Monopropylene glycol compositions

Abstract

The present invention provides a composition comprising monopropylene glycol and 2,3-pentanediol, wherein the monopropylene glycol is present at at least 98.0% by weight of the composition. The compositions of the present invention have desirable properties and can be used as a low-carbon footprint replacement for fossil-based glycol compositions in various applications.

Description

Technical Field

[0001] This invention relates to glycol compositions and their uses. More specifically, this invention relates to compositions comprising monopropylene glycol and 2,3-pentanediol. The compositions described herein can be used as low-carbon footprint alternatives to fossil-based glycol compositions in various applications. Background Technology

[0002] There is a tremendous global interest in mitigating climate change and minimizing its environmental impact. In response to this need, there is a growing demand for innovative solutions to reduce the carbon footprint of industries worldwide. As awareness of the adverse effects of fossil-based petrochemical products and greenhouse gas emissions increases, there is an urgent need for sustainable alternatives.

[0003] Monopropylene glycol is an important raw material used in a variety of applications and industrial processes. In particular, it is used to prepare polymers such as polyesters and polyurethanes. While monopropylene glycol is produced industrially from petrochemical products derived from crude oil, there is a strong desire to obtain this compound from renewable resources due to environmental concerns. In this regard, it is known that sugars contained in plant matter can be converted into monopropylene glycol through catalytic hydrogenolysis.

[0004] Further glycol compositions are still needed. In particular, there is a need for monopropylene glycol compositions that exhibit the desired properties, especially concerning the manufacture of polymers, and that can be readily prepared from renewable resources. These and other requirements are met by the present invention. Summary of the Invention

[0005] In one aspect, the present invention provides a composition comprising: at least 98.0% monopropylene glycol by weight of the composition; and 2,3-pentanediol.

[0006] In other respects, the present invention relates to the use and methods of the compositions described herein. The invention also relates to methods for preparing the compositions and the compositions obtainable by said methods.

[0007] Detailed description

[0008] Diol Composition

[0009] This invention provides a composition comprising a mixture of diols. As used herein, the term "diol" refers to an aliphatic compound containing two hydroxyl groups attached to different carbon atoms, wherein the carbon atoms may or may not be adjacent.

[0010] The composition contains monopropylene glycol (also known as MPG, 1,2-propanediol or propane-1,2-diol) and 2,3-pentanediol (also known as pentane-2,3-diol).

[0011] The composition comprises at least 98.0% monopropylene glycol by weight of the composition. Preferably, the composition comprises at least 98.1%, at least 98.2%, at least 98.3%, at least 98.4%, at least 98.5%, or at least 99.0% monopropylene glycol by weight of the composition.

[0012] Furthermore, the composition contains 2,3-pentanediol (also known as pentane-2,3-diol). In one embodiment, the composition contains 0.1% to 2.0% 2,3-pentanediol by weight of the composition. Preferably, the composition contains 0.1% to 1.5% 2,3-pentanediol by weight of the composition.

[0013] In one embodiment, the composition further comprises 1,2-butanediol (also known as butane-1,2-diol). In one embodiment, the composition comprises 0.1%-0.5% 1,2-butanediol by weight of the composition. In one embodiment, the composition comprises 0.1%-0.4% 1,2-butanediol by weight of the composition. In a particular embodiment, the composition comprises 0.1%-0.3% 1,2-butanediol by weight of the composition.

[0014] In one embodiment, the composition comprises at least 98.0% monopropylene glycol, 0.1%-1.5% 2,3-pentanediol, and 0.1%-0.5% 1,2-butanediol by weight of the composition.

[0015] In one embodiment, the composition comprises at least 98.1% monopropylene glycol by weight of the composition, 0.1%-1.5% 2,3-pentanediol by weight of the composition, and 0.1%-0.3% 1,2-butanediol by weight of the composition.

[0016] In one embodiment, the composition further comprises 2,3-butanediol (also known as butane-2,3-diol). In one embodiment, the composition comprises 0.001% to 0.5% 2,3-butanediol by weight of the composition. In one embodiment, the composition comprises 0.001% to 0.1% 2,3-butanediol by weight of the composition.

[0017] In one embodiment, the composition comprises at least 98.0% monopropylene glycol, 0.1%-1.5% 2,3-pentanediol, 0.1%-0.5% 1,2-butanediol, and 0.001%-0.5% 2,3-butanediol by weight of the composition.

[0018] In one embodiment, the composition comprises at least 98.1% monopropylene glycol, 0.1%-1.5% 2,3-pentanediol, 0.1%-0.3% 1,2-butanediol, and 0.001%-0.1% 2,3-butanediol by weight of the composition.

[0019] Preferably, the composition is substantially anhydrous, meaning that the composition contains less than 0.2% water by weight of the composition. In one embodiment, the composition contains less than 0.1%, more preferably less than 0.05% water by weight of the composition. More preferably, the composition is anhydrous.

[0020] Preferably, the composition is a bio-based composition obtained from renewable resources. As used herein, the term "bio-based" refers to a composition or compound having a modern carbon percentage (pMC) of at least 80%, as determined using the ASTM D6866-21 test method. This test method is a standard method for determining the bio-based carbon content of solid, liquid, and gaseous samples using radiocarbon analysis experiments, and it distinguishes between carbon derived from contemporary bio-based materials and carbon derived from fossil-based materials.

[0021] Therefore, preferably, the composition has at least 80% pMC, as measured using the ASTM D6866-21 test method. Particularly, preferably, the composition has at least 90% pMC, more preferably 95%. Even more preferably, the composition has at least 99% pMC, for example, 100%.

[0022] In one embodiment, the composition is a bio-based composition, wherein both monopropylene glycol and 2,3-pentanediol are bio-based compounds. In another embodiment, the composition is a bio-based composition, wherein all carbon-containing compounds in the composition are bio-based.

[0023] In one embodiment, the composition is a bio-based composition prepared from woody raw materials (e.g., hardwood or softwood). The woody raw materials can be derived from, for example, pine, poplar, beech, aspen, spruce, eucalyptus, ash, oak, maple, chestnut, willow, or birch. The woody raw materials can also be any combination or mixture of these.

[0024] Preparation method

[0025] The compositions of the present invention can be obtained by any suitable means known in the art. For example, the composition can be prepared by mixing diol compounds in desired amounts.

[0026] However, preferably, the compositions of the present invention are obtained by a method comprising the catalytic hydrogenolysis of a carbohydrate composition.

[0027] More particularly, the composition is preferably obtained by a method comprising:

[0028] - In a reactor, in the presence of water and a catalyst, a carbohydrate composition is contacted with hydrogen under certain conditions to subject the carbohydrate composition to catalytic hydrogenolysis to produce an aqueous mixture comprising monopropylene glycol, monoethylene glycol and 2,3-pentanediol.

[0029] - The aqueous mixture is subjected to a distillation process to remove a portion of the monoethylene glycol from the aqueous mixture, thereby forming a first fraction containing monopropylene glycol and 2,3-pentanediol and a second fraction containing purified monoethylene glycol;

[0030] - The first fraction is subjected to a distillation process and the composition of the present invention is recovered therefrom as a product.

[0031] To prepare the compositions of the present invention, it is preferable to use a carbohydrate composition comprising a specific combination of sugars. Preferably, the carbohydrate composition comprises glucose, xylose, and one or more sugars selected from galactose, arabinose, mannose, and fructose. More preferably, the carbohydrate composition comprises each of glucose, xylose, galactose, arabinose, mannose, and fructose.

[0032] The amount of sugar in a carbohydrate composition can be expressed as a weight percentage of the total dry matter content of the carbohydrate composition. The term "total dry matter content" as used herein refers to the total amount of solids (including suspended solids and soluble or dissolved solids) in the carbohydrate composition. The total dry matter content can be determined by drying the sample at 105°C for 24 hours after removing the liquid. The effectiveness of liquid removal can be ensured by weighing the sample, drying it again at the specified temperature for two hours, and then reweighing the sample. If the measured weights are the same, drying is complete, and the total weight can be recorded.

[0033] In one embodiment, the carbohydrate composition comprises 85% to 97% by weight of glucose; 1% to 10% by weight of xylose; 0.1% to 2% by weight of galactose; 0.1% to 2% by weight of arabinose; 0.1% to 5% by weight of mannose; and 0.1% to 2% by weight of fructose, wherein the amounts are based on the total dry matter content of the carbohydrate composition.

[0034] In a preferred embodiment, the carbohydrate composition comprises 90% to 95% by weight of glucose; 4% to 8% by weight of xylose; 0.1% to 1% by weight of galactose; 0.1% to 1% by weight of arabinose; 0.1% to 1% by weight of mannose; and 0.1% to 2% by weight of fructose, wherein the amounts are based on the total dry matter content of the carbohydrate composition.

[0035] As is known in the art, sugars can exist in monomeric and oligomeric forms. As used herein, the term "monomer" refers to a sugar molecule that is not coupled or linked to any other sugar molecule. Monomeric sugars are also called monosaccharides. As used herein, the term "oligomer" refers to a sugar molecule composed of two or more monomers coupled or linked together. Examples of oligomeric sugars include disaccharides and trisaccharides.

[0036] Preferably, based on the total dry matter content of the carbohydrate composition, the carbohydrate composition has a total monomeric sugar content of at least 90% by weight. More preferably, based on the total dry matter content of the carbohydrate composition, the monomeric sugar content of the carbohydrate composition is at least 94% by weight, for example, at least 95% by weight.

[0037] Monomeric sugars and oligosaccharides in carbohydrate compositions can be determined qualitatively and quantitatively by high-performance liquid chromatography (HPLC) by comparison with standard samples. Examples of suitable methods can be found, for example, Sluiter, A. et al., “Determination of Sugars, Byproducts, and Degradation Products in Liquid Fraction Process Samples,” Technical Report, National Renewable Energy Laboratory, 2008, and Sluiter, A. et al., “Determination of Structural Carbohydrates and Ligninin Biomass,” Technical Report, National Renewable Energy Laboratory, 2012 revised edition.

[0038] Preferably, the carbohydrate composition is a bio-based composition. For example, the carbohydrate composition may be derived from plant-based raw materials.

[0039] More preferably, the carbohydrate composition is derived from woody raw materials, such as hardwood or softwood. Typically, woody raw materials consist essentially of cellulose, hemicellulose, lignin, and extractives. Cellulose is a polysaccharide composed of chains of glucose units. Hemicellulose contains polysaccharides such as xylan, mannan, and dextran.

[0040] Wood raw materials can be derived from, for example, pine, poplar, beech, aspen, spruce, eucalyptus, ash, oak, maple, chestnut, willow, or birch. Wood raw materials can also be any combination or mixture of these.

[0041] When woody raw materials are used as carbohydrate sources, carbohydrate compositions can be prepared by a method comprising the following steps: subjecting a woody raw material containing sawdust to at least one pretreatment to form a liquid phase and a fraction containing solid cellulose particles; and subjecting the fraction containing solid cellulose particles to enzymatic hydrolysis to form a lignin fraction and a carbohydrate fraction. The carbohydrate fraction can optionally be purified and then used as a carbohydrate composition in a catalytic hydrogenolysis process.

[0042] As used herein, "pretreating" and "pretreatment" refer to processes that convert woody raw materials into fractions containing solid cellulose particles. As a result of pretreatment, in addition to fractions containing solid cellulose particles, liquid fractions may also be formed. Liquid fractions can be separated from fractions containing solid cellulose particles. Fractions containing solid cellulose particles may also include a certain amount of lignocellulose particles and free lignin particles. Lignocellulose contains lignin chemically bound to the cellulose particles.

[0043] Wood raw materials can be provided by subjecting wood raw materials to mechanical treatments selected from debarking, slicing, splitting, cutting, beating, grinding, crushing, splitting, sieving, and / or washing to form wood raw materials. Alternatively, wood raw materials can be purchased.

[0044] Pretreatment of wood raw materials may include one or more different pretreatment processes. During these different pretreatment processes, the wood raw materials themselves undergo changes. The purpose of at least one pretreatment process is to form fractions containing solid cellulose particles for further processing.

[0045] Pretreatment may include subjecting wood raw materials to precooking. Specifically, pretreatment may include subjecting wood raw materials received from mechanical processing to precooking. Pretreatment may include impregnation and / or steam explosion, and includes subjecting the wood raw materials to precooking prior to impregnation and / or steam explosion, wherein the precooking of the wood raw materials is carried out at atmospheric pressure using steam at a temperature of 100°C-130°C. During precooking, the wood raw materials are treated with low-pressure steam. Precooking may also be carried out using steam at temperatures below 100°C, below 98°C, or below 95°C. Precooking has the additional benefit of reducing or removing air from the interior of the wood raw materials.

[0046] Precooking can be carried out in at least one precooking reactor. In one embodiment, the precooking reactor is operatively arranged before the impregnation reactor and / or the pressurization reactor, and configured to subject the wood raw material to precooking with steam at atmospheric pressure and a temperature of 100°C–130°C.

[0047] Pretreatment may also include subjecting the wood raw material to at least one impregnation treatment with an impregnation liquid. Impregnation treatment may be performed on wood raw materials received from mechanical processing and / or from pre-cooking. Pretreatment may include subjecting the wood raw material to at least one impregnation treatment with an impregnation liquid selected from water, at least one acid, at least one base, at least one alcohol, or any combination or mixture thereof, prior to steam explosion.

[0048] A feeder can be used to transfer wood feedstock from mechanical processing and / or from precooking to impregnation processing. The feeder can be a screw feeder, such as a plug screw feeder. The feeder can compress the wood feedstock during the transfer. When the wood feedstock enters the impregnation processing, it can expand and absorb the impregnation liquid.

[0049] The impregnation liquid may contain water, at least one acid, at least one base, at least one alcohol, or any combination or mixture thereof. The at least one acid may be selected from inorganic acids such as sulfuric acid (H₂SO₄), nitric acid, phosphoric acid; organic acids such as acetic acid, lactic acid, formic acid, carbonic acid, and any combination or mixture thereof. In one embodiment, the impregnation liquid contains sulfuric acid, such as dilute sulfuric acid. The concentration of the acid may be 0.3 wt%-5.0 wt%, 0.5 wt%-3.0 wt%, 0.6 wt%-2.5 wt%, 0.7 wt%-1.9 wt%, or 1.0 wt%-1.6 wt%. The impregnation liquid can be used as a catalyst for the hydrolysis of hemicellulose in woody raw materials. In one embodiment, impregnation is carried out by using only water, i.e., by self-hydrolysis. In one embodiment, the woody raw material may be impregnated by alkaline hydrolysis. NaOH and Ca₂(OH)₃ may be mentioned as examples of alkalis used in alkaline hydrolysis.

[0050] The impregnation treatment can be carried out using an impregnation reactor configured to subject the wood raw material to at least one impregnation treatment with an impregnation liquid selected from water, at least one acid, at least one alcohol, or any combination or mixture thereof. Therefore, the impregnation treatment can be carried out in at least one impregnation reactor or vessel. In one embodiment, two or more impregnation reactors are used.

[0051] The transfer from one impregnation reactor to another can be carried out using a feeder, such as a screw feeder. The feeder, together with steam, can homogenize the liquid concentration differences within the wood chips, thereby allowing the impregnation liquid to penetrate the wood chips more easily.

[0052] Impregnation can be performed by conveying the wood raw material through at least one impregnation reactor, that is, transferring the wood raw material into the impregnation reactor, dispersing it within the reactor, and transferring it out of the reactor, so that the wood raw material is homogeneously impregnated with the impregnation liquid. Impregnation can be carried out as a batch process or in a continuous manner.

[0053] The residence time of the woody material in the impregnation reactor, i.e., the time the woody material is in contact with the impregnation liquid, can be from 5 seconds to 5 minutes, or 0.5 to 3 minutes, or about 1 minute. The temperature of the impregnation liquid can be, for example, 20 to 99°C, or 40 to 95°C, or 60 to 90°C. Maintaining the temperature of the impregnation liquid below 100°C has the additional effect of inhibiting or reducing the dissolution of hemicellulose.

[0054] After impregnation, the wood material can be stored in, for example, a storage tank or silo for a predetermined period of time to allow the impregnating liquid to be absorbed and stabilized. This predetermined period of time can be 15 to 60 minutes, for example, about 30 minutes.

[0055] Pretreatment may include subjecting the wood raw material to steam explosion. As used herein, the term "steam explosion" refers to a semi-hydrolysis process in which the wood raw material is treated in a reactor with steam under conditions that cause a sudden, explosive decompression of the wood raw material, resulting in the rupture of the wood fiber structure.

[0056] Wood feedstock from mechanical processing, precooking steps, and / or impregnation treatments can undergo steam explosion. In one embodiment, preprocessing includes at least one of mechanically processing wood material to form wood feedstock, precooking of wood feedstock, impregnation treatment of wood feedstock, and steam explosion of wood feedstock. In another embodiment, preprocessing includes mechanically processing wood material to form wood feedstock, precooking of wood feedstock, impregnation treatment of wood feedstock, and steam explosion of wood feedstock. Wood feedstock can be stored, for example, in sawdust bins or silos, between different processes. Alternatively, wood feedstock can be continuously transported from one process to another.

[0057] Steam explosion can be carried out in a pressurized reactor. Steam explosion can be achieved in a pressurized reactor by treating the wood material with steam at a temperature of 130 to 240°C at a pressure of 0.17 to 3.25 MPaG, followed by a sudden explosive decompression of the wood material. The wood material can be treated with steam for, for example, 1 to 20 minutes, 2 to 16 minutes, 4 to 13 minutes, 3 to 10 minutes, or 3 to 8 minutes before the sudden explosive decompression.

[0058] Wood feedstock can be introduced into the pressure reactor using a compression conveyor, such as a screw feeder. During transport using a screw feeder, if used, a portion of the impregnation liquid absorbed by the wood feedstock is removed as pressate, while some remains in the feedstock. The wood feedstock can be introduced into the pressure reactor along with steam and / or gas. The pressure of the pressure reactor can be controlled by adding steam. The pressure reactor can be operated continuously or as a batch process.

[0059] Wood materials, such as those that have already undergone impregnation treatment, can be introduced into a pressure reactor at a temperature of 25 to 140°C. The residence time of the wood materials in the pressure reactor can be from 0.5 to 120 minutes. In this context, the term "residence time" refers to the time between the introduction or entry of the wood materials into the pressure reactor and the exit or discharge of the wood materials from the same pressure reactor.

[0060] Due to the semi-hydrolysis of woody raw materials caused by steam treatment in the reactor, the hemicellulose present in the woody raw materials can be hydrolyzed or degraded into, for example, xylose oligomers and / or monomers. Therefore, steam explosion of the woody raw materials can lead to the formation of an output stream. The output stream from the steam explosion can be steam separated. The output stream from the steam explosion can be mixed or combined with a liquid. The output stream from the steam explosion can be mixed with a liquid to form a liquid fraction and a fraction containing solid cellulose particles. The liquid can be pure water or water containing C5 sugars. The water containing C5 sugars can be recycled water from the separation and / or washing of the fraction containing solid cellulose particles prior to enzymatic hydrolysis. The output stream can be mixed with a liquid, and the resulting bulk can be mechanically homogenized to break up agglomerates.

[0061] This method may include separating and recovering a liquid fraction and a fraction containing solid cellulose particles. The separated or recovered fraction containing solid cellulose particles may be washed before undergoing enzymatic hydrolysis. The fraction containing solid cellulose particles may be diluted with water and / or other liquids containing at least soluble carbohydrates.

[0062] The above pretreatment can be performed alone or in combination. The pretreated material can then be mixed with a suitable liquid (e.g., water) to form a slurry containing solid cellulose particles. The fraction containing solid cellulose particles can be separated from the liquid fraction by a suitable separation method, such as solid-liquid separation.

[0063] Enzymatic hydrolysis of fractions containing solid cellulose particles can be carried out at temperatures of 30 to 70°C, 35 to 65°C, 40 to 60°C, 45 to 55°C, or 48 to 53°C. Enzymatic hydrolysis can be carried out at atmospheric pressure. The pH of the fractions containing solid cellulose particles can be maintained at 3.5 to 6.5, 4.0 to 6.0, or 4.5 to 5.5. The pH of the fractions containing solid cellulose particles can be adjusted by adding alkali and / or acid. Enzymatic hydrolysis can be continued for 20 to 120 hours, 30 to 90 hours, or 40 to 80 hours. Enzymatic hydrolysis can be carried out continuously, as a batch process, or as a combination of continuous and batch processes.

[0064] In one embodiment, enzymatic hydrolysis is carried out at temperatures of 30 to 70°C, 35 to 65°C, 40 to 60°C, 45 to 55°C, or 48 to 53°C while maintaining the pH of the fraction containing solid cellulose particles at a pH of 3.5 to 6.5, 4.0 to 6.0, or 4.5 to 5.5, and wherein enzymatic hydrolysis is allowed to continue for 20 to 120 hours, 30 to 90 hours, or 40 to 80 hours.

[0065] In one embodiment, enzymatic hydrolysis can be performed as a single-step hydrolysis process, wherein a fraction containing solid cellulose particles is subjected to enzymatic hydrolysis in at least one first hydrolysis reactor. Following hydrolysis, the hydrolysis products, i.e., the hydrolysate, can be separated, wherein a solid lignin fraction (which may also contain unhydrolyzed cellulose in addition to lignin) is separated from a liquid carbohydrate fraction. The single-step hydrolysis process can also be performed as a batch process, comprising, for example, multiple reactors operating in parallel, wherein each reactor can receive a portion of the fraction containing solid cellulose particles. Furthermore, separate parallel lines and parallel reactors can be used.

[0066] In one embodiment, enzymatic hydrolysis can be performed as a two-step or multi-step hydrolysis process. In a two-step or multi-step hydrolysis process, a fraction containing solid cellulose particles may first undergo a first enzymatic hydrolysis in at least one first hydrolysis reactor. The resulting liquid carbohydrate fraction, which may also contain unhydrolyzed cellulose, can then be separated from the solid lignin fraction. The solid fraction can then undergo a second or subsequent enzymatic hydrolysis, for example, in at least one second hydrolysis reactor. At least one of the first and second or any subsequent enzymatic hydrolysis can be performed as a batch process or as a continuous process comprising, for example, one or more reactors operating in parallel. After the second or any subsequent enzymatic hydrolysis, the hydrolysis products, i.e., the hydrolysate, can be separated, wherein the solid lignin fraction is separated from the liquid carbohydrate fraction.

[0067] The reaction time in the first hydrolysis reactor can be 8-72 hours. The reaction time in the second and / or any subsequent hydrolysis reactors can be 8-72 hours.

[0068] Enzymes act as catalysts for enzymatic hydrolysis. Enzymatic reactions lower the pH and may also reduce viscosity by shortening the length of cellulose fibers. Subjecting components containing solid cellulose particles to enzymatic hydrolysis results in the conversion of cellulose into sugar monomers under the action of enzymes. Lignin, present in components containing solid cellulose particles, can exist in a substantially solid form.

[0069] Enzymatic hydrolysis is performed using at least one enzyme. The at least one enzyme may be selected from cellulase, hemicellulase, laccase, and lignin peroxidase. Cellulase is a multi-protein complex composed of co-enzymes with different specific activities, and can be classified into exo- and endo-cellulases (glucanases) and β-glucosidases (cellobiases). The enzyme may be a commercially available mixture of cellulases or manufactured on-site.

[0070] Cellulose is an insoluble linear polymer of repeating glucose units linked by β-1-4-glucosidic bonds. During enzymatic hydrolysis, the cellulose chain is disrupted by breaking at least one β-1-4-glucosidic bond.

[0071] Enzymatic hydrolysis may result in the formation of lignin and carbohydrate fractions. In one embodiment, the lignin fraction is in solid form. In another embodiment, the carbohydrate fraction is in liquid form. The formed lignin and carbohydrate fractions can be separated and recovered prior to catalytic conversion.

[0072] Separation during the preparation process can be achieved through filtration and / or centrifugation. Filtration can be vacuum filtration, filtration based on negative pressure, filtration based on positive pressure, or pressurized filtration.

[0073] The carbohydrate fraction recovered from enzymatic hydrolysis can be purified. Purification of the carbohydrate fraction can be carried out using at least one of the following methods: membrane filtration, crystallization, sterilization, pasteurization, evaporation, chromatography, ion exchange, and charcoal filtration. Purification of the carbohydrate fraction has the added benefit of providing the desired target mass of sugars.

[0074] While the preferred carbohydrate composition is derived from woody raw materials, it should be understood that sugars from other sources can also be used in the catalytic hydrogenolysis process. For example, a carbohydrate composition derived from corn starch can be used.

[0075] As described above, the catalytic conversion process involves contacting a carbohydrate composition with hydrogen in a reactor under certain conditions in the presence of water and a catalyst, thereby subjecting the carbohydrate composition to catalytic hydrogenolysis to produce an aqueous mixture comprising monopropylene glycol, monoethylene glycol, and 2,3-pentanediol.

[0076] Catalytic conversion can be carried out in the presence of a catalyst system comprising one or more catalysts. In one embodiment, the catalyst system comprises or is composed of a first catalyst. In one embodiment, the catalyst system comprises or is composed of at least a first catalyst and at least a second catalyst. In one embodiment, the catalyst system comprises or is composed of at least a first catalyst and at least a second catalyst. The first catalyst may be a heterogeneous solid catalyst. The second catalyst may be a homogeneous catalyst. In one embodiment, the first and second catalysts may be heterogeneous catalysts, for example, supported on a support.

[0077] The first catalyst may contain an active metal component selected from Groups 8, 9, or 10 of the IUPAC periodic table, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum, or mixtures thereof. In one embodiment, the first catalyst comprises or is composed of a heterogeneous Ni alloy (e.g., Raney nickel). The active metal component of the first catalyst may be supported on a support comprising activated carbon, alumina, silica, silicon carbide, zirconium oxide, zinc oxide, titanium dioxide, or mixtures thereof. The active metal component of the first catalyst may account for 0.05-70% by weight of the total catalyst weight.

[0078] The second catalyst may contain at least one active component selected from tungsten oxide, tungsten sulfide, tungsten hydroxide, tungsten bronze oxide, tungstic acid, tungstate, metatungstic acid, metatungstate, paratungstic acid, paratungstate, peroxytungstic acid, peroxytungstate, and tungsten-containing heteropolyacids. In one embodiment, the second catalyst comprises or is composed of homogeneous sodium tungstate.

[0079] The first catalyst is effective in hydrogenation. The second catalyst is effective in cracking (also known as reverse aldol condensation).

[0080] In one embodiment, the second catalyst is a homogeneous catalyst and the second catalyst can be recovered, purified, and recycled for reuse in catalytic conversion.

[0081] The catalytic conversion can be carried out at temperatures of 120-300℃, 180-270℃, or 230-270℃. The initial pressure at room temperature can be 1-15 MPa or 9-12.5 MPa. The catalytic conversion can be carried out continuously. The time for subjecting the feedstock to catalytic conversion can be 5 minutes to 3 hours, preferably 30 minutes to 2.5 hours.

[0082] Catalytic conversion can be carried out in a conversion reactor, such as a fixed-bed or slurry reactor. Catalytic conversion can be performed as a slurry reaction. Hydrogen and the feedstock can be added to the reactor individually or as a combined feed. A second catalyst, present in liquid form, can be added to the reactor separately or together with the feedstock. The first catalyst can be provided to the reactor separately from the feedstock, preferably before the feedstock is fed into the reactor. Liquid and gaseous reaction products can be removed from the reactor. The reaction products can be cooled and depressurized. After depressurization, the gaseous products can be directed to a gas / liquid separator to separate the desired liquid product.

[0083] Catalytic conversion leads to hydrogenolysis of the carbohydrate composition, resulting in an aqueous mixture comprising monopropylene glycol, monoethylene glycol, and 2,3-pentanediol. The aqueous mixture may also contain other glycols, such as 1,2-butanediol and 2,3-butanediol.

[0084] The aqueous mixture is then subjected to a distillation process, which removes a portion of the monoethylene glycol from the aqueous mixture, thereby forming a first fraction containing monopropylene glycol and 2,3-pentanediol and a second fraction containing purified monoethylene glycol.

[0085] The aqueous mixture is distilled in at least one distillation column. The aqueous mixture can be fed into the distillation column in liquid form or as steam or a mixture thereof. The purified monoethylene glycol can be removed from the distillation column as a side stream, preferably from the bottom of the column, while the fraction containing monopropylene glycol and 2,3-pentanediol, which is the top stream, can be recovered from the distillation column.

[0086] The distillation of this aqueous mixture can be carried out at temperatures ranging from 50 to 250°C, for example, 100 to 200°C. Distillation can be carried out at pressures of at least 0.1 kPa, at least 10 kPa, or at least 50 kPa. Pressures can be up to 400 kPa, up to 200 kPa, or up to 120 kPa. Those skilled in the art will understand how to vary the temperature and pressure in relation to each other to achieve suitable conditions.

[0087] The composition of the present invention can be recovered from the first fraction by subjecting the first fraction to a distillation process.

[0088] Preferably, the composition of the present invention is recovered from the first fraction by a distillation process including the following steps:

[0089] - The first fraction is introduced as a mixture feed into a first distillation column having 20-200 theoretical stages, where the first distillation process is carried out;

[0090] - A distillation solvent is introduced into the first distillation column, wherein the distillation solvent is a diol or sugar alcohol having a boiling point at least 80°C higher than that of monopropylene glycol at atmospheric pressure, and wherein the weight ratio of the distillation solvent to the total mixture feed is 2.5:1-10:1;

[0091] - The feed mixture is purified by a first distillation process using a distillation solvent at a top temperature of 70-140°C and a top pressure of 0.01-0.2 bar, with a reflux ratio of 2-50; and

[0092] - Recycle the composition of the present invention.

[0093] Distillation is generally considered a process of separating components or substances from a mixture through selective boiling and condensation. Distillation can result in substantially complete separation into near-pure components, or it can be a partial separation that increases the concentration of selected components in the mixture. The distillation process utilizes the differences in relative volatility between the different components in the mixture.

[0094] A "theoretical level," "theoretical plate," or "distillation level" can also be called a hypothetical region or level in which two phases (e.g., the liquid and gas phases of a substance) are in equilibrium with each other. Such an equilibrium level can also be called an equilibrium level, an ideal level, or a theoretical plate.

[0095] The performance of many separation processes depends on having a series of equilibrium stages and can be enhanced by providing more of these stages. In other words, having more theoretical plates increases the efficiency of a separation process, whether it is distillation, absorption, chromatography, adsorption, or similar processes.

[0096] When designing the distillation of certain media, the number of theoretical stages is usually designed or considered first, and then the theoretical stages define the physical height of the distillation column. In a distillation column, the theoretical stages, or distillation classes, can be formed by trays or packing, also known as a packed bed. A packed bed can be a structured packed bed or a random packed bed.

[0097] A combination of a specified number of theoretical stages and a specified reflux ratio, along with a specified amount of distillation solvent, achieves efficient separation of monopropylene glycol from the mixed feed.

[0098] The first stage (hereinafter referred to as the "mixture feed") may be fed into the first distillation column in liquid form or as steam or vapor or as any mixture thereof.

[0099] Prior to the distillation process, one or more separation or purification processes may occur. For example, water, alcohols (e.g., methanol and ethanol), organic acids, sugar alcohols (e.g., glycerol), catalysts, and residual sugars may be removed in separate steps in a desired order. Typically, water and alcohols with the lowest boiling points are removed first, followed by components with boiling points higher than monoethylene glycol. The remaining components may consist primarily of diols with boiling points close to monopropylene glycol, which can then be separated in further purification steps.

[0100] The first distillation process is carried out in the first distillation column, in which the distillation solvent is fed to help or assist in the separation of the desired components from the mixture feed.

[0101] The distillation solvent is a diol or sugar alcohol having a boiling point at least 80°C higher than that of monopropylene glycol at atmospheric pressure. The distillation solvent may have a boiling point at least 85°C or at least 90°C higher than that of monopropylene glycol at atmospheric pressure. The distillation solvent may have a boiling point 80-100°C, 82-98°C, or 85-95°C higher than that of monopropylene glycol at atmospheric pressure. The distillation solvent may have a boiling point of 265-350°C, 265-300°C, or 275-300°C. In one embodiment, the distillation solvent is a diol having a boiling point at least 80°C higher than that of monopropylene glycol at atmospheric pressure.

[0102] In one embodiment, the distillation solvent is a sugar alcohol having a boiling point at least 80°C higher than that of monopropylene glycol at atmospheric pressure.

[0103] In one embodiment, the weight ratio of distillation solvent to total mixture feed is 5:1 to 8:1. The specified amount of distillation solvent used during the distillation process effectively aids in the separation.

[0104] In one embodiment, the distillation solvent is triethylene glycol or tripropylene glycol. In one embodiment, the distillation solvent is triethylene glycol.

[0105] The distillation solvent used has the added benefit of a boiling point higher than that of monopropylene glycol and also higher than that of other diols in the mixed feed. Therefore, the distillation solvent used may not boil in the first distillation column, and even with a large amount of distillation solvent used, the vapor flow in the first distillation column will not increase. Therefore, due to the amount of distillation solvent used, the column size does not need to be significantly increased.

[0106] The first distillation column may contain 20-200, 40-120, 40-80, or 60-120 theoretical stages. A number of 20-200 theoretical stages has the added benefit of enabling separation with fairly high efficiency, allowing for the use of reasonable reflux ratios.

[0107] The mixture can be introduced into the first distillation column at a point lower than the point at which the distillation solvent is introduced into the first distillation column.

[0108] The feed mixture can be introduced into the first distillation column at a point located between two theoretical stages. The distillation column may contain packing or a packed bed, one of which contains two or more theoretical stages. In such a case, the feed mixture can be introduced into the distillation column at a point located between two such packed beds.

[0109] The mixture feed can be introduced into the first distillation column at a point located below, above, or on at least one theoretical stage. When using a plate as the theoretical stage, the mixture feed can be introduced on or above the theoretical stage.

[0110] In one embodiment, the distillation solvent is introduced into the first distillation column at any point between theoretical stages 1-10, 2-9, or 3-7, calculated from the top of the first distillation column. The distillation solvent may be introduced into the first distillation column above the uppermost theoretical stage, calculated from the top of the first distillation column.

[0111] In one embodiment, the first distillation process is carried out with a reflux ratio of 3-40, 4-30, 5-20, or 6-10. The reflux ratio can generally be defined as the ratio of the liquid returned to the top of the distillation column to the liquid removed or recovered as product from the distillation column.

[0112] In one embodiment, the first distillation process is carried out at a top temperature of 75-135°C, or 90-130°C, or 100-120°C.

[0113] In one embodiment, the first distillation process is carried out at a bottom temperature of 150-230°C, or 160-200°C, or 170-190°C.

[0114] In one embodiment, the first distillation process is carried out at a top pressure of 0.01 to 0.2 bar, or 0.015 to 0.1 bar, or 0.02 to 0.1 bar.

[0115] In one embodiment, the pressure drop on the distillation column is 0.05 to 0.2 bar, or 0.07 to 0.15 bar, or 0.08 to 0.1 bar.

[0116] In one embodiment, the residence time of the mixed feed and distillation solvent in the first distillation column is 1 to 10 minutes, or 1.2 to 7 minutes, or 1.5 to 6 minutes, or 1.8 to 5.4 minutes.

[0117] The bottom temperature of the first distillation column can be maintained at a maximum of 230°C. Maintaining the bottom temperature of the distillation column at a maximum of 230°C has the additional effect of inhibiting or reducing the degradation of compounds.

[0118] As used herein, the term "top temperature" refers to the temperature of the vapor space located above the uppermost packed bed or stage in a distillation column and below the vapor tubes of the distillation column. Those skilled in the art will appreciate that the temperature within a distillation column may differ, for example, from the temperature in a condenser or reboiler operatively connected to the distillation column.

[0119] The term "bottom temperature" used in this article refers to the temperature of the liquid at the bottom of the column.

[0120] The term "top pressure" as used in this article refers to the pressure in the vapor space above the uppermost packed bed or stage and below the vapor tubes of the distillation column.

[0121] In one embodiment, at least one condenser is used in the distillation process. In one embodiment, the distillation apparatus includes at least one condenser. The condenser used may be a partial condenser, a total condenser, or a combination thereof. The condensers may be thermally integrated or they may use a cooling medium, such as cooling water, or they may operate using air cooling.

[0122] In one embodiment, a reboiler is used during the distillation process. In another embodiment, the distillation apparatus includes a reboiler. The reboiler can operate at a vapor pressure of 0.06 to 0.4 bar, or 0.1 to 0.2 bar.

[0123] In one implementation, the method includes:

[0124] - Remove impurities and distillation solvent from the bottom stream of the first distillation column; and

[0125] - Remove monopropylene glycol and 2,3-pentanediol from the top stream of the first distillation column.

[0126] In one embodiment, the method includes recycling the distillation solvent removed from the bottom stream of the first distillation process back into the first distillation column. The distillation solvent can then be directed from the first distillation column to a recovery column. In the recovery column, lighter components can be removed in the top stream from the recovery column, and the distillation solvent can be removed in the bottom stream from the recovery column. The bottom stream, primarily containing the distillation solvent, can then be directed back into the first distillation column and thus reused. If desired, a portion of the recycled distillation solvent stream can be continuously discharged to reduce or limit the accumulation of heavier degradation compounds (if these occur).

[0127] In one embodiment, the method includes providing monopropylene glycol and 2,3-pentanediol removed from the top stream of the first distillation process to a second distillation column, wherein the second distillation process is carried out.

[0128] Preferably, the method includes providing monopropylene glycol and 2,3-pentanediol removed from the top stream of the first distillation process to a second distillation column, wherein a second distillation process is carried out to recover the composition of the present invention.

[0129] In one embodiment, the second distillation process is carried out at a top temperature of 104 to 140°C, or 90 to 130°C, or 100 to 120°C.

[0130] In one embodiment, the second distillation process is carried out at a bottom temperature of 134 to 170°C, or 145 to 165°C, or 150 to 160°C.

[0131] In one embodiment, the second distillation process is carried out at a top pressure of 0.1 to 0.5 bar.

[0132] In one implementation, the second distillation process is carried out at a bottom pressure of 0.15 to 0.6 bar.

[0133] As a result of the second distillation process, the composition of the present invention can be recovered as a bottom stream or as a side stream in the stripping section. The top stream containing a mixture of 2,3-butanediol with water and light components can also be recovered.

[0134] In another aspect, the present invention provides a composition comprising at least 98.0% by weight of monopropylene glycol and 2,3-pentanediol; wherein the composition may be obtained by the preparation method described herein.

[0135] Performance and Applications

[0136] The compositions of the present invention exhibit desirable properties and can be used in a variety of applications. Specifically, the bio-based compositions described herein can be used as a low-carbon footprint alternative to fossil-based monopropylene glycol compositions.

[0137] The compositions of the present invention are liquid compositions. Specifically, these compositions are liquid at standard ambient temperature and pressure (1.013 bar, 25°C).

[0138] These compositions are particularly suitable for the manufacture of polymers. For example, polyesters are typically prepared by the condensation polymerization of diols with dicarboxylic acids or their derivatives, while polyurethanes are typically prepared by reacting diols with diisocyanates. Therefore, the compositions of the present invention can be used as a source of diol monomers for the preparation of these and other polymers. Due to the specific diols present in the compositions, the resulting polymers can have characteristic structures and properties.

[0139] Therefore, one aspect of the invention relates to the use of the compositions of the invention in polymer manufacturing. A method for manufacturing a polymer is also provided, involving the use of the compositions of the invention as starting materials. This method may include contacting the compositions of the invention with one or more other monomers under conditions that result in the formation of a polymer comprising a diol monomer. The polymer is preferably a polyester or polyurethane.

[0140] The compositions of the present invention have been found to exhibit desirable electrical conductivity, which may be advantageous for their use in polymer preparation. In this regard, it is known that the mechanical properties and processability of polyesters are affected by the electrical conductivity of the glycol monomer composition (e.g., as discussed in EP2679615A1).

[0141] Preferably, the composition has a conductivity of less than 0.01 μS / cm, more preferably less than 0.002 μS / cm, and even more preferably less than 0.001 μS / cm. The conductivity can be measured using a conductivity meter such as the SevenExcellence S700 (Mettler Toledo). The conductivity is measured at a temperature of 25°C.

[0142] This composition can also be used in other applications. For example, it can be used in coolants and heat transfer fluids, de-icing agents, food products, pharmaceutical compositions, cosmetic compositions, and detergent compositions. The low electrical conductivity of this composition makes it particularly suitable for fluids used in cooling systems, such as those used in data centers, electronic equipment, and industrial machinery, for which it is important to minimize the risk of electrical damage to sensitive components and circuits.

[0143] The present invention is further illustrated by the following embodiments, which are for illustrative purposes only. These embodiments should not be construed as limiting the scope or content of the invention in any way.

[0144] Example

[0145] Example 1

[0146] Gas chromatography (GC) can be used to quantify the various diol compounds present in the compositions disclosed in this invention. Suitable methods are described in more detail below. Moisture content was determined according to ASTM E1064.

[0147] GC was performed according to ASTM E2409, using the relative response factor (RRF) to determine the wt% amount of the component. Measurements were performed using the TRACE1310 GC basic model (Thermo Fisher), with the following settings:

[0148]

[0149] The amount of each component in the composition was determined using a chromatogram as an area percentage (Ar.%). To calculate the wt% of each component, the corresponding RRF value was applied using the following equation:

[0150]

[0151]

[0152] The table below provides the retention time (RT), relative retention time (RRT; relative to monopropylene glycol), and RRF value (using an RRF value of 1 for any unknown component) for selected components:

[0153]

[0154] In contrast to the other diol components listed above, extensive studies were required to determine the presence of 2,3-pentanediol in the composition. GC-MS analysis revealed two unknown peaks, and a database search indicated they were most likely attributable to 1-methoxy-butanol. However, this compound was ruled out based on its retention time. Since attempts to separate the unknown component by extractive distillation were unsuccessful, intermittent distillation was used to produce a sample solution containing an increased concentration of the unknown component. This sample solution was then analyzed using one-dimensional and two-dimensional ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS), with 2D-UHPLC-MS analysis performed using a "multiple heart-cutting" technique. The most probable molecular weight of the unknown component was determined to be 104.15 g / mol. This led to various possible structures, including pentanediol isomers and methylbutanediol isomers. Four possible pentanediol isomer standards (1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, and 1,5-pentanediol) were ruled out based on their retention times. Then, another pentanediol (2,3-pentanediol) and three different methylbutanediol standards (3-methyl-1,3-butanediol, 2-methyl-1,3-butanediol, and 2-methyl-1,4-butanediol) were evaluated. Methylbutanediol compounds were excluded based on their retention times or because their intensities in the mass spectra differed from those of the sample solutions. However, for 2,3-pentanediol, the retention time and mass spectra were consistent with those of the sample solutions. Spiking with the standard solutions also resulted in an increase in the peak area of ​​the sample solutions. As a result of these extensive studies, it can be concluded that the unknown component is 2,3-pentanediol.

[0155] Example 2

[0156] A carbohydrate composition derived from corn starch was subjected to a catalytic hydrogenolysis process as described herein. This carbohydrate composition primarily (>89% by weight) contained glucose, with minor amounts of xylose, galactose, arabinose, mannose, and fructose. The reaction produced an aqueous diol mixture containing monopropylene glycol, monoethylene glycol, 1,2-butanediol, and 2,3-pentanediol. This aqueous mixture was then subjected to a distillation process to remove some of the monoethylene glycol and water, as well as the co-catalyst and heavy components. The resulting diol mixture was recovered as a distillate.

[0157] The sample of the diol mixture was analyzed using the method described in Example 1. The composition of the sample was determined as follows:

[0158]

[0159] Example 3

[0160] The raw material containing hardwood chips was pretreated and then subjected to an enzymatic hydrolysis process as described herein to produce a carbohydrate composition. Analysis of a sample of this carbohydrate composition revealed that it was predominantly (>89% by weight) glucose, with minor amounts of xylose, galactose, arabinose, mannose, and fructose.

[0161] The carbohydrate composition is subjected to catalytic hydrogenolysis as described herein to produce an aqueous glycol mixture comprising monopropylene glycol, monoethylene glycol, 1,2-butanediol, and 2,3-pentanediol. This aqueous mixture is then subjected to a distillation process to remove some of the monoethylene glycol and water, as well as the co-catalyst and heavy components. The resulting glycol mixture is recovered as the distillate.

[0162] The sample of the diol mixture was analyzed using the method described in Example 1. The sample was found to have the following composition:

[0163]

[0164] Example 4

[0165] The diol mixture was prepared as described in Example 2 and then subjected to a distillation process to produce the diol composition of the present invention.

[0166] The distillation process is carried out in two steps. The first step is an extractive distillation step, in which monoethylene glycol and other high-boiling components are primarily removed to the bottom product. The extractant used in the first step contains 99.4 wt% triethylene glycol (TEG), 0.5 wt% diethylene glycol, and 0.1 wt% water. In the second step, the distillate from the first step is further processed, and low-boiling components are removed as a distillate. The final product is separated into side streams.

[0167] The two-step experiment was conducted on a distillation column with an inner diameter of 250 mm and structured packing as internal components. For the first distillation step, the column was equipped with 3.86 m of structured packing below the feed position. Additionally, 3.54 m of structured packing was installed between the feed and TEG feed positions. An additional 0.96 m of structured packing was used above the TEG feed position. For the second distillation step, the column was equipped with 3.54 m of structured packing below the feed position and 2.57 m of structured packing above the feed position. The liquid sidestream product was collected 1.12 m above the bottom container. CYPlus was used in all cases. TM Structured packing.

[0168] The first distillation step is carried out under the following conditions:

[0169]

[0170] Monoethylene glycol was removed to the bottom product and the concentration of monoethylene glycol in all distillate samples was <1 wt%.

[0171] The second distillation step is carried out under the following conditions:

[0172]

[0173] The sample containing the obtained product was analyzed using the method described in Example 1. The sample was found to have the following composition:

[0174]

[0175] Example 5

[0176] The various physical and chemical properties of the product of Example 4 and the fossil-based monopropylene glycol composition (≥99.5% MPG; obtained from Carl Roth GmbH & Co. KG) were evaluated. A comparison of their properties is shown in the table below:

[0177]

[0178] The product of Example 4 exhibits the desired combination of properties. In particular, it exhibits the desired electrical conductivity compared to fossil-based compositions.

[0179] All publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference in their entirety. Furthermore, the materials, methods, and examples given are illustrative only and not restrictive.

[0180] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0181] It should be understood that although this disclosure has been described in conjunction with its detailed description, the foregoing description is intended to illustrate and not limit the scope of the invention as defined by the appended claims. Other aspects, advantages, and modifications are within the scope of the claims.

Claims

1. A composition comprising: Propylene glycol, wherein the amount of said propylene glycol is at least 98.0% by weight of the composition; and 2,3-Pentanediol.

2. The composition of claim 1, wherein the composition comprises monopropylene glycol in an amount of at least 98.1%, at least 98.2%, at least 98.3%, at least 98.4%, or at least 98.5% by weight of the composition.

3. The composition according to claim 1 or claim 2, wherein the composition comprises 2,3-pentanediol in an amount from 0.1% to 2.0% by weight of the composition.

4. The composition of claim 3, wherein the composition comprises 2,3-pentanediol in an amount from 0.1% to 1.5% by weight of the composition.

5. The composition according to any one of the preceding claims, wherein the composition further comprises 1,2-butanediol.

6. The composition of claim 5, wherein the composition comprises 1,2-butanediol in an amount from 0.1% to 0.5% by weight of the composition.

7. The composition of claim 1, wherein the composition comprises: Monopropylene glycol, wherein the amount of said monopropylene glycol is based on at least 98.0% by weight of the composition; 2,3-Pentanediol, wherein the amount of 2,3-pentanediol is from 0.1% to 1.5% by weight of the composition; and 1,2-Butanediol, wherein the amount of 1,2-butanediol used is from 0.1% to 0.5% by weight of the composition.

8. The composition according to any one of the preceding claims, wherein the composition further comprises 2,3-butanediol.

9. The composition of claim 8, wherein the composition comprises 2,3-butanediol in an amount from 0.001% to 0.5% by weight of the composition.

10. The composition according to any one of the preceding claims, wherein the composition contains less than 0.2% water by weight of the composition.

11. The composition according to any one of the preceding claims, wherein the composition is a bio-based composition.

12. The composition according to claim 11, wherein the composition is prepared from wood raw materials.

13. The composition according to any one of the preceding claims, wherein the composition has a conductivity of less than 0.002 μS / cm.

14. Use of the composition of any of the preceding claims in the manufacture of polymers.

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