Method to manufacture biofuel by the hydrodeoxygenation of esterified lignin-derived compounds

Abstract

Method to produce an upgraded oil using a lignin-rich feedstock, said method comprises the following steps: - 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; - providing an acidic composition having a pH of less than 1, said acidic composition comprising:  an acid selected from the group consisting of: sulfuric acid; an alkylsulfonic acid; and an arylsulfonic acid; and  an alcohol selected from the group consisting of C1-C8 linear alcohol and C3-C8 branched alcohol and mixtures thereof; - combining said lignin-rich feedstock with said acidic composition into a reaction mixture; - heating up said mixture to a temperature ranging from 25oC to 120oC; and - allowing sufficient time of reaction to convert at least a portion of said lignin-derived material into said at least one esterified lignin derivative; - separating said at least one esterified lignin derivative from said acidic composition; - performing a hydrodeoxygenation reaction on said at least one esterified lignin derivative, wherein the hydrodeoxygenation reaction is carried out in the presence of a hydrogen-rich source at a temperature ranging from 250oC to 400oC under a H2 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.

Description

[0001] METHOD TO MANUFACTURE BIOFUEE BY THE HYDRODEOXYGENATION OF ESTERIFIED LIGNIN-DERIVED COMPOUNDS

[0002] FIEED OF THE INVENTION

[0003] The present invention is directed to a method of converting lignin from biomass into valuable smaller chemicals, more specifically, in one instance, there is provided a method to convert lignin obtained using a modified Caro’s acid delignification process into small valuable chemicals.

[0004] BACKGROUND OF THE INVENTION

[0005] Petroleum is the cornerstone of the present chemical industry. Not only is it the most commonly used fuel in transportation, heating oils and electricity generation but it is also the primary raw material for the overwhelming majority of the basic chemicals used in plastics, adhesives and whole variety of synthetic materials just to name a few. The ever-growing demands and limits of the availability of this non-renewable resource is forcing the chemical industry to increase their research on the use of renewable resources as an alternative to petroleum.

[0006] In recent years, extensive work has been carried out to develop more efficient clean and renewable energy sources to partially or completely replace fossil fuels (e.g., natural gas, petroleum, and coal).

[0007] Bio-fuels derived from renewable resources have inherent benefits of resource abundancy and carbon neutrality. Lignocellulosic biomass such as, but not limited to wood, grasses and other plant materials, contains three main components: cellulose fibers; lignin; and hemicelluloses. Pulping of lignocellulosic biomass has a primary goal to separate the fibers from the lignin. Lignin is a three- dimensional polymer which figuratively acts as a mortar to hold all the fibers together within the plant.

[0008] Lignin accounts for, in some biomass, up to 30 percent of the lignocellulose biomass, and has a great potential to replace at least a portion of the petroleum -based chemical products. However, it is still greatly underused as such an alternative. Lignin is the second most abundant organic natural material encountered in nature. However, approximately 98% of it is still simply burned to provide heat or used in the production of energy. Lignin is made up of various aromatic compounds and its complexity comes from the diversity and degree of crosslinking between the various monomeric units which comprises it. These are called lignols and fall under one of three main categories: coniferyl alcohol; sinapyl alcohol; and paracoumaryl alcohol.

[0009] Fast pyrolysis (operating at >500 °C, in inert atmosphere) is the most common thermochemical process for biomass conversion and by far the only industrially realized approach to convert dry biomass into liquid fuels (known as bio- oil or pyrolysis oil) with a higher heating value (HHV) of 15-20 MJ / kg [3], Whereas, hydrothermal liquefaction (HTL), operating at 200-400 °C under high pressure up to 20 MPa, is a more suitable and advantageous process for converting wet biomass (microalgae) or organic wastes (such as kitchen waste, wastewater sludge) directly to bio-crude oils (or HTL bio-oils) with an HHV of 25-30 MJ / kg [L.Planteetal., “Bioenergy from biofuel residues and waste,” Water Environ. Res., vol. 91, no. 10, pp. 1199-1204, 2019, doi: 10.1002 / wer.l214.].

[0010] Although the use of bio-oils offers environmental benefits by reducing CO2 emission, the poor quality of bio-oil, e.g., thermal-instability, high viscosity and acidity, and low heating value, makes it unsuitable for direct applications as drop-in fuels [V.T.T.Energy,“99 / 00150 Characterization of biomassbased flash pyrolysis oils,” Fuel Energy Abstr., vol. 40, no. 1, pp. 15-16, 1999, doi: 10.1016 / s0140- 6701(99)92423-2; Z. Si, X. Zhang, C. Wang, L. Ma, and R. Dong, “An overview on catalytic hydrodeoxygenation of pyrolysis oil and its model compounds,” Catalysts, vol. 7, no. 6, pp. 1-22, 2017, doi: 10.3390 / catal7060169; and A. Pawar, N. L. Panwar, and B. L. Salvi, “Comprehensive review on pyrolytic oil production, upgrading and its utilization,” J. Mater. Cycles Waste Manag., vol. 22, no. 6, pp. 1712-1722, 2020, doi: 10.1007 / sl0163-020-01063-w]. For example, the water content of pyrolysis bio-oil (15-30 wt.%) is considerably greater than that of petroleum crude oil (< 1 wt.%). High water content in the oil could cause problems to the engine ignition, not to mention the significantly lower energy content [M. H. Marzbali et al., “Wet organic waste treatment via hydrothermal processing: A critical review,” Chemosphere, vol. 279, p. 130557, 2021, doi: 10. 1016 / j. chemosphere.2021.130557], In addition, oxygen (O2) content in the bio-oil from fast pyrolysis (35-50 wt.%) is much larger than that of petroleum crude oil (< 1 wt.%). Such high O content makes bio-oil dissolvable in polar solvents like acetone and methanol, but poorly mixable with fossil fuels [S. Zhang et al., “Liquefaction of biomass and upgrading of bio-oil: A review,” Molecules, vol. 24, no. 12, pp. 1-30, 2019, doi: 10.3390 / molecules24122250], Besides, the presence of high O content in bio-oil results in a low stability and strong acidity / corrosiveness and hence some negative impacts on storage and transportation of the oil, as well as some corrosion issues for bio-oil downstream upgrading / processing reactors [M. Zhang et al., “A review of bio-oil upgrading by catalytic hydrotreatment: Advances, challenges, and prospects,” Mol. Catal., vol. 504, no. September 2020, p. 111438, 2021, doi: 10.1016 / j.mcat.2021.111438],

[0011] Catalytic hydro-de-oxygenation (HDO) is one of the most promising ways to upgrade bio-oils. It can efficiently reduce oxygen content of pyrolysis bio-oil using high pressure H2, while maintaining a high oil yield [C. Guo, K. T. V. Rao, Z. Yuan, S. (Quan) He, S. Rohani, and C. (Charles) Xu, “Hydrodeoxygenation of fast pyrolysis oil with novel activated carbon-supported NiP and CoP catalysts,” Chem. Eng. Sci., vol. 178, pp. 248-259, 2018, doi: 10. 1016 / j.ces.2017. 12.048], However, this process normally operates under high pressure hydrogen gas, which raises safety concerns and process costs [W. Jin, L. Pastor-Perez, D. K. Shen, A. Sepulveda-Escribano, S. Gu, and T. Ramirez Reina, “Catalytic Upgrading of Biomass Model Compounds: Novel Approaches and Lessons Learnt from Traditional Hydrodeoxygenation - a Review,” ChemCatChem, vol. 11, no. 3, pp. 924-960, 2019, doi: 10. 1002 / cctc.201801722],

[0012] United States patent application US 2013 / 0232853A1 discloses a method of production of biobased chemicals, biofuels, and lignin residues from lignin sources, including waste lignin. This method may allow for selectively producing biobased chemicals, biofuels, and lignin residues from lignin sources using certain processing methods. The methods for production of these biobased chemicals, biofuels, and lignin residues may be provided by chemical-induced processing, catalytic oxidative lignin depolymerization processing, and catalytic hydroprocessing. Further, the catalytic hydroprocessing from processes including catalytic reduction processing, catalytic hydrodeoxygenation processing, and / or catalytic / dehydrogenation processing may also be used. The method described herein also provides a means in which waste from the process(es) may be reduced and / or recycled.

[0013] Because of the heterogeneity of lignin and the substantial issues caused by the re-condensation of lignin monomers, there has not been a satisfactory approach to extract lignin from biomass and to further convert the extracted lignin to value added chemicals. Alkali lignin is particularly susceptible to condensation reaction. Since alkaline pulping represents the most widespread delignification and pulping processes across the world, the majority of the lignin thus extracted is not salvageable for further chemical processes and is typically used as a source of heat as it is simply burned. Pyrolysis, on the other hand, is a method to produce lignin-derived molecules from lignocellulosic biomass. Conventional pyrolysis oil generates aldehydes which can polymerize over time and thus render such bio-oil unstable over time. Most bio-oils generated from pyrolysis have the same drawbacks. Their delignification process yields bio-oil which contains aldehydes, their aldehyde content makes them unstable for long-term storage. Pyrolysis oil also has other drawbacks which include: having a high oxygen content (making them less desirable for combustion in engines); they are largely non-volatile; and they may be corrosive. Pyrolysis Oil is obtained by heating biomass at temperatures of 425-600°C & 1-20 bar in the absence of oxygen in 10-30 mins to yield bio-oil, bio char and syngas

[0014] The process referred to as Fast Pyrolysis Oil consists of heating biomass at temperatures of 425- 700°C in seconds to yield a bio-oil, bio char and syngas. The main difference between regular pyrolysis oil is the speed of the reaction, which yields higher bio-oil and less bio char. The yields obtained are as follows: 60-65wt% bio-oil (with a Tan (mg / KOH) 50-100; a water content (wt.%) of 15-30; a HHV(MJ / kg) 25-30; an oxygen content (wt.%) 45-50; 10-20wt% bio char; and 15-20wt% gas.

[0015] In a hydrotreating (HDO) process carried out at 300-400°C under pressures ranging from 10-100 bar, there is a yield of 50% hydrotreated oil; carbon content of 85-90 wt.%, H 12-15wt.%, oxygen lwt.%; 35% water; 15% gas

[0016] Hydrothermal liquefaction (HTL) is a process where biomass, water, and an additive are fed into a Continuous stirred tank reactor (CSTR) or a plug flow reactor or both where the contents inside the tank are heated to 300-400°C and 180-300bar. This produces bio crude, aqueous phase, bio char and flue gas. The yields (wt.%) from a HTL process include: bio oil 15-30% (with an oxygen content 10-15%); biochar 20-30%; gas 15-20%; and an aqueous Phase 30-40%.

[0017] Over the past decades there has been many attempts and research into coprocessing of raw bio-oils into an existing refinery by using a FCC with vacuum gas oil (VGO) and then hydrotreating, however given bio-oils need to undergo HDO (oxygen removal) as well as issues with solid formation (coking), and high tan numbers, water%. The risk being too high which lead current models to investigate upgrading the biooil via HDO in a separate reactor / process as to essentially bring the bio-oil within specification (low oxygen, low water, low acid number, etc.). Since HDO, in general, is an exothermic process and with bio-oils having 15-50% oxygen content, this makes it very exothermic, and also leads to deactivation of the catalyst and coking formation (plugging). In light of the state of the art, there is still a need for an approach which efficiently converts biomass into a valuable bio-oil all the while overcoming one or many of the drawbacks known from the commonly applied methods whether these drawbacks are from the feedstock or the upgrading process of the oil obtained from the feedstock.

[0018] SUMMARY OF THE INVENTION

[0019] According to an aspect of the present invention, there is provided a method to convert biomass into a biofuel.

[0020] The applicant has a patented delignification process produces a bio-oil feedstock that is substantially free of cellulose derivatives and hence its composition is enhanced compared to pyrolysis biooil. The pyrolysis of delignified biomass thermally decomposes the liquid portion of the delignified biomass in the absence of air to produce a liquid (bio-oil) through the application of a high heat transfer rate to the biomass particles. The applicant’s patented delignification process separates cellulose from the other biomass constituents (lignin and hemicellulose) at a recovery rate of +99% and depolymerizes lignin and hemicellulose into a liquid-rich organic liquid called Lignin-Hemicellulose-Depolymerization- Organics (LHDO). The LHDO obtained by the implementation of the above mentioned delignification process contains virtually no aldehydes and all acids are converted once the LHDO is upgraded using hydrodeoxygenation (HDO). This eliminates the need for bio-oil aldehyde's role in bio-oil stability from thermal application or stability over time. Aldehydes present in pyrolysis bio-oil 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-oils. 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-oil by oxidation followed by mild temperature hydrotreating stage to eliminate polymerization that occurred through during hydrocracking process.

[0021] It is noteworthy to point out that current pyrolysis of biomass generally yields a large amount of bio-char (up to 30-40%). This is highly undesirable as bio-char is low in value and the potential to use the remaining bio-oil as a fuel additive which is the high value product is greatly diminished to the high amount of conversion of biomass into bio-char. LHDO obtained from delignification of lignocellulosic biomass material using a modified Caro’s acid, overcomes the problem caused by the presence of aldehyde by circumventing the production thereof. The oxidizing power of modified Caro’s acid used favors the production of carboxylic acids and allows to achieve complete or very near to complete oxidation of the LHDO. Upon analysis, the aldehyde levels are below detection limits. According to a preferred embodiment of the present invention, the LHDO comprises lignin-derived material selected from the group consisting of: lignin monomers (20 to 50 wt.% of said lignin-derived material); lignin depolymerization products (50 to 80 wt.% of said lignin-derived material), wherein lignin depolymerization product is not a monomer but a soluble lignin-derivative, i.e. a breakdown compound.

[0022] However, a difficulty arose when wanting to extract the lignin depolymerization products present in the liquid recovered from a modified Caro’s acid-driven delignification of biomass material. The various lignin monomers obtained from such a process were found to be hydrophilic and thus miscible with the remaining sulfuric acid present in the liquid recovered.

[0023] According to an aspect of the present invention, the inventors have developed a method which overcomes both the difficulties caused by the presence of a strong acid, inorganic impurities (such as sulfate salts, chlorides) and water in the liquid recovered but can also allow for the synthesis of various diester compounds and facilitate the recovery of such from a stream containing lignin depolymerization compounds as well as dissolved hemicellulose. It was surprisingly and unexpectedly discovered that a mixture of valuable aromatic and aliphatic esters could be produced from lignin-originating aromatic monomers obtained from the delignification of biomass performed using a modified Caro’s acid (i.e. H2SC>4,in the presence of a modifier and a source of peroxide).

[0024] The inventors have discovered that attempts to extract some of the lignin-derived material prior to esterification led to very poor yields. The one step that is deemed of some use was to concentrate the LHDO by reducing the water content which in turn would increase the efficiency of the esterification reaction.

[0025] According to an aspect of the present invention, there is provided a method to produce an upgraded oil using a lignin-rich feedstock, said method comprises the following steps; 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; providing an acidic composition having a pH of less than 1, said acidic composition comprising:

[0026] ■ an acid selected from the group consisting of: sulfuric acid; an alkylsulfonic acid; and an arylsulfonic acid; and

[0027] ■ an alcohol selected from the group consisting of Ci-Cs linear alcohol and C’s-G branched alcohol and mixtures thereof; combining said lignin-rich feedstock with said acidic composition into a reaction mixture; heating up said mixture to a temperature ranging from 25°C to 120°C; and allowing sufficient time of reaction to convert at least a portion of said lignin-derived material into said at least one esterified lignin derivative; separating said at least one esterified lignin derivative from said acidic composition; performing a hydrodeoxygenation reaction on said at least one esterified lignin derivative, wherein the hydrodeoxygenation reaction is carried out in the presence of a hydrogen-rich source at a temperature ranging from 250°C to 400°C under a H2 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.

[0028] According to a preferred embodiment of the present invention, the catalyst is a metal catalyst. Preferably, the catalyst is a Nickel-molybdenum (NiMo) catalyst.

[0029] According to a preferred embodiment of the present invention, the alcohol is selected from the group consisting of: methanol; ethanol; n-propanol; isopropanol; n-butanol; isobutanol; n-pentanol; neopentanol; isopentanol; isoamyl alcohol and mixtures thereof.

[0030] According to a preferred embodiment of the present invention, the alcohol and the sulfuric acid are present in a molar ratio ranging from 2.85: 1 (alcohol : sulfuric acid) to 10: 1 (alcohol : sulfuric acid).

[0031] More preferably, the alcohol and the sulfuric acid are present in a molar ratio ranging from 3: 1 (alcohol : sulfuric acid) to 5: 1 (alcohol : sulfuric acid).

[0032] According to a preferred embodiment of the present invention, the lignin-containing material results from a delignification reaction of a lignocellulosic material using a modified Caro’s acid.

[0033] According to a preferred embodiment of the present invention, the alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propane sulfonic acid and combinations thereof.

[0034] According to a preferred embodiment of the present invention, the arylsulfonic acid is selected from the group consisting of: toluenesulfonic acid; benzene sulfonic acid; and combinations thereof.

[0035] According to a preferred embodiment of the present invention, said lignin-rich feedstock comprises more than 80 wt% of lignin-based compounds obtained from delignification of biomass. Preferably, said lignin-rich feedstock comprises more than 85 wt% of lignin-based compounds obtained from delignification of biomass. More preferably, said lignin-rich feedstock comprises more than 90 wt% of lignin-based compounds obtained from delignification of biomass. Even more preferably, said lignin-rich feedstock comprises more than 95 wt% of lignin-based compounds obtained from delignification of biomass. Yet even more preferably, said lignin-rich feedstock comprises more than 97.5 wt% of ligninbased compounds obtained from delignification of biomass.

[0036] According to a preferred embodiment of the present invention, said lignin-rich feedstock also comprises dissolved hemicellulose resulting from a prior delignification reaction where said lignin-rich feedstock was generated.

[0037] According to a preferred embodiment of the present invention, said method further comprises a pretreatment procedure using an alkaline salt for the removal of sulfuric acid present in the crude bio-oil. Preferably, said alkaline salt is a hydroxide salt selected from the group consisting of: KOH; Ca(OH)2; and the like. Preferably, said alkaline salt is Ca(OH)2 •

[0038] According to a preferred embodiment of the present invention, said hydrodeoxygenation reaction lasts for a period of time of about 2h.

[0039] According to a preferred embodiment of the present invention, said hydrodeoxygenation reaction lasts is carried out a temperature of about 350°C.

[0040] According to a preferred embodiment of the present invention, said hydrogen-rich source is selected from the group consisting of: formic acid, alcohols, for example, ethanol; gaseous hydrogen; and the like. According to a preferred embodiment of the present invention, said upgraded oil has a char content of less than 5 wt. %. Preferably, said upgraded oil has a char content of less than 2 wt. %. More preferably, said upgraded oil has a char content of less than 1 wt. %.

[0041] According to a preferred embodiment of the present invention, the method further comprises a step of recovering the upgraded oil.

[0042] DETAILED DESCRIPTION OF THE INVENTION

[0043] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles of the present invention. These examples are provided for the purposes of explanation, and not limitation, of those principles and of the invention.

[0044] According to an aspect of the present invention, there is provided a method to convert biomass into a biofuel. Preferably, the delignification is carried out at much milder conditions that conventional kraft process or other widely employed delignification approach. Preferably also, this result is a completely cellulose-free stream of lignin and hemicellulose depolymerization organics (LHDO).

[0045] According to a preferred embodiment of the present invention, a lignocellulosic biomass feedstock is delignified using a modified Caro’s acid. The resulting delignification yields a stream of cellulose and a stream of solubilized lignin and hemicellulose depolymerized organics (LHDO). Preferably, said ligninhemicellulose depolymerized organics (LHDO) is a composition comprising: a strong acid and said lignin- derived material; said lignin-derived material comprises: lignin monomers (20 to 50 wt.%); lignin depolymerization products (50 to 80 wt.%). The terms lignin depolymerization products or material may be used interchangeably herein with the term lignin oligomers, in either instance they are meant to distinguish lignin-derived material which are not considered to be lignin monomers.

[0046] According to a preferred embodiment of the present invention, the LHDO obtained from a delignification reaction of lignocellulosic biomass using a modified Caro’s acid, comprises what can be considered as a bi-modal lignin-derived product distribution. There is a large concentration of compounds in the C3-C10 range and another large concentration of compounds in the C12-C30 range. Preferably, esterification reactions (especially with alcohols as large as butanol) are meant to increase the molecular weight of lighter lignin-derived material (such as lignin monomers) as well as react with the carboxylic acid groups and thus make them larger and less hydrophilic. Also esterification allows to obtain and isolate various esters of lignin monomers.

[0047] Preferably, to achieve such streams, the biomass comprising lignin, hemicellulose and cellulose fibers may be mechanically treated to reduce particle size prior to contacting it to a modified Caro’s acid.

[0048] Reaction for catalytic upgrading of biomass origin bio-oil into a drop-in fuel

[0049] According to an aspect of the present invention, the process disclosed herein provides for complete upgrading and production of drop-in fuels from lignocellulosic biomass (such as found in wood, trees, straw, agricultural waste, and waste paper).

[0050] According to a preferred embodiment of the method of the present invention, the process utilizes a unique lignin-rich oil from the crude bio-oil produced using SixRing’s patented delignification process. The aforementioned crude bio-oil is produced without the cellulose portion of the biomass which enhances its properties and makes it more suitable and easily upgraded to drop-in fuels. The lignin-rich oil stream refers to an oil resulting from the delignification of lignocellulosic biomass. According to a preferred method of the present invention, the lignin-rich oil is obtained as a byproduct of delignification using milder conditions (temperature and pressure) than conventional chemical delignification such as those used during the kraft process.

[0051] According to a preferred embodiment of the method of the present invention, the delignification of the biomass was carried out as follows. In a 10L glass reactor vessel 3,368g H2SO4 (93%), 3,746g H2O2 (29%), 576g H2O and 310g of a modifier (such as a taurine-related compound) were mixed to a molar ratio of 10: 10: 10: 1. This modified acid / peroxide blend can be used to delignify lignocellulosic biomass to produce cellulose. When biomass (wood shavings at a 5% mass loading) is added to this blend at this scale the reaction is very exothermic and will run away. To prevent a runaway reaction which would result in degradation of cellulose and keeping the mixture in control, small amounts of water (500g each) are added to the reactor when the mixture reaches certain predetermined temperatures: 35°C (1staddition of water); 37°C (2ndaddition of water); 39°C (1staddition of water); and 41°C (4thaddition of water, until the temperature increase in the reactor is small enough to keep the reaction going, but not run away. In cases when too much water is added, the reaction stops and the biomass will not be delignified completely. No external cooling was applied in any of the experiments. The delignification of the wood shavings was thus carried out at low temperatures and at atmospheric pressure. It is worth noting that external cooling can be applied in another preferred embodiment. The resulting streams of the above exemplary process include: a cellulose stream comprising solid cellulose fibers and a lignin-rich stream comprising the lignin removed from the biomass as well as dissolved hemicellulose depolymerized during the delignification and present in the lignin-rich liquid phase.

[0052] According to a preferred embodiment of the method of the present invention, one of the advantages of this approach is that compared to other approaches using the entire biomass to generate biofuel, this approach focusses on the LHDO 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. By removing the primary constituent of lignocellulosic biomass (cellulose) from treatment to manufacture biofuel, one increases the aromatic carbon compositions and thus increases the value of the biofuel.

[0053] According to another aspect of the present invention, there is provided a method which comprises as a sub-method to perform a controlled exothermic delignification of biomass, said process comprising the steps of: providing a vessel; providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; providing an aqueous acidic composition comprising a sulfuric acid component; providing a peroxide component; providing a modifier; exposing said biomass to said sulfuric acid source and peroxide component, creating a reaction mass ; 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 97 wt% of said lignin and hemicellulose from said biomass; and wherein said lignin and hemicellulose are recovered separately from the cellulose, for further processing into a bio-oil.

[0054] According to a preferred embodiment of the method of the present invention, the stream of LHDO is exposed to a pH adjustment prior to undergoing upgrading (i.e. HDO reaction). According to a preferred embodiment of the method of the present invention, the stream of LHDO is substantially free of cellulose (i.e. less than 5 wt. % cellulose). More preferably, the stream of LHDO contains less than 2 wt. % cellulose. Even more preferably, the stream of LHDO contains less than 1 wt. % cellulose. Yet even more preferably, the stream of LHDO contains less than 0.5 wt. % cellulose. Yet even more preferably, the stream of LHDO contains less than 0.1 wt. % cellulose.

[0055] 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.

[0056] According to yet another aspect of the present invention, there is provided a method which comprises as a sub-method for the delignification of biomass, said sub-method comprising the steps of: providing a vessel; providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; providing an aqueous acidic composition comprising a sulfuric acid component; providing a peroxide component; exposing said biomass to said sulfuric acid source and peroxide component, creating a reaction mass; 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 95 wt% of said lignin and hemicellulose from said biomass; and controlling the temperature of the delignification reaction by addition of water into said vessel.

[0057] According to yet another aspect of the present invention, there is provided a method which comprises a sub-method for the delignification of biomass, said sub-method comprising the steps of: providing a vessel; providing biomass comprising lignin, hemicellulose and cellulose fibers into said vessel; providing an aqueous acidic composition comprising a sulfuric acid component; providing a peroxide component; exposing said biomass to said sulfuric acid source and peroxide component, creating a reaction mass; 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 95 wt% of said lignin and hemicellulose from said biomass; and controlling the temperature of the delignification reaction by controlling the addition of biomass into said vessel.

[0058] Preferably, to achieve such streams, the biomass comprising lignin, hemicellulose and cellulose fibers is exposed to a modified Caro’s acid composition having a pH of less than 1, 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: o sulfuric acid; o a compound comprising an amine moiety and a sulfonic acid moiety; and o 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: o sulfuric acid; o a compound comprising an amine moiety; o a compound comprising a sulfonic acid moiety; and o 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: o an alkylsulfonic acid; and o 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: o sulfuric acid; o a heterocyclic compound; and o 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: o sulfuric acid; o a modifying agent comprising a compound containing an amine group; and o 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: o sulfuric acid; o a modifying agent comprising an alkane sulfonic acid and o 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: o sulfuric acid; o a substituted aromatic compound; and o 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: o sulfuric acid; o a modifying agent comprising an arylsulfonic acid; o a peroxide; and o 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: o sulfuric acid; o a heterocyclic compound; o an alkanesulfonic acid and o 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: o sulfuric acid; o a carbonyl-containing nitrogenous base compound; and o 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; for a period of time sufficient to remove substantially all of the lignin present on said biomass material. The process can be carried out for a varying duration of time depending on the particle size of the biomass being fed into the process. The process can last from 2 to 20 hours depending on that characteristic. Moreover, the temperature of the resulting mixture also has an impact on the duration of the process as the reaction is highly exothermic, precautions are taken to prevent a runaway degradation of the cellulose. This would result in a carbon black resulting product with no value. The process is preferably run at temperatures below 50°C, more preferably at temperatures below 40°C. The process of delignification is preferably performed with a cooling means adapted to control the heat generated by the chemical reaction of delignification and maintain the temperature to avoid an undesirable ‘runaway’ reaction.

[0059] 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. Preferably, for a modified Caro’s acid comprising sulfuric acid, peroxide and taurine (as the modifier component), the molar composition is as follows: H2O : H2O2 : H2SO4 : Taurine in a molar ratio of 56 : 10: 10: 1. Preferably, for a modified Caro’s acid comprising TEOA / MSA, the molar composition is as follows: H2O : H2O2 : H2SO4 : TEOA : MSA in a molar ratio of 56 : 10: 10: 1 : 1.

[0060] According to a preferred embodiment of the approach to obtain low lignin cellulose, 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.

[0061] 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.

[0062] According to a preferred embodiment of the approach to obtain low lignin cellulose, 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; andtaurates; as well as aminoalkylsulfonic acids where the alkyl is selected from the group consisting of C1-C5 linear alkyl and C1-C5 branched alkyl.

[0063] Preferably, said linear alkylaminosulfonic acid is selected form the group consisting of: methyl; ethyl (taurine); propyl; and butyl.

[0064] Preferably, branched aminoalkylsulfonic acid is selected from the group consisting of: isopropyl; isobutyl; and isopentyl.

[0065] Preferably, said alkylsulfonic acid is selected from the group consisting of: alkylsulfonic acids where the alkyl groups range from Ci-Ce and are linear or branched; and combinations thereof. More preferably, said alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propane sulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butane sulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t- butylhexanesulfonic acid; and combinations thereof.

[0066] Preferably, said arylsulfonic acid is selected from the group consisting of: toluene sulfonic acid; benzesulfonic acid; and combinations thereof.

[0067] Preferably, said compound comprising a sulfonic acid moiety is methane sulfonic acid.

[0068] According to a preferred embodiment of the approach to obtain low lignin cellulose (i.e. MCA cellulose), said Composition C may further comprise a compound comprising an amine moiety. Preferably, the compound comprising an amine moiety has a molecular weight below 300 g / mol. Preferably also, the compound comprising an amine moiety is a primary amine. More preferably, the compound comprising an amine moiety is an alkanolamine. Preferably, the compound comprising an amine moiety is a tertiary amine. According to a preferred embodiment of the approach to obtain low lignin cellulose, the alkanolamine is selected from the group consisting of: monoethanolamine; diethanolamine; triethanolamine; and combinations thereof. Preferably, the alkanolamine is triethanolamine.

[0069] According to a preferred embodiment of the approach to obtain low lignin cellulose, said 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.

[0070] Preferably, 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.

[0071] Preferably, in Composition C, said compound comprising an amine moiety is triethanolamine and said compound comprising a sulfonic acid moiety is methane sulfonic acid.

[0072] 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 a peroxide; 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.

[0073] According to 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 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. 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.

[0074] According to 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 alkane sulfonic acid and a peroxide; and wherein sulfuric acid and said alkane sulfonic acid are present in a molar ratio of no less than 1: 1. Preferably, said alkanesulfonic acid is selected from the group consisting of: alkane sulfonic acids where the alkyl groups range from Ci-Ce and are linear or branched; and combinations thereof. Preferably, said alkane sulfonic acid is selected from the group consisting of: methane sulfonic acid; ethanesulfonic acid; propane sulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; iso-pentylsulfonic acid; t-pentylsulfonic acid; pentane sulfonic 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 alkane sulfonic 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 alkane sulfonic 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.

[0075] 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 a peroxide; 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 toluene sulfonamides. 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.

[0076] 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; 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. Preferably, the compound containing an amine group is selected from the group consisting of: imidazole; N-methylimidazole; triazole; monoethanolamine (MEO A); diethanolamine (DEO A); triethanolamine (TEO A); 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; toluene sulfonic acid; benzenesulfonic acid; and combinations thereof.

[0077] 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 a peroxide; 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 toluene sulfonic acid. 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 alkane sulfonic 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: alkylsulfonic acids where the alkyl groups range from C1-C6 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; pentane sulfonic acid; t-butylhexanesulfonic acid; and combinations thereof. More preferably, said alkylsulfonic acid is methane sulfonic acid. 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 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. 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.

[0078] Preferably, the temperature of the reaction mass is kept below 55°C for the duration of the delignification reaction. Preferably, the temperature ofthe reaction mass 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 reaction mass 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 reaction mass is kept below 40°C for the duration of the delignification reaction.

[0079] Preferably, the temperature ofthe reaction mass 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. More preferably,, the temperature of the reaction mass 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.

[0080] Preferably during the delignification, the temperature of the mixture reaction mass 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. More preferably, the temperature of the reaction mass 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. Yet even more preferably, the temperature of the reaction mass 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.

[0081] Preferably for the delignification, 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.

[0082] 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 .

[0083] According to another aspect of the present invention there is provided a method which comprises as a sub-method, a step of converting LHDO into at least one esterified lignin derivative and to recover such, said method comprising the steps of: a. providing a LHDO comprising a lignin-containing material resulting from a delignification reaction of a lignocellulosic material using a modified Caro’s acid, wherein said lignin-containing material comprises a total acid content ranging from 35-70% , preferably, said lignin-containing material is present in an amount of at least 3%; wherein said lignin-derived material comprises: lignin monomers (20 to 50 wt.%); lignin depolymerization products (50 to 80 wt.%); b. optionally, removing at least a portion of water present in said LHDO; c. adding the LHDO to a flask containing magnetic stir bar; d. concentrating the material using a rotary evaporator until all volatile solvent was removed; e. weighing the residue, and f. adding a required mass of alcohol solvent (preferably 1 : 1 or 8: 1 alcohol:LHDO by weight); g. placing the mixture in an oil bath on a heating stir plate, where the bath has a temperature set to either 25 or 100 °C; h. stirring the reaction mixture at the desired temperature for up to 16 hours; i. optionally, cooling the reaction mixture; j. filtering the reaction mixture to remove precipitated solids; k. rinsing the filtered precipitated solids with additional alcohol, collecting, drying and weighing said solids; l. concentrating the filtrate by evaporation and then transferring a resulting concentrated filtrate to a separatory funnel; m. adding water and ethyl acetate, and extracting the product into an organic phase; n. optionally repeating the extracting step; o. collecting an organic phase; p. extracting an aqueous phase; q. optionally, combining the organic phases and transferring the combined organic phases back into the separatory funnel, r.optionally, washing the combined organic phases with two portions of a pH 2 sulfate buffer solution; s. optionally, drying the organic phase over MgSC , filtered into a round bottom flask, and evaporating the remaining volatiles; and t. optionally, weighing the residue and calculating a yield.

[0084] Preferably, the alcohol solvent is selected from the group consisting of: methanol; ethanol; n- propanol; isopropanol; n-butanol; isobutanol; n-pentanol; neo-pentanol; isopentanol; isoamyl alcohol and mixtures thereof. Preferably, the alcohol is n-butanol.

[0085] Preferably, the alcohol solvent and the sulfuric acid are present in a molar ratio ranging from 2.85: 1 (alcohol : sulfuric acid) to 10: 1 (alcohol : sulfuric acid). More preferably, the alcohol solvent and the sulfuric acid are present in a molar ratio ranging from 3 : 1 (alcohol : sulfuric acid) to 5 : 1 (alcohol : sulfuric acid).

[0086] According to a preferred embodiment of the present invention, the lignin-containing material results from a delignification reaction of a lignocellulosic material using a modified Caro’s acid.

[0087] According to a preferred embodiment of the present invention, the at least one esterified lignin derivative is selected from the group consisting of: alkyl malonate; alkyl maleate; alkyl succinate; alkyl oxalate; dialkyl malonate; dialkyl maleate; dialkyl succinate; dialkyl oxalate; alkyl vanillate and alkylparaben. Preferably, said at least one esterified lignin derivative is selected from the group consisting of: dibutyl malonate; dibutyl maleate; dibutyl succinate; and dibutyl paraben.

[0088] According to a preferred embodiment of the present invention, the alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propane sulfonic acid and combinations thereof.

[0089] According to a preferred embodiment of the present invention, the arylsulfonic acid is selected from the group consisting of: toluenesulfonic acid; benzene sulfonic acid; and combinations thereof.

[0090] Preferably, the LHDO has an acid content ranging from 40-45% prior to the addition into the flask.

[0091] According to a preferred embodiment of the present invention, said lignin monomers are present in an amount ranging from 20 to 50 wt.% of said lignin-derived material. According to a preferred embodiment of the present invention, said lignin depolymerization products are present in an amount ranging from 50 to 80 wt.% of said lignin-derived material.

[0092] According to a preferred embodiment of the present invention, there is provided a method to generate various aliphatic ester compounds and / or aromatic ester compounds by reacting lignin with a composition of sulfuric acid and an alcohol.

[0093] According to a preferred embodiment of the present invention, there is provided a method to generate various aliphatic ester compounds selected from the group consisting of: dialkyl malonate; dialkyl maleate; dialkyl succinate; and dialkyl oxalate.

[0094] According to a preferred embodiment of the present invention, there is provided a method to generate various aromatic ester compounds selected from the group consisting of: alkyl vanillate and alkylparaben.

[0095] According to a preferred embodiment of the present invention, the feedstock which can be employed in the process include but is not limited to: raw & concentrated liquid Lignin-Hemicellulose- Depolymerization-Organics (LHDO); kraft lignin; alkali lignin; and the like. Methods: General Procedure for Esterification Reactions

[0096] LHDO feedstock obtained from a delignification of lignocellulosic biomass using a modified Caro’s acid contains: dissolved lignin (present as: lignin monomers; lignin depolymerization products; and a combination thereof); dissolved hemicellulose; inorganic impurities (such as sulfate salts, chlorides); and water.

[0097] LHDO concentrate aims to reduce the presence of water and compared to the raw LHDO, it contains 30-40% less water. Of course, more water can be removed from the LHDO feedstock but as a cost to the overall process, the costs related water removal must be considered versus the benefit. Water removal has several benefits which include a more efficient esterification step as there is less water to impede the reaction.

[0098] The yield values are expressed in terms of percentage of dissolved lignin and hemicellulose that gets esterified and converted into the bio-oil. Higher yields means a greater percentage of the material as a whole gets converted into partially or fully esterified LHDO and becomes organic-soluble. Water content indicates how hydrophobic that material is. Even though the material is organic-soluble it can still be somewhat hydrophilic. Lower water content indicates a more hydrophobic product, while higher water content indicates less hydrophobic product. Preferably, lower water content is desirable.

[0099] Total Acid Number (TAN) gives an indication of the efficiency of the reaction. The definition of TAN is the mass in mg of KOH required to neutralize 1 g of oil, which means that the more acid the oil contains, the higher the TAN value will be. The starting LHDO contains a of lot of carboxylic acid compounds and would therefore have a very high TAN value (above 500). As these acids get converted into esters, they no longer react with KOH and so the TAN value will decrease, and so the more acid groups that get converted into esters, the lower the TAN value of the finished product will be. Lower TAN value means fewer carboxylic acids in the finished product which, in turn, means greater conversion efficiency. Yield values: above 60% is excellent, 50 - 60% is good, 30 - 50% is moderate, below 30% is poor. Water content values: above 1.5% is poor, between 0.5 - 1.5% is moderate, between 0.5 - 0.2% is good, below 0.2% is excellent. TAN values: above 150 is poor, between 100 - 150 is moderate, between 50 - 100 is good (matches pyrolysis oil), below 50 is excellent.

[0100] LHDO obtained from a delignification of lignocellulosic biomass using a modified Caro’s acid as described hereinabove added to pre-weighed round bottom flask containing magnetic stir bar. Material was concentrated on a rotavap (bath temperature 50 °C, vacuum gradually decreased to 1 mbar) until all volatile solvent was removed. Residue was weighed, and then the required mass of alcohol solvent was added (either 1: 1 or 8: 1 alcohol :LHDO by weight). The mixture was placed in an oil bath on a heating stir plate, and the bath temperature was set to either 25 or 100°C (80°C when methanol was used as the alcohol). For reactions carried out at 25°C, an air condenser was used, and for the reactions carried out at 80 or 100°C, a reflux condenser was used. In the LHDO, the acid is present in a concentration ranging from 30-70 %, more preferably from 40 - 65%. More preferably, the raw LHDO has an acid content of between 40 - 45%. Based on these numbers, acid concentration of the reaction mixture will range from 3 - 35% depending on the dilution factor upon combining the LHDO with the alcohol.

[0101] The reaction mixture was then stirred at the desired temperature for 16 hours. After 16 hours, the reaction mixture was removed from the oil bath, left to cool, if necessary, and then filtered through a medium fritted filter to remove precipitated solids. The solids were rinsed with additional alcohol, collected, dried overnight in a 45°C oven, and then weighed. The filtrate was concentrated on a rotary evaporator and then transferred to a separatory funnel. Water and ethyl acetate were added, and the product was extracted into the ethyl acetate phase. The organic phase was collected, and the aqueous phase was extracted two additional times with fresh ethyl acetate. The organic phases were combined and transferred back into the separatory funnel, where they were washed with two portions of a pH 2 sulfate buffer solution. The organic phase was then dried over MgSO4, filtered into a round bottom flask, and evaporated on a rotary evaporator to remove all volatiles. The residue was then weighed and the yield calculated.

[0102] HDO Upgrading

[0103] Bio-oil HDO upgrading experiments were performed in a 500 mL stainless steel Parr autoclave reactor (Illinois, USA) which are equipped with a magnetic stirrer, pressure gauge, and thermocouples. The bio-oil was upgraded by HDO in supercritical ethanol (with critical point at 241 °C and 63 bar).

[0104] Supercritical ethanol is an effective hydrogen-donating solvent to avoid the risk of utilizing pure hydrogen at small scale experimentation during catalytic upgrading process. It acts as an in -situ hydrogen donor, capable of generating hydroxyl and hydrogen radicals reacted with bio crude oil [

[0012] J.-H. Lee, L- G. Lee, J.-Y. Park, and K.-Y. Lee, “Efficient upgrading of pyrolysis bio-oil over Ni-based catalysts in supercritical ethanol,” Fuel, vol. 241, pp. 207-217, 2019, doi: 10.1016 / j .fuel.2018.12.025; and R. Jogi et al., “Biocrude production through hydro-liquefaction of wood biomass in supercritical ethanol using iron silica and iron beta zeolite catalysts,” J. Chem. Technol. Biotechnol., vol. 94, no. 11, pp. 3736-3744, 2019, doi: 10.1002 / jctb.6181], According to a preferred embodiment of the present invention, a pretreatment procedure using Ca(0H)2 was developed to remove sulfuric acid in the feedstock crude bio-oil, and a sulfur-water-removed (SWR) crude bio-oil was obtained for upgrading.

[0105] According to a preferred embodiment of the present invention, a 500 mb Parr autoclave reactor was fdled with 70 g pretreated bio-oil and 70 g ethanol-water mixed solvent (1: 1 w / w), and Ru / C catalyst (10 wt.% of bio-oil on dry base). The reactor was sealed and leak-proof tested with compressed nitrogen and then the residual air inside the reactor was removed by purging and vacuuming with pressurized nitrogen for 3 times. The reactor was then pressurized using pure hydrogen to 35 bar and heated to 300 and 350 °C under constant stirring (-300 rpm) and held at this temperature for 2 h.

[0106] At the end of each run, the reactor was quenched in a water bath. After the reactor was cooled to ambient temperature (-25 °C), the gaseous products were collected into a gas bag and analyzed using a GC-TCD to determine the gaseous product composition and yield. The reactor was then opened, and the reaction mixture was transferred into a 500 mb beaker. The reactor and stirrer were washed with dichloromethane three times, and the resultant washings were combined with the reaction mixture. Afterward, the mixture of reaction content and washings was filtered under vacuum. The solid product retained on the filter paper (VWR® Grade 413 Filter Paper) was oven-dried at 105 °C for 12 h to recover solid residue (the used catalyst with carbon / coke deposited), while the filtrate was extracted with dichloromethane to remove water and then evaporated under reduced pressure to remove solvents to recover upgraded oil for further analysis (CHNS elemental compositions, GC-MS, FTIR, etc.). According to a preferred embodiment of the present invention, different commercial refining and hydrogenation catalysts can be considered within the scope of the invention. Preferably, the catalyst is selected from the group consisting of: Ruthenium on activated carbon Ru / C; Ruthenium on activated carbon with ferrous oxide Ru / C-Fe2O3; nickel-molybdenum (NiMo); cobalt-molybdenum (CoMo); and Platinum and palladium on Zeolite Y and HZSM-5. According to a preferred embodiment of the present invention, a combination of the above listed catalyst is employed.

[0107] Total acid number (TAN) is an important quality testing for crude oil refining. It provides an indication of the weak organic acids and strong inorganic acids present within oil, and it is essential to maintain and protect equipment, preventing damage in advance. The desired TAN range for drop-in fuel will be in same range of the crude oil to be blended in which ensure the overall TAN for the blended drop- in fuel meets the correspondent standard for that fuel ASTM D8045. Viscosity has a very critical role in fuel systems, and it affects the fuel’s ability to lubricate fuel system components, and atomization. Poor fuel atomization results in poor combustion, which leads to multiple issues such as loss of power and fuel economy. The targeted viscosity range usually depends on the drop-in fuel target. In other words, the viscosity range shall be within the ASTM range values to ensure the conformance with the aforementioned standards once the drop-in blending is completed. This also is governed by the percentage of drop-in fuel value and it usually reflects on the final viscosity number measured of the blended fuel.

[0108] The yields of products (upgraded bio-oil, carbon / coke, gas products) were calculated by the wt.% of the product in relation to dry mass of the LHDO crude bio-oil feedstock.

[0109] GC-MS (Agilent Technologies, 5977A MSD, with HP-5MS column) was used to analyze the chemical composition of the volatile fraction of the LHO crude bio-oil and the upgraded oils at 300 and 350 °C, and the results are listed in Table 2, after upgrading process. As it is clearly shown, all the acids originally were presented in the LHDO crude bio-oil were removed and disappeared. This supports the hypothesis that these acids were converted into esters. The HDO upgrading also markedly increased the concentrations of hydrocarbons and aromatics in the upgraded oils.

[0110] Table 1: Results of HDO upgrading of the SWR crude bio-oil Moreover, the presence of high oxygen content in bio-oil results in low stability and strong acidity / corrosiveness and hence some negative impacts on storage and transportation of the oil, as well as some corrosion issues for bio-oil downstream upgrading / processing reactors. This is compared to fast pyrolysis bio-oil which is a dark, viscous liquid with a higher presence of water and numerous chemical compounds in a variety of reactive functional groups such as carbonyl compounds, makes bio-oil highly oxygenated, acidic (pH 2.5), and subject to phase separation and polymerization over time or with heating. Furthermore, oxygen (O) content in the bio-oil from fast pyrolysis (35-50 wt.%) is much larger than that of petroleum crude oil (< 1 wt.%). Such high oxygen content makes bio-oil dissolvable in polar solvents like acetone and methanol, but poorly miscible with fossil fuels.

[0111] Hydrodeoxygenation tests were carried out for lignin-rich oil LHDO at 300°C & 350°C, 35 bar H2pressure, using sets of commercial catalyst, 2h reaction time, and obtained an upgraded oil that was clear, miscible with hydrocarbon fuels such as diesel, jet fuel, and vacuum gas oil (VGO). The upgraded oil have much lower TAN and viscosity values, in particular for the upgraded oil at 350°C with the TAN and viscosity are as low as 2.5 mgKOH / g and 3.4 cP, respectively.

[0112] After the upgrading process, all acids in the crude bio-oil disappeared. It is hypothesized that the acids were converted into esters. The hydrodeoxygenation (HDO) upgrading also markedly increased the concentrations of hydrocarbons and aromatics in the upgraded oils. Tables 1 and 2 show the comparable results for the raw and upgraded bio-oil.

[0113] Table 2: Volatile compositions (based on GC-MS) of the SWR crude bio-oil and upgraded biooils from HDO upgrading at 300 and 350 °C for 2 h with 35 bar hydrogen gas According to a preferred embodiment of the present invention, HDO upgrading of feedstock oil at 300°C and 350°C in ethanol-water mixed solvent (50 / 50, w / w) under 35 bar hydrogen gas for 2h produced an upgraded oil at 18.1 wt.% and 21.2 wt% yield, respectively.

[0114] According to a preferred embodiment of the present invention, the upgraded bio-oil has a much lower TAN and viscosity values, as well as increased concentrations of esters, hydrocarbons and phenols and free of carboxylic acids when compared with the feedstock crude bio-oil.

[0115] The elemental, GC-MS and FTIR characterizations of upgraded bio-oil suggest effective hydro-deoxygenation (HDO) and hydro-de-sulfurization (HDS) during the HDO upgrading.

[0116] According to a preferred embodiment of the present invention, the upgraded bio-oil at 350°C has much better quality: much lower TAN (2.5 mg KOH / g), lower viscosity (3.4 cP at 50°C), and complete solubility in gasoline and VGO than the upgraded oil obtained at 300 °C.

[0117] In one experiment, a total of 105 grams of upgraded oil was obtained by HDO from the feedstock crude oil at 350°C.

[0118] Hydrodeoxygenation of esterified LHDO

[0119] An esterified oil sample obtained as per the method described herein was subjected to a hydrodeoxygenation reaction to produce an upgraded oil from a lignin-rich feedstock.

[0120] The esterified lignin derivative which comprises the esterified oil sample mentioned above, underwent a hydrodeoxygenation reaction carried out in the presence of a hydrogen-rich source at a temperature ranging from 300°C to 400°C under a H2 pressure ranging from 15 to 50 bar 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

[0121] Tables 3 through 9 lists various HDO experiments on esterified LHDO coming from a variety of lignocellulosic sources as well as various processing parameters, such a temperature, time of reaction, catalyst used. The tables also provide the resulting oil yield (in %wt.), SR yield (in %wt.)„ gas yield (in %wt.), and water and other low boiling points products (in %wt.). Table 3: Results of a hydrodeoxygenation of an esterified LHDO (from a hardwood source) where the co-solvent during the reaction is ethanol

[0122] Table 4: Results of a 2-hour hydrodeoxygenation reaction on an esterified LHDO (Hardwood source) where the co-solvent during the reaction is propanol and the hydrogen is administered as a gas

[0123]

[0124] Table 5: Results of a 2-hour hydrodeoxygenation reaction at 260°C on an esterified LHDO

[0125] (canola or Hardwood source) where the co-solvent during the reaction is propanol and the hydrogen is generated by formic acid and the catalyst is Albermarle (from calcination at 600°C)

[0126] Table 6: Results of a 2-hour hydrodeoxygenation reaction at 260°C on an esterified LHDO

[0127] (canola) where the co-solvent during the reaction is propanol and the catalyst is Albermarle (from calcination at 600°C)

[0128] Table 7: Results of a 2-hour hydrodeoxygenation reaction at various temperatures on an esterified LHDO (from a date palm source) where the co-solvent during the reaction is propanol, hydrogen gas is used and the catalyst is Albermarle (from calcination at 600°C)

[0129] Table 8: Results of a 2-hour hydrodeoxygenation reaction at various temperatures on an esterified LHDO (from a double esterified canola) where the co-solvent during the reaction is propanol, hydrogen gas is used and the catalyst is Albermarle (from calcination at 600°C)

[0130] Table 9: Results of a hydrodeoxygenation of an esterified LHDO (Hardwood source) where the co-solvent during the reaction is ethanol Tables 10 through 14 refer to the same examples as listed in the previous tables (tables 3 to 9) but, in these instances, provide the TAN (mg KOH / g) (before), the total acid number (TAN) in mg KOH / g (after), the density (g / mL) of the resulting oil; the nitrogen content (N %); the carbon content (C %); the hydrogen content (H %); the sulfur content (S %); the oxygen content (O %) and the heat energy(HHV) in MJ / kg.

[0131] Table 10: Results of a 2-hour hydrodeoxygenation reaction on an esterified LHDO (Hardwood source) where the co-solvent during the reaction is propanol and the hydrogen is administered as a gas

[0132] Table 11: Results of a 2-hour hydrodeoxygenation reaction at 260°C on an esterified LHDO (canola or Hardwood source) where the co-solvent during the reaction is propanol and the hydrogen is generated by formic acid and the catalyst is Albermarle (from calcination at 600°C)

[0133] Table 12: Results of a 2-hour hydrodeoxygenation reaction at 260°C on an esterified LHDO

[0134] (canola) where the co-solvent during the reaction is propanol and the catalyst is Albermarle (from calcination at 600°C)

[0135]

[0136] Table 13: Results of a 2-hour hydrodeoxygenation reaction at various temperatures on an esterified LHDO (from a double esterified canola) where the co-solvent during the reaction is propanol, hydrogen gas is used and the catalyst is Albermarle (from calcination at 600°C) Table 14: Results of a 2-hour hydrodeoxygenation reaction at various temperatures on an esterified LHDO (from a double esterified canola) where the co-solvent during the reaction is propanol, hydrogen gas is used and the catalyst is Albermarle (from calcination at 600°C)

[0137] According to a preferred embodiment of the present invention, the produced upgraded bio-oil was utilized as drop-in fuel with hydrocarbon fuels, namely, diesel, jet fuel, and then subjected to ASTM standard testing for the aforementioned hydrocarbon fuels. Third-party ASTM testing results confirmed the suitability of the upgraded oil as a drop-in fuel and met all the ASTM tests conducted by the certified third-party agency.

[0138] 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.

Claims

1. Method to produce an upgraded oil using a lignin-rich feedstock, said method comprises the following steps; providing said 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; providing an acidic composition having a pH of less than 1, said acidic composition comprising:■ an acid selected from the group consisting of: sulfuric acid; an alkylsulfonic acid; and an arylsulfonic acid; and■ an alcohol selected from the group consisting of Ci-Cs linear alcohol and C’s-G branched alcohol and mixtures thereof; combining said lignin-rich feedstock with said acidic composition into a reaction mixture; heating up said mixture to a temperature ranging from 25°C to 120°C; and allowing sufficient time of reaction to convert at least a portion of said lignin-derived material into said at least one esterified lignin derivative; separating said at least one esterified lignin derivative from said acidic composition; performing a hydrodeoxygenation reaction on said at least one esterified lignin derivative, wherein the hydrodeoxygenation reaction is carried out in the presence of a hydrogen-rich source at a temperature ranging from 250°C to 400°C under a H2 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.

2. The method according to claim 1 where the alcohol is selected from the group consisting of: methanol; ethanol; n-propanol; isopropanol; n-butanol; isobutanol; n-pentanol; neo-pentanol; isopentanol; isoamyl alcohol and mixtures thereof.

3. The method according to any one of claims 1 and 2 where the alcohol and the sulfuric acid are present in a molar ratio ranging from 2.85: 1 (alcohol : sulfuric acid) to 10: 1 (alcohol : sulfuric acid).

4. The method according to any one of claims 1 to 3 where the alcohol and the sulfuric acid are present in a molar ratio ranging from 3: 1 (alcohol : sulfuric acid) to 5: 1 (alcohol : sulfuric acid).

5. The method according to any one of claims 1 to 4 where lignin-containing material results from a delignification reaction of a lignocellulosic material using a modified Caro’s acid.

6. The process according to any one of claims 1 to 5, wherein the alkylsulfonic acid is selected from the group consisting of: methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid and combinations thereof.

7. The process according to any one of claims 1 to 6, wherein the arylsulfonic acid is selected from the group consisting of: toluenesulfonic acid; benzenesulfonic acid; and combinations thereof.

8. The method according to any one of claims 1 to 7, wherein said lignin-rich feedstock comprises more than 80 wt% of lignin-based compounds obtained from delignification of biomass.

9. The method according to any one of claims 1 to 8, wherein said lignin-rich feedstock comprises more than 85 wt% of lignin-based compounds obtained from delignification of biomass.

10. The method according to any one of claims 1 to 9, wherein said lignin-rich feedstock comprises more than 90 wt% of lignin-based compounds obtained from delignification of biomass.

11. The method according to any one of claims 1 to 10, wherein said lignin-rich feedstock comprises more than 95 wt% of lignin-based compounds obtained from delignification of biomass.

12. The method according to any one of claims 1 to 11, wherein said lignin-rich feedstock comprises more than 97.5 wt% of lignin-based compounds obtained from delignification of biomass.

13. The method according to any one of claims 1 to 12, said lignin-rich feedstock also comprises dissolved hemicellulose resulting from a prior delignification reaction where said lignin-rich feedstock was generated.

14. The method according to any one of claims 1 to 13, wherein said method further comprises a pretreatment procedure using an alkaline salt for the removal of sulfuric acid present in the crude bio-oil.

15. The method according to claim 14, wherein said alkaline salt is a hydroxide salt selected from the group consisting of: KOH; Ca(OH)2; and the like.

16. The method according to claim 15, wherein said alkaline salt is Ca(OH)2 .

17. The method according to any one of claims 1 to 16, wherein said hydrodeoxygenation reaction lasts for a period of time of about 2h.

18. The method according to any one of claims 1 to 17, wherein said hydrodeoxygenation reaction lasts is carried out a temperature of about 350°C.

19. The method according to any one of claims 1 to 18, wherein said hydrogen-rich source is selected from the group consisting of: formic acid, alcohols, for example, ethanol; gaseous hydrogen; and the like.

20. The method according to any one of claims 1 to 19, wherein said upgraded oil has a char content of less than 5 wt. %.

21. The method according to any one of claims 1 to 19, wherein said upgraded oil has a char content of less than 2 wt. %.

22. The method according to any one of claims 1 to 19, wherein said upgraded oil has a char content of less than 1 wt. %.

23. The method according to any one of claims 1 to 22, further comprising a step of recovering the upgraded oil.

24. The method according to any one of claims 1 to 22, wherein said at least one esterified lignin derivative is selected from the group consisting of: alkyl malonate; alkyl maleate; alkyl succinate; alkyl oxalate; dialkyl malonate; dialkyl maleate; dialkyl succinate; dialkyl oxalate; alkyl vanillate and alkylparaben. Preferably, said at least one esterified lignin derivative is selected from the group consisting of: dibutyl malonate; dibutyl maleate; dibutyl succinate; and dibutyl paraben

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