WO2025131657A1 - Method for treating a liquid carbonaceous feedstock resulting from a hydrothermal liquefaction treatment - Google Patents

Abstract

The invention relates to a method for treating a liquid feedstock that comprises at least partially carbonaceous products resulting from a hydrothermal liquefaction treatment, referred to as a biocrude feedstock (1), with a view to reducing the content of mineral compounds thereof, such that the treatment comprises: - a step a) of diluting the biocrude feedstock with a diluent (8) which comprises an organic liquid phase so as to obtain a diluted biocrude feedstock (9); - a step b) of bringing the diluted biocrude feedstock obtained in step a) into contact with at least one solvent (3) which comprises an aqueous liquid phase, with counter-current liquid-liquid extraction, so as to obtain a raffinate (5) comprising the biocrude feedstock depleted in mineral compounds and the diluent, and an extract (4) comprising the solvent enriched in mineral compounds; and - a step c) of separating the raffinate (5) obtained in step b), so as to obtain the biocrude feedstock depleted in mineral compounds (7), and a phase comprising the diluent (8).

Description

PROCESS FOR TREATING A LIQUID CARBONACEOUS FEED FROM A HYDROTHERMAL LIQUEFACTION TREATMENT

Technical Field

The present invention relates to the production of recoverable chemical products or biofuels from biomass, in particular lignocellulosic biomass. More specifically, the invention concerns biomass hydrothermal liquefaction processes, also known by the acronym HTL according to their Anglo-Saxon name "HydroThermal Liquefaction", which make it possible to transform biomass into a carbonaceous feedstock known as "biocrude". This feedstock known as "biocrude" must then be treated, in particular by hydroconversion, hydrotreatment, hydrocracking, catalytic cracking, to obtain the desired chemical products with the desired specifications.

Prior art

Hydrothermal liquefaction (for more details, please refer to the publication "Continuous Hydrothermal Liquefaction of biomass: a critical review", D. Castello, TH Pederson, LA Rosendahl, Energies 2018, 11, 3165) is a process for converting a feedstock in the presence of water at a pressure between 100 and 350 bar (between 10 ⁷ Pa and 3.5. 10 ⁷ Pa) and at a temperature between 250 and 450°C. Catalysts can be used for hydrothermal liquefaction, such as pH modifiers, NaOH, KOH, K2CO3, Na ₂ CC>3, etc.

The products of hydrothermal liquefaction are called "biocrude," consisting mainly of organic molecules, an aqueous phase comprising water-soluble organic compounds (alcohols, acids, ketones, phenols, etc.) and salts, gas, and possibly biochar. Biochar is a solid product rich in carbon, "char" coming from the English word "charcoal." The gas produced is mainly _CO2 but can also contain hydrogen, methane, and CO.

In the hydrothermal liquefaction process, water can be present as a liquid or in a relatively dense supercritical state. Water near the critical point (374°C, 221 bar) has very different properties from water at room temperature. These near-critical properties allow water to play several roles in the conversion process, such as being a reactant, a catalyst, or a source of hydrogen. Near the critical point or in the supercritical state, water has properties that facilitate liquefaction, such as a low dielectric constant that allows solubilization of nonpolar molecules and a sufficiently high ion product to favor ionic reactions. leading to liquid products versus radical reactions leading to solid or gaseous products.

The reactions occurring in the hydrothermal liquefaction process are numerous and complex, but include depolymerization reactions including hydrolysis, dehydration, decarboxylation, and repolymerization reactions including condensation.

The yields and composition of the biocrude depend on the operating conditions, but also on the feedstock treated by hydrothermal liquefaction. For example, for a feedstock consisting of wood, a mass yield of biocrude of around 40-45% and a gas yield of 40-45% are obtained by hydrothermal liquefaction.

The feedstock for hydrothermal liquefaction may be biomass, preferably selected from plants, grasses, trees, wood chips, seeds, fibers, seed coats, aquatic plants, algae, hay and other sources of lignocellulosic materials, such as, for example, those from organic waste, municipal waste, agro-food waste, animal waste, forestry waste, sawmill waste, slaughter residues, agricultural and industrial waste (such as, for example, sugar cane bagasse, waste from oil palm cultivation, sawdust or straw). The feedstock for hydrothermal liquefaction may also come from pulp and paper by-products, whether recycled or not, or from by-products from paper mills, waste such as used plastics, used tires. The feedstock may also be a mixture of at least two of these materials.

Biocrude obtained by hydrothermal liquefaction is a complex mixture of compounds, consisting mainly of hydrocarbons and oxygenated compounds. In general, the oxygenated compounds are organic acids, ketones, oxygenated aromatic compounds, alcohols, aldehydes, esters, ethers and water. Water generally represents less than 15% by weight of the biocrude. In the case of a lignocellulosic biomass feedstock, the biocrude contains compounds derived from cellulose, hemicellulose and lignin (a structure present in lignocellulosic biomass).

The biocrude obtained by hydrothermal liquefaction has an oxygen, sulfur and nitrogen content that varies greatly depending on the hydrothermal liquefaction load (algae, wood, etc.). For example, biocrude from hydrothermal liquefaction of wood generally consists of from 5 to 20% by weight of oxygen, less than 0.5% by weight of sulfur and less than 5% by weight of nitrogen in the dry biocrude (without water).

Biocrude can contain up to 4% by weight of inorganic (mineral) compounds, mainly metals such as sodium, potassium but also calcium, iron, etc. These mineral compounds can come from the catalysts used for hydrothermal liquefaction, from the hydrothermal liquefaction feedstock itself, and from metals possibly used to grind the hydrothermal liquefaction feedstock. Sodium and potassium can be present in relatively large quantities in biocrude, as the hydrothermal liquefaction process generally uses alkali-based catalysts (NaOH, KOH, K2CO3, Na2CO3...) in significant quantities.

This content of inorganics, particularly metals, generally does not allow the use of biocrude as fuel because the quantity of ash is too high.

To be transformed into biofuels (gasoline, kerosene, diesel, marine fuel) or into chemical products, the biocrude must be treated, in particular to reduce the heteroatoms and more particularly the oxygen it contains. This treatment may include at least one operation chosen from hydroconversion, hydrotreatment, hydrocracking, or catalytic cracking. However, these operations use catalysts known to those skilled in the art to be sensitive to metal content (in particular alkali or alkaline-earth metals such as Na, K, Ca, etc.). These metals in fact poison the catalysts: they deactivate them at least partially.

It is therefore necessary to purify the biocrude, that is to say to reduce its content of mineral compounds, particularly metallic ones, so that its subsequent treatments can be carried out successfully.

Patent applications WO18177877, WO19092173, WO21121662 disclose treatments aimed at purifying biocrudes, and in particular at recovering the metal salts they contain for recycling, with different types of separation devices, using acidic aqueous phases or even washing agents, but the implementation and execution of these separation/treatment operations appear complex.

The invention therefore aims to develop a treatment to reduce the content of mineral compounds, particularly metallic ones, in a biocrude type load, a treatment which is preferably simple to implement, and preferably economical in terms of tools and/or utility consumption.

Summary of the invention

The invention firstly relates to a method for treating a liquid feedstock which comprises at least partly carbonaceous products and which is obtained from a hydrothermal liquefaction treatment, known as a biocrude feedstock, with a view to reducing its content of mineral compounds, in particular metallic compounds, such that said treatment comprises:

- a step a) of diluting the biocrude load with a diluent which comprises an organic liquid phase which has a viscosity and a density lower than that of the biocrude load, so as to obtain a diluted biocrude load,

- a step b) of contacting the diluted biocrude charge obtained in step a) with at least one solvent (3) which comprises a liquid aqueous phase, with counter-current liquid-liquid extraction, so as to obtain, on the one hand, a raffinate (5) comprising the biocrude charge depleted in mineral compounds and diluent, and on the other hand an extract comprising the solvent enriched in mineral compounds,

- a step c) of separation of the raffinate (5) obtained in step b), so as to obtain, on the one hand, the biocrude charge depleted in mineral compounds, and on the other hand a phase comprising the diluent.

Thus, the invention succeeds in significantly reducing the content of mineral compounds in a biocrude type feedstock, the reduction being sufficient to allow subsequent treatment steps of such a feedstock to be carried out without having to modify its conventional operation, in particular by retaining the type of catalyst usually used for these hydroconversion type steps, hydrotreatment, hydrocracking, or even catalytic cracking.

And to do this, the invention first uses dilution with a "light" organic diluent (less dense and less viscous than biocrude), then a countercurrent liquid/liquid extraction with an aqueous solvent. And it has proven that this dilution + extraction combination is very effective.

Counter-current liquid/liquid extraction can be implemented quite simply, using a gravity extraction type extraction column for example (or several in series or in parallel).

Carrying out an extraction in such a column requires a sufficient difference in density between the phases present (often greater than 50 kg/m ³ ), and the greater the difference in density, the easier this implementation will be. Furthermore, the viscosity of one or both phases plays an important role in this operation, because the more it increases, the more the transfer of material between phases will be slowed down on the one hand, and the more the capacity of the column is likely to decrease, in terms of possible charge flow rate per unit of column section. Countercurrent columns are interesting because they allow the desired solutes to be extracted much better than in a co-current column or in a stirred tank. Indeed, the number of theoretical stages can reach high values (between 2 and 15 in the vast majority of cases), and with minimized solvent consumption.

According to one embodiment of the invention, step b) of contacting is carried out with a single solvent. This may be an aqueous solution, which may be pure water, demineralized water, water with soluble organic molecules, or even an acidic aqueous solution.

According to another embodiment of the invention, step b) of contacting is carried out with at least two different solvents, in particular two solvents. In this case, preferably, step b) of contacting the diluted biocrude feed obtained in step a) is carried out with at least two separate solvents which are brought into contact with said feed in separate contacting zones. This may be a first solvent which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5 and a second solvent which is an acidic aqueous liquid phase, having a pH lower than 6.5, with countercurrent liquid-liquid extraction, so as to obtain, on the one hand, a raffinate comprising the biocrude feed depleted in mineral compounds and the diluent, and on the other hand an extract comprising the solvents enriched in mineral compounds.

In this other embodiment, preferably, the first solvent S1 is chosen from pure water, demineralized water, water with soluble organic molecules. And preferably, the second solvent S2 is an acidic aqueous solution, having a pH less than 6.5.

Advantageously, the second solvent S2 is an acidic aqueous solution containing from 10 ppm, in particular from 100 ppm, to 20% by weight of at least one strong or weak acid, organic or mineral, in particular chosen from at least one of the following acids: acetic acid, nitric acid, sulfuric acid, hydrochloric acid, citric acid, oxalic acid, lactic acid, formic acid, and possibly soluble organic molecules.

The or at least one of the solvents when there are several can also be an aqueous solution acidified by injecting carbon dioxide into the aqueous solution (which may already contain a acid among those mentioned above). Indeed, the hydrothermal liquefaction step prior to the treatment according to the invention tends to generate carbon dioxide, which can therefore be advantageously used to acidify the solvent(s), if necessary.

In step b) of contact with two solvents, the ratio Ri of the flow rate of the first solvent Qsi to the flow rate of the diluted biocrude load _Qm is preferably between 0.05 and 5, preferably between 0.1 and 3.

In step b) of contact with two solvents, the ratio R2 of the flow rate of the second solvent QS2 to the flow rate of the diluted biocrude load Q _m is preferably between 0.05 and 5, preferably between 0.1 and 3.

Preferably, contacting step b) comprises dedicated or additional decantation to improve decantation between the two aqueous and organic phases. The decantation device used (e.g., a decanter) may be located after the last liquid-liquid extraction column or between two liquid-liquid extraction columns in series that are used in separation step c). The extraction column (or one of those used in step c) may have a short residence time decantation function, which tends to separate the phases in a non-optimal manner, and it is possible that a residual free water fraction (drops) is entrained in the raffinate 25. In this case, a decanter may be placed on the downstream line to better separate the water (and not upstream of the column). If the contact between the two liquid phases is done via two separate columns, then a decanter can be placed between the two columns, or just one at the outlet of the second column (or no decanter at all).

Advantageously, the method of the invention also comprises:

- a step d) of recycling at least part of the phase comprising the diluent as diluent in step a) of dilution.

This recycling can be partial or total: it can be supplemented by the addition of external diluent if necessary, but it is very interesting, because it allows a drastic reduction in consumption by diluting the treatment process according to the invention.

Advantageously, the method of the invention also comprises:

- a step e) of treatment of the extract obtained in step b) to reduce its content of mineral compounds,

- a step f) of recycling at least part of the extract with reduced content of mineral compounds obtained in step e) as a solvent in step b) of contacting.

Here again, we can therefore recycle at least partially this extract, preferably by purifying it beforehand, to replace all or part of the (aqueous) solvent used during liquid/liquid extraction, which also reduces the water consumption of the process of the invention.

Step e) can also allow these mineral compounds, for example metal salts, to be recovered with a view to recycling them.

Preferably, during dilution step a), the diluent has a final boiling point of at most 150°C, preferably at most 100°C.

Preferably, the diluent used in dilution step a) is chosen from a light cut present in the biocrude feed or a chemical compound or mixture of chemical compounds, in particular from the family of alcohols, ethers, ketones and hydrocarbons. The process can be started with a diluent with a boiling temperature close to that of the phase comprising the diluent to be recycled according to step d), which is a light cut of the biocrude, then this phase will gradually accumulate in the recycling loop over time and will thus gradually replace the initial diluent.

Preferably, at the end of dilution step a), the diluted biocrude load has a dynamic viscosity at 20°C of at most 7 cP, preferably at most 4 cP, and a density at 15°C of at most 950 kg/m ³ , preferably at most 900 kg/m ³ .

Preferably, during dilution step a), the ratio R of the flow rate Qd of the diluent to the flow rate Qb of the biocrude load is at most 10, and in particular at least 0.1, the ratio R preferably being between 0.5 and 3.

Preferably, contacting step b) is carried out at a pressure of between 0.5.10 ⁵ Pa and 5.10 ⁵ Pa, and at a temperature of between 15 and 100°C, while remaining lower than the boiling point of the diluent at the contacting pressure.

Preferably, separation step c) is a treatment comprising at least one evaporation, one distillation, one flash, and may use an exchanger followed by a separator tank.

Preferably, the solvent used in contacting step b) is chosen from at least one of the following solutions: a pure aqueous solution, a demineralized aqueous solution, an aqueous solution containing soluble organic compounds, an acidic aqueous solution. In the case of an acidic aqueous solution, it may contain from 10 ppm to 20% by weight of a strong or weak organic or mineral acid, such as acetic acid, nitric acid, sulfuric acid, hydrochloric acid, citric acid, oxalic acid, lactic acid, formic acid or any other acid.

As seen above, it can in fact be made up in whole or in part of the extract after treatment by step e) aimed at reducing its content of mineral salts, in particular metallic salts: this is the recycling of step f) described above.

It can be a mixture of at least two of these solutions.

The invention also relates to a biomass treatment process comprising hydrothermal liquefaction of biomass, then a treatment aimed at reducing the content of mineral compounds in the biocrude obtained, as described above, then possibly a conversion treatment of the treated biocrude of the hydroconversion, hydrotreatment, hydrocracking, catalytic cracking type in order to produce biofuels and/or other chemical compounds (biosourced).

According to one embodiment, contacting step b) may be preceded and/or followed by a decantation step b1) and/or b2).

The invention also relates to an installation for treating a liquid load comprising products at least partly carbon-based and resulting from a hydrothermal liquefaction treatment, called biocrude load, with a view to reducing the content of mineral compounds, in particular metallic compounds, which implements the method described above.

The invention also relates to an installation for treating a liquid load comprising at least partly carbon-based products and resulting from a hydrothermal liquefaction treatment, called biocrude load, with a view to reducing the content of mineral compounds, in particular metallic compounds, such that said installation comprises

- a device a) for diluting the biocrude load with a diluent which comprises an organic phase which has a viscosity and a density lower than that of the biocrude load, so as to obtain a diluted biocrude load

- a device b) for contacting the diluted biocrude charge obtained with device a) with at least one solvent which comprises an aqueous phase, said device comprising a counter-current liquid-liquid extraction column, preferably gravity-driven, so as to obtain on the one hand a raffinate comprising the biocrude charge depleted in mineral compounds and diluent, and on the other hand an extract comprising the solvent enriched in mineral compounds

- a device c) for separating the raffinate obtained with device b), so as to obtain on the one hand the biocrude load depleted in mineral compounds and on the other hand a phase comprising the diluent.

The dilution device may be a tank-type device fed by both the biocrude feed and the diluent. It may also simply be achieved by a plurality of supply lines that converge to a common line(s) where the mixture/diluent Dilution is carried out dynamically up to the contacting device, using appropriate valves.

The contacting device is preferably a gravity-fed counter-current liquid/liquid extraction column. It may be a single column or a plurality of columns, connected in series or in parallel. The column(s) may be equipped at the top and/or bottom of the column with settling devices.

According to one embodiment, the contacting device uses only one solvent.

According to another embodiment, the device b) for contacting the diluted biocrude load obtained in step a) uses at least two distinct solvents, including a first solvent which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5, and a second solvent which is an acidic aqueous liquid phase, having a pH lower than 6.5: said device may comprise a column (2) for counter-current liquid-liquid extraction, preferably gravity-driven, the first and second solvents having distinct inlets and arranged at different heights of the column.

According to this other embodiment, according to a variant, at least one of the first and second solvents comprises at least two separate inlets arranged at different heights of the column. Thus, one of the solvents can have two different injection points, at different column heights, for example an injection point at the top of the column and (at least) another at an intermediate column height, or two injection points at different intermediate column heights.

For example, at least one of the inlets for the first solvent may be at the top of the column. It is also possible that one of the inlets for the second solvent may be at the top of the column.

For example, at least one of the inlets of the second solvent is at an intermediate height of the column, in particular at a height H ₂ relative to the total height H of the column such that the ratio H ₂ /H is between 0.2 and 0.8.

It is also possible that it is rather one of the inlets of the first solvent which is at an intermediate height of the column, in particular at the height H ₂ in question.

The total height H is understood to mean the useful height of the column, as is known in the field of liquid-liquid extraction or distillation columns. If the first solvent (or the second solvent) has a second inlet into the column at an intermediate height H3, then this intermediate height H3 is preferably lower than the height H2 of the inlet of the second solvent (or first solvent).

Advantageously, this height H3 of the second inlet of the first solvent (or of the second solvent) can be such that, H being the total height of the column, the ratio H3/H is between 0.05 and 0.4.

The separation device is, for example, at least one device chosen from: a distillation column, an evaporator, an exchanger followed by a separator flask, in particular a so-called “flash” separator flask.

The installation according to the invention may also comprise a device for recycling at least part of the phase comprising the diluent obtained with device c) as a diluent for the dilution device a). This recycling device may consist of pipe(s) providing a fluid connection between the two devices a) and c) and controlled in a known manner by valves.

The installation according to the invention may provide that the contacting device b) comprises a counter-current liquid/liquid extraction column equipped at the bottom of the column and/or at the top of the column with a decantation device b1) b2).

List of Figures

Figure 1: this figure very schematically represents an installation implementing the biocrude treatment process according to the invention.

This figure therefore does not represent all the equipment in the installation, but only those that are most useful for understanding the invention. The various devices and other features are not necessarily to scale, nor necessarily represented in space as they might be in an industrial site.

Description of the embodiments

The invention aims to treat biocrude-type loads in order to reduce their content of mineral compounds, particularly metallic ones.

As a reminder, the characteristics of a biocrude type feedstock of interest to the invention may be as follows: The biocrude obtained by hydrothermal liquefaction is a complex mixture of compounds consisting mainly of hydrocarbons and oxygenated compounds. In general, the oxygenated compounds are organic acids, ketones, oxygenated aromatic compounds, alcohols, aldehydes, esters, ethers and water. Water generally represents less than 15% by weight of the biocrude.

In the case of a lignocellulosic biomass feedstock, the biocrude contains compounds derived from cellulose, hemicellulose and lignin (structure present in lignocellulosic biomass).

The biocrude obtained by hydrothermal liquefaction has an oxygen, sulfur and nitrogen content that varies greatly depending on the hydrothermal liquefaction load (algae, wood, etc.). For example, biocrude from hydrothermal liquefaction of wood generally consists of 5 to 20% by weight of oxygen, less than 0.5% by weight of sulfur and less than 5% by weight of nitrogen in the dry biocrude (without water).

Biocrude can contain up to 4% by weight of inorganics, mainly metals such as sodium, potassium but also calcium, iron, etc. Inorganics can come from the catalysts used for hydrothermal liquefaction, the hydrothermal liquefaction feedstock, and the metals used to grind the hydrothermal liquefaction feedstock. Sodium and potassium can be present in significant quantities in biocrude because the hydrothermal liquefaction process uses alkali-based catalysts (NaOH, KOH, K2CO3, Na2CO3, etc.) in significant quantities.

Biocrude is generally characterized by a kinematic viscosity at 50°C between 10 and 40,000 cSt, a dynamic viscosity at 50°C between 10 and 40,000 cP, a density at 15°C between 0.9 and 1.2 and a final distillation temperature exceeding 750°C.

Biocrude has a very wide distillation range, from room temperature to over 750°C. For example, for biocrude from hydrothermal liquefaction of wood, approximately 10% by weight of the biocrude is vaporized in the range 20-180°C, 10% by weight to 45% by weight of the biocrude is vaporized in the range 180-350°C and 45% by weight to 80% by weight of the biocrude is vaporized above 350°C.

Figure 1 shows an installation for implementing the invention which will be described below.

The biocrude 1 from the hydrothermal liquefaction unit has a flow rate Qb. The biocrude 1 is mixed with the recycled diluent 8 (whose origin will be described later) having a flow rate Qd such that 0.1 < Qd/Qb < 10 and preferably such that 0.5 < Qd/Qb < 3. The flow rates are in mass per unit of time. The recycled diluent 8 is a compound or a mixture of compounds having a dynamic viscosity at 20°C of less than 4 cP, and generally not less than 0.3 cP, and a density at 15°C between 600 and 850 kg/m ³ . Dilution is carried out by providing in the biocrude supply line 1 to the extraction column 2 a tapping of a pipe bringing the diluent: the mixing between the biocrude and the diluent is carried out in the common pipe section downstream of the tapping. (“upstream” and “downstream” are understood in this text by taking into account the progression of the biocrude load in the installation).

The mixture 9, biocrude + diluent, called “diluted biocrude”, here has a dynamic viscosity at 20°C less than or equal to 7 cP, preferably less than or equal to 4 cP and a density at 15°C less than or equal to 950 kg/m ³ , preferably less than or equal to 900 kg/m ³ • and generally not less than 600 kg/m ³ . These properties are obtained by choosing an adequate nature of diluent and a diluent flow rate (relative to the biocrude flow rate).

The diluent 8 may be a light fraction present in the biocrude (the process may start with an initial diluent, which will gradually be substituted by the recycled phase containing the diluent, as indicated above) or a chemical compound (or a mixture of chemical compounds) present or not in the biocrude. The diluent may consist, for example, of compounds from the family of alcohols, ethers, ketones and hydrocarbons.

The final boiling point of diluent 8 is preferably less than or equal to 150°C, and preferably less than or equal to 100°C. It is preferably at least 60°C.

The diluted biocrude 9 feeds a liquid-liquid extraction column called gravity 2 at its foot and has a mass flow rate Qm. Column 2 extends along a vertical or essentially vertical longitudinal axis.

Liquid-liquid extraction is carried out using a solvent 3 consisting of an aqueous solution, which may be pure water, demineralized water, water with soluble organic molecules, an acidic aqueous solution containing from 10 ppm to 20% by weight of an acid such as acetic acid, nitric acid, sulfuric acid, hydrochloric acid, citric acid, formic acid or any other acid, or a mixture of these different aqueous solutions.

Solvent 3 can come from the recycling of extract 4 (described later), if extract 4 has previously undergone treatment to reduce its inorganic content (evaporation for example) and by adding for example acid if necessary. Solvent 3 feeds column 2 in the upper position (column head) with a flow rate Qs. The flow rate Qs of solvent 3 is chosen such that 0.05 < Qs/Qm < 5 and preferably 0.3 < Qs/Qm < 3.

Extraction column 2 has the following characteristics:

- Operating pressure P between 0.5 bar abs (0.5.10 ⁵ Pa) and 15 bar abs (15.10 ⁵ Pa), preferably between 0.9 bar abs (0.9.10 ⁵ Pa) and 1.5 bar abs (1.5.10 ⁵ Pa).

- Operating temperature T between 15°C and 150°C, preferably between 20°C and 60°C

- T/S between 5 and 80 m/h, preferably between 10 and 40 m/h, with:

S the passage section of column 2, in m ²

T the total volume traffic in column 2, T being defined as follows

T = Qrn/rhOm + Qs/ rho _s , expressed in m ³ /h

With rho _m and rho _s the densities, for example in kg/m ³ , respectively of the diluted biocrude 9 and of the solvent 3 in the operating conditions of column 2 (pressure, temperature).

The useful height of column 2 is between 1.5 m and 50 m high, preferably between 1.8 m and 25 m. The column can be of different types: packed column, perforated tray column, mechanically stirred column, pulsed column or other.

In column 2, two phases are mixed and brought into contact: an organic phase (the diluted biocrude 9) and an aqueous phase (solvent 3). In column 2, one phase is dispersed in the other, which is the continuous phase.

The organic phase is called the light phase because its density is lower than the other phase, the aqueous phase. The aqueous phase is called the heavy phase.

The dispersed phase can be the heavy phase (solvent 3) or the light phase (diluted biocrude 9), but preferably the light phase (diluted biocrude 9). If the dispersed phase is the heavy phase (solvent 3), the column is preferably equipped with a decanter at its bottom. The decanter will be at the top of the column if the dispersed phase is the light phase (diluted biocrude 9). A decanter can also be provided at the bottom and top of the column.

Column 2 allows a theoretical number of stages to be reached between 2 and 15, and preferably between 2.5 and 7. The effluents from column 2 are:

- A raffinate 5 consisting mainly of the biocrude, the diluent and the compounds present in the solvent (mainly water). The quantity of inorganic/mineral compounds present in raffinate 5 is much lower than that in the diluted biocrude 9, due to the efficiency of the liquid-liquid extraction.

- An extract 4 consisting mainly of solvent, extracted inorganics, compounds present in the diluted biocrude 9, such as diluent and biocrude.

The raffinate 5 feeds a separation device 6 based on the boiling temperature, such as a distillation column, an evaporator, an exchanger followed by a flash separator drum. This device makes it possible to separate a “diluent” 8 (which can be recycled to the inlet of column 2), which consists of a light constituent or a mixture of light constituents, and a demineralized biocrude 7 having a significantly reduced content of inorganics, in particular metals, compared to biocrude 1.

The invention achieves a reduction (by weight) in the content of inorganic compounds in the biocrude, such as mineral salts/metal salts, of at least 50% (by weight) and in particular at least 70% (by weight). It is thus possible to achieve biocrude qualities with contents of at most 500 ppm, in particular at most 400 or 300 or 200 or 100 ppm of all of these inorganic compounds.

Examples

Comparative example 1 (state of the art)

A biocrude from hydrothermal liquefaction of lignocellulosic biomass has a dynamic viscosity at 20°C of 142 cP and a density at 15°C of 985 kg/m ³ . The biocrude contains several inorganics including sodium Na, potassium K and calcium Ca. The sodium concentration is 912 ppm by weight, that of potassium is 640 ppm by weight and that of calcium is 30 ppm by weight.

The biocrude is diluted with 2-butanone (or methyl ethyl ketone, or MEK) with a MEK/biocrude mass ratio of 1 to reduce density and viscosity. MEK has a density at 15°C of 805 kg/m ³ and a dynamic viscosity at 20°C of 0.42 cP. It has a boiling point of 79.6 °C.

The diluted biocrude has a dynamic viscosity at 20°C of 1.7 cP and a density at 15°C of 890 kg/m ³ . A contact test of the diluted biocrude with demineralized water is carried out in a closed 3-liter reactor with a water/diluted biocrude mass ratio equal to 0.5. The reactor, equipped with a propeller, is stirred at 500 rpm for 1 hour and then left to stand for 1 day. The reactor is used at 40°C under 1 atm (10 ⁵ Pa).

The decanted organic phase is separated and then analyzed. The analysis results indicate a sodium content of 98 ppm by weight, a potassium content of 51 ppm and a calcium content of 13 ppm in the organic phase after contacting, i.e. in the raffinate.

Example 2 according to the invention

The same diluted biocrude as in Example 1 is contacted with demineralized water in a Sulzer ECR type agitated countercurrent liquid-liquid extraction column 2, with an internal diameter of 32 mm and a useful height of 1800 mm. The operation is carried out at 40°C under 1 atm (10 ⁵ Pa). The dispersed phase is the light phase (diluted biocrude 9).

The flow rate of diluted biocrude is 6 kg/h and the flow rate of demineralized water (3) is 3 kg/h. The ratio of the mass flow rates of water and diluted biocrude is 0.5.

The column is stirred at a stirring speed of 90 rpm during operation. The organic phase (diluted biocrude 9) feeds the column from the bottom, and the aqueous phase (demineralized water 3) feeds the column from the top.

The column has a theoretical number of stages estimated at around 3 under the conditions of use presented.

The organic phase thus treated and exiting at the top of the extraction column is analyzed. The analysis results indicate a sodium content of 3 ppm by weight, a potassium content of 2 ppm and a calcium content of 10 ppm in the organic phase after liquid-liquid extraction.

The sodium, potassium and calcium contents obtained with these two examples are compiled in Table 1 below:

Table 1

From the comparison of these two examples, we see that the process of the invention using a particular liquid-liquid extraction with a countercurrent aqueous phase is much more efficient than simple contacting in a stirred reactor: with the invention we can dramatically reduce the sodium content of the biocrude from 912 ppm to 3 ppm, that is to say that we can in fact almost eliminate all the sodium. And this is also the case for potassium. We also observe a strong reduction in calcium and iron.

Claims

Claims 1. Method for treating a liquid feed which comprises at least partly carbonaceous products and which comes from a hydrothermal liquefaction treatment, called biocrude feed (1), with a view to reducing the content of mineral compounds, in particular metallic compounds, characterized in that said treatment comprises - a step a) of diluting the biocrude load with a diluent (8) which comprises an organic liquid phase which has a viscosity and a density lower than that of the biocrude load, so as to obtain a diluted biocrude load (9), - a step b) of contacting the diluted biocrude charge obtained in step a) with at least one solvent (3) which comprises a liquid aqueous phase, with counter-current liquid-liquid extraction, so as to obtain, on the one hand, a raffinate (5) comprising the biocrude charge depleted in mineral compounds and diluent, and on the other hand an extract (4) comprising the solvent enriched in mineral compounds, - a step c) of separation of the raffinate (5) obtained in step b), so as to obtain, on the one hand, the biocrude charge depleted in mineral compounds (7) and on the other hand a phase comprising the diluent (8). 2. Method according to the preceding claim, characterized in that it comprises - a step d) of recycling at least part of the phase comprising the diluent (8) as diluent in step a) of dilution. 3. Method according to one of the preceding claims, characterized in that it comprises - a step e) of treatment of the extract (4) obtained in step b) to reduce its content of mineral compounds, - a step f) of recycling at least part of the extract with reduced content of mineral compounds obtained in step e) as solvent (3) in step b) of contacting. 4. Method according to one of the preceding claims, characterized in that, during dilution step a), the diluent has a final boiling point of at most 150°C, preferably at most 100°C. 5. Method according to one of the preceding claims, characterized in that, at the end of dilution step a), the diluted biocrude load (9) has a dynamic viscosity at 20°C of at most 7 cP, preferably at most 4 cP, and a density at 15°C of at most 950 kg/m ³ , preferably at most 900 kg/m ³ . 6. Method according to one of the preceding claims, characterized in that, during the dilution step a), the ratio R of the flow rate Qd of the diluent to the flow rate Qb of the biocrude load (1) is at most 10, and in particular at least 0.1, the ratio R preferably being between 0.5 and 3. 7. Method according to one of the preceding claims, characterized in that step b) of contacting is carried out at a temperature between 15 and 100°C and lower than the boiling point of the diluent (8) at the contacting pressure, and at a contacting pressure between 0.5.10 ⁵ Pa and 5.10 ⁵ Pa. 8. Method according to one of the preceding claims, characterized in that separation step c) is a treatment comprising at least one evaporation, one distillation, or which uses an exchanger followed by a separator tank. 9. Method according to one of the preceding claims, characterized in that the diluent (8) used in dilution step a) is chosen from a light cut present in the biocrude load or a chemical compound or mixture of chemical compounds, in particular from the family of alcohols, ethers, ketones and hydrocarbons. 10. Method according to one of the preceding claims, characterized in that the solvent (3) used in step b) of contacting is chosen from at least one of the following solutions: a pure aqueous solution, a demineralized aqueous solution, an aqueous solution containing soluble organic compounds, an acidic aqueous solution. 11. Method according to one of the preceding claims, characterized in that step b) of contacting is preceded and/or followed by a step b1) and/or b2) of decantation. 12. Method according to one of the preceding claims, characterized in that step b) of contacting the diluted biocrude feed (9) obtained in the dilution step a) is carried out with at least two separate solvents which are brought into contact with said feed in separate contacting zones and comprising a first solvent which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5 and a second solvent which is an acidic aqueous liquid phase, having a pH lower than 6.5, with countercurrent liquid-liquid extraction, so as to obtain, on the one hand, a raffinate (5) comprising the biocrude feed depleted in mineral compounds and diluent, and on the other hand an extract (4) comprising the solvents enriched in mineral compounds, 13. Installation for treating a liquid load comprising products which are at least partly carbonaceous and which come from a hydrothermal liquefaction treatment, called biocrude load, with a view to reducing the content of mineral compounds, in particular metallic compounds, characterized in that said installation comprises - a device a) for diluting the biocrude load with a diluent (8) which comprises an organic phase which has a viscosity and a density lower than that of the biocrude load (1), so as to obtain a diluted biocrude load (9) - a device b) for contacting (2) the diluted biocrude charge (9) obtained in step a) with at least one solvent (3) which comprises an aqueous phase, said device comprising a counter-current liquid-liquid extraction column (2), preferably gravity-driven, so as to obtain on the one hand a raffinate (5) comprising the biocrude charge depleted in mineral compounds and diluent and on the other hand an extract (4) comprising the solvent enriched in mineral compounds - a device c) for separating (6) the raffinate obtained with device b), so as to obtain, on the one hand, the biocrude charge depleted in mineral compounds (7) and, on the other hand, a phase comprising the diluent. 14. Installation according to the preceding claim, characterized in that the device b) for contacting (2) the diluted biocrude load (9) obtained in step a) uses at least two separate solvents, including a first solvent which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5, and a second solvent which is an acidic aqueous liquid phase, having a pH lower than 6.5, said device comprising a column (2) for counter-current liquid-liquid extraction, preferably gravity-driven, the first and second solvents having separate inlets and arranged at different heights of the column. 15. Installation according to claim 13 or 14, characterized in that the separation device (6) comprises at least one device chosen from a distillation column, an evaporator, an exchanger followed by a separator tank, in particular a so-called “flash” separator tank. 16. Installation according to one of claims 13 to 15, characterized in that it comprises a device for recycling at least part of the phase comprising the diluent obtained with the separation device c) as diluent (8) for the dilution device a). 17. Installation according to one of claims 13 to 16, characterized in that the contacting device b) comprises a counter-current liquid/liquid extraction column (2) equipped at the bottom of the column and/or at the top of the column with a decantation device b1) b2).