WO2024013033A1

WO2024013033A1 - New method for preparing cashew nut shell oil

Info

Publication number: WO2024013033A1
Application number: PCT/EP2023/068928
Authority: WO
Inventors: Audrey ROY; Benoît BRIOU; Catherine Caillet; Farid Chemat
Original assignee: Orpia Innovation; Avignon Universite
Priority date: 2022-07-13
Filing date: 2023-07-07
Publication date: 2024-01-18
Also published as: FR3137920A1

Abstract

The invention relates to the use, for carrying out a method for extracting, using a solvent, an extract containing or consisting of a natural or technical CNSL oil and optionally tannins from cashew nut shells, in particular ground cashew nut shells, of continuous injection into an extractor of cashew nut shells, in particular ground cashew nut shells, constituting the extraction material, involving the passage of the extraction material from the inlet of the extractor enclosure to the outlet of the extractor enclosure, the injection being carried out against the direction of flow of the solvent, the extraction material forming a porous system with the solvent. The invention also relates to the corresponding method.

Description

DESCRIPTION

Title: New process for preparing cashew nut shell oil

The present invention relates to a new process for preparing cashew nut shell oil. The invention also relates to a new cashew nut shell extract containing or consisting of a natural or technical CNSL oil and possibly tannins.

BACKGROUND OF THE INVENTION

Cashew nuts comprise 55 to 65% by weight of shells and 35 to 45% by weight of kernels. Cashew nut shells therefore constitute an agricultural waste generated by cashew nut processing factories and thus an inexpensive starting material. In particular, cashew nut shells contain a dark reddish brown caustic oil, of the order of 15 to 40% by weight, rich in phenolic lipids and have potential for the production of high value-added fuels and chemicals allowing an alternative eco-responsible and local to products from the oil industry.

“Cashew Nut Shell Liquid” or CNSL is a natural oil made from cashew nut shells. The main components of crude CNSL are phenolic compounds: anacardic acid, cardol and cardanol. Methyl cardol is also present, but in trace amounts (<5%).

Each of these compounds is itself a mixture of products, comprising an alkyl or alkenyl chain, said alkenyl chain having 1, 2 or 3 double bonds (Scheme 1):

cardo anacardic acid! methyl cardol cardanol 65% 15 to 20% trace 10%

Scheme 1 - chemical structures of the main constituents of natural CNSL. CNSL can be classified into 2 types, depending on the extraction method used:

• Natural CNSL, an extract obtained by extraction using a low boiling point solvent or obtained mechanically without heating,

• Technical CNSL, obtained by hot processes, in particular by roasting at high temperatures, e.g. >200°C.

Technical CNSL includes a reduced amount of anacardic acid compared to natural CNSL, due to partial decarboxylation during heating or roasting. In some cases, the decarboxylation is even complete, and the CNSL no longer contains anacardic acid.

By “undecarboxylated raw CNSL” or “natural CNSL” we therefore mean a CNSL which has not undergone, or which has only partially undergone, decarboxylation of anacardic acid. Raw, non-decarboxylated CNSL is therefore characterized by the presence of anacardic acid as the majority species within the mixture.

To date, the valorization of CNSL oil is a promising route given the potential presented by the components that constitute it.

The qualification of natural or technical CNSL therefore depends on the composition of the different components, in particular the level of anacardic acid and consequently on the extraction method used to obtain the oil.

Various mechanical, thermal or chemical extraction techniques using a solvent are known from cashew nut shells to obtain natural or technical CNSL.

Mechanical extraction by compression using a press is effective and makes it possible to obtain natural CNSL rich in anacardic acid but this is limited by its yield because significant quantities of oil, of the order of 10 to 15% by weight, remains trapped in residue after pressing. In addition, mechanical extraction leads to higher viscosities of the extraction material favoring clogging problems, but also favoring thermo-oxidative instability, the extraction materials being able to be subjected to temperature rises during pressing favoring the decarboxylation of anacardic acid.

Thermal or pyrolysis extraction involves the application of heat that converts most of the anacardic acid to cardanol, producing technical CNSL. The technique is suitable if a cardanol-rich CNSL is desired.

Mechanical and/or thermal extraction techniques are mainly used to produce CNSL on an industrial scale, despite their drawbacks described above. Cold or hot solvent extraction involves a large quantity of solvent which involves considerations of its toxicity, its recycling and its origin (petro- or bio-sourced), leading to environmental and health problems.

During solvent extraction, treatments of the extraction material are known in the prior art in order to increase the efficiency of the extraction. For example, British patent GB 758,768 dating from 1956 teaches a preliminary step of heat treatment of the extraction material and adjustment to a humidity level of 10 to 26% in this step.

Methods for extracting CNSL using supercritical fluids have been implemented. So-called green solvents such as water and carbon dioxide can be used and have an ecological advantage. However, such an extraction method requires an energy-consuming device due to the necessary operating conditions of temperature and/or pressure. For example, Solano et al. (Actualidades Biologicas, vol. 27, no.1, January 3, 2005, pages 59-63) describes a process for extracting CNSL by supercritical CO2, in which the extraction is carried out in batches and at a pressure of 17.2 MPa to 18.6 MPa.

Solvent extraction methods have the advantage of achieving oil residue in the cake at a content of less than 1% by weight. However, they are generally carried out in batches, involving large volumes of solvent to manage and thus limiting their use on industrial volumes and their use in a continuous industrial process.

Many extraction methods can be used to extract oils from plants, but it is important to note that the quality and quantity of the solutes extracted depend on the association, or even synergy, between the method used. and the characteristics of the extraction device and the nature of the plants. It is reported in the examples of patent GB 758,768 cited above, solvent extractions on a heat-treated seed flour such as that of cotton seeds, that of rice bran or that of flax seeds; in these extractions the concentration of oil extracted in the miscella is 15 to 25.5%. Only vegetable oils are exemplified; no examples involve cashew nut shells.

Vegetable oils are defined as fatty substances resulting from the extraction of an oilseed plant (seeds, fruits, almonds, nuts), consisting mainly of triglycerides and/or fatty acids. Triglycerides are triesters of fatty acids and glycerol. The triglyceride and/or fatty acid contents in vegetable oils may vary from time to time but are generally greater than 90% by mass. The differences between vegetable oils are mainly in the profile of fatty acids in esterified or free form as well as in the proportion of minor constituents, that is to say less than 10% in mass, such as phospholipids, diglycerides, monoglycerides, phytosterols and tocopherols.

CNSL has a very different composition with mainly (i.e. greater than 90% by mass) phenolic compounds substituted by a fatty chain, saturated or not, generally made up of 15 carbon atoms as indicated above. Thus, despite the fact that it is qualified as an oil, CNSL is chemically very different from classic vegetable oils such as soybean, rapeseed, sunflower oil or more specific oils such as linseed, cottonseed or plenty more rice bran. Indeed, the latter are mainly made up of linoleic acid, oleic acid, palmitic acid or even stearic acid, in the form of fatty acid triglycerides or in the form of free fatty acid. Therefore, any vegetable oil extraction technique is not necessarily obviously transposable to CNSL oil.

There is a need to valorize cashew nut shells through an extraction process to obtain an oil comprising high added value compounds such as CNSL oil and tannins contained in cashew nut shells and to obtain a material after extraction, the cake, as natural and ecological alternatives to petrochemical products.

There is a need to use an extraction method allowing continuous extraction of cashew nut shells for industrial purposes and needs under unconstrained conditions in temperature and pressure, and eco-responsible.

There is a need to improve and optimize the extraction yield of an extract containing or consisting of natural or technical CNSL oil possibly including other substances of interest such as tannins.

There is a need to obtain a natural CNSL oil rich in anacardic acid.

One of the aims of the invention is the use of an extraction process suitable for obtaining an oil from cashew nut shells.

Another aim of the invention is a high-performance, efficient industrial extraction process that can be operated continuously.

Another aim of the invention is to obtain a natural or technical CNSL oil.

Another aim of the invention is to obtain tannins from cashew nut shells.

Another aim of the invention is to obtain a cake which can be valorized.

A first object of the present invention is the use, for the implementation of a solvent extraction process of an extract containing or consisting of a natural or technical CNSL oil and possibly tannins from cashew shells, especially crushed, a continuous introduction into an extractor of cashew nut shells, in particular crushed, constituting the extraction material, causing said extraction material to pass through from the entrance to the enclosure of the extractor until the outlet of said extractor enclosure, said introduction being carried out countercurrent to the direction of the flow of said solvent, said extraction material forming with the solvent a porous system.

According to a particular embodiment, the invention relates to the use, for the implementation of a solvent extraction process of an extract containing or consisting of a natural or technical CNSL oil and possibly tannins. from cashew nut shells, in particular crushed, a continuous introduction into an extractor of cashew nut shells, in particular crushed, constituting the extraction material, causing said material to pass through extraction from the entrance to the extractor enclosure to the outlet of said extractor enclosure, said introduction being carried out counter-current to the direction of the flow of said solvent, said extraction material forming with the solvent a porous system, and in which the extraction process is carried out in an extractor comprising several stages, in particular N stages, N varying from 2 to 10, preferably N equal to 4, and at a pressure of 0.05 to 0.5 MPa, preferably 0.1 MPa.

In the case of cashew nut shells, the inventors have discovered that the extraction material, consisting of cashew nut shells, in particular crushed, forms with an extraction solvent a porous system, allowing a yield similar to a batch extraction and/or extraction requiring temperature and pressure constraints. Such a porous system allows continuous introduction into an extractor and the implementation of a counter-current extraction process using the extraction solvent under mild temperature conditions, i.e. at a temperature below 140°C. , and pressure, or at atmospheric pressure. Advantageously, the use of this porous system does not require overpressure of the extraction solvent.

Thus this discovery on the adaptability of cashew nut shells to continuous solvent extraction leading to optimized yields opens the possibility of implementing an industrializable process for continuous liquid/solid extraction under conditions ambient, that is to say unconstrained in temperature and pressure, making it possible to process industrial quantities of the order of tons per hour of cashew nut shells and to continuously obtain a CNSL oil. Such a process makes it possible to simultaneously manage and control the flows of material and solvent used and thus to optimize the yield of extracted oil and the volume of solvent used.

The cashew nut consists of an outer shell, a fitted inner shell, testa and a kernel.

“Cashew nut shell” means the parts of the nut that differ from the kernel.

The term “crushed cashew nut shell” means the fragmented parts of the nut which differ from the kernel.

The cashew nut consists of approximately 55 to 65% by weight of shells and 35 to 45% by weight of kernels. The cashew nut shell contains CNSL oil which is caustic and dark reddish brown in color (15-40%) rich in non-isoprenoid phenolic lipids. The kernel or kernel of the cashew nut is edible and has a rich protein content (19.5%) and ranks third in the world's production of edible nuts.

Cashew nut shells are notably agricultural waste generated by cashew nut processing factories.

By “the extraction material” is meant the material, in solid form, composed of cashew nut shells, in particular crushed, comprising compounds of interest miscible in an extraction solvent, which is intended to undergo a treatment to extract said compounds of interest.

By “extract” we mean all the compounds of interest that can be extracted during an extraction process.

By “solute” is meant the compounds of interest contained in the extraction material which are miscible in a solvent and which can be extracted by a solvent extraction process.

The term “solvent” means a liquid in which at least one of the compounds obtained from cashew nut shells can be dissolved.

By “porous system” is meant the system generated by the shells, in particular crushed, of cashew nuts with the solvent during extraction. This system presents a porosity and a tortuous nature of movement of the solvent during the extraction which define a kinetics of dissolution of the solutes in the solvent and influences the liquid/solid extraction. The porous system formed by cashew nut shells has intrinsic characteristics that are specific and distinct from other plant materials. Indeed, the system composed of pieces of tangled cashew nut shells is generally similar to a porous material, into which the solvent can infiltrate. The sizes, interstitial volumes and densities of the cashew nut shells thus constitute intrinsic parameters of this porous system, since they will influence the diffusion of the solute from the plant material towards the solvent and consequently on the process of extraction from the CNSL.

By “interstitial volume” is meant the volume accessible to the solvent in the interstices of the extraction material consisting of cashew nut shells, in particular crushed, forming the porous system. For example, the porous system is considered with crushed cashew nut shells with an average particle size of 1 mm to 1 cm mixed with a solvent arriving at the surface of the shells. The system is not agitated. Thus, the interstitial volumes are between approximately 15 and approximately 60% of the total volume of the porous system.

Cashew nut shell extract contains CNSL compounds and may contain tannins.

By “tannin” we mean a compound from the polyphenol family present in cashew nut shells.

Tannins are compounds present in the majority of plants. Some of them have been known for centuries and are used in many fields.

Structurally, they can be classified into three categories:

- Hydrolyzable tannins, which consist of gallic acid (gallotanin) or hexahydroxydiphenic acid (ellagitannin) chemically linked to one or more polyols or sugars or terpenoids.

- Condensed tannins, which are made up of oligomers or polymers of catechin (also called flavanol).

- Complex tannins, which are made up of a catechin unit linked to a gallotanin or ellagitannin motif.

The tannins contained in the cashew shell are composed in particular of gallic acid and gallic acid derivatives, as well as flavonoids (such as leufolin and isohemiphloin). For the purposes of the present invention, CNSL compounds (anacardic acid, cardanol, cardol and methylcardol) are not considered tannins because they are not chemically linked to polyols or catechin oligomers/polymers.

The extractor is defined as a device making it possible to implement the method of the invention. The extractor of the continuous extraction process comprises an enclosure equipped with:

- an entry end intended to introduce the extraction material,

- an outlet end intended for the evacuation of the extraction material, after extraction thereof.

By “the passage of the extraction material from the entrance to the enclosure to the exit from the extractor enclosure” is meant the transport within the extractor enclosure in which the extractor enclosure takes place. the extraction process, by technical means of the extractor such as an endless screw, of the extraction material from an entrance to the enclosure intended for introduction to an outlet intended to evacuate the material after extraction. The direction of crossing, corresponding to that of the entrance to the exit of the enclosure, defines the direction of introduction of the extraction material.

The direction of solvent flow in the extractor is defined as the direction of solute enrichment of the solvent which is parallel to the direction of introduction of the extraction material.

By “counter-current” we mean the fact that the direction of introduction of the extraction material and that of the flow of the solvent in the extractor are in opposite directions.

Advantageously in the counter-current extraction process, the freshly introduced extraction material is brought into contact with the solvent enriched in solute which will leave the extractor enclosure. The fresh solvent which enters the other end of the extractor is in contact with the extraction material depleted in solute.

The counter-current makes it possible to maintain a practically constant exchange potential throughout the extractor and can thus reduce the quantity of solvent used and consequently the price of the separation of the solutes and the solvent and that of the regeneration of the solvent. .

According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out by percolation of the solvent through the extraction material or by immersion in the solvent of the material extraction.

According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out by percolation of the solvent through the extraction material.

By “percolation” is meant a liquid/solid extraction of solute from a solid phase extraction material by an extraction solvent which is defined as a liquid solubilizing said solute. Percolation consists of passing the liquid through a medium containing said extraction material permeable to said liquid. The solid phase is crossed by a liquid, not saturated in solute, allowing the extraction of said solute without problem of saturation. It also makes it possible to limit possible thermal degradation of the extracted compounds.

Percolation has the advantage of being able to be implemented with the use of a solvent dispersion nozzle and of being applicable at several points in the extractor enclosure. As the extractor is equipped with internal filtration systems, percolation does not require additional filtration and/or clarification steps. In addition, percolation extraction devices are compact, which facilitates their deployment on an industrial scale (saving space/floor space).

According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out by immersion of the extraction material in the solvent.

The term “immersion extraction” means a liquid/solid extraction involving covering or immersion of the extraction material with the extraction solvent. The immersion of the extraction material can be sequential, that is to say with an immersion time controlled in sequences and/or partial, that is to say that the extraction material is partially covered (up to a minimum of 50%, in particular from 50% to 100%) by the solvent. The extraction material can be stirred during the operation, which promotes the diffusion of the solute in the extraction solvent. In addition, extraction by immersion has the advantage of ensuring a homogeneous residence time of the extraction material in the solvent.

Both immersion methods, namely sequential and partial, can be used simultaneously.

The two extraction methods, namely by percolation and by immersion, can also be adapted simultaneously.

According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out in an extractor comprising several stages, in particular N stages, N varying from 2 to 10, of preferably N equal to 4. For example N is equal to 2, 3, 4, 5, 6, 7, 8, 9 or 10, in particular 4, 6 or 10.

According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out in a pilot extractor comprising 3 to 6 stages, preferably 4 stages.

According to a particular embodiment, the present invention relates to the use as defined above, in which the extraction process is carried out in an extractor on an industrial scale comprising 3 to 10 stages. The inventors also noted for the porous system generated by the cashew nut shells and the extraction solvent, that a limited number of solvent extraction steps could be carried out to extract almost all of the CNSL. contained in cashew nut shells, especially crushed.

The term “stage” means a segment of the extractor comprising means enabling an extraction step to be carried out. We understand that an extractor can contain several successive stages and configured to allow successive extraction stages on the extraction material.

In the extractor, the stages can be configured to follow one another along a longitudinal axis of the extractor, which can be oriented horizontally or vertically.

Another object of the present invention is a process for preparing an extract containing or consisting of a natural or technical CNSL oil and possibly tannins by extraction with a solvent from cashew nut shells, in particular crushed, comprising the following steps: a) a step of introducing cashew nut shells, in particular crushed, constituting the extraction material, continuously, into an extractor, causing said extraction material to pass through from the inlet from the extractor enclosure to the outlet of said extractor enclosure, b) a step of extracting a solute contained in the extraction material, said step comprising N step(s) of extraction by a solvent during the passage of said extraction material in the extractor, N varying from 2 to 10, said extraction material and the solvent forming a porous system, in which the direction of said introduction is against current of that of the solvent flow, in which for each extraction step i, i varying from 1 to N, leads to obtaining an extracted liquid phase i containing a solute i and the solvent, said solute i forming with the solvent a miscella i, which miscella i is recovered in a tank i, c) a recovery step:

- of each above-mentioned miscella i, i varying from 1 to N, in a tank F to obtain said extract containing or consisting of CNSL and possibly tannins and

- possibly cake, resulting from the extraction material after step b) of extraction of the solute, at the outlet of the extractor enclosure. By “solute” we mean the compounds of interest contained in the material to be extracted and which are miscible in the extraction solvent.

By “miscella” we mean the solution resulting from an extraction consisting of the solute and the solvent.

Reservoir F is defined as the final reservoir for recovering the extract resulting from the extraction process according to the invention.

The term “cake” means the solid residue of the material from the extraction of cashew nut shells, obtained at the outlet of the extractor enclosure and which is depleted in solute after implementation of a processing process. extraction of the solute from the extraction material.

In a counter-current extraction process, when the N extraction stages are indexed with an increasing index i according to the direction of introduction of the extraction material, we understand that the miscella i of the reservoir i is more enriched in solute than the miscella (i+1) of the reservoir (i+1).

Advantageously in the solute extraction step b), each miscella i is filtered before their recovery in the tank i), in particular by using a filter at the inlet of the tank.

Advantageously, the recovery step c) comprises a step of filtration of the miscellas i.

Advantageously, the recovery step c) further comprises a step of concentrating the extract, in particular by a step of separating the solute and the solvent, in particular by evaporation of the solvent.

Advantageously, the process of the invention further comprises steps of filtration, concentration or elimination of the residual extraction solvent of the extract obtained in step c). Such steps and their implementation are known to those skilled in the art.

According to a particular embodiment, the present invention relates to a process for preparing an extract containing or consisting of a natural or technical CNSL oil and optionally tannins by extraction with a solvent from cashew nut shells, in particularly crushed, comprising the following steps: a) a step of introducing cashew nut shells, in particular crushed, constituting the extraction material, continuously, into an extractor, causing said extraction material to pass through from the entrance to the extractor enclosure to the outlet of said extractor enclosure, b) a step of extracting a solute contained in the extraction material, said step comprising N step(s) ) extraction by a solvent during the crossing of said material extraction in the extractor, N varying from 2 to 10, said extraction material and the solvent forming a porous system, in which the direction of said introduction is countercurrent to that of the solvent flow, in which for each extraction step i, i varying from 1 to N, leads to obtaining an extracted liquid phase i containing a solute i and the solvent, said solute i forming with the solvent a miscella i, which miscella i is recovered in a tank i, c) a recovery step:

- possibly cake, resulting from the extraction material after step b) of extracting the solute, at the outlet of the extractor enclosure, in which steps a), b) and c) are carried out a pressure of 0.05 to 0.5 MPa, preferably 0.1 MPa.

Advantageously, extraction steps a), b) and c) of the process of the invention are carried out at atmospheric pressure, i.e. at a pressure of 0.1 MPa.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which said extraction is carried out by percolation or by immersion, preferably by percolation.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which said extraction is carried out by percolation.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which said extraction is carried out by immersion.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the cashew nut shells are crushed and are obtained in a preliminary step of grinding the cashew nut shells before step a).

Advantageously, the grinding step can be implemented at the entrance to the extraction enclosure.

According to a particular embodiment, the present invention relates to an extraction process as defined above, further comprising a step of heat treatment of cashew nut shells or crushed cashew nut shells before step a ). Advantageously, the heat treatment is carried out at a temperature above 140°C, preferably 180 to 250°C or 400 to 600°C, making it possible to decarboxylate the anacardic acid in order to obtain an extract containing technical CNSL. Without limitation, the heat treatment step can be carried out by roasting, for example during the preparation treatment for separating the kernels from the shells of cashew nuts.

Advantageously, the heat treatment can be carried out under conditions of temperature or treatment duration making it possible to achieve a composition having a determined ratio of anacardic acid and cardanol.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which steps a), b) and c) are carried out at a temperature of 20 to 140°C, in particular of 20 to 70°C, and/or at a pressure of 0.05 to 0.5 MPa, preferably approximately 0.1 MPa.

The expression MPa corresponds to 10 ⁶ Pascal and is equivalent to 10 bars.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which steps a), b) and c) are carried out at a temperature of 20 to 70°C and at a pressure from 0.05 to 0.5 MPa, preferably around 0.1 MPa.

The range of 20 to 140°C includes the following ranges: 20 to 40°C, 40 to 60°C, 60 to 80°C, 80 to 100°C, 100 to 120°C, 120 at 140°C.

The 20 to 70°C range includes the following ranges: 20 to 30°C, 30 to 40°C, 40 to 50°C, 50 to 60°C, 60 to 70°C.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which steps a), b) and c) are carried out at a temperature of 20 to 140°C, in particular of 20 to 70°C and at a pressure of 0.05 to 0.5 MPa, preferably approximately 0.1 MPa.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which step b) comprises N extraction steps, N varying from 3 to 10, preferably from 3, 4 , 5 or 6.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the solvent is chosen from ethyl acetate, butyl acetate, hexane, cyclohexane, 2-methyltetrahydrofuran, methanol and ethanol. Ethyl acetate has the advantage of being a non-hazardous solvent for humans. It does not belong to the CMR class (Carcinogenic, Mutagenic and Reprotoxic) and it is class 3 according to the ICH Q3C directive. It is also not harmful to the environment. It is a solvent that can be obtained in a biosourced manner. This solvent is selective for CNSL (traces of gallic acid).

Butyl acetate is a solvent that is not dangerous for humans (it does not belong to the CMR class), nor for the environment. It presents less risk of flammability than ethyl acetate. This solvent is selective for CNSL (traces of gallic acid).

Methanol has the advantage of being a solvent commonly used in industry. It is characterized by a low boiling point, around 65°C, which allows the use of less energy-intensive elimination processes. This solvent makes it possible to obtain an extract containing CNSL and tannins from cashew nut shells.

Ethanol has the advantage of being a biosourced solvent commonly used in industry. It presents less risk to humans than methanol (class 3 solvent according to the ICH Q3C directive). This solvent makes it possible to obtain an extract containing CNSL and tannins from cashew nut shells.

Hexane has the advantage of being commonly used in industry. It is characterized by a low boiling point, around 69°C, which allows the use of less energy-intensive elimination processes. This solvent is very selective for CNSL (no trace of tannin).

Cyclohexane has the advantage of being a less dangerous alternative to hexane. This solvent is very selective for CNSL (no tannin).

2-methyltetrahydrofuran has the advantage of being a biosourced solvent which does not belong to the CMR class. This solvent is selective for CNSL (traces of tannins).

Table 1: Boiling temperature of extraction solvents According to a particular embodiment, the present invention relates to an extraction process as defined above, in which:

- the solvent used is methanol or ethanol and leads to an extract comprising CNSL and tannins from cashew nut shells,

- and said method comprises an additional separation step d) in which said extract comprising CNSL and tannins is separated into a CNSL oil and a residue containing said tannins.

In this embodiment, the use of methanol or ethanol as extraction solvent makes it possible to extract as solute, in addition to CNSL compounds, other compounds such as tannins from cashew nut shells. The extract obtained includes CNSL compounds and tannins from cashew nut shells.

Advantageously said additional separation step d) is carried out by a step of selective solubilization of the extract in an alkane type solvent (preferably hexane and cyclohexane). This solvent is miscible with CNSL, however the tannins are not soluble in this solvent.

Step d) can be carried out by other separation methods known to those skilled in the art.

By way of non-limiting examples, separation step d) can be carried out by: the use of a clarifying agent such as gelatin, polyethylene glycol (PEG) or polyvinylpolypyrrolidone (PVPP), or separation on silica column or micro/ultrafiltration

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which:

- the solvent used is ethyl acetate, butyl acetate, hexane, cyclohexane or 2-methyltetrahydrofuran and leads to an extract consisting of substantially pure CNSL,

- and said process comprises an additional step of extraction e) of the cake obtained in step c) with a solvent chosen from ethanol or methanol to obtain a solution containing tannins.

In this embodiment, the use of ethyl acetate, butyl acetate, hexane, cyclohexane or 2-methyltetrahydrofuran, in particular hexane, as solvent extraction allows only CNSL compounds to be extracted as solute. Tannins are not solubilized in the medium of the porous system. The extract obtained substantially only includes the CNSL compounds. Traces of tannins of the order of less than 1% may nevertheless be present, for example in the case of the use of ethyl acetate.

The tannins contained in the cake are then extracted with an extraction step e).

Advantageously said extraction step e) of the cake is carried out by percolation or immersion in methanol or in ethanol by a similar process comprising similar steps a), b) and c) applied to the cake as extraction material.

Step e) can be carried out by other extraction methods known to those skilled in the art for extracting tannins such as maceration.

By way of non-limiting examples, the extraction step e) of the cake can be carried out by: extraction in a solvent such as methanol, ethanol, acetone, basic water, hot water (from 60 to 100°C) or a mixture of these solvents, extraction by supercritical or ionic fluid, or solvent extraction assisted by microwaves or ultrasound.

According to a particular embodiment, the present invention relates to an extraction process as defined above, comprising an additional step of heat treatment of the extract to obtain a technical CNSL oil.

Advantageously, the heat treatment is carried out at a temperature above 140°C, preferably from 140 to 250°C at atmospheric pressure of 0.1 MPa and results in the decarboxylation of anacardic acid to cardanol.

Advantageously, the extract is pretreated in order to remove the residual solvent.

For your information :

- Decarboxylation temperature of anacardic acid: from 140°C at atmospheric pressure (in the presence of solvent). It is possible to “distill” anacardic acid under vacuum at high temperature (from 180°C), however part of the product can be degraded by decarboxylation during the process.

- Boiling temperature of cardanol: between 180 and 200°C under vacuum (P < 5 mbar).

- Boiling temperature of cardol/methyl cardol: between 190 and 220°C (P < 5 mbar). According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the crushed cashew nut shells have an average particle size of 1 mm to 1 cm, preferably 3 to 8 mm. and/or a humidity level of 5 to 10%, in particular 6.0 to 6.5%.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the crushed cashew nut shells have an average particle size of 1 mm to 1 cm, preferably 3 to 8 mm. .

The range from 1 mm to 1 cm includes the following ranges: 1 to 2 mm; 2 to 3 mm; 3 to 4 mm; 4 to 5 mm; 5 to 6 mm; 6 to 7 mm; 7 to 8 mm; 8 to 9 mm; from 9mm to 1cm.

The range from 3mm to 8mm includes the following ranges: 3.00 to 3.50mm; from 3.50 to 4.00 mm; from 4.00 to 4.50 mm; from 4.50 to 5.00 mm; from 5.00 to 5.50 mm; from 5.50 to 6.00 mm; from 6.00 to 6.50 mm; from 6.50 to 7.00 mm; from 7.00 to 7.50 mm; from 7.50 to 8.00 mm.

We understand that the variability in size of crushed cashew nut shells and its residue generates a complex porous system which influences liquid/solid extraction. Advantageously the shells are crushed in order to achieve an average particle size of 1 mm to 1 cm making it possible to define a porosity and a tortuous nature of movement of the solvent during percolation which are optimized for dissolution kinetics of the CNSL compounds.

A small particle size, of the order of 1 mm to 1 cm, will allow an increase in the contact surface with the solvent, favoring extraction efficiency.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the cashew nut shells have a humidity level of 5 to 10%, in particular from 6.0 to 10%. 6.5%.

The 5 to 10% range includes the following ranges: 5.0 to 5.5%; from 5.5 to 6.0%; from 6.0 to 6.5%; from 6.5 to 7.0%; from 7.0 to 7.5%; from 7.5 to 8.0%; from 8.0 to 8.5%; from 8.5 to 9.0%; from 9.0 to 9.5%; from 9.5 to 10.0%.

The range of 6.00 to 6.50% includes the following ranges: 6.00 to 6.10%; from 6.10 to 6.20%; from 6.20 to 6.30%; from 6.30 to 6.40%; from 6.40 to 6.50%. The moisture content of the solid phase extraction material can influence the state of the porous system and its affinity with the solvent during extraction.

It has been shown that pre-drying cashew nut shells to reduce their moisture content has little impact on the extraction yield of CNSL.

Advantageously, the process according to the invention does not require a step of drying the cashew nut shells constituting the extraction material before entering the extractor.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has an interstitial volume of 15 to 60% and/or a density of 0.4 to 1.6 , preferably from 0.4 to 0.9 or preferably from 0.9 to 1.6.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has interstitial volume of 15 to 60%.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has a density of 0.4 to 1.6.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has a density of 0.4 to 0.9.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the porous system has a density of 0.9 to 1.6.

The range of 15 to 60% includes the following ranges: 15 to 20%, 20 to 30%, 30 to 40%, 40 to 50%, 50 to 60%.

The range from 0.4 to 1.6 includes the following ranges: from 0.4 to 0.5; from 0.5 to 0.6; from 0.6 to 0.7; from 0.7 to 0.8; from 0.8 to 0.9; from 0.9 to 1.0; from 1.0 to 1.1; from 1.1 to 1.2; from 1.2 to 1.3; from 1.3 to 1.4; from 1.4 to 1.5; from 1.5 to 1.6.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which during the extraction the extraction material: solvent ratio is from 1:0.5 to 1:10 per volume, in particular from 1:1 to 1:2 per volume The range 1:0.5 to 1:10 includes the following ranges: 1:0.5 to 1:1; from 1:1 to 1:2; from 1:2 to 1:3; from 1:3 to 1:4; from 1:4 to 1:5; from 1:5 to 1:6; from 1:6 to 1:7; from 1:7 to 1:8; from 1:8 to 1:9; from 1:9 to 1:10.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step a) the retention time in the extractor of the extraction material, defined as the duration time separating the entry into the extractor of a fraction of the extraction material and the exit from the extractor of said same fraction of the extraction material, is 40 minutes to 6 hours.

At the exit from the extractor the extraction material, having undergone at least one CNSL extraction step, is depleted in CNSL compared to the extraction material entering the extractor.

The range from 40 minutes to 6 hours includes the following ranges: 40 min to 1 hour; of

I a.m. to 2 a.m.; from 2 a.m. to 3 a.m.; from 3 a.m. to 4 a.m.; from 4 a.m. to 6 a.m.

The term “retention time in the extractor” means the duration of time elapsed between the entry into the extractor of a fraction of the extraction material and the exit of said fraction of the extraction material from the extractor. extractor.

Advantageously, the speed of movement of the extraction material in the extractor is constant, allowing constant movement in the extractor and limiting clogging phenomena.

Advantageously, the movement of the extraction material can also be adapted sequentially over time in the extractor, so that a fraction of the extraction material i in a stage i of the extractor is not in movement during the extraction step i.

Advantageously, the retention time of the extraction material in each stage i of the extractor is from 5 min to 3 hours, in particular from 5 to 20 min or from 20 min to 1 hour.

It was observed, in the case of the system of crushed cashew nut shells, in a continuously percolated process with three different solvents, namely with hexane, methanol and ethyl acetate, that After less than two hours of extraction, a plateau of maximum solute extraction yield was reached for the three solvents.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step a) the mass flow rate in the extractor of the extraction material is from 0.5 to 5000 kg/h, in particular from 0.5 to 5 kg/h (for example for a pilot extractor) or from 1,000 to 5,000 kg/h (for example for an industrial extractor), preferably from 1 to 2, 5 kg/h or 1,600 to 3,200 kg/h. According to a particular embodiment in a pilot extractor, the present invention relates to an extraction process as defined above, in which in step a) the mass flow rate in the extractor of the extraction material is 0.5 to 5 kg/h, in particular from 1 to

2.5 kg/h.

The range from 0.5 to 5 kg/h includes the following ranges: from 0.5 to 1 kg/h, from 1 to 1.5 kg/h; from 1.5 to 2 kg/h; from 2 to 2.5 kg/h; 2.5 to 3 kg/h; from 3 to 3.5 kg/h; from 3.5 to 4 kg/h; from 4 to

4.5 kg/h; 4.5 to 5 kg/h.

The range from 1 to 2.5 kg/h includes the following ranges: from 1 to 1.25 kg/h; from 1.25 to 1.50 kg/h; from 1.50 to 1.75 kg/h; from 1.75 to 2 kg/h; from 2 to 2.25 kg/h; from 2.25 to 2.50 kg/h.

Advantageously, the process according to the invention as defined above is implemented to continuously produce 0.3 to 0.8 kg/h of extract containing or consisting of CNSL, possibly tannins.

The range of 0.3 to 0.8 kg/h includes the following ranges: 0.3 to 0.4 kg/h; from 0.4 to 0.5 kg/h; from 0.5 to 0.6 kg/h; from 0.6 to 0.7 kg/h; from 0.7 to 0.8 kg/h.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step a) the mass flow rate in the extractor on an industrial scale of the extraction material is from 1,000 to 5,000 kg/h, in particular from 1,600 to 3,200 kg/h.

The 1000 to 5000 kg/h range includes the following ranges: 1000 to 1500 kg/h; from 1,500 to 2,000 kg/h; from 2000 to 2,500 kg/h; from 2,500 to 3,000 kg/h; from 3,000 to 3,500 kg/h; from 3,500 to 4,000 kg/h; from 4,000 to 4,500 kg/h; from 4,500 to 5,000 kg/h.

The 1,600 to 3,200 kg/h range includes the following ranges: 1,600 to 2,000 kg/h; from 2,000 to 2,400 kg/h; from 2,400 to 2,800 kg/h; from 2,800 to 3,200 kg/h.

We understand that the process according to the invention has the advantage of allowing continuous industrial quantities not accessible by traditional batch extraction methods.

With an estimated yield of 30%, the process according to the invention with a flow rate of 2,400 kg/h would make it possible to produce approximately 720 kg of extract per hour continuously.

Advantageously, the process according to the invention as defined above is implemented to continuously produce from 480 to 960 kg/h of extract containing or consisting of CNSL, possibly tannins.

The range from 480 to 960 kg/h includes the following ranges: from 480 to 600 kg/h; from 600 to 720 kg/h; from 720 to 840 kg/h; from 840 to 960 kg/h. It is also understood that the duration of the process can be adapted to the quantity of cashew nut shells to be treated or adapted to the volume of the extraction solvent and vice versa, unlike the implementation of an extraction process by a batch solvent.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step b) at each of the N extraction steps, said miscella i recovered in a reservoir i is returned in circulation as a solvent to percolate the extraction material, giving a miscella enriched in solute in said reservoir i, said recirculation taking place in particular using a pump i.

The recirculation of miscella i in stage i allows optimization of the use of the solvent.

Advantageously, in one embodiment, the recirculation flow rate of the miscella i is calculated as a function of the configuration of the extractor and in particular the configuration of the reservoir i so that the miscella i recirculated from the pump remains in its tank i.

The recirculation flow rate of the miscella i can also be calculated as a function of the configuration of the extractor and in particular the configuration of the tank i so that the miscella i overflows from the tank i in order to recover the miscella i towards the neighboring tank (i- 1) or to a final extract recovery tank.

In a counter-current extraction process, when the N extraction stages are indexed with an increasing index i according to the direction of introduction of the extraction material, it is understood that the reservoir (i-1) is that corresponding to stage (i-1) which is intended to be used to extract an extraction material comprising more solute than the extraction material present in stage i. When i=1, the tank with an index 0 corresponds to the tank F for recovering the final extract.

According to a particular embodiment, the present invention relates to a process as defined above, in which the flow rate of the extraction solvent is modulated over time so that in the extraction step b), the miscella i recovered does not overflow from the tank i, then in the recovery step c), after the extraction step i when the miscella i is more concentrated in solute, the recirculation flow rate is increased by the pump i so that the miscella i overflows from tank i towards the neighboring tank (i-1) or towards a tank F for recovering the final extract.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step c), each reservoir i is positioned to overflow onto tank i -1, when i = 1, tank i -1 corresponding to tank F.

“Reservoir F” means the final recovery reservoir of the extract obtained by the extraction process according to the invention.

It is understood that the sum of successive overflows from a tank i to a neighboring tank (i-1) can be controlled or programmed to optimize the counter-current extraction process, for example by controlling the flow rate of the solvent flow or by influencing the configuration of the tanks.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the ratio between the mass flow rate in the extractor of the extraction material and the flow rate of the solvent introduced into the extractor is 1:1 to 1:3, preferably 1:2.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which in step c) the quantity of solute of all the N miscellas recovered represents 15 to 50%, preferably from 20 to 40%, by mass of the total mass of said extract in tank F.

In the process according to the invention, the mass concentration of the solutes in the final miscella recovered is 15 to 50%, preferably 20 to 40% by total mass of the final miscella. A content of 20 to 40% is an indicator of optimization of the use of the quantity of solvent.

The “15 to 50%” range includes the following ranges: 15 to 20%; from 20 to 25%, from 25 to 30%, from 30 to 35%, from 35 to 40%; from 40 to 45%; from 45 to 50%.

According to a particular embodiment, the present invention relates to an extraction process as defined above, in which the overall extraction yield, defined as the ratio between the mass of solute extracted and the mass of nut shells. cashew, is 20 to 50%.

The “20 to 50%” range includes the following ranges: 20 to 25%, 25 to 30%, 30 to 35%, 35 to 40%, 40 to 45%, 45 to 50%.

An overall yield beyond the amount of CNSL naturally present in cashew shells (estimated at approximately 35%) is an indicator of the presence of extracted tannins.

Another object of the present invention relates to a porous system comprising the shells, in particular crushed, of cashew nuts and the solvent, obtained or capable of being obtained by the process according to the invention as defined above. The porous system of the invention is a state obtained during the extraction process. The characteristics of the porous system are defined during the solvent extraction step, i.e. in the case of percolation extraction when the solvent passes through the extraction material.

Another object of the present invention relates to an extract containing or consisting of cashew nut shell oil, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a natural CNSL oil, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing 60 to 80% by weight of anacardic acid, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: 60 to 80% by weight of anacardic acid, 3 to 15% by weight of cardanol, 15 to 25% by weight of cardol and methyl cardol, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a natural CNSL oil and tannins, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: 60 to 80% by weight of anacardic acid, 2 to 15% by weight of cardanol, 15 to 25% by weight of cardol and methyl cardol, from 0 to 15% by weight of tannins, obtained or capable of being obtained by the process as defined above. According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a technical CNSL oil, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: less than 5% by weight of anacardic acid, 60 to 80% by weight of cardanol, 15 to 30% by weight of cardol and methyl cardol, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of a technical CNSL oil and tannins, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above containing or consisting of: less than 5% by weight of anacardic acid, 60 to 80% by weight of cardanol, 15 to 30% by weight of cardol and methyl cardol, from 0 to 15% by weight of tannins, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to an extract as defined above, containing or consisting of cashew nut shell oil, said oil having the following composition: from 60 to 80% by weight of acid anacardic, 3 to 15% by weight of cardanol, 15 to 25% by weight of cardol and methyl cardol, or of the following composition:

- less than 5% by weight of anacardic acid, from 60 to 80% by weight of cardanol, from 15 to 30% by weight of cardol and methylcardol, said extract being obtained by the process according to the invention as defined below -above. Another object of the present invention relates to a natural or technical CNSL oil from cashew nut shells, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to a natural CNSL oil from cashew nut shells as defined above containing or consisting of: 60 to 80% by weight of anacardic acid, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to a natural CNSL oil from cashew nut shells as defined above containing or consisting of: 60 to 80% by weight of anacardic acid, 3 to 15% by weight of weight of cardanol, from 15 to 25% by weight of cardol and methyl cardol, obtained or capable of being obtained by the process as defined above.

According to a particular embodiment, the present invention relates to a technical CNSL oil from cashew nut shells as defined above containing or consisting of: less than 5% by weight of anacardic acid, from 60 to 80% by weight of weight of cardanol, from 15 to 30% by weight of cardol and methylcardol, from 0 to 15% by weight of tannins, obtained or capable of being obtained by the process as defined above.

Another object of the present invention relates to a cashew nut shell cake obtained or capable of being obtained by the process as defined above.

The cashew nut shell cake obtained at the end of the process according to the invention as defined above, comprises less than 5%, preferably less than 1% of CNSL and can be recycled.

By way of non-limiting example, the cake obtained according to the process of the invention can be used in a gasification process consisting of the conversion of biomass into gas. It can also be converted into fuel briquettes serving as a solid fuel substitute for coal and firewood for domestic cooking. The degradation of the cake can be accelerated by bioactivation and thus used in composting. The cake comes out of the extractor continuously and can be easily recovered, processed or shaped.

Another subject of the present invention relates to a composition of tannins derived from cashew nut shells obtained or capable of being obtained by the process as defined above.

The tannins are as previously defined above.

It should be noted that the process described in the invention makes it possible to obtain a natural CNSL, in which the main phenolic compounds (anacardic acid, cardanol, cardol) have not been thermally degraded.

Figure 1 represents an embodiment of the process by the invention by percolation implemented in a continuous counter-current Solid-Liquid extraction installation with 4 stages comprising an inlet end (1), an outlet end (2), a barrel (3) comprising a single screw (5) arranged horizontally above a series of 4 retention tanks (41, 42, 43, 44) R1, R2, R3 and R4 aligned from the inlet end (1) of the extraction material along the longitudinal axis of the screw with an inclination (10), nozzles (6) at each stage for percolating the extraction material, a system solvent supply (7) comprising a solvent inlet pipe (71) located at the outlet end and comprising at each stage i, a pump i (8) connected to a reservoir i (41, 42, 43 , 44), filtration means (9) present in the barrel and/or at the inlet of the tanks, a recovery tank F (45) connected to the tank R1.

Figure 2 represents the extract yields obtained with the three techniques implemented, respectively with Soxhlet extraction, single-stage extraction by maceration and continuous extraction by percolation, carried out with two different solvents, hexane and methanol. .

Figure 3 shows the extract yields for continuous percolation extraction as a function of extraction time for 3 different extraction solvents, hexane, methanol and ethyl acetate.

Figure 4 is a photo of a pilot device for the extractor from the company Vatron-Mau, model EVA 100, making it possible to implement a process for extracting cashew nut shells continuously, against the current, on 4 floors.

Figure 5 shows the estimated concentration of solutes in the miscella at each stage of the extractor. Tl

We will now describe, in a non-limiting manner, with reference to Figure 1, an embodiment of the process implemented by a continuous counter-current Solid-Liquid extraction installation.

Description of an installation (pilot)

The extractor below is described for 4 stages, that is to say N equal to 4, but we understand that it can be adapted for N equal to 3 to 10 stages, in particular to 4 to 6 stages.

The 4-stage extractor includes an enclosure comprising:

- an inlet end (1) connected to a hopper (11),

- an outlet end (2),

- a barrel (3) comprising a single screw (5) arranged horizontally above a series of 4 retention tanks R1, R2, R3 and R4 aligned (41, 42, 43, 44) from the end entry (1) of the extraction material along the longitudinal axis of the screw,

- nozzles (6) on each floor to percolate the extraction material,

- a solvent supply system (7) comprising a solvent inlet pipe (71) located at the outlet end and at each stage i, a pump i (8) connected to a tank i,

- filtration means (9) present in the barrel and/or at the entrance to the tanks,

- a recovery tank F (45) connected to tank R1.

The endless screw has a diameter of 50 to 500 mm, preferably 80 to 120 mm. The screw (5) is configured to rotate continuously in one direction. A hopper (11) is positioned in such a way as to feed the start of the endless screw at the entrance to the extractor enclosure.

The tanks (41, 42, 43, 44) are positioned side by side, and advantageously equipped with a filtration means (9), such as a filter, for example a filtration cloth. These tanks (41, 42, 43, 44) are placed on an inclined plane (10) relative to the horizontal plane, and are configured so that the tank Ri can overflow by supplying the tank Rj.i which adjoins it, for example the tank R4 (44) can overflow by supplying the tank R3 (43), R3 can overflow onto R2 (42), R2 onto R1 (41) and R1 towards a tank F (45) for recovering the extract. The extractor is segmented into 4 stages corresponding to each tank.

In the extractor, in operation, contact between the solvent and the extraction material occurs by percolation using a nozzle (8). The direction of the solvent flow is opposite to that of the introduction of the crushed cashew shells. The fresh solvent introduced is in contact with the material depleted in solute, while the fresh material is in contact with the solvent enriched in solute. Each tank is linked to a pump (8) and a dispersion nozzle (6) which ensure the recirculation of the solvent in said tank i. Advantageously, temperature sensors and plate heat exchangers are regularly distributed along the extractor.

The extractor can be chosen from the extractors of the Vatron-Mau company.

Description of an embodiment

In one embodiment of the process, the cashew nut shells previously crushed and with a particle size of 1 mm to 1 cm, preferably 3 and 8 mm, are introduced into a hopper at the inlet end (1) of the extractor enclosure.

All of the operations described below are carried out at a temperature of 20 to 80°C, preferably 50 to 70°C and at atmospheric pressure (0.1 MPa).

At start-up before the extraction stages, the tanks (41, 42, 43, 44) are filled with solvent. Fresh solvent is introduced through a pipe (71) located at the outlet end of the extractor enclosure directly into the R4 tank (44). Solvent is charged until the tank R1 (41) is filled to its maximum capacity, by a set of overflow of the tanks, the tank R1 (41) not having to overflow towards the tank F (45) intended for the recovery of the extract.

The endless screw (5) is started, then once the desired rotation speed is reached, the valve of the hopper (11) containing the crushed cashew nut shells is opened, and the hopper is then constantly fed with the crushed cashew shells.

The crushed cashew shells are fed into the inlet end (1) of the extractor enclosure into the barrel (3) and transported to the other outlet end (2) of the extractor enclosure. the extractor by rotating the screw (5). The retention time or residence in the extractor enclosure varies from 40 min to 6 h, it depends in particular on the rotation speed of the screw.

At the nominal operating point, the mass flow rate of crushed cashew nut shells is 1 kg. h ^-1 .

When the entire screw (5) is loaded with the crushed hulls, the extraction stage at each stage of the extractor begins.

Extraction step on floor i

For each stage i, a withdrawal valve, positioned at the bottom of each tank i (41, 42, 43, 44), is open. This will allow the supply, via a pipe, of the recirculation pump i (8) attached to this tank. At the same time, the recirculation pump (8) is put into operation, at a flow rate calculated according to the volume of the tank, allowing recirculation of the solvent in the same tank, advantageously 1 m ³ .h' ¹ for a 30L tank.

The solvent is dispersed by the corresponding nozzle (6) which is configured to bring the solvent into contact with the extraction material by a percolation phenomenon. Particularly during percolation a porous system is formed from the extraction material and the solvent.

Advantageously in this porous system, the exchange surface between the solvent and the extraction material allows the solvent to solubilize the solutes present in the extraction material, namely the CNSL compounds and possibly tannins.

The solvent and solute form a miscella. The miscella (CNSL/solvent) is separated from the extraction material by filtration means (9) which may be present in the barrel and/or at the inlet of the tanks.

At the end of percolation and by gravity in stage i, the solvent is then recovered in tank i.

The filtration cloth present in the tank makes it possible to retain certain solid particles which may be carried by the solvent, while at the bottom of the tank, the liquid filtrate is made up of the CNSL/solvent solute mixture.

In tank i, the miscella will be transferred a second time, thanks to the recirculation pump (8) and the pipes, above the endless screw loaded with crushed cashew nut shells.

A second percolation of the extraction material with miscella i is carried out and leads to the filling of reservoir i with a miscella enriched in solute.

In the same way as previously, solid/liquid separation is ensured by the filtration fabric within the tank i itself.

Transfer for the counter-current process

The transfer of solvent from one tank to another is carried out by overflow. Advantageously, the flow rate of the pump is then increased in order to cause the tank i to overflow towards the tank (i-1).

Thus the miscella from tank i is transferred to tank (i-1).

The recirculation of the solvent in the second tank (i-1) is started, two percolations are carried out with the solvent contained in the tank (i-1), and so on until the last tank R1 (41).

The last tank R1 overflows into a retention tank F (45). Once all of the solvent loaded with solute has been recovered in the retention tank F (45), the contents of the tank are transferred to a distillation unit. The solvent is then distilled under reduced pressure and at a temperature of 20 to 110°C, preferably at 50°C, in order to obtain CNSL.

The distillation temperature is below 110°C, i.e. a temperature lower than the decarboxylation temperature of anacardic acid.

The solvent thus distilled can then be introduced again into the continuous counter-current extraction process.

We understand that the extraction steps i can be carried out concomitantly.

Description of an industrial installation

The pilot extractor above is adaptable for an industrial installation of 6 to 10 floors. To increase the material flow, the endless screw can be replaced by a material transport belt allowing a material flow of around 1,600 to 3,200 kg/h, i.e. a volume of CNSL estimated at 480 to 960 kg/h. The size of the tanks is therefore adapted to the industrial scale, the volume of a tank being for example 1.2 m ³ .

Example 1: Comparative study of solvent extraction techniques.

Three solvent extraction techniques applied to the extraction of CNSL from the same raw material consisting of crushed cashew shells of the same origin and variety, were studied and compared. a) Soxhlet extraction

Solvent: Hexane

The cashew nut shells were provided by Orpia Innovation. Hexane (VWR, technical grade) was used without prior purification. The operating setup consisted of a Soxhlet extractor (250 mL), a condenser, a flask (250 mL), a heating mantle, a cellulose cartridge (33x100 mm) and cotton. The cashew shells were crushed for 15 seconds using a Waring-type kitchen blender. Grinding resulted in a mixture of sticky brown paste and fine cashew shell residue.

20g of cashew nut shells crushed in a blender were introduced into the Soxhlet cartridge, the latter was supplemented with cotton up to the surface of the cartridge. 200 mL of hexane were introduced into the flask previously tared for a shell/solvent ratio 1:10 (w/v). Heating was started and extraction continued for 6 hours at hexane reflux. After extraction, the solvent present in the flask was evaporated, under reduced pressure of 50 to 250 mbar at 50°C with an R-300 rotavapor connected to a V-600 vacuum pump from the Bûchi company. Then the product constituting the extract was dried under vacuum at room temperature for 1h30. Obtaining a brown oil, m = 6.78g, mass yield of the extract = 33.9%.

Solvent: Methanol

The same operating protocol was implemented with methanol as solvent. In this case a brown oil and a solid deposit were observed at the end of evaporation and the overall yield of the extract was higher (42.5%) than that with hexane as solvent, this being due to the presence of tannins. b) 1-stage extraction: maceration

Solvent: Hexane

The cashew nut shells were provided by Orpia Innovation. Hexane (VWR, technical grade) was used without prior purification. The operating setup consisted of a double-jacketed glass reactor, a magnetic stirrer and a Huber brand cryothermostat (model: Ministat 125). The hulls were crushed for 15 seconds using a Waring-type kitchen blender. Grinding resulted in a mixture of sticky brown paste and fine hull residue.

10g of hulls crushed in a blender were introduced into the 250 mL double-jacketed reactor, the latter was supplemented with 100 mL of hexane for a crushed hulls/solvent ratio 1:10 (w/v) with rotary stirring at a speed of 800 rpm. The temperature of the water circulating in the double wall was set at 55°C and the maceration continued for 6 hours. The suspension was then centrifuged (5000 g, 5 min, 20°C), the supernatant was recovered then vacuum filtered using a Büchner filter. The hull residues were washed on the Büchner filter with 2x15 mL of hexane. The solvent was then evaporated under reduced pressure of 50 to 250 mbar at 50° C. with an R-300 rotavapor connected to a V-600 vacuum pump from the Büchi company. Then the product constituting the extract was dried under vacuum at room temperature for 36 hours. Obtaining a brown oil, m = 2.85g, mass yield of the extract r = 28.5%.

Solvent: Methanol

The same operating protocol was implemented with methanol as solvent. For the case of methanol, a brown oil and a solid deposit were observed at the end of evaporation and the overall mass yield of the extract was higher (36.4%) than that with hexane as solvent, this being due to the presence of tannins. c) Continuous extraction by percolation

Solvent: Hexane

The cashew nut shells were provided by Orpia Innovation. Hexane (VWR, technical grade) was used without prior purification. The operating setup consisted of an automatic Soxhlet (Bûchi B-811), a glass container (200 mL), a cellulose cartridge (33x100 mm) and cotton. The hulls were crushed for 15 seconds using a Waring-type kitchen blender. Grinding resulted in a mixture of sticky brown paste and fine hull residue.

20g of hulls crushed in a blender were introduced into the Soxhlet cartridge, the latter was supplemented with cotton up to the surface of the cartridge. 200 mL of hexane were introduced into the glass container for a shell/solvent ratio 1:10 (w/v). The automatic Soxhlet was set to “continuous extraction” mode, which made it possible to mimic the conditions of the continuous extraction process (the condensed solvent was not maintained in the extraction chamber). Heating was started and extraction continued for 6 hours at hexane reflux.

After extraction, the solvent was evaporated, under a reduced pressure of 50 to 250 mbar at 50° C. with an R-300 rotavapor connected to a V-600 vacuum pump from the Bûchi company. Then the product constituting the extract was dried under vacuum at room temperature for 1 hour 30 minutes. Obtaining a brown oil, m = 6.25g, mass yield of the extract r = 31.2%.

Solvent: Methanol

The same operating protocol was implemented with methanol as solvent. For the case of methanol, a brown oil and a solid deposit were observed at the end of evaporation and the overall mass yield of the extract was higher (42.3%) than that with hexane as solvent, this being due to the presence of tannins. d) Comparison

Figure 2 represents the yields obtained with the three techniques implemented with two different solvents. The mass yields of the extract obtained were higher in methanol than in hexane in the 3 extraction processes analyzed, probably indicating the presence of tannins with the use of methanol.

The continuous percolation extraction process of Example 1c) constitutes an alternative to classic batch extraction by Soxhlet in view of the yields observed.

Generally speaking, unlike a Soxhlet process, the continuous percolation process made it possible to increase the exchange of material between the solid and liquid phases, to reduce the quantity of extraction solvent and to improve productivity.

Hexane as an extraction solvent made it possible to obtain natural CNSL with a much higher purity than that using methanol. In fact, the use of hexane does not lead to the dissolution of tannins in the extract. The presence of residual solvents (such as methanol) can be eliminated by techniques known to those skilled in the art.

Example 2: Kinetics: Optimization of the time of continuous extraction by percolation.

The kinetics of the continuous extraction was studied with a protocol similar to example 1.c) for the 3 solvents (hexane, methanol and ethyl acetate) in which the reaction was stopped at different times t = 15 min , 30 mins, 45 mins, 60 mins, 120 mins and 180 mins.

In a continuous extraction by percolation, Figure 3 indicates that at t = 2h, the maximum mass yield of extract was reached for the 3 solvents.

The continuous extraction process by percolation made it possible to reduce extraction times for very correct and almost maximum yields.

Methanol presented better extract mass yields, but involved the presence of tannins in the extract.

Ethyl acetate, a biosourced solvent, made it possible to recover more extract after the 2 hours required, however its extraction kinetics were lower than for hexane, a petrosourced solvent. The compromise of a slightly longer extraction time for a more efficient and eco-responsible extraction is a criterion for choosing the extraction solvent.

Example 3: separation of CNSL and tannins by selective solubilization in hexane.

The cashew nut shells were provided by Orpia Innovation. Methanol and hexane (VWR, technical grade) were used without prior purification.

The operating setup consisted of an automatic Soxhlet (Bûchi B-811), a glass container (200 mL), a cellulose cartridge (33x100 mm, reference 900820, lot 1930), a 500 mL balloon and cotton. The cashew nut shells were finely ground using of a Robot Coupe Blixer 2 kitchen grinder for 15 seconds, grinding resulted in a mixture of sticky brown paste and fine hull residue.

The crushed hulls (m _c = 22.827 g) were introduced into the cartridge located in the extraction chamber, the latter was then supplemented with cotton up to its surface. 200 mL of MeOH were introduced into the glass container for a shell/solvent ratio 1:10 (w/v). The MeOH was heated to boiling and the extraction continued for 6 h at reflux. The mixture was transferred into the flask and the solvent was then evaporated under reduced pressure at 50° C. with a rotary evaporator and then the product was dried under vacuum at room temperature for 1 hour 30 minutes. Obtaining an oily mixture with solid residues (tannins), m _p = 10.038 g (rs _O xhi _e t = 44.0%).

The oily mixture obtained underwent a hot resolubilization step in hexane. The operating setup consisted of a 500 mL flask, a flask heater, a water cooler and a magnetic bar. 110 mL of technical hexane were introduced into the flask and brought to the boil with stirring (v = 800 rpm). After maceration for 1 hour 30 minutes, the mixture was filtered hot under vacuum on a Büchner with filter paper (porosity 4).

On the one hand for the filtrate, the hexane was evaporated under reduced pressure at 50°C (rotary evaporator) then the product was dried under vacuum at room temperature for 2 hours. Obtaining a monophasic filtrate of CNSL, mcNSL = 7.066 g, TCNSL = 31.0%.

On the other hand, for the solid residue, the filter + filter paper assembly was washed with 2x15 mL of MeOH, this solution was reintroduced into the flask which underwent resolubilization and which contained traces of solids insoluble in water. 'hexane. The MeOH was then evaporated under reduced pressure of 50 to 250 mbar at 50° C. (rotary evaporator) then the product was dried under vacuum at room temperature for 2 hours. Obtaining a dark solid residue, m _tanins = 2.289 g, Ranins ⁼ 10.03%.

It should be noted that some product losses were observed during the resolubilization stage since the 44% yield of the CNSL/tannin mixture was not found.

Example 4: Continuous multi-stage counter-current extraction process

In the case of the porous system consisting of cashew nut shells, the process according to the invention in which the extraction material, ie the cashew nut shells, are introduced continuously from the inlet to the outlet of the enclosure of an extractor and in which the flow of solvent is in counter-current to that of the extraction material is compatible with the introduction of several extraction stages.

In the case of the porous system made up of cashew nut shells, the use of several extraction stages, combined with continuous and counter-current extraction, has the effect of:

- to optimize the volume of solvent used during counter-current extraction, since the miscella from stage i is reinjected and reused as solvent in stage (i-1) and this successively in a stage to another maximizing the contacts and exchanges of the extraction material with the solvent,

- to offer degrees of freedom to optimize the overall extraction yield and/or to control the solute content in the miscella recovered at the extractor outlet,

- to be able to size the parameters of the extractor in order to control, modulate and manage the flows of material and solvent which are continually moving during extraction in continuous production,

- in the course of the solvent against the current in the extractor enclosure, to gradually enrich the solute miscellas while retaining the proportion of the constituents of the CNSL present in the cashew nut shells, c that is to say that there is no or little denaturation of the anacardic acid in the extraction material; the process therefore makes it possible to obtain natural CNSL rich in anacardic acid, i.e. an anacardic acid content of around 60 to 80% by total mass of the CNSL,

- to implement an industrial process in which the path of the extraction material from the inlet of the extractor to the outlet of the extractor and the path of the solvent flow from the outlet of the extractor to the outlet extractor input are uninterrupted.

Example 5: Comparison of extraction yields a) Batch extraction process: extraction by maceration

The operating protocol used consisted of maceration in the extraction solvent. 30 g of cashew nut shells previously coarsely ground (2-10 mm) were introduced into a 250 mL beaker equipped with a double jacket heated to 50°C. Then 67 mL (60 g) of ethyl acetate were then introduced into the beaker in order to obtain a shell/solvent ratio of 1/2. The beaker was covered to prevent evaporation of the solvent, then the mixture was left to macerate for 1 hour. Once the time had elapsed, the mixture was separated on filter paper in order to recover the miscella (solvent + CNSL mixture), which was then evaporated using a rotary evaporator (50 °C, 250 mbar). The desolvented CNSL was thus recovered and then weighed in order to determine the gross extraction yield (mass of raw CNSL/mass of extracted shells).

The yield of CNSL obtained in ethyl acetate after 1 hour of maceration at 50°C was 28%. b) Continuous extraction process in stages: Counter-current extraction of CNSL on a pilot scale

Trial 1

A pilot-scale test campaign is carried out using a 4-stage counter-current extractor (model EVA 100, Supplier: VATRON-MAU). The essential parts of the device according to Figure 1 are shown in the photo of the extractor in Figure 4.

The characteristics of the extractor are as follows:

• Dimensions of the extractor: L = 2000 mm x Diam = 200 mm

• Tank volumes = 3.5L

• Recirculation flow = 2 L/h

• Maximum extraction material capacity in the extractor = 3.75 kg (in this example, there are approximately 1.5 kg of extraction material present in the extractor)

• Retention time = 22 min / floor or 1 hour 30 minutes in total.

Approximately 20 kg cashew nut shells previously coarsely crushed (2-10 mm) are introduced into the loading hopper of the extractor. Once the extractor is filled with ethyl acetate heated to 50°C, an endless screw is started to begin introducing the shells into the extractor with a flow rate of 1.0 kg/h. When the first shells have passed through the extractor, ethyl acetate is pumped into the extractor at a rate of 2.0 kg/h to obtain a solid/liquid flow rate ratio of 1/2. Continuous extraction is maintained for 1 hour 30 minutes, at a temperature of 50°C. The miscella leaving the extractor is collected gradually, then evaporated using a rotary evaporator (50 °C / 250 mbar then 1 mbar to finish) in order to obtain the desolvented raw CNSL.

The estimated yield is 39%.

In order to determine the concentration gradient in the extractor, samples of 20 mL of miscella are taken at each level using a tap located at the bottom of the tank. THE Samples are then desolvented using a rotary evaporator (50 °C / 250 mbar then 1 mbar to finish) in order to determine the CNSL content.

The estimated solute concentrations in the miscella for each stage are presented in Figure 5.

Test 2

Using the protocol described in test 1, a new test is carried out, this time with a flow rate of 1.3 kg/h. Once the first shells have passed through the extractor, ethyl acetate is pumped into the extractor at a flow rate of 1.95 kg/h in order to obtain a solid/liquid flow rate ratio of 1/ 1.5. Continuous extraction is maintained for 1 hour 30 minutes, at a temperature of 50°C. The miscella leaving the extractor is collected gradually, then evaporated using a rotary evaporator (50 °C / 250 mbar then 1 mbar to finish) in order to obtain the desolvented raw CNSL.

The estimated yield is 38%.

Materials

Ethyl acetate (GRP Rectapur; <0.05% H2O; VWR Chemicals)

Hexane (Technical grade, mixture of isomers, VWR Chemicals)

Cashew nuts (Origin: Ivory Coast)

Claims

1. Use, for the implementation of a solvent extraction process of an extract containing or consisting of a natural or technical CNSL oil and possibly tannins from cashew nut shells, in particular crushed, a continuous introduction into an extractor of cashew nut shells, in particular crushed, constituting the extraction material, causing said extraction material to pass through from the entrance to the extractor enclosure until the outlet of said extractor enclosure, said introduction being carried out counter-current to the direction of the flow of said solvent, said extraction material forming with the solvent a porous system, and in which the extraction process is carried out in an extractor comprising several stages, in particular N stages, N varying from 2 to 10, preferably N equal to 4, and at a pressure of 0.05 to 0.5 MPa, preferably 0.1 MPa.

2. Use according to claim 1, in which the extraction process is carried out by percolation of the solvent through the extraction material or by immersion in the solvent of the extraction material.

3. Process for preparing an extract containing or consisting of a natural or technical CNSL oil and optionally tannins by extraction with a solvent from cashew nut shells, in particular crushed, comprising the following steps: a) a step of introducing cashew nut shells, in particular crushed ones, constituting the extraction material, continuously, into an extractor, causing said extraction material to pass through from the entrance to the enclosure of the extractor until the outlet of said extractor enclosure, b) a step of extracting the solute comprising N step(s) of extraction with a solvent as said extraction material passes through the extractor, N varying from 2 to 10, said extraction material and the solvent forming a porous system, in which the direction of said introduction is countercurrent to that of the solvent flow, in which for each extraction step i, i varying from 1 to N, leads to obtaining an extracted liquid phase i containing a solute i and the solvent, said solute i forming with the solvent a miscella i, which miscella i is recovered in a reservoir i, c) a recovery step:

4. Method according to claim 3, in which the cashew nut shells are crushed and are obtained in a prior step of grinding the cashew nut shells before step a), and/or further comprising a treatment step heat treatment of cashew nut shells or crushed cashew nut shells before step a), and/or in which steps a), b) and c) are carried out at a temperature of 20 to 140°C, in particularly from 20 to 70°C.

5. Method according to one of claims 3 to 4, in which the solvent is chosen from ethyl acetate, butyl acetate, hexane, cyclohexane, 2-methyltetrahydrofuran, methanol and ethanol.

6. Method according to claim 5, in which:

- and said method comprises an additional separation step d) in which said extract comprising CNSL and tannins is separated into a CNSL oil and a solid residue containing said tannins.

7. Method according to claim 5, in which:

8. Method according to one of claims 3 to 7, comprising an additional step of heat treatment of the extract to obtain a technical CNSL oil.

9. Method according to one of claims 3 to 8, in which the cashew nut shells have an average particle size of 1 mm to 1 cm, and/or a humidity level of 5 to 10%, in particular 6 .0 to 6.5%, and/or in which the porous system has an interstitial volume of 15 to 60%, and/or a density of 0.4 to 1.6 and/or in which during extraction the extraction material: solvent ratio is 1:0.5 to 1:10 by volume, in particular 1:1 to 1:2.

10. Method according to one of claims 3 to 9, wherein in step a) the retention time in the extractor of the extraction material, defined as the duration of time separating entry into the extractor of a fraction of the extraction material and the outlet of the extractor of said same fraction of the extraction material, is 40 min to 6 h, and/or in which in step a) the mass flow rate in the extractor of the extraction material is 0.5 to 5000 kg/h, in particular 0.5 to 5 kg/h or 1000 to 5000 kg/h.

11. Method according to one of claims 3 to 10, wherein in step b) at each of the N extraction stages, said miscella i recovered in a tank i is recirculated as a solvent to percolate the material extraction, giving a miscella i enriched with solute in said same reservoir i, said recirculation taking place in particular using a pump i, and/or in which, in step c), each reservoir i is positioned to overflow onto reservoir i -1, when i = 1, reservoir i -1 corresponding to reservoir F.