SE2230428A1

SE2230428A1 - A method for the production of bio-oil

Info

Publication number: SE2230428A1
Application number: SE2230428A
Authority: SE
Inventors: Hultgren Anders Edling
Original assignee: Votion Biorefineries Ab
Priority date: 2022-12-19
Filing date: 2022-12-19
Publication date: 2024-06-20
Also published as: WO2024132812A1

Abstract

ABSTRACT The present invention relates to a method for the production of a bio-oil from a biomass, and the bio-oil obtained by the method. The method comprises liquifying the biomass by thermal treatment at a temperature of from 100 °C to 400 °C in the presence of a 5 base and a non-aqueous fluid.

Description

A METHOD FOR THE PRODUCTION OF A BIO-OIL FIELD OF THE INVENTION The present invention relates to a method for the production of a bio-oil from a biomass, and the bio-oil obtained by the method.

TECHNICAL BACKGROUND The current and expected demand for biofuels greatly exceeds the available supply. Advanced biofuels are of particular interest, as this class of biofuels does not compete with food crops for feedstock biomass. There is great potential for bioenergy from residues and wastes from wood logging and wood processing - this global potential has been estimated to be 2.4 Gm3 per year (28 EJ per year), and the economic-ecological potential for Europe's existing disturbed forests was estimated to be 405 IV|m3 (Smeets & Faaij, Bioenergy potentials from forestry in 2050, Climatic Change, 2007).

Lignocellulosic materials are more complex and difficult to process than are sugars and vegetable oils, and thus, cannot be economically converted into biofuels and biochemicals by the currently available technologies. A biorefinery needs flexibility to process a variety of feedstocks with seasonal availability, so the process must tolerate a wide range of feed compositions.

A major barrier to the efficient conversion of lignocellulosic materials to biofuels is liquefaction of the raw materials at high yields. The most prominent methods currently in use for the production of bio-oils from lignocellulosic materials are hydrothermal liquefaction and pyrolysis.

Hydrothermal liquefaction (HTL) processes typically operate at high temperatures and pressures, requiring expensive equipment. Yields of HTL processes are limited by repolymerization and condensation reactions that lead to the formation of char and other solids.

NP0796SE-P Pyrolysis of biomass into bio-oil is most commonly done via flash pyrolysis at temperatures of 400 to 700 °C, requiring expensive equipment. Pyrolysis yields are also limited by the formation of char. Pyrolysis of lignocellulosic materials with higher lignin content has been reported to result in higher amounts of char. Pyrolysis oils are highly corrosive and unstable due to the high levels of acids, water, and aldehydes. The challenging properties of pyrolysis oils currently limit large-scale processes to co- refining, where the pyrolysis oils are blended into crude oil-derived streams, for example, with vacuum gas oil when fed to a fluidized bed catalytic cracking unit.

Complete dissolution ofthe biomass material without char formation or solid residue is desirable in order to maximize the yield of the process. lt is also desirable to minimize the yield loss to C02 during the liquefaction process by operating at moderate temperatures, since losses to C02 have been observed to increase with increasing temperature.

A challenge for the production of biofuels and biochemicals from lignocellulosic biomass materials is the presence of metals that can inhibit or deactivate catalysts used in refining processes such as hydroprocessing. Certain methods for the demetallization of bio-oils disclose low product phosphorus levels but have not effectively reduced the levels of other metals. For example, the method described in WO 2015/095453 A1 was effective for reducing phosphorus but not potassium. ln traditional crude oil refineries, hydroprocessing catalyst beds are protected by guard beds that comprise an inert trapping material, hydrodemetallization catalysts, or a combination of both. The higher the metal content in the hydroprocessing feed and/or the longer the time period between catalyst changeouts or catalyst skims, the larger the gua rd bed needed.

Phosphorus is of particular concern, as it is present in bio-oils in the form of phospholipids and, thus, is more difficult to remove than water-soluble metals. Both phospholipids and phosphorus are known to deactivate hydroprocessing catalysts. Other metals, such as calcium and magnesium, have been reported to be bound to phospholipids. ln order to remove phosphorus from bio-oils, the phospholipids must be decomposed. Decomposition of the phospholipids facilitates removal of phosphorus either in the aqueous phase or at the interface between the two phases. lt is desirable to reduce both the content of phosphorus and metals such as aluminium, calcium, magnesium, manganese, phosphorus, potassium, and sodium of the bio-oil via demetallization prior to hydroprocessing to maximize the time period between catalyst changeouts or catalyst skims and to minimize the volume of guard bed required. I\/|oreover, it is also desirable to reduce the content of phosphorus and metals by a means that allows for hydroprocessing of the entire bio-oil, as opposed to, for example, removal of fractions of the bio-oil containing high levels of metals prior to hyd roprocessing.

As is apparent from the above, there is still a need for an improved method for efficient liquefaction of biomass and reduction ofthe metal content in bio-oils.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for the production of a bio- oil. A further object is to provide a bio-oil with a low metal content. The bio-oil provided is flowable and is a suitable feedstock for hydroprocessing into fuels or chemicals.

The present invention is a feedstock-flexible process that converts biomass with a lignin content of up to about 40 wt% into bio-oils that are suitable for further refining into fuels or chemicals by means such as hydroprocessing.

NP0796SE-P The present invention utilizes mild or moderate temperatures and pressures, allowing for lower equipment costs than HTL or pyrolysis, and simplifies the addition of feedstock to the conversion process.

To increase the overall process yield, particularly on a carbon basis, organic compounds can be recovered from aqueous and gaseous streams. Organic compounds released into an aqueous phase that is separated from the bio-oil can be recovered by liquid-liquid extraction or other processes to avoid yield losses to Wastewater. Gases formed in the liquefaction and demetallization steps can be captured and utilized as biogas or fed to other reactive processes, such as reforming or shift conversion to produce hydrogen for use in hydroprocessing ofthe bio-oil.

Complete liquefaction of biomass into its constituent monoaromatic compounds is not required or even desired. Rather, a production of a bio-oil without char formation maximizes yield and provides flexibility for downstream use. This enables fuel and chemicals with a range of molecular weights to be produced.

The method of the present invention provides a bio-oil having a long boiling temperature range, wherein the bio-oil comprises high boiling fractions. This is an advantage as it provides flexibility as to the end products to be obtained from the bio- oil.

The method and the bio-oil according to the present invention are defined in the appended claims.

LIST OF DEFINITIONS Hydroprocessing: a number of catalytic processes in the presence of hydrogen gas for removal ofsulphur, oxygen, nitrogen and metals, or saturation of olefins and aromatics. Hydroprocessing encompasses hydrocracking, hydrotreating, hydrodewaxing, and hydrodemetallization.

NP0796SE-P Hydrocracking: a catalytic process for breaking down large organic molecules into smaller molecules by the breaking of carbon-carbon bonds in the presence of hydrogen gas.

Hydrotreating: a catalytic process for the removal of heteroatoms from chemicals, bio- gas, bio-oils, oils, or fuels in the presence of hydrogen. Hydrotreating also includes saturation of olefins and aromatics. Hydrotreating encompasses hydrodearomatization (HDA), hydrodenitrogenation (HDN), hydrodesulfurization (HDS), hydrodeoxygenation (HDO), hydrofinishing, and olefin saturation.

Hydrodesulfurization (HDS): a catalytic process for removing sulphur (S) from chemicals, bio-gas, oils, bio-oils, or fuels in the presence of hydrogen gas. HDS reactions release sulphur as hydrogen sulphide (H25).

Hydrodenitrogenation (HDN): a catalytic process for removing nitrogen (N) from chemicals, bio-gas, oils, bio-oils, or fuels in the presence of hydrogen gas. HDN reactions release nitrogen as ammonia (NH3). Also known as hydrodenitrification. Hydrodeoxygenation (HDO): a catalytic process for removing oxygen (O) from chemicals, bio-gas, oils, bio-oils, or fuels in the presence of hydrogen gas. HDO reactions release oxygen as water.

Hydrodemetallization (HDM): a catalytic process for the removal of metals from chemicals, bio-gas, oils, bio-oils, or fuels in the presence of hydrogen gas. Hydrofinishing: a final hydrotreating step after hydrocracking and/or hydrotreating that improves the colour and oxidation stability of the product.

Hydrodewaxing: the reduction of the wax content, such as paraffin wax (C18-C36 hydrocarbons), from hydroca rbons during oil refining in the presence of hydrogen gas. Hydrodewaxing includes dewaxing by shape-selective hydrocracking, isomerization, and combinations of shape-selective hydrocracking and isomerization.

Shape-selective hydrocracking: hydrocracking using shape-selective catalysts. Shape-selective catalysts: catalysts whose shape, such as pore structure, affects a chemical reaction. Hydrodewaxing via shape-selective hydrocracking uses the pore structure to selectively crack normal paraffins.

NP0796SE-P Simulated Distillation: a method for determination of the boiling point distribution in an oil or fractions thereof by gas chromatography according to EN 15199-1, where the percentage distilled is calculated as a function of temperature.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the simulated distillation of bark oil by chromatography. The cumulative weight percentage recovered is presented as a function of the boiling point of the components of the sample (x-axis: effective temperature; y-axis: cumulative weight percent recovered).

Figure 2 shows the simulated distillation of bark oil by gas chromatography. The area percentage is presented as a function of the boiling point of the components of the sample (x-axis: effective temperature; y-axis: analysis area percentage).

DETAILED DESCRIPTION OF THE INVENTION In a first aspect, the present invention relates to method for providing a bio-oil, comprising the steps of: a) adding a biomass with a lignin content of from 0 to 40 wt%; b) adding a non-aqueous fluid; Û ) adding a base, preferably a strong base or a superbase; d) subjecting the biomass to thermal treatment at a temperature of from 100 °C to 400 °C, preferably of from 110 to 380 °C, more preferably of from 120 to 320 °C; to obtain a bio-oil; e) adding a first acid to the liquid comprising bio-oil; f) optionally adding one or more of water, a second acid, a bio-oil, or a solvent, to the bio-oil obtained to obtain a mixture; g) subjecting the bio-oil obtained in e), or the mixture obtained in step f), to a temperature of from 10 °C to 320 °C, preferably of from 80 °C to 250 °C, more preferably of from 120 °C to 200 °C, to obtain a second mixture comprising an aqueous phase and a bio-oil; NP0796SE-P h) removing the aqueous phase from the second mixture to obtain a demetallized bio-oil; i) optionally repeating steps f)-h); and j) optionally subjecting the demetallized bio-oil to hydroprocessing; whereby the demetallized bio-oil obtained has a total metal content of less than 200 ppm, preferably of from 0 to 50 ppm, and a total phosphorus content of less than 10 ppm.

The steps a) to j) may be performed in consecutive order. Alternatively, steps a), b) and c) could be performed in any order. Steps e) and f) may be performed in the reverse order. Step d) has to be performed after steps a), b) and c) and before e) and f). Step g) and h) have to be performed in said order after the last of steps e) and f).

Steps f)-h) may be repeated at least once. Repeating steps f)-h) enables reduction of the total metal content and facilitates efficient phosphorus removal. ln one embodiment, an acid is added when step f) is performed for the first time, and when repeated, water without acid is added.

All aspects and embodiments disclosed herein can be combined with any other aspect and/or embodiment disclosed herein.

The term ”biomass”, as used herein, does not comprise animal-based biomass. Algae is defined herein as non-animal-based biomass. The biomass used in the present invention may originate from agriculture, aquaculture, food industry, forest, forest industry, grassland, or combinations thereof. The biomass is preferably originating or being selected from softwood, hardwood, straw, bagasse, grass, algae, seagrass, seaweed, cones, needles, leaves, bark, nutshell, fruit kernel, husk, corn stover, agriculture residues, forest residues, food industry residues and other biomass types. The biomass may have been processed.

NP0796SE-P ln one embodiment the biomass comprises from 0.1 to 99 wt% of carbohydrates as calculated on total dry weight of the biomass. ln one embodiment the biomass comprises lignin at a level of from 0.1 to 40 wt%, as calculated on total dry weight of the biomass. The lignin content is determined as Klason lignin, which is the residue obtained after removal of the carbohydrate portion of wood or plant tissue by total acid hydrolysis. The content of Klason lignin is determined by a gravimetric method, for example by TAPPI Standard T 222.

The term ”fluid” is used herein for gases as well as liquids.

The method according to the present invention provides a bio-oil having a total metal content of less than 200 ppm, preferably of from 0 to 50 ppm, more preferably of from 0 to 20 ppm, even more preferably of from 0 to 10 ppm; and a total phosphorus content of less than 10 ppm, preferably of from 0 to 5 ppm. ln one embodiment the biomass, or the mixture of biomass and non-aqueous fluid, has a water content of from 0.1 to 65 wt%, preferably from 0.5 to 45 wt%, more preferably from 1 to 40 wt%, as calculated on the total weight ofthe biomass. ln one embodiment the biomass provided in a) is subjected to steam explosion to obtain wood pellets or black pellets with a water content of from 5 to 12 wt%, preferably from 5 to 10 wt%, more preferably from 5 to, and not including, 10 wt%. The steam explosion may be performed at a temperature of 150-220 °C. The biomass may be dried by heating or pressing. ln one embodiment, the non-aqueous fluid is selected from at least one of C1.10alcohol, C130 hydrocarbon, or a bio-oil, an ether, an alkyl acetate, sulfolane, a fluid stream recycled from a hydroprocessing step, or mixturesthereof. The use of a recycled process stream, such as bio-oil or a fluid stream from a hydroprocessing step, reduces the requirement for fresh non-aqueous fluid, such as a C140 alcohol.

NP0796SE-P ln one embodiment the non-aqueous fluid added in step b) is a C1-10 alcohol. Preferably, the C1-10 alcohol has a boiling point of from 50 to 250 °C. Preferably the C1-10 alcohol is selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, glycerol, propylene glycol, cresol, resorcinol, hydroquinone, guaiacol, catechol, phenol, or benzyl alcohol, or any combination thereof. Preferably, the alcohol is derived from renewable sources. The alcohol component of the non- aqueous fluid functions not only as a solvent but also as a capping agent of lignin derivatives via alkylation, thereby suppressing repolymerization reactions between reactive phenolic compounds that lead to char formation. Selection of the alcohol impacts the solubility and solvation characteristics of the resulting bio-oil, wherein selection of an alcohol with more hydrophobic character results in more hydrophobic lignin derivatives.

More preferably, the C140 alcohol is methanol, ethanol, or a combination of methanol and ethanol. The recovery of methanol or ethanol is relatively energy-efficient in comparison with other solvents, and distillation may be performed at relatively low temperature. The use of ethanol facilitates precipitation of potassium sulphate and other sulphate salts when a sulfuric acid is added in step e). Consequently, the use of ethanol is preferred when precipitating salts, while other alcohols may be used earlier in the process, i.e., during liquefaction ofthe biomass and/or lignin (i.e. steps a) to d) as disclosed herein). Ethanol may also dissolve both hydrophobic and hydrophilic molecules. ln one embodiment the non-aqueous fluid added in step b) comprises a C140 hydrocarbon or a mixture of C140 hydrocarbons. Preferably, the C140 hydrocarbon is a saturated hydrocarbon, more preferably a C1.30alkane, which may be branched, linear, or cyclic. The C140 hydrocarbon is preferably selected from propane, butane, hexane, heptane, octane, nonane, decane, undecane and dodecane, which may be branched or NP0796SE-P linear, or from cyclic (naphthenic) hydrocarbons, such as those produced from the saturation of lignin and lignin derivatives. ln one embodiment the non-aqueous fluid added in step b) comprises a bio-oil. The bio- oil added as a non-aqueous fluid in step b) or the bio-oil added in step f) is each independently prefera bly selected from a bio-oil recycled from a process comprising the method according to the present invention; tall oil pitch (TOP); crude tall oil; pyrolysis oil; softwood oil; hardwood oil; bagasse oil; lignin oil; bark oil; sawdust oil; hydrothermal liquefaction oil; turpentine; vegetable oil; oil obtained from any one of lignocellulosic material, grass, algae, seagrass, seaweed, agriculture raw material, such as agriculture residues, aquaculture residues, animal residues, food industry residues, forest residues; or any combination thereof. ln one embodiment, vegetable oils are excluded as feedstock. A reason for this is not to compete with resources from food industry. Examples of vegetable oils excluded are açaí palm oil, avocado oil, Brazil nut oil, buriti oil, canola oil, carapa oil, coconut oil, corn oil, cottonseed oil, grape seed oil, graviola oil, hazelnut oil, hemp seed oil, jambu oil, linseed oil, olive oil, palm oil, palm kernel oil, passion fruit oil, peanut oil, pracaxi oil, rapeseed oil, rice bran oil, safflower oil, sesame oil, Solarium oil, soybean oil, sunflower oil, tucumä oil, and walnut oil. I\/|ore preferably, the bio-oil added as a non-aqueous fluid in step b) or the bio-oil added in step f) is each independently selected from a bio-oil recycled from a process comprising the method presented herein; tall oil pitch; crude tall oil; pyrolysis oil; softwood oil; hardwood oil; bagasse oil; lignin oil; bark oil; sawdust oil; hydrothermal liquefaction oil; turpentine; oil obtained from any one of lignocellulosic material, algae, seagrass, seaweed, cones, needles, leaves, bark, nutshell, fruit kernel, husk, corn stover, agriculture raw materials, agriculture residues, food industry residues or forest residues; or any combination thereof. ln one embodiment, the non-aqueous fluid comprises a C140 alcohol and a bio-oil that is recycled from the process disclosed herein.

NP0796SE-P Liquefaction of biomass can be carried out in the presence of a catalyst to aid in the depolymerization of lignin and suberin, as well as decomposition of cellulose and hemicellulose. Base-catalyzed depolymerization of lignin suppresses repolymerization and char formation during liquefaction and thus is favoured over acid-catalyzed depolymerization. Complete dissolution of the biomass without char formation is desirable in order to maximize the yield ofthe process.

The base added in step c) is selected from a weak base, a strong base or a superbase; preferably a strong base or a superbase. Use of a homogeneous base, i.e., without a support, rather than a heterogeneous supported base, as catalyst, avoids operational difficulties involved with the separation and recovery ofthe catalyst from the resulting bio-oil, as well as deactivation of the heterogeneous catalyst.

A weak base can be selected from organic bases, such as pyridines, anilines, tertiary aliphatic amines; or from inorganic bases, such as sodium bicarbonate. A weak base, when used, is preferably used in combination with a strong base or superbase. A weak organic base may also function as a solvent or co-solvent. ln one embodiment the strong base is selected from sodium sulphide, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, caesium hydroxide, lithium hydroxide, rubidium hydroxide, strontium hydroxide, or any combination thereof. The strong base is preferably selected from sodium sulphide, potassium hydroxide, or sodium hydroxide, or any combination thereof. More preferably, the strong base is potassium hydroxide. Addition of a metal hydroxide, such as sodium hydroxide or potassium hydroxide, to a mixture comprising biomass and an alcohol, such as methanol or ethanol, provides for the formation of potassium alkoxide, e.g. potassium methoxide or potassium ethoxide, upon heating, which is a stronger base than potassium hydroxide, thus improving the process economy in the conversion of biomass to bio-oil. Alternatively, a metal alkoxide in an alcohol solution, such as potassium ethoxide in ethanol solution, can be added to the biomass. 11 NP0796SE-P A superbase is defined in IUPAC as a compound that has a very high basicity. ln this specification the same definition is used. ln one embodiment ofthe present invention, the superbase is selected from organometallic or inorganic compounds, such as a Grignard reagent; hydrides ofalkali-metals, such as lithium hydride, potassium hydride, or sodium hydride; combinations of organolithium compounds with alkali metal alkoxides, such as n-butyllithium and potassium tert-butoxide; or from organic compounds, such as phosphazenes, e.g. Schwesinger phosphazenes, proazaphosphatranes , such as Verkade proazaphosphatranes; phosphines; amidines; such as Schwesinger vinamidines; guanidines; or metal amides, such as lithium diisopropylamide; or any combination thereof. Specific examples of alkali metal alkoxides are a|ka|i-metal C14; alkoxides, such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, or potassium tert-butoxide. ln one embodiment, the mixture subjected to thermal treatment in step d) comprises 5- 50 wt% biomass, 1-35 wt% base, and 30-94 wt% ofa non-aqueous fluid up to a maximum or a total of 100 %, as calculated on the total weight of the mixture. Preferably, the mixture comprises 8-40 wt% biomass, 5-25 wt% base, and 40-87 wt% of a non-aqueous fluid, up to a maximum or a total of 100 %, as calculated on the total weight of the mixture. More preferably, the mixture comprises 10-35 wt% biomass, 10-20 wt% base, and 50-80% of a non-aqueous fluid, up to a maximum or a total of 100 %, as calculated on the total weight of the mixture.

Conversion of the biomass includes the liquefaction of solids, reduction of the viscosity of the resulting bio-oil, and reduction of the final boiling point of the bio-oil, and occurs via base-catalyzed depolymerization of biomass components, such as lignin and suberin, as well as decomposition of polysaccharides such as cellulose and hemicellulose.

By dispersing the biomass with a non-aqueous fluid, the base (e.g., KOH) can form alkoxide ions instead of hydroxide ions, increasing the strength ofthe base and thereby 12 NP0796SE-P improving the rate and extent of Conversion ofthe biomass. Use of a stronger base, such as an alkoxide instead of the corresponding hydroxide, can also reduce the amount of base required for liquefaction. Consequently, it is advantageous to minimize water during liquefaction, e.g. by limiting the initial water content of the mixture. Preferably, no free water is added in steps a) to d). The term ”free water” is used herein for water that is, or was, not contained in the biomass.

Water can be formed via dehydration reactions during the liquefaction process. Said water can be removed by evaporation, distillation, or liquid-liquid extraction once the |ignin material has been liquefied. By using a non-aqueous fluid, such as an alcohol, a bio-oil, or a C130 hydrocarbon, with a boiling point above 100 °C, water can be selectively removed by evaporation, or distillation. The skilled person in the field is well equipped to select said alcohol, bio-oil, or C130 hydrocarbon. ln one embodiment, the temperature in step d) is from 140 to 280 °C, more preferably of from 160 to 245 °C, even more preferably of from 170 to 240 °C.

By thermal treatment at a temperature of from 100 °C to 400 °C, preferably of from 110 °C to 380 °C, more preferably of from 120 °C to 320 °C; during a time period of from 0.5 to 360 min, or from 1 to 360 min, or preferably from 5 to 300 min, more preferably of from 16 to 300 min, in step d), a liquid comprising bio-oil is provided without any extraction of solid materials being carried out.

The time period required to convert the biomass to a bio-oil depends on the temperature of the mixture, i.e. the biomass, base, and non-aqueous liquid. The time for the thermal treatment in step d) is preferably long enough to provide heat uniformity. Achieving a certain extent of conversion requires shorter time periods when using higher temperatures. The quality and yield of the resulting bio-oil also depend on the temperature applied, wherein excessively high temperatures (> 380 °C) result in significant yield losses due to decarboxylation and gas formation, as well as char formation. Excessively high temperatures also require a greater energy input than that 13 NP0796SE-P needed to liquefy the biomass into a bio-oil. The required time period also depends on the temperature that the components, i.e. the biomass, base, and non-aqueous fluid, have when they are added to the mixture.

As used herein, time period is equal to residence time. Whereas time period is usually used for a batch process and residence time is usually used for a continuous process, the terms may be used interchangeably herein. ln one embodiment the time period is from 5 to 360 min, preferably from 16 to 240 min, more preferably from 16 to 180 min, even more preferably from 30 to 120 min, most preferably from 35 to 90 min.

The temperature during the thermal treatment in step d) may be changed gradually, continuously, or in several heating stages over a period of time. The desired temperature may be reached by using pre-heated biomass, or pre-heated non-aqueous fluid, or pre-heated base, from any of the previous steps a) to c); and/or by heating in step d).

When performing several heating stages, the biomass may be liquefied during any or all of the first heating stage(s), with biomass conversion being performed to the desired extent during the final heating stage(s). The temperature could be kept constant, or essentially constant, during any one heating stage. Essentially constant is in this context defined as a temperature variation of less than 10% of the desired temperature. Removing water prior to the final heating stage ensures that the base is in the alkoxide form rather than the hydroxide form, thereby improving the effectiveness of the base during the biomass liquefaction. Water, when present, may be removed by distillation, evaporation or by liquid-liquid extraction.

The thermal treatment in step d) may be performed at conditions where the non- aqueous fluid is in a near-supercritical or supercritical state. As used herein, the near- supercritical state denotes the state where the fluid is in the vicinity of its critical point, such as 20 °C below its critical temperature, for example at temperatures of 220-240 °C when using ethanol at a pressure of 63 bar. 14 NP0796SE-P The liquefaction process of steps a)-d) may be performed batch-wise or in continuous operation, in a single vessel or in multiple vessels. Different types of equipment may be used, such as a stirred tank reactor, plug flow reactor, or vessels in series. Digesters used in the pulp industry in various configurations, such as batch, continuous, horizontal, and multitube reactors, are examples of suitable equipment. Heat exchange can be attained in various configurations, such as using a heated vessel, multitube heat exchangers, or combinations thereof. Heating the mixture in stages, to different temperatures for different times, can be accomplished with different types of vessels in series using various residence times and different configurations. For example, the first stage of liquefaction may take place in a stirred tank at a first temperature with a long residence time, followed by a second liquefaction stage at a higher temperature with a shorter residence time than that of the first stage. Pre-heated base, and/or pre-heated non- aqueous fluid(s), may be added between stages of liquefaction.

Addition of the C140 alcohol can be performed at any point or at multiple points throughout the liquefaction in step d). ln one embodiment, methanol and/or ethanol are added in the vapor phase, preferably above the boiling point of water. Water is condensed and removed from the process, while methanol and/or ethanol vapours are recycled to the reactor. This distillation process can be done under vacuum or under pressure. The advantage with this procedure is continuous removal of water. lf the liquefaction is done in two stages, the second stage could be performed at a higher pressure than the first so that the alcohol is in the liquid phase in the second stage and in the gas phase in the first stage. An advantage of using relatively low pressure in the first stage is simplified feeding of biomass and/or lignin to the reactor. ln one embodiment any solids remaining from the biomass are removed from the lignin oil obtained in step d). The removed solids may be used for sugar production or as a pulp material.

NP0796SE-P An acid, preferably a strong acid, e.g., hydrochloric acid, sulfuric acid, or nitric acid, added in step e) neutralizes or acidifies the liquid comprising the bio-oil. The addition of the acid may also precipitate salts. ln one embodiment, the method further comprises removal of the precipitated salts from the bio-oil. The precipitated salts are preferably removed by filtration.

Acids and bases used in the method according to the present invention can be selected so as to obtain precipitates that can be used as fertilizers or other useful products. The skilled person is well equipped to choose suitable acids and bases to this end. For example, addition of sulfuric acid or nitric acid causes potassium ions occurring in the bio-oil to precipitate as potassium sulphate and potassium nitrate, respectively. Thus, in a preferred embodiment the acid for salt precipitation, i.e., the first acid, is selected from sulfuric acid or nitric acid.

The bio-oil obtained in step e), is subjected to demetallization, preferably by acid treatment. Demetallization provides for the removal of metals from the bio-oil. Demetallization of the bio-oil, i.e., steps f) -h) ofthe present invention, may comprise addition of one or more of water, a second acid, a bio-oil, or a solvent, to the bio-oil obtained in step d) to obtain a mixture. The obtained bio-oil, or the mixture comprising the obtained bio-oil, is subjected to a temperature of from 10 °C to 320 °C, preferably of from 80 °C to 250 °C, more preferably of from 120 °C to 200 °C, to obtain a second mixture comprising an aqueous phase and bio-oil, followed by removal of the aqueous phase to obtain a demetallized bio-oil. The entire process of liquefaction and demetallization may be performed continuously or batchwise. The latter would minimize the required equipment. ln one embodiment of step f), the added bio-oil is dispersed in a solvent. The dispersion of the added bio-oil may be performed either before or after any addition of water. Addition of a water-insoluble solvent in step f) can be advantageous for the subsequent removal ofthe aqueous phase. The solvent aids in the separation of the aqueous phase from the bio-oil. The need for a solvent depends on the miscibility of the bio-oil with 16 NP0796SE-P water, which can vary widely depending on the composition ofthe bio-oil. For example, tall oil pitch and crude tall oil are not readily miscible with water, thus, addition of a solvent to such bio-oils is not necessary from a phase separation sta ndpoint. However, a solvent may be desirable for reducing the viscosity of a bio-oil to facilitate transport or mixing. The mixture of bio-oil and solvent is preferably in a liquid form at a temperature above 120°C, or above 150 °C. ln one embodiment, the solvent added in step f) is selected from a water-insoluble C4-6 alcohol, preferably butanol; ethers, such as methyl tetrahydrofuran; alkyl acetates, such as butyl acetate or ethyl acetate; a liquid stream recycled from a hydroprocessing step, or mixtures thereof. The hydroprocessing step from which a liquid stream can be recycled may be the hydroprocessing in step j) according to the invention. Using a recycled stream lowers the requirement for fresh solvent. Solvents of bio-renewable origin are preferred in the production of fuel and chemicals. ln one embodiment of step f), one or more acids are added, preferably selected from mineral acids, e.g., hydrochloric acid, sulfuric acid, or nitric acid; or organic acid, such as citric acid, formic acid, lactic acid, oxalic acid, or acetic acid. I\/|ore preferably sulfuric acid or nitric acid is added in step e). The addition of the one or more acids preferably adjusts the pH ofthe aqueous phase in the mixture to a pH of 1-6, preferably a pH of 1- 4, more preferably a pH of 1-2. lf sufficient acid is added in step e), any acid addition in step f) may be omitted. The acid in step e) and the acid in step f) could be the same or different.

The contents of steps a)-c) and f) may be mixed by any suitable mixing method to obtain the mixture.

The present method allows for a large amount of water to be present in the mixture when it is heated during demetallization. The mixture may have a water content of from to 90 wt%, based on the total weight ofthe mixture; preferably 15-75 wt%, and more 17 NP0796SE-P preferably 20-60 wt%. lncreasing the water content improves removal of metals. Alternatively, repeating the steps without increasing the water content can also improve the removal of metals.

The desired temperature in step g) may be reached by using pre-heated bio-oil, pre- heated liquids added in step f); or by direct heating of the mixture obtained in step f). When the contents of step f) are pre-heated prior to obtaining the mixture in step f), said mixture is obtained at a time point when said contents are still warm or hot. Preferably, when step g) is carried out for the first time, the temperature is from 120 °C to 200 °C, more preferably of from 140 °C to 200 °C, and not including 200 °C, even more preferably from 150 to 200°C, and not including 200 °C, or most preferably of from 150 to 190°C. This temperature is required for effective decomposition ofthe phospholipids and subsequent phosphorus removal. However, when step g) is repeated, the phospholipids have already been decomposed and lower temperatures may be used, such as from 10 °C to 200 °C. The temperature used depends on the composition of the bio-oil, whereby the temperature used shall be sufficient for phase separation. When the biomass does not contain phospholipids, lower temperatures, such as from 10 °C to 200 °C, may be used the first time step g) is carried out.

A higher temperature facilitates a lower content of phosphorus in the obtained demetallized bio-oil. However, if the temperature is too high, e.g., above 200 °C, the separation ofthe organic and aqueous phases becomes more difficult, due to increasing emulsification. Additionally, temperatures below 200 °C are preferred to avoid excess energy usage in the form of heat input beyond that required for an efficient phase separation.

When steps are repeated, lower temperatures may be used in subsequent repetitions than originally used. Heavy bio-oils with high viscosities require higher temperatures than lighter bio-oils to achieve effective mixing and, subsequently, an efficient phase 18 NP0796SE-P separation. The use of a solvent can be advantageous to decrease the viscosity of the bio-oil without increasing the temperature.

The mixture of step f) may be subjected to the desired temperature gradually, continuously, or in several stages over a period of time. The time required for heating depends on the rate of heating and the thoroughness of mixing. The mixture is subjected to the desired temperature for a period of from 0.01 to 10 minutes. ln one embodiment, the phases ofthe mixture in step g) are allowed to separate before water is removed. The time required for phase separation depends on the temperature of the mixture, the composition of the mixture, the optional addition of an emulsion breaker, and the process equipment used. Phase separation can be carried out in a batch process or continuous process. ln a continuous process using a decanter, for example, the mixture is continuously fed to the decanter, while an aqueous stream and an organic stream are continuously removed from the decanter.

Removal of the aqueous phase from the bio-oil is critical for the removal of metals from the bio-oil, as the metals are partitioned into the aqueous phase. Poor phase separation thereby results in poor demetallization performance. Removal of the aqueous phase by evaporation does not facilitate demetallization, as the metals are not removed with the water in this case. Removal of the aqueous phase can be facilitated by the use of mechanical means, such as a centrifuge, decanter, decanter centrifuge, coalescer, electrostatic coalescer, oil desalter, API (American Petroleum Institute) separator, or by a combination of these; electrical means, such as electrostatic desalting units; chemical means, such as addition of an emulsion breaker; or by a combination ofthese. Suitable emulsion breakers, also known as demulsifiers, are selected from amines, such as octylamine or dioctylamine; alcohols, such as ethanol or long-chain alcohols; polyhydric alcohols, such as propylene glycol or polyethylene glycol; fatty acid alkoxylates; oxyalkylated alkyl phenols; oxyalkylated alkyl resins; sulfonates; other nonionic 19 NP0796SE-P surfactants comprising both hydrophilic and hydrophobic groups; or combinations thereof.

When removal of the aqueous phase in step h) is facilitated by the use of mechanical means, the need for repeating the washing steps may be eliminated due to the effectiveness of the phase separation resulting in efficient removal of metals. ln one embodiment, after removal ofthe aqueous phase in step h) using a decanter, the bio-oil is subjected to centrifugation to remove any remaining water.

While optional, repeating steps f)-h) enables further reduction of the total metal content, including further phosphorus removal. ln one embodiment, an acid is added the first time step f) is carried out, and when repeated, water without acid is added. Using water without acid in the final repetition of step b) reduces the corrosivity of the demetallized bio-oil in downstream processing, thus without needing a base for neutralization. Addition of a base to the demetallized bio-oil is not desirable, as this would result in the addition of metals, nitrogen compounds, or other species that are hydroprocessing catalyst inhibitors or catalyst poisons.

The aqueous phase obtained in step h) may be demineralized and/or extracted with an organic solvent to separate organic compounds from the aqueous phase. The water added in step f) may be demineralized water, including distilled water; or the aqueous phase recycled from step h). Recycling the aqueous phase may be performed to reduce the need for demineralized water, whereby recycled water is used the first time or times step f) is carried out, and fresh water is used when step f) is repeated, at least once. Using demineralized water in the final execution of step f) ensures that no metals are introduced to the bio-oil from the wash water.

Residual water, when present in the demetallized bio-oil, may be removed by distillation, evaporation, membrane separation, liquid-liquid extraction, or by any other NP0796SE-P suitable method. The obtained demetallized bio-oil preferably has a water content of less than 10 wt%, more preferably of from 0.01 to 5 wt%, most preferably of from 0.01 to 1 wt%. ln one embodiment the demetallized bio-oil obtained in step h) is subjected to further treatment, such as hydroprocessing, to obtain fuels or chemicals.

Hydroprocessing of the bio-oil may comprise passing the bio-oil through a guard bed, followed by hydrotreating and optionally, mild hydrocracking and/or hydrodewaxing, and lastly, hydrofinishing the bio-oil with various catalysts. Fractionation is performed to obtain the product fuel and/or chemicals. Hydroprocessing, hydrotreatment, hydrocracking, hydrodewaxing, hydrofinishing and fractionation are concepts well known to the skilled person. ln another aspect, the present invention relates to a bio-oil obtained by the method according to the present invention. ln a further aspect, the present invention relates to a bio-oil having a total metal content of less than 200 ppm, preferably of from 0 to 50 ppm, more preferably of from 0 to 20 ppm, even more preferably of from 0 to 10 ppm; and a total phosphorus content of less than 10 ppm, preferably of from 0 to 5 ppm. As used herein the total metal content preferably refers to the content of metal selected from aluminium, calcium, magnesium, manganese, phosphorus, potassium, and sodium. ln one embodiment, the bio-oil has a total metal content of less than 20 ppm, from 0.01 to 20 ppm, preferably of from 0.01 to 10 ppm; and the total phosphorus content is from 0.01 to 10 ppm or from 0.01 to 5 ppm. 21 NP0796SE-P ln one embodiment the bio-oil has a total metals content of less than 20 ppm, preferably of from 0 to 10 ppm, and a total phosphorus content of less than 10 ppm, preferably of from 0 to 5 ppm.

Preferably, at least 25 wt%, preferably at least 50 wt% of the demetallized bio-oil boils above 440 °C.

The present invention is further illustrated by the below examples. The presented examples should not be seen as limiting the scope of the invention, and the skilled person would realize that there are obvious alternatives and modifications that could be carried out. Experimental methods presented without specific conditions in the following examples generally follow the conventional conditions known to the person skilled in the art. Unless otherwise stated, parts and percentages as used herein are parts by weight and weight percent.

EXAMPLES Example 1: Production of bio-oil 1. Liquefaction of biomass: a. 60 g biomass (a dried, ground mixture of pine and spruce bark), 60 g potassium hydroxide, and 280 g ethanol were added to an autoclave. b. The mixture was heated to 150 °C and held at this temperature with stirring for 3 hours. c. Subsequently, the temperature was increased to 240 °C and kept at this level for 30 minutes. 2. Acidification and salt separation: a. The contents in the autoclave were cooled to 60 °C and transferred into a beaker. b. Concentrated sulfuric acid (23 mL) was slowly added to the bark-ethanol- base mixture. 22 NP0796SE-P c. Salt was separated from the bio-oil via filtration, with the salt being rinsed with ethanol. d. Ethanol was removed from the mixture using a rotary evaporator. 3. Demetallization a. 100 mL of bio-oil was added to an autoclave. b. Sulfuric acid in water (100 mL, pH 1) was added to the bio-oil. c. The mixture was stirred while heated to about 170 °C. d. After the target temperature was reached, the stirring was turned off, and the two phases were given 30 minutes to separate. e. After the contents in the autoclave had coo|ed to 90 °C, for ease of handling, the contents were transferred to a separation funnel. 50 mL of butanol and 50 mL of 2-methyl tetrahydrofuran were added to the bio- oil sample. f. An aqueous phase and an oil phase were collected. g. The water and butanol were boiled off using a rotary evaporator, leaving the isolated bio-oil.

RESULTS Liquefaction of the biomass into a bio-oil was achieved, whereby no char formation was observed. The simulated distillation of the demetallized bio-oil was done by gas chromatography, whereby the entire sample was vaporized and exited the column, showing that no solids were present. The final boiling point was determined to be 654 °C.

Elemental analysis ofthe resulting bio-oil was made by a LECO CHN elemental analyzer using a combustion method.

The metal contents of the bio-oil and the demetallized bio-oil were analyzed using inductively coupled plasma mass spectroscopy (ICP SCAN CI\/I-38) and the results are shown in Table 2. The simulated distillation of the bio-oil (gas chromatography, EN 15199-1) is shown in Figure 1, presenting the cumulative weight percent recovered as a function of the boiling point ofthe components ofthe sample, and Figure 2, presenting the area percentage as a function of the boiling point ofthe components ofthe sample.

Table 1: Biomass and bio-oil properties units Biomass (Bark) Bio-oil Elemental analysis wt.% C 48.8 67.1 H 6.1 8.5 N 0.3 0.1 O 44.8 24.3 Dry matter content wt.% 96 Caloric value IVIJ/kg 19.7 26.3 Table 2: Demetallization results: Metal analyses of bio-oil and treated products [mg/kg] P K Ca Na Al I\/lg I\/|n Bio-Oil 27.4 24,800 14.6 418 33.6 63.7 34.7 Demetallized 0.3 8.8 1.3 3.9 1.2 < 0.2 < 0.2 bio-oil 24

Claims

1. A method for providing a bio-oil, comprising the steps of: a) adding a biomass with a lignin content of from 0 to 40 wt%; b) adding a non-aqueous fluid; c) adding a base, preferably a strong base or a superbase; d) subjecting the mixture comprising biomass, a base, and non-aqueous fluid, to thermal treatment at a temperature of from 100 °C to 400 °C, preferably of from 110 to 380 °C, more preferably of from 120 to 320 °C; to obtain a liquid comprising bio-oil; e) adding a first acid to the liquid comprising bio-oil; f) optionally adding one or more of water, a second acid, a bio-oil, or a solvent, to the bio-oil to obtain a mixture; g) subjecting the liquid obtained in step e), or the mixture obtained in step f), to a temperature of from 10 °C to 320 °C, preferably of from 80 °C to 250 °C, more preferably of from 120 °C to 200 °C, to obtain a second mixture comprising an aqueous phase and a bio-oil; h) removing the aqueous phase from the second mixture to obtain a demetallized bio-oil; i) optionally repeating steps f)-h); and j) optionally subjecting the demetallized bio-oil to hydroprocessing; whereby the demetallized bio-oil obtained has a total metal content of less than 200 ppm, preferably of from 0 to 50 ppm, and a total phosphorus content of less than 10 ppm.

2. The method according to claim 1, wherein the biomass originates or is selected from softwood, hardwood, straw, bagasse, grass, algae, seagrass, seaweed, cones, needles, leaves, bark, nutshell, fruit kernel, husk, corn stover, agriculture residues, forest residues, food industry residues and other biomass types. NP0796SE-P

The method according to any one of the previous claims, wherein the biomass, or the mixture of biomass and non-aqueous fluid, has a water content of from 0.1 to 65 wt%, preferably of from 0.5 to 45 wt%, more preferably of from 1 to 40 wt%.

The method according to any one of the previous claims, wherein no free water is added in steps a) to d).

The method according to any one of claims 1-4, wherein the non-aqueous fluid is selected from a C1-10 alcohol, a bio-oil, a C1-30 hydrocarbon, ether, a|ky| acetate, sulfola ne, a fluid stream recyc|ed from hydroprocessing; or any combination thereof.

The method according to any one of the previous claims, wherein the C1-10 alcohol is selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, glycerol, propylene glycol, cresol, resorcinol, hydroquinone, guaiacol, catechol, phenol, or benzyl alcohol, preferably methanol or ethanol; or any combination thereof.

The method according to any one ofthe previous claims, wherein the strong base is selected from sodium sulphide, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, caesium hydroxide, lithium hydroxide, rubidium hydroxide, strontium hydroxide; preferably sodium sulphide, potassium hydroxide, or sodium hydroxide; or any combination thereof.

The method according to any one of the previous claims, wherein the superbase is selected from organometallic or inorganic compounds, such as a Grignard reagent; hydrides of alkali-metals, such as lithium hydride, potassium hydride, or sodium hydride; combinations oforganolithium compounds with alkali metal alkoxides, such as n-butyllithium and potassium tert-butoxide; phosphazenes; proazaphosphatranes; phosphines; amidines, such as Schwesinger vinamidines; guanidines; or metal amides, such as lithium diisopropylamide; or any combination thereof.NP0796SE-P

9. The method according to any one of the previous claims, wherein the mixture subjected to thermal treatment in step d) comprises 5-50 wt% biomass, 1-35 wt% base, and 30-94 wt% of a non-aqueous fluid, up to a maximum or a total of 100 %, as calculated on the total weight of the mixture.

10. The method according to any one ofthe previous claims, wherein biomass solids are removed from the bio-oil obtained in step d).

11. The method according to c|aim 10, wherein the removed solids are used for sugar production or as a pulp material.

12. The method according to any one of the previous claims, wherein in any of steps b) and f) a bio-oil is added, and is independently selected from a bio-oil recycled from a process comprising the method of c|aim 1, tall oil pitch, crude tall oil, pyrolysis oil, softwood oil, hardwood oil, bagasse oil, lignin oil, bark oil, sawdust oil, hydrothermal liquefaction oil, turpentine, vegetable oil, or oil obtained from any one of grass, algae, seagrass, seaweed, cones, needles, leaves, bark, nutshell, fruit kernel, husk, corn stover, aquaculture residues, animal residues, agriculture raw materials, agriculture residues, or forest residues; or any combination thereof.

13. The method according to any one of the previous claims, wherein the temperature in step d) is from 140 to 280 °C, preferably from 160 to 245 °C, more preferably from 170 to 240 °C.

14. The method according to any one of the previous claims, wherein the mixture in step d) is subjected to the desired temperature gradually, continuously, or in several stages over a period of time, whereupon any water present is removed.NP0796SE-P The method according to any one of the previous claims, further comprising a step of removing salts from the liquid comprising bio-oil obtained in step e), preferably by filtration. The method according to any one of the previous claims, wherein any of the first acid and second acid is independently a strong acid, preferably independently selected from sulfuric acid, hydrochloric acid, or nitric acid. The method according to any one of the previous claims, wherein steps f)-h) are repeated at least once. The method according to any one of the previous claims, wherein the bio-oil is subjected to the hydroprocessing in step j), to obtain fuel or chemicals. The method according to any one ofthe previous claims, wherein a so|vent selected from a water insoluble C4-6 alcohol, ethers, alkyl acetates, a liquid stream recycled from the hydroprocessing step, or mixtures thereof, is added during step f). The method according to any one of the previous claims, wherein the demetallized bio-oil has a total metal content of less than 20 ppm, preferably of from 0 to 10 ppm, and a total phosphorus content of less than 10 ppm, preferably of from 0 to 5 ppm. A bio-oil obtainable by the method according to any one ofthe previous claims. The bio-oil according to claim 21, wherein at least 25 wt%, preferably at leastwt%, of the bio-oil boils above 440 °C. A bio-oil having a total metal content of less than 200 ppm, preferably of from 0 to 50 ppm, more preferably of from 0 to 20 ppm, even more preferably of from 0 toppm; and a total phosphorus content of less than 10 ppm, preferably of from 0 toppm.