Patent Application
20110160419
The present invention relates to a process for the manufacture of vinyl propionate from alcohols resulting from the fermentation of renewable starting materials; preferably, the renewable starting materials are plant materials.
Vinyl esters, in particular vinyl propionate, are known for their uses as monomer in (co)polymers, generally by emulsion. Vinyl propionate makes possible the synthesis of homopolymers or copolymers with vinyl chloride or with alkyl acrylates, such as, for example, t-butyl acrylate.
One of the problems posed by the processes for the synthesis of vinyl esters of the prior art is that they are carried out starting from non-renewable starting materials of fossil (oil) origin, in particular ethylene. In point of fact, the resources of these starting materials are limited and the extraction of oil requires drilling to increasingly deep depths and under technical conditions which are always more difficult, requiring sophisticated equipment and the use of processes which are always more expensive in energy. These constraints have a direct consequence with regard to the cost of manufacturing ethylene and thus with regard to the cost of manufacturing vinyl esters.
Advantageously and surprisingly, the inventors of the present patent application have employed a process for the industrial manufacture of vinyl propionate from renewable starting materials.
The process according to the invention makes it possible to dispense, at least in part, with starting materials of fossil origin and to replace them with renewable starting materials.
The vinyl propionate obtained according to the process according to the invention is of such a quality that it can be used in all the applications in which the use of vinyl propionate is known, including in applications with the highest standards.
A first subject matter of the invention is vinyl propionate in which at least a portion of the carbon atoms is of renewable origin, it being possible for this portion of renewable origin to be determined according to the standard ASTM D 6866-06.
Carbon atoms of renewable origin are also known as contemporary or bio resource carbon atoms.
A second subject matter of the invention is a composition comprising vinyl propionate and in particular a composition, more particularly a solution, comprising at least 80% by weight, preferably at least 90% by weight, of vinyl propionate, with respect to the total weight of the composition, the carbon atoms of said vinyl propionate being, at least in part, carbon atoms of renewable origin.
Such a concentrated vinyl propionate solution has never been obtained with the processes for the synthesis of renewable vinyl esters of the prior art.
Another subject matter of the invention is a process for the manufacture of vinyl propionate which comprises a stage of acyloxylation of ethylene by propanoic acid in which at least a portion of the carbon atoms of the ethylene and/or of the propanoic acid is of renewable origin.
More specifically, a subject matter of the invention is a process for the manufacture of vinyl propionate comprising the following stages:
a) fermentation of renewable starting materials and optionally purification in order to produce at least one alcohol chosen from ethanol and mixtures of alcohols comprising ethanol;
b) dehydration of the alcohol obtained in order to produce, in a first reactor, at least one alkene chosen from ethylene and mixtures of alkenes comprising ethylene and optionally purification of the ethylene;
c) production of acrylic acid from renewable starting materials,
d) hydrogenation of the acrylic acid in the presence of molecular hydrogen in order to produce propanoic acid,
e) introduction, into a third reactor, of the ethylene obtained on conclusion of stage b) and of the propanoic acid obtained on conclusion of stage d), and implementation of the reaction for the acyloxylation of the ethylene,
f) isolation and optionally purification of the vinyl propionate obtained on conclusion of stage e).
Another subject matter of the invention is the vinyl propionate capable of being obtained by the process according to the invention or more generally the vinyl propionate obtained, at least in part, from renewable starting materials.
The invention also relates to the uses of the vinyl propionate obtained from materials of renewal origin or of a composition comprising at least 80% of vinyl propionate obtained from materials of renewable origin and in particular to the uses of said vinyl propionate or of said composition in the manufacture of homopolymers or of copolymers with vinyl chloride or with alkyl acrylates, such as, for example, t-butyl acrylate.
Other subject matters, aspects or characteristics of the invention will become apparent on reading the following description.
Stage a) of the process for manufacture of vinyl propionate according to the invention comprises the fermentation of renewable starting materials in order to produce at least one alcohol, said alcohol being chosen from ethanol and mixtures of alcohols comprising ethanol.
A renewable starting material is a natural resource, for example animal or plant resource, the stock of which can be reconstituted over a short period on the human scale. In particular, it is necessary for the stock to be able to be renewed as quickly as it is consumed. For example, plant materials exhibit the advantage of being able to be cultivated without their consumption resulting in an apparent reduction in natural resources.
Unlike the materials resulting from fossil materials, renewable starting materials comprise 14C. All the samples of carbon drawn from living organisms (animals or plants) are in fact a mixture of 3 isotopes: 12C (representing approximately 98.892%), 13C (approximately 1.108%) and 14C (traces: 1.2×10−10%). The 14C/12C ratio of living tissues is identical to that of the atmosphere. In the environment, 14C exists in two predominant forms: in the form of carbon dioxide gas (CO2) and in the organic form, that is to say in the form of carbon incorporated in organic molecules.
In a living organism, the 14C/12C ratio is kept constant metabolically as the carbon is continually exchanged with the external environment. As the proportion 14C is constant in the atmosphere, it is the same in the organism, as long as it is living, since it absorbs this 14C in the same way as the surrounding 12C. The mean 14C/12C ratio is equal to 1.2×10−12.
12C is stable, that is to say that the number of 12C atoms in a given sample is constant over time. 14C is radioactive and the number of 14C atoms in a sample decreases over time (t), its half life being equal to 5730 years.
The 14C content is substantially constant from the extraction of the renewable starting materials up to the manufacture of the vinyl propionate according to the invention and even up to the end of the use of the object comprising vinyl propionate.
Consequently, the presence of 14C in a material, this being the case whatever the amount thereof, gives an indication with regard to the origin of the molecules constituting it, namely that they originate from renewable starting materials and not from fossil materials.
The amount of 14C in a material can be determined by one of the methods described in the standard ASTM D6866-06 (Standard Test Methods for Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis).
This standard comprises three methods for measuring organic carbon resulting from renewable starting materials, known as biobased carbon. The proportions shown for the vinyl ester of the invention are preferably measured according to the mass spectrometry method or the liquid scintillation spectrometry method described in this standard and very preferably by mass spectrometry.
These measurement methods evaluate the ratio of the 14C/12C isotopes in the sample and compare it with a ratio of the 14C/12C isotopes in a material of biological origin giving the 100% standard, in order to measure the percentage of organic carbon in the sample.
Preferably, the vinyl propionate according to the invention comprises an amount of carbon resulting from renewable starting materials of greater than 20% by weight, preferably of greater than 40% by weight, with respect to the total weight of carbon of the vinyl propionate.
In other words, the vinyl propionate can comprise at least 0.25×10−10% by weight of 14C and preferably at least 0.5×10−5% by weight of 14C.
Advantageously, the amount of carbon resulting from renewable starting materials is greater than 75% by weight, preferably equal to 100% by weight, with respect to the total weight of carbon of the vinyl propionate.
Use may be made, as renewable starting materials, of materials of plant origin, materials of animal origin or materials of plant or animal origin resulting from recovered materials (recycled materials).
Within the meaning of the invention, the plant materials comprise at least sugars and/or starches.
The plant materials comprising sugars are essentially sugarcane and sugar beet; mention may also be made of maple, date palm, sugar palm, sorghum or maguey. The plant materials comprising starches are essentially cereals and legumes, such as corn, wheat, including soft wheat, barley, rice, potato, cassava or sweet potato, or algae.
Mention may in particular be made, among the materials resulting from recovered materials, of plant or organic waste comprising sugars and/or starches.
Preferably, the renewable starting materials are plant materials.
The fermentation of the renewable materials is carried out in the presence of one or more appropriate microorganisms; this microorganism may optionally have been modified naturally, by a chemical or physical stress, or genetically; the term then used is mutant. Conventionally, the microorganism used is Saccharomyces cerevisiae or one of its mutants.
Use may also be made, as renewable starting materials, of cellulose or hemicellulose, indeed even of lignin, which, in the presence of appropriate microorganisms, can be converted to materials comprising sugar. These renewable materials include straw, wood or paper, which can advantageously originate from recovered materials.
The lists presented above are not limiting.
Preferably, the fermentation stage (a) is followed by a purification stage intended to separate the ethanol from the other products. For example, a distillation stage can be carried out in order to separate the ethanol from the other products.
The dehydration of the alcohol or alcohols obtained in stage a) is carried out in stage b) of the process for the manufacture of vinyl propionate in order to produce, in a first reactor, at least one alkene chosen from ethylene and mixtures of alkenes comprising ethylene, the byproduct from the dehydration being water.
Generally, the dehydration of the alcohol is carried out using an alumina-based catalyst, such as the catalyst sold by Eurosupport under the trade name ESM 110® (undoped trilobe alumina comprising little, approximately 0.04%, residual Na2O). Preferably, the alumina is a γ-alumina.
The operating conditions for the dehydration come within the general knowledge of a person skilled in the art; by way of indication, the dehydration is generally carried out at a temperature of the order of 400° C.
Another advantage of the process according to the invention is its saving in energy: the fermentation and dehydration stages of the process according to the invention are carried out at relatively low temperatures, of less than 500° C., preferably of less than 400° C.; in comparison, the stage of cracking and steam cracking oil to give ethylene is carried out at a temperature of the order of 800° C.
This saving in energy is also accompanied by a decrease in the level of CO2 emitted to the atmosphere.
Stage c) of the process for the manufacture of vinyl propionate consists of the manufacture of acrylic acid from renewable starting materials.
According to a first alternative form, this stage c) is carried out starting from glycerol resulting from the methanolysis of vegetable oils, that is to say from a material of renewable origin.
In stage c) of this first alternative form, the glycerol, advantageously in the form of an aqueous solution with a concentration of between 10 and 50% by weight, is subjected either to a reaction for the dehydration of the glycerol, in order to form acrolein, and then to a reaction for the oxidation of the acrolein formed in the presence of molecular oxygen, in order to produce acrylic acid, or to a reaction for the oxydehydration of the glycerol in the presence of molecular oxygen, in order to form acrylic acid.
These dehydration and oxidation reactions are known to a person skilled in the art: for example, in the case where the dehydration and then oxidation are carried out in two separate stages, use may be made of the teaching of the document EP 1 710 227.
In the case where an oxydehydration is carried out in one stage, in the same reactor, the glycerol is dehydrated to give acrolein in a first step and then, in the presence of molecular oxygen, the acrolein is oxidized to give acrylic acid; this oxydehydration is described in particular in the application FR 2 884 817 of Arkema SA.
The oxydehydration reaction is generally carried out in the presence of a mixture of catalysts and more particularly of a mixture of a solid acid catalyst (suitable for the dehydration reaction) and of an oxidation catalyst, such as the solid catalysts comprising at least one element chosen from the list Mo, V, W, Re, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Te, Sb, Bi, Pt, Pd, Ru and Rh, present in the metallic form or in the oxide, sulfate or phosphate form (suitable for the oxidation reaction). The reaction is preferably carried out in the gas phase at a temperature of between 250° C. and 350° C. and a pressure of between 1 and 5 bar.
According to a second alternative form of the stage c), the acrylic acid is obtained by fermentation of renewable starting materials, in order to produce 3-hydroxypropionic acid, optionally purification, followed by a dehydration of the 3-hydroxypropionic acid to give acrylic acid, optionally in the presence of molecular oxygen.
Use may be made, as renewable starting material, of the starting materials comprising sugar, starch, cellulose or hemicellulose used during stage (a). Preferably, the starting materials comprise glucose.
The fermentation of the renewable materials is carried out in the presence of one or more appropriate microorganisms; this microorganism may optionally have been modified naturally, by a chemical or physical stress, or genetically; the term then used is mutant. Conventionally, the microorganism used is chosen from Escherichia coli or one of its mutants. This fermentation is known to a person skilled in the art and is described in the international patent applications WO 02/42418 and WO 2008/089102.
The dehydration of the 3-hydroxypropionic acid to give acrylic acid can be carried out, in the liquid phase or in the gas phase, by a dehydration catalyst.
These catalysts can generally consist of a heteropolyacid salt in which the protons of said heteropolyacid are exchanged with at least one cation chosen from elements belonging to Groups I to XVI of the Periodic Table of the Elements, these heteropolyacid salts comprising at least one element chosen from the group consisting of W, Mo and V. Mention may particularly be made, among mixed oxides, of those based on iron and on phosphorus and of those based on cesium, phosphorus and tungsten. The catalysts are chosen in particular from zeolites, Nafion® composites (based on sulfonic acid of fluoropolymers), chlorinated aluminas, phosphotungstic and/or silicotungstic acids and acid salts, and various solids of the type comprising metal oxides, such as tantalum oxide Ta2O5, niobium oxide Nb2O5, alumina Al2O3, titanium oxide TiO2, zirconia ZrO2, tin oxide SnO2, silica SiO2 or silicoaluminate SiO2/Al2O3, impregnated with acid functional groups, such as borate BO3, sulfate SO4, tungstate WO3, phosphate PO4, silicate SiO2 or molybdate MoO3 functional groups, or a mixture of these compounds. The preceding catalysts can additionally comprise a promoter, such as Au, Ag, Cu, Pt, Rh, Pd, Ru, Sm, Ce, Yt, Sc, La, Zn, Mg, Fe, Co, Ni or montmorillonite.
The preferred catalysts are phosphated zirconias, tungstated zirconias, silica zirconias, titanium or tin oxides impregnated with tungstate or phosphotungstate, phosphated aluminas or silicas, heteropolyacids or heteropolyacid salts, iron phosphates and iron phosphates comprising a promoter.
This dehydration can be carried out at a temperature of 350 to 400° C., optionally in the presence of molecular oxygen. The presence of molecular oxygen makes it possible to increase the lifetime of the catalyst during the reaction.
Use may also be made of the dehydration which is known to a person skilled in the art and is described in example 17 to 26 of the international patent application WO 02/090312.
Reference may also be made to the report “Process Economics Program Report 259—Chemicals from biobased C3S” by Ronald Bray (SRI Consulting) in carrying out the stage c).
The hydrogenation of the acrylic acid in the presence of molecular hydrogen is carried out in stage d), in order to obtain propanoic acid.
This selective hydrogenation can be carried out according to two main processes:
Stage e) of acyloxylation of the ethylene is generally carried out in the gas phase in a fixed bed reactor using a palladium or palladium acetate catalyst on a support which can be SiO2 or Al2O3, at a temperature generally ranging from 175 to 200° C.
Cocatalysts, for example based on gold, rhodium, platinum or cadmium, can be added.
Alkali metal acetates can also be added for the purpose of improving the selectivity and the activity of the catalysts.
Preferably, at least one purification stage is carried out during the fermentation stage and/or during the stage of dehydration of the alcohol and/or during the stages of producing the acid.
The optional purification stages (purification of the alcohol(s) obtained in stage a), purification of the alkene(s) obtained in stage b) or purification of the acids obtained in stages c) and d)) are advantageously carried out by absorption on conventional filters, such as molecular sieves, zeolites, carbon black, and the like) or by distillation of the products obtained in stages a), b), c) or d).
If the alcohol obtained in stage a) was purified so as to isolate the ethanol, the alkene obtained in stage b) is ethylene.
If the alcohol obtained in stage a) was not purified, a mixture of alkenes comprising ethylene is obtained on conclusion of stage b).
Advantageously, at least one purification stage is carried out during stage a) and/or stage b) in order to obtain ethylene with a sufficient degree of purity to react with the propanoic acid. It will be preferable to obtain ethylene with a degree of purity of greater than 85% by weight, preferably of greater than 95% by weight and more preferably 99% by weight.
Particularly preferably, the alcohol obtained in stage a) is purified so as to isolate the ethanol; consequently, the alkene obtained at stage b) is ethylene.
The main impurities present in the ethylene resulting from the dehydration of the ethanol are ethanol, propane and acetaldehyde.
Advantageously, the ethylene will have to be purified, that is to say that the ethanol, the propane and the acetaldehyde will have to be removed, in order to be able to easily carry out the acyloxylation stage e).
The ethylene, the ethanol, the propane and the acetaldehyde can be separated by carrying out one or more low-temperature distillations.
The boiling points of these compounds are as follows:
The ethylene, the ethanol, the propane and the acetaldehyde are cooled to approximately −105° C., preferably −103.7° C., and then distilled in order to remove the ethylene.
Another advantage of the process according to the present invention relates to the impurities. The impurities present in the ethylene resulting from the dehydration of the ethanol are completely different from those present in the ethylene resulting from steam cracking. In particular, the impurities present in the ethylene resulting from steam cracking include dihydrogen and methane, this being the case whatever the composition of the initial feedstock.
Conventionally, the separation of dihydrogen and methane is carried out after compression to 36 bar and cooling to approximately −120° C. Under these conditions, the dihydrogen and the methane, which are liquids, are separated in the demethanizer and then the ethylene is recovered at 19 bar and −33° C.
The process according to the present patent application makes it possible to dispense with the stage of separation of dihydrogen and methane and also makes it possible to cool the mixture to −105° C. at atmospheric pressure instead of −120° C. at 36 bar. The cooling of this separation stage can also be carried out under pressure in order to increase the boiling point of the compounds to be separated (for example approximately 20 bar and −35° C.). These differences also contribute to rendering the process according to the invention more economic (saving in equipment and saving in energy, which is also accompanied by a reduction in the level of CO2 emitted to the atmosphere).
Another advantage is that the ethylene obtained in stage b) of the process according to the invention does not comprise acetylene, in contrast to the ethylene obtained by cracking or steam cracking. In point of fact, acetylene is highly reactive and brings about oligomerization side reactions; the production of acetylene-free ethylene is thus particularly advantageous.
Another advantage is that the process according to the invention can be carried out in production units located on the site of production of the starting materials. In addition, the size of the production units of the process according to the invention is much smaller than the size of a refinery: this is because refineries are large plants generally situated far from the centers of production of the starting materials and fed via pipelines.
Advantageously, at least one purification stage is carried out during stage c) and/or stage d) in order to obtain propanoic acid with a sufficient degree of purity to react with the ethylene. It will be preferable to obtain propanoic acid with a degree of purity of greater than 85% by weight, preferably of greater than 95% by weight and more preferably 99% by weight.
The process for the manufacture of vinyl propionate according to the invention is illustrated by the following example.
In this plant, 96% ethanol obtained by fermentation of glucose is evaporated in an evaporator and then preheated in a heat exchanger before being injected at the top of a reactor with a diameter of 127 mm containing a catalytic bed brought to 300-400° C. and consisting of a layer of ESM 110® alumina from Eurosupport, representing a volume of 12 700 cm3 and a weight of 6500 g, the ratio of the flow rate by volume of ethanol to the volume of catalyst being 1 h−1. The mixture of water and ethylene produced in the reactor is cooled in the heat exchanger before being conveyed to a gas/liquid separator, where the ethylene and the water mixed with byproducts are separated.
Manufacture of Propionic Acid from Glycerol
The preliminary stage consists in purifying the crude glycerol obtained from vegetable oil, the salts being removed. The reaction for the dehydration of the glycerol to give acrolein and the condensation of a portion of the water are then carried out. The dehydration reaction is carried out in the gas phase in a fixed bed reactor in the presence of a solid catalyst composed of a tungstated zirconia ZrO2/WO3 at a temperature of 320° C. at atmospheric pressure. A mixture of glycerol (20% by weight) and water (80% by weight) is conveyed to an evaporator, in the presence of air, in an O2/glycerol molar ratio of 0.6/1. The gaseous medium exiting from the evaporator at 290° C. is introduced into the reactor, consisting of a tube with a diameter of 30 mm charged with 390 ml of catalyst, immersed in a salt bath (KNO3, NaNO3 and NaNO2 eutectic mixture) maintained at a temperature of 320° C. At the outlet to the reactor, the gaseous reaction mixture is conveyed to the bottom of a condensation column.
In the following stage, the gas mixture is introduced, after addition of air (O2/acrolein molar ratio of 0.8/1) and of nitrogen in an amount necessary in order to obtain an acrolein concentration of 6.5 mol %, as feed into the reactor for the oxidation of acrolein to give acrylic acid. This oxidation reactor consists of a tube with a diameter of 30 mm charged with 480 ml of a commercial catalyst for the oxidation of acrolein to give acrylic acid based on mixed oxides of aluminum, molybdenum, silicon, vanadium and copper immersed in a salt bath identical to that described above, in this instance maintained at a temperature of 345° C. Before introducing over the catalytic bed, the gas mixture is preheated in a tube also immersed in the salt bath.
After passing through an absorption column, a solution of acrylic acid, of water and of other impurities is recovered.
The aqueous solution obtained is subjected to a stage of drying by a distillation in order to remove the water in the form of an azeotropic mixture with methyl isobutyl ketone (MIBK). A solution of stabilizers in MIBK, comprising the stabilizers hydroquinone, phenothiazine and butyl dibutyldithiocarbamate (respectively 35 ppm, 70 ppm and 35 ppm, with respect to the acrylic acid present in the feed stream), is continuously injected at the column top. The azeotropic mixture distills at a top temperature of 45° C. under a pressure of 1.2×104 Pa.
The dried acrylic acid recovered at the column bottom comprises no more than 0.4% of water and of other impurities.
A jacketed tubular evaporator made of stainless steel (length of the tube 100 cm, internal diameter 2.5 cm, wall thickness 4 mm) was packed over its entire length with Raschig rings made of silica.
A jacketed tubular reactor made of stainless steel identical to the evaporator was packed, from the bottom upwards, first over a length of 5 cm with Raschig rings and then the jacketed tubular reactor was packed with a homogeneous mixture of 130 ml=135.1 g of the Johnson Matthey hydrogenation catalyst of 50B type (0.3% by weight Pd on γ-Al2O3, as 2 mm spheres) and of 226 ml of Raschig rings. The remainder of the length of the jacketed tubular reactor was packed only with Raschig rings.
The intermediate space both of the jacketed tubular evaporator and of the jacketed tubular reactor was provided with an oil forming a heat-exchange fluid which exhibits a temperature of 185° C.
The acrylic acid solution obtained was introduced (from the top downwards) into the jacketed tubular evaporator with a flow rate corresponding to 8.5 g/h of acrylic acid introduced. 16 mol/h of molecular hydrogen were passed through the tubular evaporator countercurrent-wise to these mother liquors.
The mixture of acrylic acid and of molecular hydrogen exiting from the evaporator was immediately conveyed, from the bottom upwards, through the jacketed tubular reactor. The end of the latter is at atmospheric pressure. The temperature in the middle of the reactor is approximately 220° C. The unreacted acrylic acid and the propionic acid produced which is present in the gas stream produced were separated by condensation in a separator at 10° C.
The condensate comprises 813 g of propionic acid after an operating time of 100 h.
The reaction for the acyloxylation of the ethylene with the propionic acid is subsequently carried out in the gas phase in a fixed bed reactor using a palladium catalyst on an alumina support at a temperature of 180° C. At the end of the reaction, vinyl propionate obtained from renewable carbon is obtained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0854976 | Jul 2008 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR2009/051462 | 7/21/2009 | WO | 00 | 1/21/2011 |
