Method for manufacture of unsaturated alpha,beta carboxylic acids of biological origin from poly(3-hydroxyalcanoate) contained in biomass

Description

METHOD FOR MANUFACTURING ALPHA,BETA UNSATURATED CARBOXYLIC ACIDS OF BIOLOGICAL ORIGIN FROM POLY(3-HYDROXYALKANOATE) CONTAINED IN BIOMASS Technical field

[001] The present invention relates to a method for manufacturing α,β unsaturated carboxylic acids of biological origin from biomass containing a poly(3-hydroxyalkanoate) in the presence of polymerization inhibitors, comprising a thermolysis step of said biomass, in the absence of a catalyst, followed by several steps resulting in the production of α,β unsaturated carboxylic acids. Background of the art and technical problem

[002] The industrial production of α,β unsaturated carboxylic acids is currently carried out mostly from fossil raw materials. For example, acrylic acid is obtained by oxidation of propylene, or methacrylic acid can be obtained by oxidation of isobutylene.

[003] One of the possible ways to produce α,β unsaturated carboxylic acids is by thermolysis at temperatures of 150°C to 300°C of the corresponding poly(3-hydroxyalkanoates) (P3HA), according to the following reaction: [Chemical Reaction 1] Ri = H or alkyl and R2 = H or alkyl; n is a number greater than 30 If Ri = R2 = H: - Poly(3-hydroxyalkanoate) = poly(3-hydroxypropionate) (P3HP); - α,β unsaturated carboxylic acid = propenoic acid (acid Petition 870250084480, dated 09 / 19 / 2025, page 8 / 43 2 / 22 acrylic). If Ri = methyl and R2 = H: - Poly(3-hydroxyalkanoate) = poly(3-hydroxyisobutyrate) (P3HiB); - α,β unsaturated carboxylic acid = isobutenoic acid (methacrylic acid). If Ri = H and R2 = methyl: - Poly(3-hydroxyalkanoate) = poly(3-hydroxybutyrate) (P3HB); - α,β unsaturated carboxylic acid = 2-butenoic acid (crotonic acid). If Ri = H and R2 = ethyl: - Poly(3-hydroxyalkanoate) is poly(3-hydroxyvalerate) (P3HV); - α,β unsaturated carboxylic acid = 2-pentanoic acid

[004] The poly(3-hydroxyalkanoates) themselves can be obtained beforehand through chemical transformations of fossil raw materials, and also by fermentation of biomass.

[005] There is a strong market demand for such α,β unsaturated carboxylic acids, which are used as monomers in numerous applications, to be obtained from biologically sourced raw materials. This biologically sourced raw material comes from renewable organic matter (biomass) of biological origin (microorganisms, plants or animals).

[006] A potential problem with the method is that the P3HA obtained by fermentation is present inside the cell. Thermolysis is therefore conducted in the presence of the cell membrane, causing problems of reactor clogging or the presence of impurities in the final product.

[007] Several solutions have been suggested for this problem.

[008] US patent 9850192 describes a method for producing acrylic acid from genetically modified microbial biomass. Petition 870250084480, dated 09 / 19 / 2025, page 9 / 43 A modified 3 / 22 method that metabolizes glucose or any other renewable feedstock to produce a poly-3-hydroxypropionate (P3HP) homopolymer or copolymer inside microbial cells. This method includes a thermolysis step of washed / dried / crushed biomass containing P3HP in the presence of a catalyst. The method allows for the effective production of acrylic acid and limits the formation of acrylic acid oligomers, such as acrylic acid dimers, which are spontaneously formed during acrylic acid production. The acrylic acid is recovered in gaseous form and then condensed, while the catalyst and residual biomass mass can be recycled back into the method or subjected to thermal regeneration. However, there is a risk that the residue present in the reactor after thermolysis will be pasty and sticky, which would hinder its transition to an industrial scale. Example 5 and Figure 7 describe how to use the invention on an industrial scale.After fermentation, the biomass is washed and dried with an atomizer or a double-drum dryer. After the addition of the catalyst, the product is pyrolyzed in a FAST™ reactor at 250-350°C with a residence time of 0.25-1 hour using an inert gas, such as nitrogen, to send the vapors formed to the purification equipment. The vapor phase consists of 90% organic material / water and 10% inert gas. The gas is then purified, according to the method described in US patent 6646161 or US patent 20120006673, to obtain an acrylic acid still containing many impurities. Complete purification is carried out in distillation columns, as described in US patents 7332624 and 7179875, and may require crystallization operations, as described in US patents 6482981 and 71798750.

[009] Another solution consists of first extracting P3HA from the biomass with an organic solvent before carrying out thermolysis. Document US 20150376152 describes, in example 6, the extraction of Petition 870250084480, dated 09 / 19 / 2025, page 10 / 43 4 / 22 P3HP from biomass is obtained with an organic solvent, such as 2-butanone, followed by the production of acrylic acid in three steps: evaporation of the solvent and its condensation in a collecting vessel; thermal degradation of P3HP in the absence of an inhibitor, leading to the production of acrylic acid vapor; and finally, distillation and condensation of the acrylic acid in a collecting vessel containing hydroquinone to prevent the polymerization of acrylic acid.

[0010] In its patent application FR 2208914, the applicant company suggests carrying out the thermolysis of P3HA in the absence of a catalyst and in the presence of a polymerization inhibitor; characteristically, the vapor pressure is less than twice the vapor pressure of one of the inhibitors at the thermolysis temperature, preventing, as a result, the formation of polymers in the reactor, as well as in the gas phase in case of accidental condensation or at the moment of condensation of acrylic acid vapors at the top of the column.

[0011] In its patent application FR 2208916, the applicant company describes a solvent-based method that allows for the selective solubilization of P3HA from biomass, the separation of organic debris insoluble in said solvent, and the conduct of a liquid-phase thermolysis treatment in the presence of polymerization inhibitors.

[0012] Document WO 2016 / 039618 describes the thermal degradation of a dry biomass containing poly(3-hydroxybutyrate) to produce crotonic acid. Example 1 shows that crotonic acid can be obtained with a comparable yield of less than 60% from wet or dry biomass in the absence of a catalyst.

[0013] It has now been discovered that it is possible to simplify the manufacturing procedure of α,β unsaturated carboxylic acids by performing a thermolysis operation of P3HA directly on biomass mixed with at least one polymerization inhibitor, without prior separation of the cell membrane, and without resorting to solvents for Petition 870250084480, dated 09 / 19 / 2025, page 11 / 43 5 / 22 perform thermolysis without using catalysts and without injecting inert gas to carry the vapors out of the reaction zone.

[0014] More precisely, "in the absence of a catalyst" means that the thermolysis of PHA in the presence of at least one polymerization inhibitor occurs in the absence of another chemical species that accelerates or redirects the reaction kinetics. The thermolysis as considered is induced only by operating conditions, such as temperature, pressure, and residence time.

[0015] Chemical species that lead to different types of catalysis depending on the nature of the species are in fact excluded: - Homogeneous catalysis, if the catalyst and reactants form only one phase (often liquid); - heterogeneous catalysis, if the catalyst and reactants form several phases (usually a solid catalyst for reactants in the gaseous or liquid phase); Enzymatic catalysis occurs when the catalyst is an enzyme, that is, a protein.

[0016] Consequently, the invention proposes to provide a simple and easy-to-implement solution to reduce clogging phenomena and the presence of impurities in the final product, thereby maintaining high reliability and high productivity in the manufacturing methods of α,β unsaturated carboxylic acids from poly(3-hydroxyalkanoates) obtained by fermentation. Summary of the invention

[0017] The present invention relates to a method for manufacturing an α,β unsaturated carboxylic acid of biological origin from biomass containing a poly(3-hydroxyalkanoate) (P3HA) in the absence of a catalyst, wherein said method comprises the following steps: - mix the aforementioned biomass with at least one inhibitor Petition 870250084480, dated 09 / 19 / 2025, page 12 / 43 6 / 22 of polymerization; - subjecting the aforementioned biomass-inhibitor mixture to a thermolysis step, leading to obtaining, on the one hand, the aforementioned α,β unsaturated carboxylic acid in the vapor phase and, on the other hand, a solid residue; - to separate the two phases formed into a gaseous phase and a solid phase; - to purify the aforementioned gaseous phase to obtain a purified α,β unsaturated carboxylic acid; - treat the waste in its solid phase.

[0018] According to various modalities, the aforementioned method has the following characteristics, if applicable, combined. The indicated contents are expressed by weight, unless otherwise indicated. In the indicated value ranges, the extremes are considered.

[0019] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass comprises a single type of 3-hydroxyalkanoate units, and the product formed is therefore composed of a single α,β unsaturated carboxylic acid.

[0020] According to one embodiment, the poly(3-hydroxyalkanoate) is the poly(3-hydroxypropionate) and the α,β unsaturated carboxylic acid produced is acrylic acid.

[0021] According to one embodiment, the poly(3-hydroxyalkanoate) is the poly(3-hydroxybutyrate) and the α,β unsaturated carboxylic acid produced is crotonic acid.

[0022] According to one embodiment, the poly(3-hydroxyalkanoate) is the poly(3-hydroxyisobutyrate) and the α,β unsaturated carboxylic acid produced is methacrylic acid.

[0023] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass comprises a plurality of different 3-hydroxyalkanoate units and the product formed is therefore composed of a mixture of different α,β unsaturated carboxylic acids. Petition 870250084480, dated 09 / 19 / 2025, page 13 / 43 7 / 22 Examples of P3HA copolymers are poly-3-hydroxybutyrate-co-3-hydroxypropionate and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (poly-3HB-co-3HV).

[0024] According to one embodiment, the poly(3-hydroxyalkanoate) contains the 3-hydroxypropionate unit and at least one of the α,β unsaturated carboxylic acids produced is acrylic acid.

[0025] According to one embodiment, the poly(3-hydroxyalkanoate) contains the 3-hydroxybutyrate unit and at least one of the α,β unsaturated carboxylic acids produced is crotonic acid.

[0026] According to one embodiment, the poly(3-hydroxyalkanoate) contains the 3-hydroxyisobutyrate unit and at least one of the α,β unsaturated carboxylic acids produced is methacrylic acid.

[0027] According to one embodiment, the host of the biomass is a bacterium, yeast, fungus, alga, cyanobacterium, or a mixture of two or more of the elements mentioned.

[0028] According to one embodiment, biomass is subjected to a thermolysis reaction, which occurs in the presence of one or more polymerization inhibitors.

[0029] According to one embodiment, the biomass is thoroughly mixed with one or more polymerization inhibitors prior to thermolysis.

[0030] According to one embodiment, the method according to the invention includes a condensation step of the vapors of the α,β unsaturated carboxylic acid(s) obtained by the thermolysis reaction of the biomass, followed by one or more purification steps. In general, the purification operations may include distillations, liquid / liquid extractions, separations using a film evaporator, or crystallizations.

[0031] According to one embodiment, the method according to the invention includes a treatment step for said residue obtained Petition 870250084480, dated 09 / 19 / 2025, page 14 / 43 8 / 22 at the end of thermolysis, for example by converting this residue into methane through hydrothermal gasification.

[0032] The present invention meets the need indicated in the prior art. It makes it possible to avoid the risks of clogging of the thermolysis reactor and the gas phase in case of accidental condensation, and makes it possible to obtain a gas phase rich in one or more α,β unsaturated carboxylic acids that also contains polymerization inhibitors and a solid residue that can be recovered.

[0033] This solution has two advantages: it avoids solvent distillation, which consumes a lot of energy, and thermolysis is carried out on the P3HA contained in the biomass, in the solid state and not in solution, reducing the environmental and energy cost of the method.

[0034] The invention will now be explained in more detail in the description below. Detailed description of the invention

[0035] The objective of the invention is to produce α,β unsaturated carboxylic acids of biological origin on an industrial scale by means of thermolysis of poly(3-hydroxyalkanoates) contained in biomass, limiting the problems of clogging of the thermolysis reactor and / or the presence of impurities in the final product.

[0036] The term “thermolysis” of poly(3-hydroxyalkanoate) (P3HA) means its chemical decomposition into α,β unsaturated carboxylic acid that occurs under the effects of temperature. This term is synonymous with pyrolysis.

[0037] The present invention relates to a method for manufacturing α,β unsaturated carboxylic acids of biological origin from a biomass containing poly(3-hydroxyalkanoate) (P3HA) in the absence of a catalyst, said method comprising the following steps: - mix the aforementioned biomass with at least one inhibitor Petition 870250084480, dated 09 / 19 / 2025, page 15 / 43 9 / 22 of polymerization, in the solid state; - subjecting the aforementioned biomass-inhibitor mixture to a thermolysis step leading to obtaining, on the one hand, the aforementioned α,β unsaturated carboxylic acid in the vapor phase and, on the other hand, a solid residue; - to separate the two phases formed into a gaseous phase and a solid phase; - to purify the aforementioned gaseous phase to obtain a purified α,β unsaturated carboxylic acid; - treat the waste in its solid phase.

[0038] According to one embodiment, the aforementioned method for manufacturing α,β unsaturated carboxylic acids of biological origin from a biomass containing poly(3-hydroxyalkanoate) (P3HA) includes the following steps: - introduction of biomass (in powder form) and at least one polymerization inhibitor into a mixer (in solid phase) using a tube or a screw conveyor; - Mixing biomass and at least one polymerization inhibitor in a mixer-conveyor with several screw conveyors driven in a sheath or directly in a reactor known as a thermolysis reactor; - thermolysis of this mixture at a specific temperature and under controlled pressure in a system designed to treat the molten or pasty residue and generate a vapor phase and a pasty and / or solid phase; - separation of the two phases formed in a gas-liquid separator; - treatment of waste for valorization through spreading, combustion or hydrothermal gasification; - Condensation of the gas phase is achieved by successively adjusting the condensation temperature, positioning one or more Petition 870250084480, dated 09 / 19 / 2025, page 16 / 43 10 / 22 condensers in series, and separation of the resulting gaseous and liquid phases containing α,β unsaturated carboxylic acid and contaminants, which can be recycled back to the reactor or sent to the purification system; - treatment of the condensed phase to obtain the α,β unsaturated carboxylic acid using one or more distillation columns that allow, on the one hand, separating the α,β unsaturated carboxylic acid from products heavier than itself and, on the other hand, obtaining the lighter products; - purification of α,β unsaturated carboxylic acid obtained by a solid / liquid separation method such as crystallization, or by a gas / liquid separation method such as distillation.

[0039] The invention is based on the use of a biomass mixture containing a P3HA and at least one polymerization inhibitor using a solids mixing technology and the heat treatment of this mixture.

[0040] The term “biomass” means organic matter of plant (including microalgae), animal, bacterial or fungal origin that is viable as a source of biological raw materials, as opposed to fossil raw materials.

[0041] In the method according to the invention, the first step uses the biomass of a genetically modified host obtained by genetic engineering. According to one embodiment, the host biomass is a bacterium, yeast, fungus, alga, cyanobacterium, or a mixture of two or more of these elements.

[0042] Biomass is obtained by a preliminary culturing step of a recombinant host with a renewable feedstock. According to one embodiment, the renewable feedstock is selected from glucose, fructose, sucrose, arabinose, maltose, lactose, xylose, ethanol, methanol, glycerol, fatty acids, vegetable oils, and synthetic gas. Petition 870250084480, dated 09 / 19 / 2025, page 17 / 43 11 / 22 derived from biomass or a combination of those mentioned.

[0043] According to one embodiment, the biomass used in the method according to the invention comes from a bacterial fermentation process of sugars or lipids.

[0044] Depending on the culture conditions and the variety of microorganism used, homo- or copolymers of poly(3-hydroxyalkanoate) (P3HA) with different 3-hydroxyalkanoic acids are formed.

[0045] The method according to the invention advantageously comprises a prior biomass preparation step, in which the biomass is treated by washing, drying and grinding operations to provide a solid biomass (e.g., a powder) containing at least 30% by weight of P3HA, preferably at least 50% by weight of P3HA.

[0046] The biomass is then mixed with at least one polymerization inhibitor chosen from among the inhibitors conventionally employed in existing industrial methods for the production of α,β unsaturated carboxylic acids. These include phenolic derivatives such as hydroquinone (HQ) and its derivatives, such as hydroquinone methyl ether (EMHQ), 2,6-di-tert-butyl-4-methylphenol (BHT) or 2,4-dimethyl-6-tert-butylphenol (Topanol A); phenothiazines and their derivatives; nitroxide compounds such as 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-OH-TEMPO); and amine compounds with paraphenylenediamine derivatives.

[0047] According to a preferred embodiment, at least one of the aforementioned polymerization inhibitors is hydroquinone methyl ether (HME).

[0048] According to one embodiment, the percentage of the inhibitor, by weight, in the mixture is between 0.1% and 10%, preferably from 1% to 5%. Petition 870250084480, dated 09 / 19 / 2025, page 18 / 43 12 / 22

[0049] According to one embodiment, the mixing and thermolysis steps are performed continuously.

[0050] The mixture of biomass and at least one polymerization inhibitor is then subjected to thermolysis in the solid or partially molten state.

[0051] The thermolysis of the biomass-inhibitor mixture is carried out under temperature and pressure conditions that allow the chemical decomposition of P3HA and the generation of one or more α,β unsaturated carboxylic acids in the gaseous state.

[0052] According to one embodiment, the biomass feeding system and at least one polymerization inhibitor may be a tube, a screw conveyor, a conveyor belt or a hopper, a pneumatic conveyor, a vibratory conveyor or an extruder. Additionally, they may be coupled to a dosing device.

[0053] The system according to the invention for heating the biomass-inhibitor mixture also includes a reactor suitable for heating directed towards the thermolysis of P3HA. For example, heating can be carried out by exposing the mixture to microwaves, pulsed electric fields or previously heated water vapor or inert gas, by means of a preheated solid such as preheated sand, by contact with a hot surface such as in an extruder, a screw conveyor, a rotating drum or a platform. The hot surface can be heated in various ways: direct electric heating, heating by heat transfer fluid (steam, oil, molten salts).

[0054] According to one embodiment, the heat supply is made through a hot surface heated with a heat transfer fluid, in particular pressurized water vapor.

[0055] The reactor can be a carrier, but still any Petition 870250084480, dated 09 / 19 / 2025, page 19 / 43 13 / 22 type of dryer known to the technician in the subject described, for example, at the address: https: / / www.technique-ingenieur.fr / base-documentaire / 42665210production-des-medicaments- industrialisation / download / j2455 / sechage-industriel.html

[0056] According to one embodiment, the said reactor is a reactor suitable for pyrolysis, for high-temperature pyrolysis, or a fluidized reactor, or a reactor suitable for solvolysis, or even a reactor composed of hollow plates heated by a heat transfer fluid circulating in the plates. However, reactors have been identified that provide a higher yield of acrylic acid, such as: a conveyor, a rotating drum, and / or a set of heated plates.

[0057] According to one embodiment, the said reactor is a mixer-conveyor type device, for example a paddle dryer. This device includes a reactor with rotating propellers or paddles. The propeller allows mixing and homogenization of the biomass and polymerization inhibitor feeds. This mixer-conveyor also has the advantage of enabling the treatment of a large quantity of mixture. This also allows good heat transfer between the wall and the mixture. This device is normally used at moderate temperatures to dry solids; however, within the scope of the invention, by increasing the temperature, it is possible to perform thermolysis.

[0058] According to one embodiment, the said reactor is a mixer-conveyor type device, for example, a screw conveyor type. This device includes a reactor with two opposing screw conveyors in operation. The mixture is heated by the hot wall using a heat transfer fluid, such as steam. The movement of the two screws allows mixing and homogenization. Petition 870250084480, dated 09 / 19 / 2025, page 20 / 43 14 / 22 to allow the arrival of biomass and the polymerization inhibitor and subsequently, by increasing the temperature, carry out thermolysis.

[0059] According to one embodiment, the temperature in the thermolysis reactor is between 100°C and 250°C, preferably between 150°C and 200°C, to allow the thermolysis of P3HA. This temperature can also be controlled by temperature sensors located in the mixer. Moderate heating allows liquefaction of all or part of the mixture, while preventing polymerization of the α,β unsaturated carboxylic acid.

[0060] According to one embodiment, the pressure in the thermolysis reactor is between 3 kPa and 101 kPa, preferably between 15 kPa and 40 kPa.

[0061] According to one embodiment, the residence time in the thermolysis reactor is between 0.5 h and 5 h, preferably between 2 and 4 h.

[0062] The mixing of biomass and inhibitor, and the thermolysis reaction, can be carried out consecutively or simultaneously.

[0063] In the thermolysis reactor, the biomass-inhibitor mixture, under the action of heat, is converted into gaseous compounds containing one or more α,β unsaturated carboxylic acids.

[0064] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass contains a single type of 3-hydroxyalkanoate units and, therefore, the product formed is composed of a single α,β unsaturated carboxylic acid.

[0065] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass is poly(3-hydroxypropionate) and the α,β unsaturated carboxylic acid produced is acrylic acid.

[0066] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass is poly(3-hydroxybutyrate) and the α,β unsaturated carboxylic acid produced is crotonic acid. Petition 870250084480, dated 09 / 19 / 2025, page 21 / 43 15 / 22

[0067] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass is poly(3-hydroxyisobutyrate) and the α,β unsaturated carboxylic acid produced is methacrylic acid.

[0068] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass comprises a plurality of different 3-hydroxyalkanoate units and the product formed is therefore composed of a mixture of different α,β unsaturated carboxylic acids. Examples of P3HA copolymers include poly-3-hydroxybutyrate-co-3-hydroxypropionate and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (poly-3-HB-co-3HV).

[0069] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass contains the 3-hydroxypropionate unit and at least one of the α,β unsaturated carboxylic acids produced is acrylic acid.

[0070] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass contains the 3-hydroxybutyrate unit and at least one of the α,β unsaturated carboxylic acids produced is crotonic acid.

[0071] According to one embodiment, the poly(3-hydroxyalkanoate) contained in the biomass contains the 3-hydroxyisobutyrate unit and at least one of the α,β unsaturated carboxylic acids produced is methacrylic acid.

[0072] According to one embodiment, the method according to the invention allows the manufacture of various organic α,β unsaturated carboxylic acids from the poly(3-hydroxyalkanoates) contained in biomass.

[0073] Gases containing the α,β unsaturated carboxylic acid(s) can be sent to a cooling system for condensation. The resulting condensate can then be collected in a chamber designed for this purpose. Preferably the cabinet of the Petition 870250084480, dated 09 / 19 / 2025, page 22 / 43 16 / 22 tor and the chamber are under reduced pressure. The condensation system may be equipped with the injection of one or more inhibitors. To allow the recovery of one or more purified α,β unsaturated carboxylic acids, the system may have a purification device, for example one or more distillation columns, one or more liquid extraction, crystallization or membrane separation equipment.

[0074] The solid waste is then recovered, for example, by hydrothermal gasification or in the form of energy by combustion.

[0075] According to one embodiment, condensation is carried out by a successive adjustment of the pressure and by the separation of the resulting gaseous and liquid phases containing the α,β unsaturated carboxylic acid and contaminants that can be recycled back to the reactor.

[0076] According to the invention, condensation is carried out by a successive adjustment of the condensation temperature, done by placing one or more tubular or spiral condensers in series, and by separating the resulting gaseous and liquid phases containing the α,β unsaturated carboxylic acid and contaminants that can be recycled back to the reactor or sent to the purification system.

[0077] According to one embodiment, one or more polymerization inhibitors are added to the condenser.

[0078] According to one embodiment, the inhibitor is not added to the capacitor.

[0079] According to one embodiment, this condensation can be carried out by placing the α,β unsaturated carboxylic acid in the gaseous state in contact with one or more α,β unsaturated carboxylic acids in the liquid state. This contact operation can be carried out, for example, in a shower-type device, by spraying one or more liquid α,β unsaturated carboxylic acids into a chamber that collects Petition 870250084480, dated 09 / 19 / 2025, page 23 / 43 17 / 22 ta the α,β unsaturated carboxylic acids in the gaseous state.

[0080] According to one embodiment, condensation of the gas phase is carried out by a system of at least one tubular condenser type condenser at the thermolysis pressure, cooling the gas phase and collecting the resulting liquid phase in an agitated storage tank, optionally with the addition of one or more other inhibitors.

[0081] According to one embodiment, the aforementioned products heavier than the α,β unsaturated carboxylic acid are recycled upstream of the thermolysis reactor, or are mixed with the solid residue resulting from the thermolysis.

[0082] According to one embodiment, the aforementioned products lighter than the α,β unsaturated carboxylic acid are valued by combustion or gasification.

[0083] According to one embodiment, the residue obtained after the thermolysis step is valorized by hydrothermal gasification.

[0084] According to the method, hydrothermal gasification is carried out at a temperature of 350°C-450°C and at a pressure of 25 MPa.

[0085] According to one embodiment, the obtained α,β unsaturated carboxylic acid is purified by a fractional crystallization operation with several separation stages to obtain a high-purity α,β unsaturated carboxylic acid and a residue for energetic valorization.

[0086] The examples below illustrate the present invention without, however, limiting its scope. EXPERIMENTAL SECTION

[0087] Example 1: The objective of this laboratory-scale experiment is to observe the consistency of the residue after a thermolysis operation to determine if it can be handled after exiting the thermolysis reactor.

[0088] Examples 1 to 4 are performed on biomass containing Petition 870250084480, dated 09 / 19 / 2025, page 24 / 43 18 / 22 60% by weight of P3HP. The α,β unsaturated carboxylic acid obtained after thermolysis is acrylic acid (AA).

[0089] The mixing step of the biomass containing P3HP with the inhibitor is carried out by introducing 2 g of this biomass and 0 or 20 mg of EMHQ into a 50 ml two-necked flask equipped with a magnetic stir bar. The medium is stirred with a magnetic stirrer, distributing the inhibitor in the solid.

[0090] At the beginning of the experiment, the system is placed at the desired pressure, and the flask containing the biomass is placed in a heating system that allows the desired thermolysis temperature to be established (oil bath or electric heating mantle).

[0091] As soon as the thermolysis reactor exceeds 170°C, the formation of AA vapors is observed, which condense predominantly in the side condenser. After 4 hours of heating, the formation of AA vapors in the thermolysis reactor decreases and the experiment is stopped. The state of clogging and the consistency of the thermolysis residue are visually evaluated at the end of the experiment.

[0092] It is observed that the addition of the inhibitor allows a fairly hard solid to be transformed into a pasty and sticky solid which may be of value in the invention.

[0093] The operating conditions for tests 1 to 4 are presented in Table 1. [Table 1] Test Inhibitor Operating Pressure (kPa) Thermolysis Residue 1 EMHQ 100 Solid, viscous paste 2 EMHQ 55 Solid, viscous paste 3 EMHQ 20 Solid, viscous paste 4 SEM 100 Solid, sticky, very hard

[0094] The results in Table 1 demonstrate that the physical state of the residue depends on the presence of the inhibitor. The addition of the inhibitor perPetição 870250084480, dated 19 / 09 / 2025, p. 25 / 43 19 / 22 The residue becomes pasty and viscous, whereas, without the addition of inhibitor, it was quite hard and sticky. This change in the consistency of the residue allows for simpler extraction when continuous thermolysis is performed. Thermogravimetric Analysis Test

[0095] This test aims to provide information regarding the operating conditions necessary to perform the thermolysis of P3HA contained in biomass. For a better assessment of the degree of thermolysis, the test was performed with P3HP extracted from biomass.

[0096] 10 g of pure P3HP were subjected to thermogravimetric analysis. Thermogravimetric analysis is a technique that consists of measuring the mass variation of a sample as a function of time, for a given temperature. For this purpose, for each temperature condition, 1 g of P3HP is placed on the balance of the apparatus under a nitrogen flow, noting the weight loss over time. It was found that the mass loss became significant and rapid at temperatures equal to or above 170°C.

[0097] From the point of view of thermolysis, the least severe operating conditions would be: a temperature of 180°C for a residence time of 3 hours, to obtain a degree of cracking above 95%. Table 2 indicates the temperature conditions and the time required to obtain different degrees of cracking, from 10% up to complete cracking. [Table 2] Time required for: T 10% cracking 50% cracking Complete cracking (>95%) 120°C >24 h >24 h >24 h 130°C 14 h >24 h >24 h 140°C 6 h 24 h >24 h 150°C 2 h 8 h 15 h Petition 870250084480, dated 09 / 19 / 2025, page 26 / 43 20 / 22 Time required for: T 10% cracking 50% cracking Complete cracking (>95%) 160°C 1 h 30 min 6 h 10 h 170°C 1 h 4 h 8 h 180°C 45 min 2 h 3 h 190°C 30 min 1 h 15 min 1 h 45 min 200°C <30 min 45 min 1 h 210°C <30 min 40 min 50 min 220°C <30 min 35 min 40 min

[0098] The thermolysis reaction temperature of around 180°C in the method according to the invention is significantly lower than the temperature of example 1 of document WO 2016 / 039618.

[0099] The tests in Examples 5 to 7 below are performed in a laboratory.

[00100] A two-necked flask equipped with magnetic stirring was used. The side mouth of the flask is fitted with a thermometer to monitor the reaction temperature. The top mouth of the flask is fitted with a separating bridge leading to a water-cooled side condenser, which itself leads to a collector consisting of a second 50 ml flask. An additional line allows the assembly to be placed under reduced pressure using a diaphragm vacuum pump. EXAMPLE 5 (comparative): Use of biomass containing 60% P3HP without the addition of an inhibitor and without a catalyst.

[00101] 2.02 g of biomass containing 60% P3HP are placed in a 25 ml two-necked flask equipped with magnetic stirring. The flask, equipped with a separating bridge, is placed at a pressure of 20 kPa using a diaphragm vacuum pump. The flask is heated to 200°C for 4 h. The vapors generated are condensed using a water-cooled side condenser to obtain 1.06 g of acrylic acid, which is equivalent to a yield of 87%. The solid obtained Petition 870250084480, dated 09 / 19 / 2025, page 27 / 43 21 / 22 after cracking remains stuck to the walls of the bineck flask. It is very difficult to remove it from the bineck flask. Solid particles are found at the top of the flask and in the side condenser. EXAMPLE 6 (according to the invention): Use of biomass containing 60% P3HP with the addition of 1% 4-methoxyphenol (EMHQ) without a catalyst.

[00102] 2.11 g of biomass containing 60% P3HP are placed in a 25 ml two-necked flask equipped with magnetic stirring. 0.021 g of EMHQ are added to the flask and mixed with the biomass. The flask, equipped with a separating bridge, is placed at a pressure of 20 kPa using a diaphragm vacuum pump. The flask is heated to 200°C for 4 h. The generated vapors are condensed using a water-cooled side condenser to obtain 1.21 g of acrylic acid, which is equivalent to a 95% yield. The solid obtained after cracking remains compact and easily detaches from the walls of the two-necked flask. This solid breaks easily with a spatula. EXAMPLE 7 (according to the invention): Use of biomass containing 60% P3HP with the addition of 5% 4-methoxyphenol (EMHQ)

[00103] 2.19 g of biomass containing 60% P3HP are placed in a 25 ml two-necked flask equipped with magnetic stirring. 0.117 g of EMHQ are added to the flask and mixed with the biomass. The flask, equipped with a separating bridge, is placed at a pressure of 20 kPa using a diaphragm vacuum pump. The flask is heated to 200°C for 4 h. The generated vapors are condensed using a water-cooled side condenser to obtain 1.27 g of acrylic acid, which is equivalent to a 96% yield. The solid obtained after cracking remains compact and easily detaches from the walls of the two-necked flask, being easily broken with a spatula. Petition 870250084480, dated 09 / 19 / 2025, page 28 / 43 22 / 22

[00104] The results of examples 6 and 7 show that, when the method according to the invention is carried out (in the presence of an inhibitor and without a catalyst), the yield of acrylic acid reaches 95%, higher than that obtained in comparative example 5. Furthermore, the presence of the inhibitor allows for easy removal of the residue.

Claims

1. Method for manufacturing an α,β unsaturated carboxylic acid of biological origin from biomass containing a poly(3-hydroxyalkanoate) (P3HA) and in the absence of a catalyst, characterized in that it comprises the following steps: - mixing said biomass with at least one polymerization inhibitor, in the solid state; - subjecting said biomass-inhibitor mixture to a thermolysis step leading to obtaining, on the one hand, said α,β unsaturated carboxylic acid in the vapor phase and, on the other hand, a solid residue; - separating the two phases formed into a gaseous phase and a solid phase; - purifying said gaseous phase to obtain a purified α,β unsaturated carboxylic acid; - treating the residue in the solid phase.

2. Method, according to claim 1, characterized in that it comprises the following steps: - introducing biomass (in powder form) and at least one polymerization inhibitor into a mixer (in solid phase) using a tube or a screw conveyor; - mixing the biomass and at least one polymerization inhibitor in a mixer-conveyor with several screws driven in a sheath or directly in a reactor known as a thermolysis reactor; - thermolysis of this mixture at a given temperature and under controlled pressure in a system suitable for treating the molten or pasty residue, to generate a vapor phase and a pasty and / or solid phase; - separating the two phases formed in a gas-liquid separator; Petition 870250084480, dated 19 / 09 / 2025, p.30 / 43 2 / 4 - treat the residue, thus valorizing it, by means of spreading, combustion or hydrothermal gasification; - condense the gaseous phase, by a successive adjustment of the condensation temperature, positioning one or more condensers in series, and separate the gaseous and liquid phases obtained containing α,β unsaturated carboxylic acid and contaminants, which can be recycled back to the reactor or sent to the purification system; - treat the condensed phase to obtain the α,β unsaturated carboxylic acid using one or more distillation columns that allow, on the one hand, separating the α,β unsaturated carboxylic acid from products heavier than it and, on the other hand, obtaining products lighter than it; - To purify the α,β unsaturated carboxylic acid obtained by a solid / liquid separation method such as crystallization, or by a gas / liquid separation method such as distillation.

3. Method, according to claim 1 or 2, characterized in that the biomass used is previously treated by washing, drying and shredding operations to provide a biomass with at least 30% by weight of P3HA, preferably at least 50% by weight of P3HA.

4. A method according to any one of claims 1 to 3, characterized in that the poly(3-hydroxyalkanoate) contains the 3-hydroxypropionate unit and at least one of the α,β unsaturated carboxylic acids produced is acrylic acid.

5. Method according to any one of claims 1 to 3, characterized in that the poly(3-hydroxyalkanoate) is poly(3-hydroxypropionate) and the α,β unsaturated carboxylic acid produced is acrylic acid.

6. Method, according to any of the claims Petition 870250084480, dated 09 / 19 / 2025, page 31 / 43 3 / 4 1 to 3, characterized in that the poly(3-hydroxyalkanoate) contains the 3-hydroxybutyrate unit and at least one of the α,β unsaturated carboxylic acids produced is crotonic acid.

7. Method according to any one of claims 1 to 3, characterized in that the poly(3-hydroxyalkanoate) is poly(3-hydroxybutyrate) and the α,β unsaturated carboxylic acid produced is crotonic acid.

8. A method according to any one of claims 1 to 3, characterized in that the poly(3-hydroxyalkanoate) contains the 3-hydroxyisobutyrate unit and at least one of the α,β unsaturated carboxylic acids produced is methacrylic acid.

9. Method, according to any one of claims 1 to 3, characterized in that the poly(3-hydroxyalkanoate) is poly(3-hydroxyisobutyrate) and the α,β unsaturated carboxylic acid produced is methacrylic acid.

10. A method according to any of the preceding claims, characterized in that the polymerization inhibitor(s) are compounds chosen from phenolic derivatives, phenothiazine derivatives, nitroxide derivatives, or paraphenylenediamine derivatives.

11. A method, according to any of the preceding claims, characterized in that at least one of the aforementioned polymerization inhibitors is hydroquinone methyl ether.

12. A method, according to any of the preceding claims, characterized in that the thermolysis reactor is chosen from among: a conveyor, a mixer-conveyor, a dryer, a rotary drum and / or a set of heating plates.

13. Method, according to any of the preceding claims, characterized in that the thermolysis reaction is carried out at a temperature between 150°C and 200°C.

14. A method, according to any of the preceding claims, characterized in that the thermolysis reaction is carried out for two to four hours.

15. A method, according to any of the preceding claims, characterized in that the thermolysis reaction is carried out at a pressure between 15 kPa and 40 kPa.

16. Method according to claim 12, characterized in that the thermolysis reactor is a mixer-conveyor type device, for example, a propeller dryer.

17. Method according to claim 12, characterized in that the thermolysis reactor is a device composed of hollow plates heated by a heat transfer fluid circuit.

18. Method according to claim 12, characterized in that the thermolysis reactor is a screw conveyor.

19. Method according to claim 12, characterized in that the mixing of the biomass and the inhibitor and the thermolysis can be carried out consecutively or simultaneously.