Conversion of a biomass-derived hydrocarbon feedstock into acrylate salts

Abstract

The invention concerns a method and a plant for converting biomass into acrylate salts. The method successively involves: a) a step of treating the biomass to produce ethanol and CO2; b) a step of dehydrating the ethanol obtained at the end of step a) to obtain ethylene; c) a step of synthesizing acrylate salts from the ethylene obtained at the end of step b) and from the CO2 obtained at the end of step a).

Description

[0001] CONVERSION OF A HYDROCARBON FEED FROM BIOMASS INTO ACRYLATE SALTS

[0002] Technical field

[0003] The invention relates to a method for processing biomass, preferably lignocellulosic biomass, to produce acrylate salts from a single bio-based carbon source while maximizing carbon yield.

[0004] The process of fermentation of lignocellulosic biomass makes it possible to produce ethanol and CO2 which can be advantageously converted, compared to the prior art, into acrylate salts.

[0005] State of the art

[0006] Acrylate salts are derivatives of acrylic acid and are used, among other things, with acrylic acid to produce superadsorbent polymers. It is known to those skilled in the art that it is possible to synthesize acrylate salts from acrylic acid by the addition of a base, just as it is possible to synthesize acrylic acid from acrylate salts by the addition of an acid.

[0007] Currently, acrylic acid is produced industrially at high temperatures via the oxidation of propylene in the presence of a heterogeneous catalyst. However, the relatively high price of propylene has a strong impact on the price of acrylic acid and several synthetic routes for acrylic acid have been developed, notably from carbon monoxide. Patent US3023237 relates to the Reppe process for synthesizing acrylic acid from acetylene and carbon monoxide. Even though this process has been implemented industrially, the synthesis of acrylic acid via the oxidation of propylene remains more economically profitable.

[0008] Another alternative being explored is the synthesis of acrylic acid or its derivatives from carbon dioxide (CO2). CO2 has the advantage of being inexpensive, and recovering CO2 in the form of high-value-added products is an attractive approach to reducing its environmental impact. Application US2016 / 016876 discloses a process for manufacturing acrylic acid using ethylene oxide and carbon monoxide via the formation of propiolactone. In some embodiments, the propiolactone formation step is carried out in the presence of ethylene oxide and CO2.

[0009] In another approach, application US2018 / 057439 proposes to use CO2 as a precursor of carbon monoxide in the Reppe process cited above. Finally, another alternative is to use CO2 directly without going through reduction to carbon monoxide. There are numerous documents relating to the synthesis of carboxylic acids or carboxylate salts from CO2 and olefins, in particular ethylene. Examples include documents WO2019 / 053541, WO2019 / 053540, WO2015173296, CN 104418737 or CN 105622400.

[0010] Ethylene can be produced from fossil resources through a steam cracking process but also through the dehydration of bioethanol. It is well known that bioethanol can be produced by fermenting sugars from various biomasses. However, fermentations to produce ethanol generally do not have good "carbon" yields because part of it is lost in the form of CO2. In addition, ethanol produced from so-called 1st generation (1G) biomass competes with the agri-food industry and losing a large part of this resource in the form of a greenhouse gas is even more problematic.

[0011] Finally, there are also other ways to synthesize acrylic acid from lignocellulosic biomass, including lactic acid synthesis. Unlike the previous pathways, these pathways do not use CO2 or ethylene. The step of converting biomass to lactic acid generally does not produce CO2, but the step of dehydrating lactic acid to acrylic acid is far from trivial.

[0012] The invention aims to overcome all of the drawbacks mentioned above. More specifically, the invention aims to develop a process for treating biomass, preferably a so-called second-generation (2G) lignocellulosic biomass, to produce acrylate salts from ethanol and CO2 resulting from fermentation.

[0013] Objects of the invention

[0014] In the context described above, a first object of the present description is to overcome the problems of the prior art and to valorize carbon, and in particular biosourced carbon in CO2 form into high added value compounds, and in particular into acrylate salts. Specifically, the present invention relates to a process for producing acrylate salts according to an arrangement of steps, making it possible to convert biomass into ethanol and CO2 and then to convert these products into acrylate salts, using one or more of the following steps in addition to or as a replacement for certain steps of conventional syntheses of acrylate salts.

[0015] According to a first aspect, the present invention relates to a process for converting biomass into acrylate salts comprising successively: a) a step of treating the biomass to produce ethanol and carbon dioxide; b) a step of dehydrating the ethanol obtained at the end of step a) to obtain ethylene; c) a step of synthesizing acrylate salts from the ethylene obtained at the end of step b) and the carbon dioxide obtained at the end of step a) in the presence of a catalytic precursor and a solvent.

[0016] The invention is based on the recovery of CO2 which is a by-product formed during the fermentation stage of biomass into ethanol and possibly the reuse of the water produced during the dehydration stage in the other stages of the process according to the invention. This invention therefore presents a sequence of unit operations used to maximize the carbon yield of the synthesis of acrylate salts from biomass, preferably a lignocellulosic biomass, and even more preferably a so-called second generation (2G) lignocellulosic biomass.

[0017] According to one or more embodiments, step a) comprises the following sub-steps: a1) a step of pretreatment of the biomass to obtain a pretreated substrate; a2) a step of enzymatic or chemical hydrolysis of the pretreated substrate obtained at the end of step a1) to obtain an enzymatic or chemical hydrolysis must; a3) a step of alcoholic fermentation of the enzymatic or chemical hydrolysis must obtained at the end of step a2) to obtain ethanol and carbon dioxide.

[0018] According to one or more embodiments, sub-step a1) is carried out by steam explosion in acid conditions at a temperature between 150°C and 250°C and for a duration between 5 minutes and 30 minutes.

[0019] According to one or more embodiments, sub-step a2) is carried out by enzymatic hydrolysis in the presence of Trichoderma reesei cellulases.

[0020] According to one or more embodiments, when step a2) is an enzymatic hydrolysis, steps a2) and a3) are carried out simultaneously.

[0021] According to one or more embodiments, step b) comprises the following sub-steps: b1) a step of vaporizing a vaporization feed comprising the ethanol obtained at the end of step a) in a heat exchanger, said vaporization feed being introduced into said vaporization step at a pressure of between 0.1 MPa and 2.5 MPa so as to produce a vaporized feed; b2) a step of superheating said vaporized feed obtained at the end of step b1) so as to bring said vaporized feed to an inlet temperature compatible with the temperature of the dehydration reaction; b3) a step of dehydration of said feedstock from step b2) in at least one adiabatic reactor containing at least one dehydration catalyst and in which the dehydration reaction takes place, operating at an inlet temperature of between 350°C and 550°C and at an inlet pressure of between 0.3 MPa and 1.8 MPa.

[0022] According to one or more embodiments, step c) is carried out at a temperature between 105°C and 170°C, and at a pressure between 1 MPa and 10 MPa.

[0023] According to one or more embodiments, step c) is carried out in the presence of a base chosen from secondary or tertiary alcohol alkanolates.

[0024] According to one or more embodiments, step c) is carried out in the presence of a catalytic precursor based on a metal complex of a transition metal chosen from nickel (0) and palladium (0) complexes.

[0025] According to one or more embodiments, step c) is carried out in the presence of a solvent chosen from anisole, cyclohexylpyrrolidone, N,N-dibutylformamide and dimethylacetamide.

[0026] According to one or more embodiments, said method further comprises a step d) of liquid-liquid separation of the acrylate salt in the presence of a counter-solvent, immiscible with the solvent used in step c).

[0027] According to one or more embodiments, said counter-solvent is water resulting at least in part from step b) of dehydration of ethanol.

[0028] According to one or more embodiments, the biomass is a lignocellulosic biomass.

[0029] According to a second aspect, the present invention relates to an installation for the conversion of biomass into acrylate salts capable of implementing the method according to the invention, said installation comprising: - a first reaction section making it possible to produce ethanol and carbon dioxide from biomass;

[0030] - a second reaction section for dehydrating ethanol into ethylene; and

[0031] - a third reaction section for producing acrylate salts from ethylene and carbon dioxide.

[0032] List of figures

[0033] Figure 1 shows a schematic representation of one embodiment of the method and plant according to the present invention for producing acrylate salts from biomass, preferably lignocellulosic.

[0034] Description of the embodiments

[0035] Embodiments of the method according to the first aspect of the invention and of the installation according to the second aspect of the invention will now be described in detail. In the following detailed description, numerous specific details are set out in order to provide a more thorough understanding of the method and installation. However, it will be apparent to those skilled in the art that the method and installation can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0036] Definitions

[0037] In the present application, the term "comprise" is synonymous with (means the same as) "include" and "contain", and is inclusive or open and does not exclude other elements not recited. It is understood that the term "comprise" includes the exclusive and closed term "consist". Furthermore, in the present description, an effluent comprising essentially or solely compounds A corresponds to an effluent comprising at least 90% by weight, preferably at least 95% by weight, very preferably at least 99% by weight, of compounds A.

[0038] In this application, the groups of chemical elements are given by default according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII (or VI 11 B) according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification; group VI B according to the CAS classification corresponds to the metals of column 6 according to the new IUPAC classification. In the present application, biomass means any load produced biologically, preferably by fermentation of sugars from, for example, sugar plant crops such as sugar cane (sucrose, glucose, fructose, and sucrose), beets, or even starchy plants (starch) or lignocellulosic biomass or hydrolyzed cellulose (mainly glucose and xylose, galactose), containing variable quantities of water.Preferably, the biomass is a lignocellulosic biomass, and even more preferably a so-called second generation (2G) lignocellulosic biomass.

[0039] Detailed description

[0040] The present invention can be defined as a process comprising a sequence of reaction steps for producing acrylate salts from biomass, preferably lignocellulosic biomass, and even more preferably second-generation (2G) lignocellulosic biomass. More particularly, the present invention relates to a process for converting biomass into acrylate salts successively comprising: a) a step of treating the biomass, preferably lignocellulosic biomass, to produce ethanol and carbon dioxide (CO2); b) a step of dehydrating the ethanol obtained at the end of step a) to obtain ethylene; c) a step of synthesizing acrylate salts from the ethylene obtained at the end of step b) and the CO2 obtained at the end of step a).

[0041] Furthermore, the present invention can also be defined as an installation capable of implementing the method according to the invention, as illustrated in Figure 1, said installation comprising in particular:

[0042] - a first reaction section 2 for producing ethanol 3 and CO2 4 from biomass 1;

[0043] - a second reaction section 5 for dehydrating ethanol 3 into ethylene 6; and

[0044] - a third reaction section 7 for producing acrylate salts 8 from ethylene 6 and CO2 4.

[0045] First reaction section (é of the process according to the i

[0046] The first reaction section 2 makes it possible to produce ethanol 3 and CO2 4 from biomass 1. In one embodiment according to the invention, the biomass used in the process is a lignocellulosic biomass, preferably a so-called second-generation lignocellulosic biomass. Hardwoods and cereal straws are the most commonly used substrates. They consist for the most part of approximately 40% to 50% cellulose, 20% to 25% hemicellulose and 15% to 25% lignin. Other resources, dedicated forest crops, residues from alcohol-producing, sugar and cereal plants, residues from the paper industry and products from the transformation of cellulosic and lignocellulosic materials are usable.

[0047] In one embodiment according to the invention, the process for transforming biomass into ethanol more particularly comprises the following sub-steps: a1) a step of pretreatment of the biomass, preferably lignocellulosic biomass, to obtain a pretreated substrate; a2) a step of enzymatic or chemical hydrolysis of the pretreated substrate obtained at the end of step a1) to obtain an enzymatic or chemical hydrolysis must; a3) a step of alcoholic fermentation of the enzymatic or chemical hydrolysis must obtained at the end of step a2) to obtain ethanol and CO2.

[0048] Pretreatment

[0049] The pretreatment step a1) allows the production of a pretreated substrate comprising the sugars contained in the hemicelluloses in the form of monomers, essentially pentoses, such as xylose and arabinose, and hexoses, such as galactose, mannose and glucose, and to improve the accessibility of the cellulose stuck in the matrix of lignin and hemicelluloses. Many technologies exist: acid cooking treatments, alkaline cooking treatments, steam explosion treatments, or organosolvent pulping treatments. The effectiveness of the pretreatment is measured by the recovery rate of hemicelluloses and by the susceptibility to hydrolysis of the cellulose residue. Acid pretreatments, under mild conditions, and by steam explosion are the most suitable because they allow total recovery of the pentoses and good accessibility of the cellulose to hydrolysis.

[0050] Preferably, the pretreatment step a1) is carried out by steam explosion under acidic conditions at a temperature advantageously between 150°C and 250°C and for a duration advantageously between 5 and 30 minutes. In this embodiment, step a1) makes it possible to transform the hemicelluloses into monomers while minimizing losses, particularly in furfural, xylose being the majority sugar. The released sugars are then extracted by washing in the aqueous phase. The solid residue (i.e. the pretreated substrate also called herein cellulose residue) obtained at the end of the extraction then contains only cellulose and lignin.

[0051] The pretreated substrate obtained at the end of step a1) is then hydrolyzed, either by acid means (i.e. by chemical means), or by enzymatic means with the use of cellulolytic and / or hemicellulolytic enzymes. Microorganisms, such as fungi belonging to the genera Trichoderma, Aspergillus, Penicillium or Schizophyllum, or anaerobic bacteria belonging for example to the genus Clostridium, produce these enzymes, containing in particular cellulases and xylanases, adapted to the total hydrolysis of the polymers constituting plants.

[0052] The acid route, carried out using strong acid, and more specifically sulfuric acid, is effective but requires large quantities of chemicals (acid then base for neutralization). Enzymatic hydrolysis does not have this disadvantage; it is also carried out under mild conditions and is effective.

[0053] Preferably, the pretreated substrate, whether or not freed from the hydrolyzed hemicellulosic fraction and, where appropriate, from the lignin, is hydrolyzed by the cellulolytic and / or hemicellulolytic enzymes produced by the specialized strains, the cellulases of Trichoderma reesei being the most effective and the most appropriate when the carbon substrates are derived from cellulosic or lignocellulosic biomass. The pretreated substrate to be hydrolyzed is preferably suspended in an aqueous phase at a rate of 6 to 25% of dry matter, preferably 10 to 20%, the pH is adjusted between 4 and 5.5, preferably between 4.8 and 5.2 and the temperature between 40 and 60°C, preferably between 45 and 50°C. The hydrolysis reaction is started by adding the cellulases; the amount usually used is 10 mg to 30 mg of excreted protein per gram of pretreated substrate.The reaction generally lasts from 15 hours to 48 hours depending on the effectiveness of the pretreatment, the composition of the cellulase mixture and the quantity of enzymes added. The reaction is monitored by measuring the released sugars, particularly glucose. The sugar solution (wort) is then separated from the non-hydrolyzed solid fraction, mainly lignin, by filtration or centrifugation; this must is used for ethanolic fermentation. When the cellulosic fraction has been freed from the hydrolyzed hemicelluloses during the treatment step, glucose is the majority sugar contained in the must.

[0054] Fermentation

[0055] Alcoholic fermentation is a biochemical process by which the sugars (carbohydrates, mainly glucose) contained in the must are transformed into alcohol, preferably ethanol, in a liquid, airless (anaerobic) medium. The stage of fermentation of sugars to obtain ethanol is well known to those skilled in the art.

[0056] Alcoholic fermentation preferably takes place at a temperature between 25°C and 32°C. For a more complete description of classic fermentation processes, please refer to the book 'Biofuels, State of play, perspectives and challenges of development, Daniel Ballerini, Editions Technip, 2006'.

[0057] In general, ethanol is separated from the fermentation must by distillation and the residue is made up of distillation vinasses. Regular or continuous distillation of ethanol is necessary because beyond 14% ethanol, certain yeasts can be "poisoned" and this leads to a loss of productivity. Distillation is carried out to obtain an ethanolic feedstock suitable for the dehydration process described later.

[0058] The CO2 is recovered in the form of gas at the outlet of the fermenter. According to an essential aspect of the invention, the CO2 obtained at the end of the fermentation step is sent at least in part to the step of synthesis of the acrylate salts (step c) of the process according to the invention). The CO2 can be compressed before storage or before its use using compressors.

[0059] The residue from ethanolic fermentation, after separation of ethanol, can be used as an inducing carbon source or as a main carbon source for enzyme production. The concentration of this residue is preferably adjusted to obtain the carbon source concentration best suited to the cellulolytic and / or hemicellulolytic enzyme production process.

[0060] The enzymatic hydrolysis and fermentation stages can be carried out simultaneously (SSF process for “Simultaneous Saccharification and Fermentation” in English terminology), then are advantageously followed by a distillation and separation stage of the alcohol obtained.

[0061] Second reaction section according to the i

[0062] The second reaction section 5 makes it possible to produce ethylene 6 from the ethanol 3 from the first reaction section 2 (see Figure 1).

[0063] The second reaction section makes it possible to dehydrate the ethanol obtained at the end of step a) of the process according to the invention to form ethylene. The dehydration of ethanol is a process known to those skilled in the art, but optimizations are possible to reduce the energy cost of the process as described in application US2013 / 190547. Advantageously, the ethanol feedstock used in step b) of the process according to the invention is a concentrated hydrated ethanol feedstock. Concentrated hydrated ethanol feedstock is understood to mean an ethanol feedstock comprising a mass percentage of ethanol greater than or equal to 35% by weight. Preferably, said concentrated ethanol feedstock comprises a mass percentage of ethanol of between 35% and 99.9% by weight relative to the total weight of the feedstock. Preferably, said concentrated ethanol feedstock comprises a mass percentage of ethanol of between 35% and 96% by weight relative to the total weight of the feedstock.Said concentrated ethanol feedstock also advantageously comprises, in addition to water, a content of alcohols other than ethanol, such as for example methanol, butanol and / or isopentanol, of less than 10% by weight, and preferably less than 5% by weight, a content of oxygenated compounds other than alcohols such as for example ethers, acids, ketones, aldehydes and / or esters advantageously less than 1% by weight, and a content of nitrogen and sulfur, organic and mineral, advantageously less than 0.5% by weight, the weight percentages being expressed relative to the total mass of said feedstock.

[0064] In one embodiment according to the invention, step b) comprises the following sub-steps: b1) a step of vaporizing a vaporization feedstock comprising ethanol obtained at the end of step a) in a heat exchanger, said vaporization feedstock being introduced into said vaporization step at a pressure of between 0.1 MPa and 2.5 MPa so as to produce a vaporized feedstock; b2) a step of superheating said vaporized feedstock obtained at the end of step b1) so as to bring it to an inlet temperature compatible with the temperature of the dehydration reaction; b3) a step of dehydration of said feedstock from step b2) in at least one adiabatic reactor containing at least one dehydration catalyst and in which the dehydration reaction takes place, operating at an inlet temperature of between 350°C and 550°C and at an inlet pressure of between 0.3 MPa and 1.8 MPa.

[0065] The ethanol feedstock used in step b) of the process according to the invention advantageously undergoes a pretreatment step prior to step b1) of vaporization of said feedstock. Said pretreatment step makes it possible to eliminate the impurities contained in said feedstock so as to limit the deactivation of the dehydration catalyst placed downstream, and in particular the compounds containing nitrogen and the compounds containing sulfur. The oxygenated compounds present in said feedstock are not substantially eliminated.

[0066] Said step of pretreatment of the ethanol feedstock is advantageously carried out by means known to those skilled in the art, such as the use of at least one resin, the adsorption of impurities on solids preferably at a temperature between 20°C and 60°C, a sequence comprising a first hydrogenolysis step operating at a temperature between 20°C and 80°C, followed by a capture step on an acidic solid at a temperature between 20°C and 80°C and / or distillation. In the case of the use of at least one resin, said resin is preferably acidic and is used at a high temperature between 70°C and 200°C. Said resin may optionally be preceded by a basic resin.

[0067] In the case where the pretreatment step is implemented by the adsorption of impurities on solids, said solids are advantageously chosen from molecular sieves, activated carbon, alumina and zeolites.

[0068] Said ethanol feed pretreatment step makes it possible to produce a purified ethanol cut in which the organic impurities have been eliminated, in order to obtain a purified feed meeting the level of impurities compatible with the dehydration catalyst. of the load (Step b1)

[0069] The vaporization feedstock is the feedstock comprising at least in part the ethanol, optionally pretreated, obtained at the end of step a) of the process according to the invention. Said vaporization feedstock also advantageously comprises a stream of water recycled according to recycling step b5) or a stream of water external to the process. In this case, the mass ratio of the water stream, whether recycled or external to the process, to the pretreated ethanol stream is advantageously between 1 and 4, with the aim of lowering the partial pressures of ethanol in the dehydration reactor(s) and making the process more selective for ethylene.

[0070] According to one embodiment of the invention, the method comprises a step b1) of vaporizing said vaporization charge so as to produce a vaporized charge. Said vaporization is carried out by means of a heat exchange in a heat exchanger with a heat source which may be a flow internal or external to the method, or by direct heating (for example in a furnace) or any other technique known to those skilled in the art.

[0071] Said vaporization charge is introduced into said vaporization step b1) at a pressure of between 0.1 MPa and 2.5 MPa and at an inlet temperature of between 350°C and 500°C.

[0072] In a preferred embodiment, said vaporized charge undergoes compression in a compression step so as to produce a compressed charge. Said compression step is advantageously implemented in any type of compressor known to those skilled in the art. In particular, the compression step is advantageously implemented in a compressor of the radial compressor type with integrated multiplier or in a compressor comprising one or more blowers with a radial wheel placed in series without intermediate cooling or in a volumetric type compressor with or without lubrication.

[0073] The optional compression step makes it possible to create a heat pump integrated into said process, using the flows from the process, by making it possible to vaporize the vaporization load from step b1) by heat exchange with the effluent from dehydration step b3).

[0074] In the case where the optional compression step is carried out, said vaporization charge is introduced into said vaporization step b1) at a pressure of between 0.1 MPa and 1.4 MPa, preferably between 0.2 MPa and 0.6 MPa.

[0075] The pressure of said compressed charge at the end of the optional compression step is advantageously between 0.3 MPa and 1.8 MPa, preferably between 0.5 MPa and 1.3 MPa. The outlet pressure of said charge is sufficiently high so that the condensation temperature of the effluent from the last reactor is higher than the vaporization temperature of the charge entering step b1), which is a necessary condition for the feasibility of step b1).

[0076] Step b2) of overheating

[0077] Said vaporized charge, possibly compressed, can be heated in a single-phase gas type exchanger, by means of a heat exchange with any flow internal or external to the process, preferably by means of a heat exchange with the effluent from the last adiabatic reactor of step b3). In said single-phase gas type exchanger, said charge, possibly compressed, is superheated. In the case where the heat exchange is carried out with the effluent from the last adiabatic reactor of step b3), in the gaseous state, the latter is "desuperheated" without being condensed.

[0078] In the case where the optional compression step is carried out, said single-phase gas exchanger is an exchanger using a technology known to those skilled in the art which makes it possible to minimize pressure losses while having a large exchange surface area. This low-pressure gas / gas exchange induces a low heat flux density through the wall of the exchanger (low transfer coefficient), which requires a large exchange surface area. In addition, the pressure loss must be minimized in order to limit the load on the compressor of the optional compression step. For example, this exchanger may be a pressurized plate exchanger in a shell, of the Packinox® type supplied by Alphalaval®.

[0079] Said vaporized charge, possibly compressed, possibly heated in said single-phase gas exchanger, is then introduced into superheating equipment, preferably a furnace, so as to bring it to an inlet temperature in at least one adiabatic reactor compatible with the temperature of the dehydration reaction.

[0080] In one embodiment according to the invention, said feedstock from step b2) undergoes a dehydration step b3) in at least one adiabatic reactor containing at least one fixed bed of dehydration catalyst and in which the dehydration reaction takes place.

[0081] Dehydration step b3) is advantageously carried out in one or two reactors.

[0082] In the case where step b3) is implemented in a single adiabatic reactor, said compressed, and optionally heated, charge is advantageously introduced into said reactor at an inlet temperature of between 350°C and 550°C and preferably between 400°C and 500°C, and at an inlet pressure of between 0.3 MPa and 1.8 MPa, and preferably between 0.4 MPa and 0.8 MPa.

[0083] The effluent from said adiabatic reactor of step b3) advantageously has a temperature of between 270°C and 450°C and preferably between 340 and 430°C, and an outlet pressure of between 0.2 MPa and 1.6 MPa and preferably between 0.3 MPa and 0.8 MPa.

[0084] In the case where step b3) is implemented in two adiabatic reactors, said compressed, and optionally heated, charge is advantageously introduced into the first reactor at an inlet temperature of between 350°C and 550°C and preferably at a temperature of between 370°C and 500°C, and at an inlet pressure of between 0.3 MPa and 1.8 MPa, and preferably between 0.4 MPa and 1.1 MPa.

[0085] The effluent from the first adiabatic reactor advantageously leaves said first reactor at a temperature between 270°C and 450°C and preferably between 290°C and 390°C, and at a pressure between 0.3 MPa and 1.7 MPa and preferably between 0.3 MPa and 1.0 MPa.

[0086] Said effluent is then advantageously introduced into a furnace so that the inlet temperature of said effluent into the second adiabatic reactor is between 350°C and 550°C and preferably between 400°C and 500°C. Said effluent has an inlet pressure into said second reactor advantageously between 0.3 MPa and 1.7 MPa and preferably between 0.3 MPa and 0.9 MPa.

[0087] The effluent from the second adiabatic reactor leaves said second adiabatic reactor at a temperature advantageously between 270°C and 450°C and preferably between 340°C and 430°C. The outlet pressure of said effluent from the second adiabatic reactor is advantageously between 0.2 MPa and 1.6 MPa and preferably between 0.3 MPa and 0.8 MPa.

[0088] The inlet temperature of the reactor(s) may advantageously be gradually increased to avoid deactivation of the dehydration catalyst.

[0089] The dehydration reaction which takes place in at least one adiabatic reactor of step b3) of the process advantageously operates at an hourly weight rate of between 0.1 and 20 h' 1 and preferably between 0.5 and 15 h' 1 The hourly weight rate is defined as the ratio of the mass flow rate of the pure ethanol feedstock to the mass of catalyst.

[0090] The dehydration catalyst used in step b3) is a catalyst known to those skilled in the art.

[0091] Said catalyst may be an amorphous acid catalyst, a zeolitic acid catalyst, a silica-alumina catalyst, an alumina catalyst or a silica-alumina catalyst.

[0092] Said catalyst is preferably an amorphous acid catalyst or a zeolitic acid catalyst.

[0093] In the case where the dehydration catalyst used in step b3) is a zeolitic catalyst, said catalyst comprises at least one zeolite chosen from zeolites having at least pore openings containing 8, 10 or 12 oxygen atoms (8 MR, 10 MR or 12 MR). It is known in fact to define the pore size of the zeolites by the number of oxygen atoms forming the annular section of the channels of the zeolites, called "member ring" or MR in English. Preferably, said zeolitic dehydration catalyst comprises at least one zeolite having a structural type chosen from the structural types MFI, FAU, MOR, FER, SAPO, TON, CHA, EUO, MEL and BEA. Preferably, said zeolitic dehydration catalyst comprises a zeolite of structural type MFI and preferably a zeolite ZSM-5.

[0094] The zeolite used in the dehydration catalyst used in step b3) of the process according to the invention can advantageously be modified by dealumination or desilication according to any dealumination or desilication method known to those skilled in the art.

[0095] The zeolite used in the dehydration catalyst used in step b3) of the process or the final catalyst may advantageously be modified by an agent capable of reducing its total acidity and improving its hydrothermal resistance properties. Preferably, said zeolite or said catalyst advantageously comprises phosphorus, preferably added in H3PO4 form followed by steam treatment after neutralization of the excess acid by a basic precursor such as, for example, calcium. Preferably, said zeolite comprises a phosphorus content of between 1 and 4.5% by weight, preferably between 1.5 and 3.1% by weight relative to the total mass of the catalyst.

[0096] Preferably, the dehydration catalyst used in step b3) is a catalyst described in patent applications WO / 2009 / 098262, WO / 2009 / 098267, WO / 2009 / 098268, or WO / 2009 / 098269.

[0097] In the case where the dehydration catalyst used in step b3) is an amorphous acid catalyst, said catalyst comprises at least one porous refractory oxide chosen from alumina, alumina activated by a mineral acid deposit and silica alumina.

[0098] Said amorphous or zeolitic dehydration catalyst used in step b3) may advantageously also comprise at least one oxide-type matrix also called a binder. According to the invention, the term “matrix” means an amorphous, crystallized matrix, or one comprising amorphous and crystallized parts. Said matrix is ​​advantageously chosen from the elements of the group formed by clays (such as, for example, natural clays such as kaolin or bentonite), magnesia, aluminas, silicas, silica-aluminas, aluminates, titanium oxide, boron oxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates, and coal, used alone or as a mixture. Preferably, said matrix is ​​chosen from the elements of the group formed by aluminas, silicas and clays.

[0099] Said dehydration catalyst used in step b3) is advantageously shaped in the form of grains of different shapes and sizes. It is advantageously used in the form of cylindrical or polylobed extrudates such as bilobed, trilobed, polylobed of straight or twisted shape, but can optionally be manufactured and used in the form of crushed powder, tablets, rings, balls, wheels, spheres. Preferably, said catalyst is in the form of extrudates.

[0100] Said dehydration catalyst used in step b3) is advantageously implemented in at least one reactor, in a fixed bed or in a moving bed. In step b3) of the process according to the invention, the catalysts used and the operating conditions are chosen so as to maximize the production of ethylene. The overall dehydration reactions implemented in step b3) of the process according to the invention are as follows:

[0101] The conversion of the ethanol feedstock in step b) of the process according to the invention is greater than 90%, preferably 95% and more preferably greater than 99%.

[0102] A conversion below 90% has the effect of lowering the overall efficiency of the process, as a greater quantity of diethyl ether converted to ethylene is lost in the downstream separation steps.

[0103] The conversion of the ethanol charge is defined, in percentage, by the following mathematical formula:

[0104] [1 - (hourly mass of ethanol output hourly mass of ethanol input)]x100

[0105] The hourly mass of ethanol at the inlet and outlet is measured in a conventional manner, for example by chromatography.

[0106] Step b3) in which the dehydration reaction takes place is advantageously carried out in one or two reactors. A preferred reactor is a radial reactor operating in ascending or descending mode. During step b3) of the process according to the invention, the transformation of the feedstock is accompanied by the deactivation of the dehydration catalyst by coking and / or by adsorption of inhibiting compounds. The dehydration catalyst must therefore periodically undergo a regeneration step. Preferably, the reactor is used in an alternating regeneration mode, also called a swing reactor, in order to alternate the reaction and regeneration phases of said dehydration catalyst. The objective of this regeneration treatment is to burn the organic deposits as well as the species containing nitrogen and sulfur, contained on the surface and within said dehydration catalyst.The optional pretreatment step reduces the amount of basic and organic impurities, as well as cationic species that will affect the catalyst cycle time. Eliminating these species thus limits the number of catalyst regenerations.

[0107] Optionally, for example in the case where the vaporization load does not include a recycled water flow or a water flow external to the process, the number of reactors can be increased in order to compensate for the endothermicity of the reaction by the presence of intermediate furnaces in the progress of the ethanol dehydration reaction.

[0108] The effluent from the last adiabatic reactor of step b3) is optionally sent to a single-phase gas exchanger in which it is "desuperheated" without being condensed by heat exchange with the compressed feed from the optional compression step, which is itself superheated.

[0109] Said "desuperheated" effluent is then advantageously sent to a second gas / liquid type exchanger in which it is partially condensed by a heat exchange used to vaporize the vaporization charge.

[0110] In one embodiment according to the invention, the effluent from step b3) undergoes a separation step b4) into an effluent comprising ethylene at a pressure of less than 1 MPa and an effluent comprising water.

[0111] Step b4) of separating said effluent from step b3) can advantageously be implemented by any method known to those skilled in the art, such as, for example, a gas / liquid separation zone, and preferably a gas / liquid separation column.

[0112] The effluent comprising ethylene at a pressure of less than 1 MPa then advantageously undergoes compression. Said compression makes it possible to raise the pressure of said effluent to a pressure advantageously between 2 MPa and 4 MPa, necessary for its final purification.

[0113] Preferably, the effluent comprising ethylene separated at the end of step b4) is not recycled into at least one adiabatic reactor of step b3). The non-recycling of the ethylene separated at the end of step b4) into at least one adiabatic reactor of step b3) does not alter the ethylene selectivity of the process.

[0114] At least a portion of the effluent comprising water from step b4) is optionally recycled to the separation step b4). In the case where at least a portion of the effluent comprising water is recycled, said portion of the effluent comprising water is advantageously cooled using a cold fluid or a fluid from the process and is preferably purified according to the known purification methods described below.

[0115] In one embodiment according to the invention, at least a portion of the effluent comprising water from separation step b4) undergoes a purification step b5). Purification step b5) can advantageously be carried out by any purification method known to those skilled in the art. For example, purification step b5) can advantageously be carried out by the use of ion exchange resins, molecular sieves, membranes, by adding chemical agents to adjust the pH, such as for example sodium hydroxide or amines and by adding chemical agents to stabilize the products, such as for example polymerization inhibitors chosen from bisulfites and surfactants.

[0116] At least one stream of purified water and at least one stream of unconverted ethanol are then separated. The separation can advantageously be carried out by any separation method known to those skilled in the art. For example, the separation can advantageously be carried out by distillation, the use of molecular sieves, membranes, steam or heat stripping or by absorption with solvents such as, for example, glycol solvents.

[0117] A stream containing the light gases, preferably acetaldehyde and methanol, can also advantageously be separated.

[0118] The use of the purified water stream from step b5) makes it possible to separate the vast majority of the ethylene from the water before recycling it. In the process according to the invention, the ethylene is thus dissociated from the diluent, which allows the use of an inert thermal reaction diluent for the process. This also allows for improved energy recovery, without degrading the yield and selectivity to final ethylene.

[0119] Third reaction section (Step c) of the process according to the invention)

[0120] The third reaction section 7 comprises at least one reactor in which the synthesis of acrylate salts is carried out from the ethylene 6 obtained at the end of step b) and the CO2 4 obtained at the end of step a). In said reactor, the ethylene 6 from the second reaction section 5, the CO2 4 from the first reaction section 2, a catalytic precursor and a reaction solvent are brought into contact to form the active species. The term active species is understood to mean the species which is formed when the catalytic precursor, CO2 and ethylene are brought into contact. The synthesis of the acrylate salt is complete when the active species is brought into contact with a base. This base may be soluble or insoluble in the reaction solvent. The base may also be supported on a solid support. The base may already be present in the reactor when the reactants are brought into contact in the reactor or may be introduced in a step subsequent to the formation of the active species.Preferably, the base is miscible with the solvent. More preferably, the base is introduced into the reactor at the same time as the other reactants. The base.

[0121] The base is usually an alcoholate salt such as a phenolate salt or an alkanoate salt. More preferably, the base is chosen from alkanolates of secondary or tertiary alcohols (tert-butanol, isopropanol, etc.). The salts generally contain inorganic counterions such as Li, Na, Ca and Cs. The counterion of the base is the one that will be associated with the final acrylate salt if no ion exchange step is planned. Preferably, the bases will be sodium salts and the final acrylate will be a sodium acrylate.

[0122] The catalytic precursor

[0123] Generally, the catalysts are transition metal complexes. Preferably, nickel(0) and palladium(0) complexes are used in the examples. The possibility of starting from a nickel(2) or palladium(2) salt and reducing it in the presence of a reducing agent such as H2, Mg, Na or Zn to form a nickel(0) or palladium(0) complex is also conceivable. Preferably, Pd(0) is the preferred metal, preferably in the form of [Pd(PPh3)4].

[0124] In general, the most active ligands appear to be polydentate ligands containing at least one phosphine coordinated to the metal center. More preferably, these are essentially bidentate ligands of the type (P, P); (P, N); (P, O); (P, carbene). Even more preferably, the best results are obtained with (P, P) ligands, preferably 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(dicyclohexylphosphino)propane and 1,4-bis(dicyclohexylphosphino)butane.

[0125] The catalytic precursor is generally a mixture of a metal precursor and one or more ligands. Preferably, the catalytic precursor is a stoichiometric mixture of a bidentate ligand with a metal precursor. The metal precursor can be formed before the reaction (ex situ) or during the reaction (in situ) in the reaction solvent or in another solvent.

[0126] The solvent

[0127] The solvent may be selected from aromatics, halogenated aromatic compounds, ethers, alcohols, amides, ureas. The solvent is preferably selected from anisole, cyclohexylpyrrolidone, N,N-dibutylformamide and dimethylacetamide.

[0128] The reaction is generally carried out with a total pressure of between 1 MPa and 10 MPa. The ratio of the partial pressures CCh / ethylene is preferably between 1 / 10 and 10 / 1. More preferably, said ratio is between 2 / 8 and 8 / 2 and even more preferably between 2 / 1 and 1 / 2. The reaction temperature is preferably between 105°C and 170°C, preferably between 125°C and 165°C, and more preferably between 135°C and 155°C.

[0129] Step d) separation (optional)

[0130] At the end of the reaction, it is advantageous to carry out a separation step of the acrylate salt. Preferably, a counter-solvent, immiscible with the reaction solvent, is added to the reaction medium and the whole is sent to a liquid-liquid separation step. Even more preferably, the counter-solvent is water, potentially partly derived from the dehydration of the ethanol in step b). At the outlet of the liquid-liquid separation, two streams are recovered, namely:

[0131] - a 1 er stream containing the reaction solvent and the catalytic precursor; and

[0132] - a 2 ème said flux containing the counter-solvent enriched with acrylate salt and the alcohol corresponding to the base used in the reaction.

[0133] The 1st erThe flow is advantageously reinjected into the reactor, after possible drying to remove traces of water, to recycle the catalyst and continue to produce acrylate salts.

[0134] The 2nd ème stream is advantageously sent to another separation step, preferably a distillation, where the counter-solvent, the alcohol and the acrylate salt are separated.

[0135] Advantageously, the counter-solvent enriched stream can thus be recycled and returned to the liquid-liquid extraction stage.

[0136] Advantageously, the alcohol-enriched stream is sent to a base regeneration step. In this step, the alcohol is brought into contact with a strong base to reform the base, which will then be introduced into the reactor. Preferably, the strong base is sodium hydroxide, and the water produced during regeneration can optionally serve as a countersolvent.

[0137] Depending on the use to which it is put, the acrylate salt can either be recovered in the form of a concentrated solution in the countersolvent, or be isolated and purified by distillation, drying or crystallization methods known to those skilled in the art.

[0138] The acrylate salt can also be further converted to acrylic acid by adding acid.

[0139] Examples

[0140] 1 / Case of the synthesis of sodium acrylate from glucose without valorization of CO2 from the fermentation stage (non-compliant):

[0141] The equation for the glucose fermentation reaction is CeH^Oe — > 2 C2H5OH + 2 CO2. Therefore, 66.7% of the carbon in a glucose molecule is converted to ethanol and 33.3% to CO2. For a feed of 170 Kta of glucose, fermentation theoretically produces 86.8 Kta of ethanol and 83 Kta of CO2.

[0142] Assuming that the yield of ethanol dehydration to ethylene is 97%, it is possible to produce 51.2 Kta of ethylene, or at best, 172.1 Kta of sodium acrylate. Without CO2 being used to convert sodium acrylate, up to 64.7% of the carbon in glucose can be used to convert sodium acrylate (see Table 1 below).

[0143] 2 / Case of the synthesis of sodium acrylate from glucose with recovery of CO2 from the fermentation stage (compliant):

[0144] For a load of 170 Kta of glucose, fermentation theoretically allows the production of 86.8 Kta of ethanol and 83 Kta of CO2.

[0145] Assuming that the yield of ethanol dehydration to ethylene is 97%, it is possible to produce 51.2 Kta of ethylene, or at best, 172.1 Kta of sodium acrylate. To produce 172.1 Kta of sodium acrylate with 51.2 Kta of ethylene, a minimum of 80.5 Kta of CO2 is required. Fermentation therefore produces enough CO2 for the sequence to be self-sufficient in CO2.

[0146] With the CO2 recovered into sodium acrylate by the sequence described in the invention, up to 97% of the carbon in glucose can be recovered into sodium acrylate (see Table 1 below).

[0147] Table 1

Claims

CLAIMS 1. Process for converting biomass into acrylate salts comprising successively: a) a step of treating the biomass to produce ethanol and carbon dioxide; b) a step of dehydrating the ethanol obtained at the end of step a) to obtain ethylene; c) a step of synthesizing acrylate salts from the ethylene obtained at the end of step b) and the carbon dioxide obtained at the end of step a) in the presence of a catalytic precursor and a solvent.

2. Method according to claim 1, in which step a) comprises the following sub-steps: a1) a step of pretreatment of the biomass to obtain a pretreated substrate; a2) a step of enzymatic or chemical hydrolysis of the pretreated substrate obtained at the end of step a1) to obtain an enzymatic or chemical hydrolysis must; a3) a step of alcoholic fermentation of the enzymatic or chemical hydrolysis must obtained at the end of step a2) to obtain ethanol and carbon dioxide.

3. Method according to claim 2, in which sub-step a1) is carried out by steam explosion in acid conditions at a temperature between 150°C and 250°C and for a duration between 5 minutes and 30 minutes.

4. Method according to one of claims 2 or 3, in which sub-step a2) is carried out by enzymatic hydrolysis in the presence of cellulases from Trichoderma reesei.

5. Method according to claim 2, wherein when step a2) is an enzymatic hydrolysis, steps a2) and a3) are carried out simultaneously.

6. Method according to one of claims 1 to 5, in which step b) comprises the following sub-steps: b1) a step of vaporizing a vaporization feed comprising the ethanol obtained at the end of step a) in a heat exchanger, said vaporization feed being introduced into said vaporization step at a pressure of between 0.1 MPa and 2.5 MPa so as to produce a vaporized feed; b2) a step of superheating said vaporized feed obtained at the end of step b1) so as to bring said vaporized feed to an inlet temperature compatible with the temperature of the dehydration reaction; b3) a step of dehydration of said feedstock from step b2) in at least one adiabatic reactor containing at least one dehydration catalyst and in which the dehydration reaction takes place, operating at an inlet temperature of between 350°C and 550°C and at an inlet pressure of between 0.3 MPa and 1.8 MPa.

7. Method according to any one of claims 1 to 6, in which step c) is carried out at a temperature between 105°C and 170°C, and at a pressure between 1 MPa and 10 MPa.

8. Process according to any one of claims 1 to 7, in which step c) is carried out in the presence of a base chosen from secondary or tertiary alcohol alkanolates.

9. Process according to any one of claims 1 to 8, in which step c) is carried out in the presence of a catalytic precursor based on a metal complex of a transition metal chosen from nickel (0) and palladium (0) complexes.

10. Process according to any one of claims 1 to 9, in which step c) is carried out in the presence of a solvent chosen from anisole, cyclohexylpyrrolidone, N,N-dibutylformamide and dimethylacetamide.

11. Method according to any one of claims 1 to 10, further comprising a step d) of liquid-liquid separation of the acrylate salt in the presence of a counter-solvent, immiscible with the solvent used in step c).

12. Method according to claim 11, in which said counter-solvent is water resulting at least in part from step b) of dehydration of ethanol.

13. Method according to any one of the preceding claims, characterized in that the biomass is a lignocellulosic biomass.

14. Installation for the conversion of biomass into acrylate salts capable of implementing the method according to any one of claims 1 to 13, said installation comprising: - a first reaction section (2) for producing ethanol (3) and carbon dioxide (4) from biomass (1); - a second reaction section (5) for dehydrating ethanol (3) into ethylene (6); and - a third reaction section (7) for producing acrylate salts (8) from ethylene (6) and carbon dioxide (4).

Images