol. More preferably, said heterocyclic compound is a secondary amine. According to a preferred embodiment of the present invention, said heterocyclic compound is selected from the group consisting of: imidazole; triazole; and N-methylimidazole.

[0194] According to a preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,677) comprises: sulfuric acid; a modifying agent comprising a compound containing an amine group; and wherein sulfuric acid and said compound containing an amine group; are present in a molar ratio of no less than 1:1. Preferably, the sulfuric acid and said compound containing an amine group are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and compound containing an amine group are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and compound containing an amine group are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and compound containing an amine group are present in a molar ratio ranging from 16:1 to 5:1. Preferably, the sulfuric acid and compound containing an amine group are present in a molar ratio ranging from 12:1 to 6:1. According to a preferred embodiment of the present invention, the modifying agent is selected in the group consisting of: TEOA; MEOA; pyrrolidine; DEOA; ethylenediamine; diethylamine; triethylamine; morpholine; MEA-triazine; and combinations thereof. According to a more preferred embodiment of the present invention, the modifying agent is TEOA; MEOA; pyrrolidine; DEOA; ethylenediamine; triethylamine.

[0195] According to a preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,676) comprises: sulfuric acid; a modifying agent comprising an alkanesulfonic acid; and wherein sulfuric acid and said alkanesulfonic acid are present in a molar ratio of no less than 1:1. Preferably, said alkanesulfonic acid is selected from the group consisting of: alkanesulfonic acids where the alkyl groups range from C.sub.1-C.sub.6 and are linear or branched; and combinations thereof. Preferably, said alkanesulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof. More preferably, said alkanesulfonic acid is methanesulfonic acid. Also preferably, said alkanesulfonic acid has a molecular weight below 300 g/mol. Also preferably, said alkanesulfonic acid has a molecular weight below 150 g/mol. Preferably, the sulfuric acid and said alkanesulfonic acid and are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and alkanesulfonic acid are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and alkanesulfonic acid are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and alkanesulfonic acid are present in a molar ratio ranging from 16:1 to 5:1. According to a preferred embodiment of the present invention, the sulfuric acid and alkanesulfonic acid are present in a molar ratio ranging from 12:1 to 6:1.

[0196] According to preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,675) comprises: sulfuric acid; a substituted aromatic compound; and wherein sulfuric acid and said substituted aromatic compound; are present in a molar ratio of no less than 1:1. Preferably, the substituted aromatic compound comprises at least two substituents. More preferably, at least one substituent is an amine group and at least one of the other substituent is a sulfonic acid moiety. According to a preferred embodiment, the substituted aromatic compound comprises three or more substituent. According to a preferred embodiment of the present invention, the substituted aromatic compound comprises at least a sulfonic acid moiety. According to another preferred embodiment of the present invention, the substituted aromatic compound comprises an aromatic compound having a sulfonamide substituent, where the compound can be selected from the group consisting of: benzenesulfonamides; toluenesulfonamides; substituted benzenesulfonamides; and substituted toluenesulfonamides. Preferably, the sulfuric acid and said substituted aromatic compound and are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and substituted aromatic compound are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and substituted aromatic compound are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and substituted aromatic compound are present in a molar ratio ranging from 16:1 to 5:1. Preferably, the sulfuric acid and substituted aromatic compound are present in a molar ratio ranging from 12:1 to 6:1.

[0197] According to preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,674) comprises: sulfuric acid; a modifying agent comprising an arylsulfonic acid; 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. Preferably, the compound containing an amine group is selected from the group consisting of: imidazole; N-methylimidazole; triazole; monoethanolamine (MEOA); diethanolamine (DEOA); triethanolamine (TEOA); pyrrolidine and combinations thereof. According to a preferred embodiment of the present invention, sulfuric acid and the peroxide are present in a molar ratio of approximately 1:1. Preferably, the sulfuric acid and said arylsulfonic acid and are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and arylsulfonic acid are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and arylsulfonic acid are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and arylsulfonic acid are present in a molar ratio ranging from 16:1 to 5:1. According to a preferred embodiment of the present invention, the sulfuric acid and arylsulfonic acid are present in a molar ratio ranging from 12:1 to 6:1. Also preferably, said arylsulfonic acid has a molecular weight below 300 g/mol. Also preferably, said arylsulfonic acid has a molecular weight below 150 g/mol. Even more preferably, said arylsulfonic acid is selected from the group consisting of: orthanilic acid; metanilic acid; sulfanilic acid; toluenesulfonic acid; benzenesulfonic acid; and combinations thereof.

[0198] According to preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,673) comprises: sulfuric acid; a heterocyclic compound; an alkanesulfonic acid; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1. Preferably, said aqueous acidic composition comprising: sulfuric acid; a heterocyclic compound; an arylsulfonic acid; and wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1. Preferably, the arylsulfonic acid is toluenesulfonic acid.

[0199] Preferably, the sulfuric acid, the heterocyclic compound and the alkanesulfonic acid are present in a molar ratio ranging from 28:1:1 to 2:1:1. More preferably, the sulfuric acid the heterocyclic compound and the alkanesulfonic acid are present in a molar ratio ranging from 24:1:1 to 3:1:1. Preferably, the sulfuric acid, the heterocyclic compound and the alkanesulfonic acid are present in a molar ratio ranging from 20:1:1 to 4:1:1. More preferably, the sulfuric acid, the heterocyclic compound and the alkanesulfonic acid are present in a molar ratio ranging from 16:1:1 to 5:1:1. According to a preferred embodiment of the present invention, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 12:1:1 to 6:1:1. Also preferably, said heterocyclic compound has a molecular weight below 300 g/mol. Also preferably, said heterocyclic compound has a molecular weight below 150 g/mol. Even more preferably, said heterocyclic compound is selected from the group consisting of: imidazole; triazole; n-methylimidazole; and combinations thereof. Preferably, the alkanesulfonic acid is selected from the group consisting of: [0200] alkylsulfonic acids where the alkyl groups range from C.sub.1-C.sub.6 and are linear or branched; and combinations thereof. Preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof. More preferably, said alkylsulfonic acid is methanesulfonic acid.

[0201] According to preferred embodiment of the present invention, the modified Caro's acid (as disclosed in Canadian patent application 3,128,672) comprises: sulfuric acid; a carbonyl-containing nitrogenous base compound; and wherein sulfuric acid and said a carbonyl-containing nitrogenous base compound; are present in a molar ratio of no less than 1:1. According to a preferred embodiment of the present invention, the carbonyl-containing nitrogenous base compound is selected from the group consisting of: caffeine; lysine; creatine; glutamine; creatinine; 4-aminobenzoic acid; glycine; NMP (N-methyl-2-pyrrolidinone); histidine; DMA (N,N-dimethylacetamide); arginine; 2,3-pyridinedicarboxylic acid; hydantoin; and combinations thereof. Preferably, the sulfuric acid and said carbonyl-containing nitrogenous base compound and are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and carbonyl-containing nitrogenous base compound are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and carbonyl-containing nitrogenous base compound are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and carbonyl-containing nitrogenous base compound are present in a molar ratio ranging from 16:1 to 5:1. According to a preferred embodiment of the present invention, the sulfuric acid and carbonyl-containing nitrogenous base compound are present in a molar ratio ranging from 12:1 to 6:1.

[0202] The pyrolysis of biomass thermally decomposes the liquid portion of the biomass in the absence of air to produce a liquid (bio-crude) through the application of a high heat transfer rate to the biomass particles. The applicant's patented delignification process (using a modified Caro's acid) separates cellulose from the other biomass constituents (lignin and hemicellulose) at a recovery rate of +99% and can depolymerize lignin and hemicellulose into a liquid-rich organic liquid called Lignin-Hemicellulose-Depolymerized-Organics (LHDO). The applicant's LHDO contains virtually no aldehydes, and all carboxylic acids are converted once the LHDO is upgraded using hydrodeoxygenation (HDO). This eliminates the need for bio-crude aldehyde's role in bio-crude stability from thermal application or stability over time. Aldehydes present in pyrolysis bio-crude react with sugars to form higher-molecular-weight resins and oligomers via polymerization and condensation; oligomerization reactions lead to coke formation, which is highly undesirable in bio-crudes. Furthermore, the applicant's LHDO produces minimum and almost negligible char/coke during the HDO process and the upgraded LHDO is completely miscible with Jet and Diesel Fuels without the need for pre-treatment step used for pyrolysis bio-crude by oxidation followed by mild temperature hydrotreating stage to eliminate polymerization that occurred through during hydrocracking process.

[0203] It is noteworthy to point out that current pyrolysis of biomass generally yields a large amount of biochar (up to 30-40%). This is highly undesirable as biochar is low in value and the potential to use the remaining bio-crude as a fuel additive, which is the high value product, is greatly diminished due to the large amount of conversion of biomass into bio-char.

[0204] Preferably, said lignin-rich feedstock comprises more than 80 wt % of lignin-based compounds obtained from delignification of biomass. More preferably, said lignin-rich feedstock comprises more than 85 wt % of lignin-based compounds obtained from delignification of biomass. Even more preferably, said lignin-rich feedstock comprises more than 90 wt % of lignin-based compounds obtained from delignification of biomass. Yet even more preferably, said lignin-rich feedstock comprises more than 95 wt % of lignin-based compounds obtained from delignification of biomass. According to a preferred embodiment of the method of the present invention, the lignin-rich feedstock comprises more than 97.5 wt % of lignin-based compounds obtained from delignification of biomass.

[0205] In an application using a resulting stream obtained from a preferred embodiment of the process of the present invention, one can produce biofuel using a lignin-rich feedstock using a method comprising: [0206] providing a lignin-rich feedstock, wherein said lignin-rich feedstock comprises more than 60 wt % of lignin-based compounds obtained from delignification of biomass, where said lignin-based compounds are selected from the group consisting of: lignin-derived monomers, lignin-derived dimers, lignin-derived oligomers and combinations thereof; wherein said lignin-rich feedstock is substantially free of hemicellulose and cellulose; and [0207] performing a hydrodeoxygenation reaction on said lignin-rich feedstock, wherein the hydrodeoxygenation reaction is carried out in a hydrogen-rich source at a temperature ranging from 300 C. to 400 C. under a H.sub.2 pressure ranging from 15 to 50 bar, more preferably 35 bar, in the presence of a catalyst adapted for HDO reactions, for a period of time sufficient to result in an upgraded oil having a TAN of about 2.5 mg KOH/g and viscosity of 3.4 cP.

[0208] In the context of manufacture of bioethanol, it is to be understood that the presence of a low amount of hemicellulose (including but not limited to xylose) may still yield generally much improved yields in comparison to conventional cellulose which contains larger percentages of hemicellulose (including but not limited to xylose) scattered therein. For instance, since xylose is in general, the second most common sugar found in lignocellulosic biomass, it is expected that it be present in a range of 15-25% in a conventional pulp after delignification.

[0209] Preferably, the addition of a substantially free of xylose biomass additive allows for an increase in the generation of ethanol in a fermentation unit when the biomass additive is used as part of the organic waste being fermented or as the entire organic load in the fermentation unit. When converting cellulose to ethanol, it is preferable to have a biomass where the cellulose is substantially free of hemicellulose. Preferably, the biomass contains at most 10% of the original hemicellulose content from harvested lignocellulosic biomass. Preferably, the biomass contains at most 8% of the original hemicellulose content from harvested lignocellulosic biomass. Preferably, the biomass contains at most 6% of the original hemicellulose content from harvested lignocellulosic biomass. Preferably, the biomass contains at most 5% of the original hemicellulose content from said harvested lignocellulosic biomass. Preferably, the biomass contains at most 4% of the original hemicellulose content from said harvested lignocellulosic biomass. Preferably, the biomass contains at most 3% of the original hemicellulose content from said harvested lignocellulosic biomass. Preferably, the biomass contains at most 2% of the original hemicellulose content from the harvested lignocellulosic biomass. Preferably, the biomass additive contains at most 1% of the original hemicellulose content from said harvested lignocellulosic biomass. Preferably, the biomass contains at most 0.5% of said original hemicellulose content from the harvested lignocellulosic biomass.

[0210] When resorting to a biomass which was delignified using a modified Caro's acid and performed according to a process described herein, the remaining hemicellulose along with the cellulose can hover as low as 7.5 wt % or even less of the total weight of the pulp being used.

[0211] However, it is more desirable to separate out the lignin from the carbohydrate components of the lignocellulosic feedstock and, as such, incorporating a lignocellulosic feedstock post-treatment step using a caustic component adapted to dissolve hemicellulose from a mixture comprising mainly of hemicellulose and cellulose. The resulting hemicellulose content in the final solids content (comprising mainly cellulose) will be below 2 wt. %.

[0212] According to a preferred embodiment of the present invention, it has been observed that lowering the acidic content of the modified Caro's acid composition (mainly sulfuric acid, or methanesulfonic acid, depending on the modified Caro's acid blend used) will result in most of the lignin being removed in a first step with a lower removal of hemicellulose compared to a modified Caro's acid. After removal of the dissolved lignin and modified Caro's acid composition, a second step aimed at the removal of hemicellulose, using a caustic composition generates a distinct recoverable liquid stream of hemicellulose and a solid residual cellulose component. Preferably, since the modified Caro's composition has been modified, the chemicals used in the delignification of the lignocellulosic biomass are practically solely used for removing and solubilizing the lignin from the remaining biomass mixture. After the delignification is deemed sufficiently complete for the purposes of the operator, the solids (hemicellulose and cellulose) are separated from the liquid containing the modified Caro's acid as well as lignin fragments.

[0213] By using a post-treatment step to remove hemicellulose from the remaining delignified lignocellulosic components (lignin and cellulose), one can maximize the hemicellulose removal from the cellulose and minimize the peroxide consumption in the delignification step. The hemicellulose recovered is also mainly in its polysaccharide form contrary to conventional approaches where a high temperature acidic pre-treatment of lignocellulosic biomass does remove the hemicellulose from the biomass, but degrades it into xylose and its other constituents.

[0214] The process according to a preferred embodiment of the present invention uses two low temperature steps, including a low temperature post-treatment step to remove hemicellulose in the manner described herein also allows conventional enzymes or the like to be used to convert the extracted cellulose into ethanol. This also removes the necessity of finding a mixture of various enzymes capable of converting cellulose and xylose into ethanol, thus streamlining the process and ensuring a more efficient conversion of lignocellulosic biomass into ethanol.

[0215] According to a preferred embodiment of the present invention, there is provided a process capable of substantially separating out the three main constituents of lignocellulosic biomass.

[0216] According to a preferred embodiment of the present invention, there is provided a method capable of substantially separating out the three main constituents of lignocellulosic biomass and thus overcoming many difficulties encountered by previous methods.

[0217] Preferably, the process employs steps where the minimum input of energy is required in order to separate out said constituents. Preferably, the separation of the three constituents of biomass allows further processing for a number of applications which benefit from a higher purity of each of the constituents. This higher purity is meant to be understood as the hemicellulose being substantially free of cellulose and lignin; the cellulose being substantially free of hemicellulose and lignin; and lignin the being substantially free of cellulose and hemicellulose. Preferably, substantially free is meant to be understood as the main constituent being present in an amount of at least 90 wt % of total weight of the stream of interest, i.e., hemicellulose which is substantially free of cellulose and lignin would be understood as being a stream of hemicellulose which contains at least 90 wt % of hemicellulose, the same applying to the other streams. Preferably, substantially free is meant to be understood as the main constituent being present in an amount of at least 95 wt % of total weight of the stream of interest. Preferably, substantially free is meant to be understood as the main constituent being present in an amount of at least 96 wt % of total weight of the stream of interest. Preferably, substantially free is meant to be understood as the main constituent being present in an amount of at least 97 wt % of total weight of the stream of interest. Preferably, substantially free is meant to be understood as the main constituent being present in an amount of at least 98 wt % of total weight of the stream of interest. It is understood by those skilled in the art that when referring to hemicellulose, one refers to its polymeric form as well as its sugar constituents (i.e., xylose, arabinose, mannose, etc.).

[0218] In an application using a resulting stream obtained from a preferred embodiment of the process of the present invention, adding a cellulose-rich biomass which is essentially devoid of hemicellulose (which contains the xylose residues) enables one to increase the generation of ethanol from the fermentation of cellulose.

[0219] According to a preferred embodiment of the present invention, the cellulose obtained after the post-delignification caustic treatment is an unbleached cellulose which has a hemicellulose weight content of 3% wt. or lower. Preferably, the cellulose is obtained by the delignification of a lignocellulosic biomass feedstock through the exposure of such to a modified Caro's acid as per the following processes.

[0220] A preferred embodiment of the process to delignify biomass comprises the steps of: [0221] providing a vessel; [0222] providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; [0223] providing a sulfuric acid component; [0224] providing a peroxide component; [0225] exposing said remaining biomass to said sulfuric acid source and peroxide component; [0226] allowing said sulfuric acid source and peroxide component to come into contact with said biomass for a period of time sufficient to a delignification reaction to occur and remove over 90 wt % of said lignin from said remaining biomass; [0227] separating the resulting liquid portion mainly comprising dissolved lignin from a remaining solid portion comprising mainly cellulose and hemicellulose: [0228] treating said remaining solid portion of the biomass by exposing it to a caustic composition for a period of time sufficient to solubilize over 90 wt % of said hemicellulose into a caustic liquid phase; and [0229] separating said caustic liquid phase comprising said dissolved hemicellulose from a final solid portion comprising mainly cellulose.

[0230] Preferably, the removal of hemicellulose from hemicellulose-containing caustic solution consisting essentially of adding to said alkali solution a sufficient amount of a solvent consisting essentially of ethanol to precipitate said hemicellulose from said caustic alkali solution, removing the resulting precipitated hemicellulose from the caustic solution. Optionally, the caustic composition can be recovered and purified.

[0231] According to a preferred embodiment of the present invention, the modified Caro's acid composition must not comprise more than 40% by weight of H.sub.2SO.sub.4.

[0232] Preferably, said lignocellulosic biomass comprising lignin, hemicellulose and cellulose is exposed to a modified Caro's acid composition having a pH of less than 1, said modified Caro's acid composition 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: [0233] sulfuric acid; [0234] a compound comprising an amine moiety and a sulfonic acid moiety; and [0235] 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: [0236] sulfuric acid; [0237] a compound comprising an amine moiety; [0238] a compound comprising a sulfonic acid moiety; and [0239] 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: [0240] an alkylsulfonic acid; and [0241] 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: [0242] sulfuric acid; [0243] a heterocyclic compound; and [0244] 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: [0245] sulfuric acid; [0246] a modifying agent comprising a compound containing an amine group; and [0247] 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: [0248] sulfuric acid; [0249] a modifying agent comprising an alkanesulfonic acid and [0250] 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: [0251] sulfuric acid; [0252] a substituted aromatic compound; and [0253] 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: [0254] sulfuric acid; [0255] a modifying agent comprising an arylsulfonic acid; [0256] a peroxide; and [0257] 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: [0258] sulfuric acid; [0259] a heterocyclic compound; [0260] an alkanesulfonic acid and [0261] 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: [0262] sulfuric acid; [0263] a carbonyl-containing nitrogenous base compound; and [0264] 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.

[0265] According to a preferred embodiment of the present invention, exposing said biomass to said modified Caro's acid composition will allow the delignification reaction to occur and remove over 90 wt % of said lignin from said biomass.

[0266] Preferably, the delignification reaction is carried out at a temperature below 55 C. by a method selected from the group consisting of: [0267] adding water into said vessel; [0268] adding said remaining biomass into said vessel; and [0269] using a heat exchanger.

[0270] Preferably, the streams resulting from the above process according to a preferred embodiment of the present invention include: a stream rich in dissolved hemicellulose depolymerized during the caustic post-treatment; a cellulose stream comprising solid cellulose fibers; and a lignin-rich stream comprising the lignin removed from the remaining biomass.

[0271] According to a preferred embodiment of the method of the present invention, one advantage of this approach is that compared to other approaches using the entire biomass to generate biofuel, this approach focuses on the lignin-depolymerized organics (LDO) present within the lignin-rich stream. Consequently, the portion of aromatic carbons (present on lignin and lignin monomers, dimers and oligomers resulting from the delignification) is substantially higher than in the processes which employ the entire biomass (cellulose, lignin and hemicellulose). For example, in softwood trees, the proportion of cellulose is in the range of 40-50%, the percentage of lignin can range from 30-40% and the remaining balance is hemicellulose.

[0272] According to another aspect of the present invention, there is provided a process to perform a controlled exothermic delignification of lignocellulosic biomass, said process comprising the steps of: [0273] providing a vessel; [0274] providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; [0275] providing an aqueous acidic composition comprising a sulfuric acid component; [0276] providing a peroxide component; [0277] providing a modifier; [0278] exposing said remaining biomass mixture to said sulfuric acid source and peroxide component, creating a reaction mass; [0279] allowing said sulfuric acid source and peroxide component to come into contact with said remaining biomass mixture for a period of time sufficient to a delignification reaction to occur and remove over 97 wt % of said lignin from said remaining biomass mixture, to yield substantially lignin-free solid portion comprising mainly cellulose and hemicellulose: [0280] treating said remaining solid portion of the biomass by exposing it to a caustic composition for a period of time sufficient to solubilize over 90 wt % of said hemicellulose into a caustic liquid phase; and [0281] separating said caustic liquid phase comprising said dissolved hemicellulose from a final solid portion comprising mainly cellulose.
wherein said lignin is recovered separately from the cellulose, for further processing.

[0282] According to a preferred embodiment of the method of the present invention, the stream of LDO/LHDO is exposed to a pH adjustment prior to undergoing upgrading.

[0283] According to a preferred embodiment of the method of the present invention, the stream of LDO/LHDO is substantially free of cellulose (i.e., less than 5 wt % cellulose). More preferably, the stream of LDO/LHDO contains less than 2 wt % cellulose. Even more preferably, the stream of LDO/LHDO contains less than 1 wt % cellulose. Yet even more preferably, the stream of LDO/LHDO contains less than 0.5 wt % cellulose. Yet even more preferably, the stream of LDO/LHDO contains less than 0.1 wt % cellulose.

[0284] In terms of hemicellulose removal, a caustic treatment post-delignification using a modified Caro's acid provides significant advantages in terms of energy input as the caustic treatment occurs at ambient temperatures; thus, requiring less energy than a high temperature pretreatment. In addition, the caustic post-treatment is less aggressive to the structural composition of hemicellulose than a conventional delignification using a modified Caro's acid as the reaction conditions of the delignification will cause the depolymerization and further decomposition of hemicellulose in a vast range of products (including but not limited to sugars, furfural derivatives, organic acids, etc.) that are difficult to separate and capitalize on from the stream of LHDO.

[0285] It is worthy of mention that almost all efforts for lignocellulosic biomass conversion into fuels have failed due to undesired interactions among the three main biomass constituents; cellulosic ethanol represents a clear example of the aforementioned, beside the undesired properties of pyrolysis bio-oil.

[0286] According to yet another aspect of the present invention, there is provided a process to delignify biomass and recover a liquid stream which is substantially pure lignin and/or lignin monomers (i.e. lignin-based compounds make up over 90 wt. % of the liquid stream), said process comprising the steps of: [0287] providing a vessel; [0288] providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; [0289] providing an aqueous acidic composition comprising a sulfuric acid component; [0290] providing a peroxide component; [0291] exposing said remaining biomass mixture to said sulfuric acid source and peroxide component, creating a reaction mass; [0292] allowing said sulfuric acid source and peroxide component to come into contact with said remaining biomass mixture for a period of time sufficient to a delignification reaction to occur and remove over 95 wt % of said lignin from said remaining biomass mixture, to yield substantially lignin-free solid portion comprising mainly cellulose and hemicellulose: [0293] controlling the temperature of the delignification reaction by addition of water into said vessel. [0294] treating said remaining solid portion of the biomass by exposing it to a caustic composition for a period of time sufficient to solubilize over 90 wt % of said hemicellulose into a caustic liquid phase; and [0295] separating said caustic liquid phase comprising said dissolved hemicellulose from a final solid portion comprising a high purity cellulose.

[0296] According to yet another aspect of the present invention, there is provided a process to delignify biomass and recover a substantially hemicellulose free liquid stream of lignin and lignin monomers, said process comprising the steps of: [0297] providing a vessel; [0298] providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; [0299] providing an aqueous acidic composition comprising a sulfuric acid component; [0300] providing a peroxide component; [0301] exposing said remaining biomass mixture to said sulfuric acid source and peroxide component, creating a reaction mass; [0302] allowing said sulfuric acid source and peroxide component to come into contact with said remaining biomass mixture for a period of time sufficient to a delignification reaction to occur and remove over 95 wt % of said lignin from said remaining biomass mixture, to yield substantially lignin-free solid portion comprising cellulose and hemicellulose; and [0303] controlling the temperature of the delignification reaction by controlling the addition of biomass into said vessel. [0304] treating said remaining solid portion of the biomass by exposing it to a caustic composition for a period of time sufficient to solubilize over 90 wt % of said hemicellulose into a caustic liquid phase; and [0305] separating said caustic liquid phase comprising said dissolved hemicellulose from a final solid portion comprising mainly cellulose.

[0306] According to a preferred embodiment of the present invention, the lignocellulosic biomass comprising hemicellulose, lignin and cellulose is exposed to a modified Caro's acid composition selected from the group consisting of: said modified Caro's acid composition 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 as described herein.

[0307] According to a preferred embodiment of the present invention, the lignocellulosic biomass mixture comprising hemicellulose, lignin, and cellulose is exposed to a modified Caro's acid composition for a period of time sufficient to a delignification reaction to occur and remove over 95 wt % of said lignin and preferably leaving in solid form most of the hemicellulose and cellulose from said biomass. Preferably, the stream of LHDO/LDO is removed upon completion of the delignification reaction for further processing into biofuel. It is highly desirable to improve the separation of the various constituents in such a way as to increase the percent concentration of the targeted constituent (be it cellulose, hemicellulose, lignin) depending on the treatment step. In a delignification step using a modified Caro's acid where the sulfuric acid content is above 40%, approximately 85% of the hemicellulose initially present in the biomass, will be removed during the delignification step and will be present with the lignin-derived products. When performing a delignification of the biomass according to a preferred embodiment of the present invention, it is estimated that only up to 60% of the hemicellulose initially present in the biomass will be dissolved during the delignification step and will end up intermixed with the lignin derived products. Decreasing the hemicellulose content present with the lignin is greatly desirable as the LDO with contain fewer sugars and produce a higher quality bio-oil.

[0308] Preferably, said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of taurine; taurine derivatives; and taurine-related compounds.

[0309] Preferably, said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates as well as aminoalkylsulfonic acids, where the alkyl is selected from the group consisting of C.sub.1-C.sub.5 linear alkyl and C.sub.1-C.sub.5 branched alkyl. Preferably, said linear alkylaminosulfonic acid is selected from the group consisting of: methyl; ethyl (taurine); propyl; and butyl. Preferably, said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl; isobutyl; and isopentyl.

[0310] According to a preferred embodiment of the present invention, said compound comprising an amine moiety and a sulfonic acid moiety is taurine.

[0311] According to a preferred embodiment of the present invention, said sulfuric acid and a compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.

[0312] According to a preferred embodiment of the present invention, said compound comprising an amine moiety is an alkanolamine is selected from the group consisting of: monoethanolamine; diethanolamine; triethanolamine; and combinations thereof.

[0313] Preferably, said compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids; arylsulfonic acids; and combinations thereof. Preferably, said alkylsulfonic acid is selected from the group consisting of: alkylsulfonic acids where the alkyl groups range from C.sub.1-C.sub.6 and are linear or branched; and combinations thereof. More preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof. According to a preferred embodiment of the present invention, said arylsulfonic acid is selected from the group consisting of: toluenesulfonic acid; benzesulfonic acid; and combinations thereof.

[0314] According to a preferred embodiment of the present invention, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is kept below 55 C. for the duration of the delignification reaction. Preferably, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is kept below 50 C. for the duration of the delignification reaction. According to another preferred embodiment of the present invention, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is kept below 45 C. for the duration of the delignification reaction. According to a preferred embodiment of the present invention, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is kept below 40 C. for the duration of the delignification reaction.

[0315] According to a preferred embodiment of the present invention, the temperature of the remaining biomass mixture is controlled throughout the delignification reaction to subsequent additions of a solvent (water) to progressively lower the slope of temperature increase per minute from less than 1 C. per minute to less than 0.5 C. per minute.

[0316] According to another preferred embodiment of the present invention, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is controlled by an addition of a solvent (water) to reduce the slope of temperature increase per minute of the reaction mass to less than 1 C. per minute.

[0317] According to yet another preferred embodiment of the present invention, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is controlled by a second addition of a solvent (water) to reduce the slope of temperature increase per minute of the reaction mass to less than 0.7 C. per minute.

[0318] Preferably, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is controlled by a third addition of a solvent (water) to reduce the slope of temperature increase per minute of the reaction mass to less than 0.3 C. per minute.

[0319] Preferably, the temperature of the lignocellulosic biomass mixture comprising hemicellulose, lignin and cellulose is controlled by a fourth addition of a solvent (water) to reduce the slope of temperature increase per minute of the reaction mass to less than 0.1 C. per minute.

[0320] According to a preferred embodiment of the present invention, the kappa number of the resulting cellulose is below 10, preferably it is below 5.

[0321] According to a preferred embodiment of the present invention, there is provided a process to delignify biomass using an aqueous acidic composition comprising: [0322] sulfuric acid; [0323] a heterocyclic compound; and [0324] a peroxide.

[0325] According to another preferred embodiment of the present invention, there is provided a process to delignify biomass using an aqueous acidic composition comprising: [0326] sulfuric acid; [0327] a heterocyclic compound; and
wherein sulfuric acid and said a heterocyclic compound; are present in a molar ratio of no less than 1:1.

[0328] Preferably, the sulfuric acid and said heterocyclic compound are present in a molar ratio ranging from 28:1 to 2:1. More preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 24:1 to 3:1. Preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 20:1 to 4:1. More preferably, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 16:1 to 5:1. According to a preferred embodiment of the present invention, the sulfuric acid and heterocyclic compound are present in a molar ratio ranging from 12:1 to 6:1.

[0329] Also preferably, said heterocyclic compound has a molecular weight below 300 g/mol. Also preferably, said heterocyclic compound has a molecular weight below 150 g/mol. More preferably, said heterocyclic compound is a secondary amine. According to a preferred embodiment of the present invention, said heterocyclic compound is selected from the group consisting of: imidazole; triazole; and N-methylimidazole.

[0330] According to an aspect of the present invention, there is provided a process to delignify biomass, such as wood using an aqueous acidic composition comprising: [0331] sulfuric acid; [0332] a heterocyclic compound; and [0333] a peroxide. [0334] wherein the sulfuric acid and the heterocyclic compound are present in a mole ratio ranging from 2:1 to 28:1.

[0335] Preferably, said 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. Also preferably, said sulfuric acid, said compound comprising an amine moiety and a sulfonic acid moiety and said peroxide are present in a molar ratio of no more than 15:1:1.

[0336] According to a preferred embodiment of the present invention, said sulfuric acid and said compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.

[0337] According to a preferred embodiment of the present invention, said compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of: taurine; taurine derivatives; and taurine-related compounds.

[0338] According to a preferred embodiment of the present invention, said taurine derivative or taurine-related compound is selected from the group consisting of: taurolidine; taurocholic acid; tauroselcholic acid; tauromustine; 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine; homotaurine (tramiprosate); acamprosate; and taurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of C.sub.1-C.sub.5 linear alkyl and C.sub.3-C.sub.5 branched alkyl. Preferably, said linear alkylaminosulfonic acid is selected from the group consisting of: methyl; ethyl (taurine); propyl; and butyl.

[0339] Preferably, said branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl; isobutyl; and isopentyl.

[0340] According to a preferred embodiment of the present invention, said compound comprising an amine moiety and a sulfonic acid moiety is taurine.

[0341] According to a preferred embodiment of the present invention, said sulfuric acid and a compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of no less than 3:1.

[0342] According to a preferred embodiment of the present invention, said compound comprising an amine moiety is an alkanolamine is selected from the group consisting of: monoethanolamine; diethanolamine; triethanolamine; and combinations thereof.

[0343] According to a preferred embodiment of the present invention, said compound comprising a sulfonic acid moiety is selected from the group consisting of: alkylsulfonic acids and combinations thereof.

[0344] According to a preferred embodiment of the present invention, said alkylsulfonic acid is selected from the group consisting of: alkylsulfonic acids where the alkyl groups range from C.sub.1-C.sub.6 and are linear or branched; and combinations thereof.

[0345] According to a preferred embodiment of the present invention, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof.

[0346] According to a preferred embodiment of the present invention, said alkylsulfonic acid; and said peroxide is present in a molar ratio of no less than 1:1.

[0347] According to a preferred embodiment of the present invention, said compound comprising a sulfonic acid moiety is methanesulfonic acid.

[0348] According to a preferred embodiment of the present invention, in Composition C, said 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.

[0349] According to a preferred embodiment of the present invention, in Composition C, said sulfuric acid, said compound comprising an amine moiety and said compound comprising a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.

Experimental Data

[0350] The following experimentation was conducted using canola straw as the biomass feedstock. The canola straw was characterized to determine the content of acid-insoluble lignin (also known as Klason lignin) as well as carbohydrate composition. The carbohydrate composition gives an indication of cellulose and hemicellulose distribution within the biomass. Results of the characterization of the canola straw are shown in Table 1.

TABLE-US-00001 TABLE 1 Results of the characterization of canola straw used in the experiments. Parameter Units Result Klason lignin %, OD basis 16.1% Arabinan %, extracted OD basis 1.2% Xylan %, extracted OD basis 11.6% Mannan %, extracted OD basis 1.0% Galactan %, extracted OD basis 1.1% Glucan %, extracted OD basis 25.3%

Experiment #1

[0351] The following experimentation was conducted using canola straw as the biomass feedstock. The canola straw was characterized to determine the content of acid-insoluble lignin (also known as Klason lignin) as well as carbohydrate composition. The carbohydrate composition gives an indication of cellulose and hemicellulose distribution within the biomass. Results of the characterization of the canola straw are shown in Table 1.

TABLE-US-00002 TABLE 1 Results of the characterization of canola straw used in the experiments. Parameter Units Result Klason lignin %, OD basis 16.1% Arabinan %, extracted OD basis 1.2% Xylan %, extracted OD basis 11.4% Mannan %, extracted OD basis 1.0% Galactan %, extracted OD basis 1.1% Glucan %, extracted OD basis 25.3%

[0352] The canola biomass was exposed to a delignification reaction according to the method described herein. Different blends comprising a modified Caro's acid composition consisting of H.sub.2SO.sub.4:H.sub.2O.sub.2:taurine were prepared. The blends all have the same 10:10:1 molar ratio between the components, but where the acid concentration was varied between 43 and 30% wt. of the blend. Details of the blends are shown in Table 2. As the mixing releases a large amount of heat, the beakers were placed in an ice bath. The pH of the resulting composition was less than 0.5. Canola was then added into each of the blends as 3% wt. solids loading (9 g). The reaction was left stirring at 35 C. for 3 hours, after which the solids were extracted from the liquid and a yield of the solids was obtained. Table 2 shows the yield of solid cellulose for the delignification reactions of canola biomass at different acid concentration as % of the initial biomass. Hydrogen peroxide consumption in the reaction is an important metric as it is the only chemical consumed in the reaction and determines chemical consumption in large scale facilities. During these reactions, hydrogen peroxide was monitored. Table 2 shows the hydrogen peroxide consumption for each delignification reaction as % of the cellulose solids recovered. Kappa number or lignin content is typically used to ascertain the efficiency of the delignification. Kappa number is a test method that determines the amount of lignin remaining in a pulp sample and thus provides information as to the degree of delignification. Table 2 shows the Kappa number of the cellulose obtained from each delignification reaction.

TABLE-US-00003 TABLE 2 Blend compositions, cellulose yields, and hydrogen peroxide consumptions of the reactions described herein. Acid H.sub.2O.sub.2 concentration Cellulose yield consumption % H.sub.2O.sub.2 Kappa (% wt.) (% of biomass) (% of cellulose) reduction number 43.0 34.78% 2.35 1.7 40.1 38.56% 1.11 53.0 2.5 37.9 45.67% 0.90 61.7 4.0 35.3 44.56% 0.28 88.1 5.1 30.6 64.56% 0.13 94.5 16.1

[0353] Table 2 shows that as the acid concentration decreases, the cellulose yield increases and so does the Kappa number. This is expected since as the acid concentration is reduced, the reactivity of the modified Caro's acid decreases, thus leading to a less efficient delignification. This is further evidenced by the increase in cellulose yield and the increase in Kappa number, which indicates that more lignin and hemicellulose is left behind with the solids. However, there is a point where the peroxide consumption is lowered enough to result in significant financial savings, while the delignification efficiency losses are not significant. This point makes the economics of the process more attractive.

Experiment #2

[0354] The following experimentation was conducted using hardwood as the biomass feedstock. The hardwood was characterized to determine the content of acid-insoluble lignin (also known as Klason lignin) as well as carbohydrate composition. The carbohydrate composition gives an indication of cellulose and hemicellulose distribution within the biomass. Results of the characterization of the hardwood are shown in Table 3.

TABLE-US-00004 TABLE 3 Results of the characterization of hardwood used in the experiments. Parameter Units Result Klason lignin %, OD basis 19.8% Arabinan %, extracted OD basis 0.2% Xylan %, extracted OD basis 17.7% Mannan %, extracted OD basis 1.3% Galactan %, extracted OD basis 0.3% Glucan %, extracted OD basis 43.1%

[0355] The hardwood was exposed to a delignification reaction according to the method described herein. Different blends comprising a modified Caro's acid composition consisting of H.sub.2SO.sub.4:H.sub.2O.sub.2:taurine were prepared. The blends all have the same 10:10:1 molar ratio between the components, but where the acid concentration was varied between 43 and 30% wt. of the blend. Details of the blends are shown in Table 4. Hardwood was then added into each of the blends as 3% wt. solids loading (9 g). The reaction was left stirring at 35 C. for 3 hours, after which the solids were extracted from the liquid and a yield of the solids was obtained. Table 4 shows the yield of solid cellulose for the delignification reactions of hardwood at different acid concentration as % of the initial biomass, the hydrogen peroxide consumption for each delignification reaction as % of the cellulose solids recovered as well as the Kappa number of the cellulose obtained from each delignification reaction.

TABLE-US-00005 TABLE 4 Blend compositions, cellulose yields, and hydrogen peroxide consumptions of the reactions described in Experiment 2. Acid H.sub.2O.sub.2 concentration Cellulose yield consumption % H.sub.2O.sub.2 Kappa (% wt.) (% of biomass) (% of cellulose) reduction number 42.5 49.11% 1.15 1.8 40.0 56.33% 0.67 42.3% 2.5 37.5 56.78% 0.36 68.9% 5.2 35.0 63.33% 0.19 83.8% 11.7 30.0 84.56% 0.09 92.3% 33.8

[0356] Table 4 confirms the trend observed previously for canola, whereas the acid concentration decreases, the cellulose yield increases and so does the Kappa number. More importantly, the hydrogen peroxide consumption decreases significantly where it allows the determination of a more economically viable reaction.

Experiment #3

[0357] Canola biomass was exposed to two different delignification reaction according to the method described herein using two different acid concentrations 38.0 and 43.4 wt. % in a 1600 and 2700 kg scale reaction, respectively. Details of the blends are shown in Table 5. Canola was added into each of the blends as 3% wt. solids loading. The reaction was left stirring for 24 hours, after which the solids were extracted from the liquid and a yield of the solids was obtained. Table 5 shows the yield of solid cellulose for the delignification reactions of canola biomass at different acid concentration as % of the initial biomass as well as hydrogen peroxide consumption as % of the initial biomass and Kappa number for the cellulose solids obtained from each delignification reaction.

TABLE-US-00006 TABLE 5 Blend compositions, cellulose yields, hydrogen peroxide consumptions, and Kappa numbers for the cellulose solids obtained from the reactions described in Experiment #2. Acid H.sub.2O.sub.2 Blend concentration Cellulose yield consumption Kappa ID (% wt.) (% of biomass) (% of biomass) number R2B018 43.4 45% 0.90 Less than 2 R3B022 38.0 60% 0.60 Less than 2

[0358] Table 5 shows that as the acid concentration decreases, the cellulose yield increases. In terms of peroxide consumption, it decreases by 34% with respect to the modified Caro's acid with 43.4% wt. acid concentration. However, at larger scale, pulping effects are not as significant as indicated by the same Kappa number in both runs, likely due to optimized mixing and longer reaction times. This shows that it is likely that the increase in cellulose yield is due to unreacted hemicellulose remaining with the cellulose solids.

[0359] Cellulose solids were characterized before and after being exposed to a caustic solution at 8.5% wt. NaOH at a loading of 3 g oven-dry per 100 mL of caustic. The caustic treatment lasted 1 hour at room temperature, after which the solid portion was separated from the liquid via filtration. The rest of the cellulose characterization are shown in Table 6.

TABLE-US-00007 TABLE 6 Characterization parameters of the cellulose solids obtained through the delignification of canola biomass at 38% wt. acid concentration (R3B022) before and after caustic treatment. Parameter Before caustic After caustic Kappa number 1.3 0.7 Cellulose content (%) 90.8 98.3 Hemicellulose content (%) 9.2 1.7

[0360] Table 6 highlights that the caustic treatment not only it dissolves the hemicellulose, but it also aids in removing any remaining lignin content within the cellulose solids. The liquid is expected to mostly contain dissolved hemicellulose. It is understood by those skilled in the art that when referring to hemicellulose, one refers to its polymeric form as well as its sugar constituents (i.e., xylose, arabinose, mannose, etc.) and other decomposition products.

Experiment #4

[0361] The canola straw cellulose solids obtained from Experiment #1 were analyzed to determine their content of undegraded cellulose, degraded cellulose, and hemicellulose respectively, denoted as -, -, and -cellulose content using TAPPI T203. It was expected that more hemicellulose would be removed with increasing acid concentration in the delignification blend. Table 7 shows the results of the test performed on the dry delignified cellulose solids as well as the calculated hemicellulose recovery, obtained from comparing the actual hemicellulose in the solids with the theorical amount of hemicellulose in the initial biomass and the yield of delignification.

TABLE-US-00008 TABLE 7 Characterization parameters of the cellulose solids obtained through the delignification of canola biomass at the conditions shows in Table 5. Hemicellulose recovery (%) Acid - - Hemi- (Based on the Concentration Cellulose Cellulose cellulose content of initial (% wt.) (% wt.) (% wt.) (% wt.) biomass) 35.0 82.0% 5.0% 13.0% 43.4% 37.5 84.4% 5.1% 10.5% 35.3% 40.0 85.4% 5.7% 8.9% 28.7% 43.0 85.3% 7.3% 7.4% 23.2%

[0362] Table 7 shows that as acid concentration in the delignification blend increases, the blend becomes more reactive and it degrades more of the hemicellulose portion in the biomass, as indicated by the lower hemicellulose content remaining in the solid product. This is an important finding as it suggests that the parameters of the delignification described herein can be altered to favour more or less degraded hemicellulose as desired based on the intended application. It is known to those skilled in the art that pulps with higher hemicellulose content are more suitable for applications where higher pulp strength is sought after, such as in paper-marking facilities, while low hemicellulose pulps are desirable for applications where its presence is less desired, such as in the pharmaceutical, food, and textiles industries.

[0363] Table 7 also displays a trend in the degradation of pure cellulose. As the acid concentration in the blend increases, more cellulose is being degraded to a lower-molecular weight, more degraded cellulose known as -cellulose (ratio of -cellulose to -cellulose lowers from 16.5 at 35.0 C. to 11.7 at 43.0 C., displaying lower alpha-cellulose in the cellulosic portion). This is understood to be due to the function of increasing acid concentration being more reactive to attack the glycosidic bonds in cellulose and break down the cellulosic polymer at its amorphous regions. Amorphous regions of cellulose are more susceptible to acid hydrolysis. The apparent increase in alpha-cellulose with acid concentration is due to the degradation of hemicellulose and thus lowering of that portion within the solids.

Experiment #5

[0364] Sugarcane bagasse was exposed to a low acid delignification reaction containing 37.5% wt. acid according to the method described herein. Sugarcane bagasse was added into the reactor as 3% wt. solids loading. The reaction was left stirring for 24 hours, after which the solids were extracted from the liquid and a yield of the solids was obtained. After delignification, the cellulose was treated with a caustic treatment that dissolves the degraded cellulose and the hemicellulose content of the cellulose solids. The treatment was conducted by suspending 973.21 g of wet cellulose (18.5% wt. solids) in 9% wt. NaOH for 2 hours at room temperature while stirring at 150 rpm. The solids obtained after neutralization and washing were analyzed cellulose and hemicellulose content using TAPPI T203. The results of this test are summarized in Table 8 along with the analysis of the cellulose prior to caustic treatment.

TABLE-US-00009 TABLE 8 Analysis of the results of a sugarcane bagasse cellulose sample after being delignified as per Experiment #4 and post-caustic treatment. Cellulose Hemicellulose Kappa Blend ID (% wt.) (% wt.) number R3B027 96.8% 3.1% 1.2 R3B027-CT 99.5% 0.5% 0.7

[0365] Table 8 shows that the caustic treatment is able to dissolve more than 80% of the hemicellulose present in the sample and can be used successfully post-delignification to fractionate cellulose and hemicellulose through the dissolution of the hemicellulose, as indicated by the decrease in % wt. in the solids following the caustic treatment. The cellulose obtained was characterized by FT-IR and compared to a standard of microcrystalline cellulose to ascertain purity (FIG. 1). The resulting spectra virtually overlap and lead to the conclusion that the cellulose obtained is of similar quality than that of a commercial product Avicel.

[0366] It is known to those skilled in the art that a number of different precipitation and separation techniques may be employed for the isolation of the dissolved hemicellulose from the solvent. By way of example, two different techniques were used herein to demonstrate the ability to separate and isolate the dissolved hemicellulose as a pure separate stream. In a first example, the solution with the dissolved hemicellulose was evaporated under reduced pressure using a rotary evaporator.

[0367] In a second example, the solution with the dissolved hemicellulose was concentrated under reduced pressure to increase the concentration of hemicellulose in the sample. Once the sample had been concentrated, a certain amount of ethanol was added to the solution to promote the re-precipitation of the hemicellulose. Ethanol was added stepwise increasing the ethanol concentration of the mixture from 15 to 60% vol. After each ethanol additions, the corresponding hemicellulose solids were collected.

[0368] In kraft pulping, about 90% of the lignin present in the processed biomass is dissolved and removed therefrom. Kraft pulp also contains hemicellulose fragments (containing xylose) which are detrimental to the proper performance of a fermentation unit. In fact, Kraft pulping dissolves only between 40 to 60% of the hemicellulose initially present in the lignocellulosic feedstock. Therefore, it is clear that the implementation of a process according to a preferred embodiment of the present invention overcomes some of the shortcomings of the state-of-the art to produce bioethanol on a large scale using lignocellulosic biomass (or feedstock). Moreover, large-scale implementation of a preferred embodiment of the method of the present invention as taught herein will allow large-scale bioethanol production from lignocellulosic biomass rather than from starches (such as corn).

[0369] According to a preferred embodiment of the present invention, the lignocellulosic biomass is exposed to the modified Caro's acid when it is in chips ranging in size of up to 5 cm, preferably up to 3 cm and more preferably ranging between 1 and 2 cm. The water content of the biomass can vary greatly from below 10% to close to 50% and while water content does not affect the delignification reaction, operators have to make adjustments to account for the water in said biomass prior to treating such.

[0370] While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be appreciated by those skilled in the relevant arts, once they have been made familiar with this disclosure that various changes in form and detail can be made without departing from the true scope of the invention in the appended claims.