Process for extracting acrylic acid from an aqueous product

Abstract

The present technology provides a process for extracting acrylic acid from an aqueous feedstock that includes acrylic acid and one or more byproducts from catalytic dehydration of lactic acid to acrylic acid (e.g., acetol and / or 2,3-pentanedione), where the process steps include: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; and removing the extractant from the solvent phase to obtain an extraction product, where the extractant is water-immiscible and has a distribution coefficient for acrylic acid (Kd, acrylic acid) from about 1.2 to about 10.0 (weight basis).

Description

PROCESS FOR EXTRACTING ACRYLIC ACID FROM AN AQUEOUS PRODUCTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 510.177, filed June 26, 2023, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The present technology relates to a process for extracting acrylic acid from an aqueous feedstock. In particular, the present technology relates to the liquid-liquid extraction of acrylic acid from an aqueous feedstock obtained from the dehydration of lactic acid.SUMMARY

[0003] In an aspect, the present technology provides a process for extracting acrylic acid from an aqueous feedstock that includes acrylic acid and at least one of acetol or 2.3 -pentanedione, where the process steps include contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; and removing the extractant from the solvent phase to obtain an extraction product comprising acrylic acid, where the extractant is water-immiscible and has a distribution coefficient for acrylic acid (Kd, acrylic acid) from about 1.2 to about 10.0 (weight basis). The aqueous feedstock may further include one or more of acetic acid, acetaldehyde, and / or propionic acid. In one example, the extractant has an acrylic acid selectivity of 1.2 to about 50.0, preferably 1.2 to about 40.0, compared to acetol, optionally further compared to acetaldehyde, and / or acetic acid. In another example, the extractant has an acrylic acid selectivity of 0.2 to 2.0 over 2,3 -pentanedione, optionally further compared to propionic acid.

[0004] In some aspects, the process as described herein in any aspect may be a process for producing acrylic acid, where the process further includes converting lactic acid to acrylic acid to obtain the aqueous feedstock prior to extracting the acrylic acid from the aqueous feedstock.

[0005] In other aspects, the present disclosure describes use of an extractant for liquid-liquid extraction of acrylic acid from an aqueous feedstock as described herein in any aspect.DETAILED DESCRIPTION

[0006] Reference will now be made in detail to certain embodiments of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumeratedclaims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter. One aspect described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment(s).

[0007] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%’" or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g, 1%, 2%, 3%, and 4%) and the sub-ranges (e.g, 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z. unless indicated otherwise.

[0008] As used herein, the singular forms "a." "an," and "the" and similar referents in the context of describing the elements (especially in the context of the following claims) include plural referents unless the context clearly dictates otherwise. For example, reference to "a substituent" encompasses a single substituent as well as two or more substituents, and the like. It is understood that any term in the singular may include its plural counterpart and vice versa, unless otherwise indicated herein or clearly contradicted by context.

[0009] Nothing in the cited references teaches or suggests the claimed process. In addition, it is to be understood that the phraseology or terminology' employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

[0010] As used herein, the terms "for example," "for instance," "such as," or "including" are meant to introduce examples that further clarify more general subject matter. Unless otherwise specified, these examples are provided only as an aid for understanding the applications illustrated in the present disclosure and are not meant to be limiting in any fashion.

[0011] In the process and / or methods described herein, the acts can be carried out in a specific order as recited herein. Alternatively, in any embodiment disclosed herein, specific acts may be carried out any order without departing from the principles of the disclosure, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. Forexample, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0012] The term ‘"about” as used herein can allow for a degree of variability in a value or range, for example, plus or minus within 10%. within 5%. or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.

[0013] The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

[0014] As used herein, the following terms have the following meanings unless expressly stated to the contrary'.

[0015] As used herein, the term “liquid-liquid extraction” or “solvent extraction” refers to a process for separating a dissolved component (or solute) from a first solvent by transfer to a second solvent, where the second solvent is immiscible with the first solvent and has a higher affinity for the dissolved component (or solute). Stevens, G. et al., Extraction, Liquid-Liquid, Kirk-Othmer Encyclopedia of Chemical Technology7, 2018, pp. 1-60.

[0016] As used herein, the term “solvent-to-feed ratio” or “S / F” refers to the proportion of the organic solvent utilized in an extraction relative to the amount of aqueous material being treated. As used in the present disclosure, the S / F is a weight basis ratio.

[0017] As used herein, the term “extract” refers to the solvent phase (or organic solvent phase) after contacting the aqueous feedstock or raffinate with the extractant.

[0018] As used herein, the term “extractant” refers to the solvent or mixture of solvents as described herein in any aspect used for extracting acrylic acid from the aqueous feedstock or raffinate. The extractant as described herein is water-immiscible, meaning it does not form a homogenous mixture with water and forms two phases when mixed with water or an aqueous solution.

[0019] As used herein, the term “raffinate” refers to the aqueous phase obtained following contacting the aqueous feedstock with the extractant (i.e., organic polar solvent). Typically, the aqueous phase obtained during each stage of the extraction following first contacting the extractant with the aqueous feedstock is referred to as the raffinate.

[0020] An important consideration when determining the efficacy of an extractive solvent or process is the distribution coefficient (Ka), which can be calculated based on the ratio of the concentration of solute in the extract (i.e., solvent phase) over the concentration of the solute inthe raffinate. Kd indicates the affinity for the solute of interest between the two phases. Typically, a threshold value of > 1.2 represents a greater affinity of a solute for the solvent phase. The solute in extract and solute in water are calculated on a weight basis according to the following equation:[Solute] in ExtractKd [Solute] in Water

[0021] The masses of the other byproducts, other than the byproducts mentioned above, have been excluded from this calculation.

[0022] As described herein, when the solute of interest is acrylic acid, the distribution coefficient is represented as Kd, acrylic acid. Accordingly, the Kd, acrylic acid represents acrylic acid (AA) in extract (i.e., solvent phase) and acrylic acid (AA) in water (raffinate) is calculated on a weight basis according to the following equation: K _ [LAA]J_ in Extract[AA]in Water

[0023] As used herein, the term ‘'selectivity” or '‘separation factor” refers to the relationship between the organic solvent (or extractant) and solute of interest (acrylic acid) relative to other solutes (i.e., reaction byproducts (e.g., acetic acid, acetol, acetaldehyde, 2,3 -pentanedione, propionic acid or lactic acid) present in the aqueous feedstock and / or raffinate. Selectivity can be calculated according to the following equation:

[0024] Without being bound by any particular theory, it is believed that the higher the selectivity, the greater the preference the extractant has for extracting acrylic acid over the other solute. When there are multiple byproducts in the aqueous feedstock, a high selectivity value indicates that other reaction byproducts will be less likely to partition into the solvent phase.

[0025] Acrylic acid is an important intermediate and has a variety of uses in the chemical industry. For example, polymerized acrylic acid is used in the manufacture of polishes, detergents, paints, medical products, and absorbent materials. The most widely practiced process for manufacturing acrylic acid is by the oxidation of propylene, a petrochemical process that contributes to greenhouse gas emissions. Bauer, W., Jr., Acrylic Acid and Derivatives, Kirk- Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, Inc., 5thEd., pp.342-369. In order to respond to the growing demand for sustainable processes, the industry has sought to produce acrylic acid from a renewable resource. Lactic acid, such as bio-based lactic acid (naturally produced) or lactic acid obtained by chemical synthesis (Datta. R.. Hydroxy carboxylic Acids. In Kirk-Othmer Encyclopedia of Chemical Technology, 2004, pp. 1-12), aud its derivativescan be converted to acrylic acid via a highly selective catalytic dehydration reaction. For example, dehydration of lactic acid (particularly bio-based lactic acid) to acrylic acid has been described in U.S. Patent Nos. 2,859,240; 4,729,978; 4,786,756; 8,884,050; 9,422,222; 9,452,967; 9,505,697; 9,714,208; 9,809,527; 9,828,325; 9,926,256; 10,717,070; 10,723,688; 10,544.082; U.S. Pat. Appl. Publ. 20170157597; International (PCT) Pat. Appl. Publ. W02015016217; W02022109054; each of which are incorporated herein by reference in their entirety.

[0026] Dehydration of lactic acid results in an aqueous product containing acry lic acid and other organic byproducts. Xiaobo, X. et al. , Advances in the Research and Development of Acrylic Acid Production from Biomass, Chinese J. Chem. Eng., 2006, 14(4), pp. 419-427. Unlike crude acrylic acid products obtained via petrochemical routes, the presence of the combination of other organic byproducts, such as acetaldehyde, acetol (or hydroxyacetone), acetic acid, 2,3- pentanedione, and propionic acid, in the crude lactic acid dehydration product presents additional challenges in extracting and purifying the acrylic acid product. In particular, the presence of acetol and / or 2.3-pentanedione as byproducts. When lactic acid and other reaction byproducts partition into the solvent phase of the extraction matrix, they pose significant challenges in the downstream purification of acrylic acid. For example, the crude acrylic acid product obtained from dehydration of lactic acid must be purified for industrial use, particularly for use in the manufacture of super absorbent polymers. Liquid-liquid extraction (LLE) is one route for isolating acrylic acid from the crude aqueous product obtained from dehydration of lactic acid. The isolated acrylic acid may undergo further purification, including but not limited to, distillation and crystallization.

[0027] Although LLE has been utilized in extracting acry lic acid obtained in petrochemical processes, the present inventors have discovered a process for extracting acrylic acid from an aqueous feedstock containing acrylic acid and other byproducts obtained from dehydration of lactic acid.

[0028] In an aspect, the present technology' provides a process for extracting acrylic acid from an aqueous feedstock that includes acry lic acid and acetol and / or 2,3-pentanedione, where the process steps include: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; and removing the extractant from the solvent phase to obtain an extraction product comprising acrylic acid.where the extractant is water-immiscible and has a distribution coefficient for acrylic acid (Kd, from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0.

[0029] The aqueous feedstock may further include one or more of acetic acid, acetaldehyde, or propionic acid.

[0030] The process includes an aqueous feedstock that is a reaction product from dehydration of lactic acid. In any aspect of the disclosure, the aqueous feedstock obtained from dehydration of lactic acid may be a mixture of acrylic acid and other byproducts as described herein. For example, the aqueous feedstock may include acrylic acid and acetol in combination with acetaldehyde, acetic acid, optionally lactic acid, or mixtures thereof. In another example, the aqueous feedstock may include acrylic acid and 2,3-pentanedione in combination with propionic acid, optionally lactic acid, or mixtures thereof. In yet another example, the aqueous feedstock may include acrylic acid, acetol, and 2,3-pentanedione in combination with one or more of acetaldehyde, acetic acid, propionic acid, optionally lactic acid, or mixtures thereof.

[0031] The process for extracting acrylic acid from an aqueous feedstock as described herein in any aspect includes extractants having an acrylic acid selectivity over byproducts from dehydration of lactic acid.

[0032] In the present disclosure, the process may include extracting acrylic acid from an aqueous feedstock that includes acrylic acid and acetol where the process includes: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product comprising acrylic acid; wherein: the extractant is water-immiscible and has a Ka,from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0, and the extractant has an acrylic acid selectivity of 1.2 to about 50.0. preferably 1.2 to about 40.0, compared to acetol. The aqueous feedstock may further include acetaldehyde, acetic acid, and optionally lactic acid, where the extractant has an acrylic acid selectivity7of 1.2 to about 50.0, preferably 1.2 to about 40.0, compared to acetol, acetaldehyde, and / or acetic acid.

[0033] In the present disclosure, the process may include extracting acrylic acid from an aqueous feedstock that includes acrylic acid and 2,3-pentandione, where the process includes:contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product comprising acrylic acid; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (Ka, acrylic acid) from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of 0.2 to 2.0 compared to 2,3 -pentanedione. The aqueous feedstock may further include propionic acid and optionally lactic acid, where the extractant has an acrylic acid selectivity of 0.2 to 2.0 compared to 2,3-pentanedione and / or propionic acid.

[0034] The process as described herein in any aspect includes an extractant, where the extractant is a water-immiscible solvent, preferably a water-immiscible organic solvent, more preferably a water-immiscible polar organic solvent. Suitable extractants may be an oxygencontaining polar organic solvent having a molecular weight in range of about 40 g / mol to about 400 g / mol, preferably about 40 g / mol to about 350 g / mol, more preferably about 50 g / mol to about 300 g / mol. even more preferably about 70 g / mol to about 200 g / mol. For example, the oxygencontaining polar organic solvent having a molecular weight in a range of about 40 g / mol to about 400 g / mol may be selected from C2-C12 esters, C2-C 12 ethers, C2-C12 ketones, C2-C12 alcohols, C2-C12 carboxylic acids, or mixtures thereof, preferably selected from C2-C12 ethers, C2-C12 ketones, C2-C12 esters, or mixtures thereof. For clarity, as used herein a C2-C12 chain of the ester, ether, ketone, alcohol, or carboxylic acid includes the carbon forming the carbon-oxygen bond in the solvent molecule. The extractant may be an oxygen-containing polar organic solvent having a molecular weight in a range of about 40 g / mol to about 400 g / mol may be selected from diisopropyl ether (DIPE), methyl isobutyl ketone (MIBK), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), ethyl acetate, 2-ethylhexanol. 2-ethylhexanoic acid, isopropyl acetate, or combinations of two or more thereof.

[0035] The process as described herein in any aspect includes an extractant having a Ka, acrylic acid in a range of about 1.2 to about 8.0, preferably about 1.5 to about 8.0, more preferably about 1.5 to about 6.0. For example, the extractant may have a Ka. acrylic acid of at least about 1.2, 1.3. 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0 and up to about 8.0, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7.3, 7.2, 7.1, 7.0, 6.9, 6.8, 6.7, 6.6,6.5, 6.4, 6.3, 6.2, 6.1, 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1, 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4. 1 or any range including and / or in between any two of the preceding values.

[0036] The process as described herein may be carried out at any suitable temperature. Preferably, the process is carried out at a temperature that is at least 10°C below the boiling point of the solvent, more preferably at a temperature from about 15°C to about 45°C, and most preferably at a temperature of about 20°C to about 30°C.

[0037] The process as described herein in any aspect includes an extractant having a selectivity for acrylic acid compared to byproducts in the aqueous feedstock obtained from dehydration of lactic acid. For example, the acrylic acid selectivity of the extractant may be about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol. The acrylic acid selectivity of the extractant may be about 1.0 to about 7.5, preferably 2.0 to 6.0, compared to acetic acid. The acrylic acid selectivity of the extractant may be about 1.2 to about 10.0, preferably 1.2 to 7.5, compared to acetaldehyde. The acrylic acid selectivity of the extractant may be about 0.25 to about 1.00 compared to 2,3- pentanedione. The acrylic acid selectivity of the extractant comprises about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid.

[0038] In the present disclosure, the process may include extracting acrylic acid from an aqueous feedstock that includes acrylic acid, acetol, 2,3-pentanedione, propionic acid, acetaldehyde, acetic acid, and optionally lactic acid where the process includes: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffmate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product comprising acrylic acid; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (Ka, acrylic acid) from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of: about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.5, preferably 2.0 to 6.0, compared to acetic acid; about 1.2 to about 10.0, preferably 1.2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid.

[0039] The process in any aspect described herein, where the process is a single stage of batchwise multistage extraction process, may include contacting the aqueous feedstock with the extractant at a S / F ratio of about 0.1 (w / w) to about 0.5 (w / w), preferably about 0.15 (w / w) to about 0.35 (w / w), more preferably about 0.18 (w / w) to about 0.33 (w / w), even more preferably about 0.2 (w / w) to about 0.3 (w / w), or any range including and / or in between any two of the preceding values. For example, suitable S / F ratios may include about 0.1 (w / w), about 0.15 (w / w), about 0.2 (w / w), about 0.25 (w / w), about 0.3 (w / w), about 0.35 (w / w), about 0.4 (w / w), about 0.45 (w / w), about 0.5 (w / w), or any range including and / or in between any two of the preceding values. In the present disclosure, the process as described herein may be a continuous extraction process or batchwise multistage extraction process, where the S / F ratio may be greater than or equal to 0.1 (w / w), preferably greater than or equal to 0.5 (w / w), more preferably greater than or equal to 1.0. For example, the solvent to feed (S / F) ratio may be 10:1, preferably 5: 1, most preferably 1 : 1, or any range including and / or in between any two of the preceding values.

[0040] The extraction product obtained from the process as described herein in any embodiment may be acrylic acid having a purity of at least 90%, preferably at least about 95%. For example, the extraction product of the process as described herein may be acrylic acid having a purity of at least about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, or any range including and / or in between any two of the preceding values.

[0041] The process as described herein in any aspect may occur in multiple stages. For example, a first stage of the process may include contacting the aqueous feedstock with the extractant to form a raffinate (or aqueous) phase and solvent phase. After separating the raffinate and the solvent phase, one or more additional stages may be conducted for extracting any acrylic acid remaining in the raffinate phase where fresh aliquots of extractant are used. For example, in any aspect described herein the process may further include: contacting the raffinate with the extractant to form an additional solvent phase; separating the additional solvent phase from the raffinate; optionally repeating the contacting and separating steps: and optionally combining each solvent phase prior to removing the extractant.

[0042] The process may further include repeating the contacting and separating steps wherein at least three additional solvent phases are obtained. For example, the process may further include repeating the contacting and separating steps wherein at least three additional solvent phases and up to about 20 additional solvent phases are obtained. Generally, the same raffinate obtained in the initial extraction stage is subjected to repeated contacting and separating steps with freshaliquots of extractant until a desired amount of acrylic acid partitions into the one or more solvent phases obtained throughout the process. The extraction product (e.g., acrylic acid having a purity of at least 90%) represents the combined amount of extraction product removed from each solvent phase obtained after contacting the extractant with the aqueous feedstock (initial extraction stage) or raffinate (subsequent extraction stage(s)).

[0043] The process as described herein in any aspect may include having at least 50% of the acrylic acid present in the aqueous feedstock partitioned into the solvent phase. The process as described herein in any aspect may include having at least about 60% of the acrylic acid present in the aqueous feedstock partitioned into the solvent phase. The process as described herein in any aspect may include having at least 70% of the acrylic acid present in the aqueous feedstock partitioned into the solvent phase. The process as described herein in any aspect may include having at least 85% of the acrylic acid present in the aqueous feedstock partitioned into the solvent phase. The process as described herein in any aspect may include having at least 90% of the acrylic acid present in the aqueous feedstock partitioned into the solvent phase. The process as described herein in any aspect may include having greater than 50% to about 99% of the acrylic acid in the aqueous feedstock partitioned into the solvent phase.

[0044] The present disclosure describes byproducts present in the aqueous product (i.e., aqueous feedstock) obtained from dehydration of lactic acid to acrylic acid includes 2,3- pentanedione and acetol. Following extraction of acrylic acid in the process as described herein in any aspect, 2,3-pentanedione and / or propionic acid may remain present in the extraction product comprising acrylic acid. As such, the process as described herein in any aspect may further include purifying the extraction product comprising acrylic acid to obtain a substantially pure acrylic acid. As used herein, the term ‘’substantially pure” refers to a purity that is greater than 98% acrylic acid, preferably greater than 99% acrylic acid, more preferably 99.5% or greater acrylic acid. Such further purification of the extraction product to obtain a substantially pure acrylic acid is advantageous for removing 2,3-pentanedione, propionic acid, and / or other byproducts that may partition into the solvent phase.

[0045] Generally, purity refers to the proportion of a material (e.g., by mass) that is composed of by a specific compound or element within said material. In this disclosure, purify is represented as percent purity with respect to acry lic acid based on total mass of the extraction product before and / or after subjecting to further purification steps, such as distillation or crystallization. According to the present disclosure, purifying the extraction product comprising acrylic acid obtained according to the process as described herein may include distillation, crystallization, orcombinations thereof. The process may include distilling the extraction product to obtain substantially pure acrylic acid; for example, such distillation may include multi-stage fractional distillation where first the extractant (or solvent) is removed to obtain the extraction product comprising acrylic acid, then compounds with boiling points lower than acrylic acid are removed, and then acrylic acid is distilled. The fractional distillation is preferably performed under reduced pressure. The process may include crystallizing the extraction product to obtain substantially pure acrylic acid. Generally, cry stallization methods may include, but are not limited to, solvent crystallization, falling film cry stallization, melt crystallization, or combinations of two or more thereof, preferably falling film crystallization and / or melt crystallization.

[0046] The process may include both distilling and crystallizing the extraction product comprising acrylic acid to obtain substantially pure acrylic acid, preferably acrylic acid having a purity' of99.5% or greater. For example, following removing the extractant from the solvent phase to obtain an extraction product comprising acrylic acid, the process may include:(i) distilling the extraction product comprising acrylic acid to remove 2,3-pentanedione and obtain a distilled extraction product, and(ii) cry stallizing the distilled extraction product to obtain substantially pure acrylic acid.

[0047] The substantially pure acrylic acid obtained from purifying the extraction product may be acrylic acid having a purity of greater than about 99.0%. For example, the substantially pure acrylic acid may be acrylic acid having a purity of about 99.0%, about 99. 1%, about 99.2%, about 99.3%, about 99.4%, about 99.5%, about 99.6%, about 99.7%, about 99.8%, or any range including and / or in between any two of the preceding values.

[0048] In some aspects, the process for extracting acrylic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to acrylic acid may include: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and a raffinate, wherein the aqueous feedstock includes acry lic acid and acetol; ii) separating the raffinate from the solvent phase; iii) contacting the raffinate with the extractant to obtain an additional solvent phase; iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases; vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acrylic acid having a purity of at least 90%; wherein:the extractant is water-immiscible having a distribution coefficient for acrylic acid (Kd. acrylic acid) from 1.2 to 10.0, preferably 1.2 to 8.0, the extractant has an acry lic acid selectivity7of 1.2 to 50.0 compared to acetol; and the extraction product is acrylic acid having a purity of at least 90%.The aqueous feedstock may further include acetaldehyde, acetic acid, and optionally lactic acid, where the extractant has an acrylic acid selectivity of 1 .2 to 50.0, preferably 1 .2 to 40.0, compared to acetol, acetaldehyde, and / or acetic acid.

[0049] In some aspects, the process for extracting acry lic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to acrylic acid may include: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and an raffinate, wherein the aqueous feedstock includes acrylic acid and 2,3-pentanedione; ii) separating the raffinate from the solvent phase; iii) contacting the raffinate with the extractant to obtain an additional solvent phase; iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases; vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acrylic acid having a purity of at least 90%; wherein: the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Kd, acrylic acid) from 1.2 to 10.0, preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of 0.25 to 2.0 over 2,3-pentanedione.

[0050] The aqueous feedstock may further include propionic acid and / or optionally lactic acid, where the extractant has an acrylic acid selectivity of 0.25 to 2.0 over 2,3-pentanedione and / or propionic acid.

[0051] In some aspects, the process for extracting acry lic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to acrylic acid may include: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and a raffinate, wherein the aqueous feedstock includes acrylic acid, acetol, 2,3-pentanedione in combination with one or more of acetic acid, acetaldehyde, propionic acid, and optionally lactic acid; ii) separating the raffinate from the solvent phase; iii) contacting the raffinate with the extractant to obtain an additional solvent phase;iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases; vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acrylic acid having a purity of at least 90%; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid(Kd, acrylic acid) from 1.2 to 10.0, preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of: about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.5, preferably 2.0 to 6.0, compared to acetic acid; about 1.2 to about 10.0, preferably 1.2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid; the extraction product is aery lie acid having a purity of at least 90%.

[0052] The process as described herein in any aspect may be carried out as either a batchwise multistage extraction or continuous extraction operations. For example, the process may be an extraction stage of a continuous extraction process or batchwise multistage extraction process for acrylic acid. Generally, when the process is an extraction stage of a continuous process or batchwise multistage process, the process may be carried out in an extraction unit such as a column-type unit, or a series of discrete mixers and liquid-liquid separators, or centrifugal-type liquid-liquid extractors. Such extraction units may be operated as either aqueous-phase continuous / solvent dispersed, or solvent-phase continuous / aqueous dispersed.

[0053] In some aspects, the process as described herein in any aspect may be a process for producing acry lic acid, where the process further includes converting lactic acid to acrylic acid to obtain the aqueous feedstock prior to extracting the acry lic acid from the aqueous feedstock. For example, the process may include: converting lactic acid to acrylic acid via catalytic dehydration (to obtain an aqueous feedstock; and extracting acrylic acid from the aqueous feedstock as described herein in any aspect.

[0054] For example, the extracting may include: contacting the aqueous feedstock with an extractant to obtain a raffinate and solvent phase; separating the raffinate from the solvent phase;removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is a water-immiscible having a distribution coefficient for acry lic acid (Kd, acrylic acid) from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of about 1.2 to about 50.0 over acetol, optionally further compared to acetaldehyde and / or acetic acid; and the extraction product is acry lic acid having a purity7of at least 90%.

[0055] In another example, the extracting may include: contacting the aqueous feedstock with an extractant to obtain a raffinate and solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is a water-immiscible having a distribution coefficient for acrylic acid (Kd. acrylic acid) from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of about 0.25 to about 2.0 over 2,3- pentanedione, optionally further compared to propionic acid; and the extraction product is acrylic acid having a purity of at least 90%.

[0056] In yet another example, the extracting may include: contacting the aqueous feedstock that includes acrylic acid, acetol, 2,3-pentanedione, acetaldehyde, acetic acid, propionic acid, and optionally lactic acid with an extractant to obtain a raffinate and solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is a water-immiscible having a distribution coefficient for acry lic acid (Kd, acrylic acid) from about 1.2 to about 10.0 (weight basis), preferably 1.2 to 8.0, the extractant has an acrylic acid selectivity of: about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.5, preferably 2.0 to 6.0, compared to acetic acid; about 1.2 to about 10.0, preferably 1.2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid; the extraction product is acry lic acid having a purity7of at least 90%.

[0057] In an aspect, the present disclosure describes use of an extractant for liquid-liquid extraction of acrylic acid from an aqueous feedstock that includes acrylic acid and acetol, wherein the extractant is a water-immiscible solvent having a distribution coefficient for acry lic acid (Ka, acrylic acid) from about 1.2 to about 10.0. preferably 1.2 to 8.0, and has an acrylic acid selectivity of about 1.2 to about 50.0. preferably about 1.2 to about 40.0, compared to acetol. The aqueous feedstock may further include acetaldehyde, acetic acid, and optionally lactic acid, where the extractant has an acrylic acid selectivity7of about 1.2 to about 50.0, preferably about 1.2 to about 40.0, compared to acetol, acetaldehyde, and / or acetic acid.

[0058] The liquid-liquid extraction may include the steps of contacting the aqueous feedstock with the extractant to obtain a raffinate and a solvent phase; separating the raffmate from the solvent phase; and removing the extractant from the solvent phase to obtain acrylic acid, wherein the acrylic acid has a punty of at least 90%.

[0059] In an aspect, the present disclosure describes use of an extractant for liquid-liquid extraction of acrylic acid from an aqueous feedstock that includes acrylic acid, 2,3 -pentanedione, wherein the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Ka. acrylic acid) from about 1.2 to about 10.0, preferably 1.2 to 8.0, and has an acrylic acid selectivity of about 0.25 to about 2.0 compared to 2,3-pentanedione. The aqueous feedstock may further include propionic acid and / or optionally lactic acid, where the extractant has an acry lic acid selectivity of about 0.25 to about 2.0 compared to 2,3-pentanedione and / or propionic acid.

[0060] The liquid-liquid extraction may include the steps of contacting the aqueous feedstock with the extractant to obtain a raffinate and a solvent phase; separating the raffmate from the solvent phase; and removing the extractant from the solvent phase to obtain acrylic acid, wherein the acrylic acid has a purity of at least 90%.

[0061] In an aspect, the present disclosure describes use of an extractant for liquid-liquid extraction of acrylic acid from an aqueous feedstock that includes acrylic acid, acetol, 2,3- pentanedione, acetic acid, acetaldehyde, propionic acid, and optionally lactic acid, wherein the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Ka, acrylic acid) from about 1.2 to about 10.0, and wherein the extractant has an acrylic acid selectivity of about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.5,preferably 2.0 to 6.0, compared to acetic acid; about 1.2 to about 10.0, preferably 1.2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid.

[0062] The liquid-liquid extraction may include the steps of: contacting the aqueous feedstock with the extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; and removing the extractant from the solvent phase to obtain acrylic acid, wherein the acrylic acid has a purity of at least 90%.

[0063] The present invention, thus generally described, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present invention.EXAMPLESMaterials and MethodsTable 1. Water-Immiscible Extraction Solvents

[0064] All solvents were procured from Sigma- Aldrich with a minimum purity level of 97%.

[0065] The aqueous feedstock used in the present examples was the reaction product (or based on the compositional makeup of the reaction product) from the dehydration of biobased lactic acid. In addition to water, the aqueous feedstock includes acrylic acid and other organic byproducts of the dehydration of lactic acid. As shown in Table 2. two test solutions were used,Test Solution 1 and Test Solution 2. Test Solution 1 is a simulated aqueous feedstock prepared based on the compositional analysis of crude acrylic acid product from the lactic acid dehydration reactions. Test Solution 2 was a reaction product obtained from lactic acid to acrylic acid dehydration reactions.Table 2. Aqueous Feedstocksreaction products was quantified, though other components are present in trace amounts.Experimental Design

[0066] Experiments were conducted at ambient temperature (approx. 20-25 °C) and pressure (about 1 atm). Test Solution 1 was the aqueous feedstock used for testing in Experiment 1. The extractions were carried out in 40 mL scintillation vials with a small vortex mixer used for agitation. Experiments 2.1 and 2.2 were conducted in 250 mL separatory funnels with Test Solution 2 as the aqueous feedstock. The aqueous and solvent phases were mixed manually by vigorously shaking the separatory funnel for 2 minutes, taking care to vent periodically.

[0067] Each extraction solvent was added to a fixed amount of aqueous feedstock, utilizing a 0.2 solvent-to-feed ratio (S / F) on a weight basis. The two resultant liquid phases were then agitated for two minutes before stopping and allowing phase separation. Once separation was achieved as indicated by the presence of a sharp interface between the two layers, the layers were separated. The masses of the two layers were recorded to ensure a total mass recovery of >98% (extract + raffinate). A sample of both the solvent and aqueous layers were retained for gas chromatography (GC) analysis. An additional sample of the aqueous layer after each extraction w as retained forliquid chromatography (LC) analysis. The 0.2 S / F was maintained for each subsequent extraction by considering the weight of the raffinate from the previous extractive stage when determining how much extraction solvent to add. Each experiment had 5 extractive stages to simulate a multistage process.Gas Chromatography-Flame Ionization Detector (GC-FID)

[0068] In this method, the samples were diluted 4x (weight basis) in Optima-grade acetone. A split ratio of 100: 1 was used to introduce the solution into the inlet, which was held at 240°C. Ultra-pure hydrogen was flowed through the column at 40 mL / min. Separation was achieved using a30 m DB-WAX UI (0.2 5mmx 0.25 pm, Agilent P / N 122-7032UI) GC column. The temperature program for the GC oven was 35°C (5 min) to 240°C at 10°C / min and held at 240°C for 4.5 minutes. Acrylic acid and the other minor byproducts were quantified based on a calibration curve generated by using standards of each component.

[0069] The concentration of the following components of the aqueous material were calculated using GC: acetic acid, acetaldehyde, 2,3-pentanedione, propionic acid, and acrylic acid. Acetol was quantified via GC analysis and via LC analysis. The retention times of the product and byproducts are listed in Table 3.Table 3. GC Retention TimesHigh Performance Liquid Chromatography-UV (HPLC-UV)

[0070] The samples were prepared including three dilution levels in acidified w ater to ensure that the compounds were within the specified calibration range. The 1:2 dilution was employed for the quantification of acetol, acetic acid, and lactic acid present in amounts <3% by weight. Acrylic acid present in a concentration range of 1-9% by weight was evaluated by using a 1:50 dilution, and a 1 :100 dilution was used for samples containing >9% acrylic.Table 4. HPLC Retention Times

[0071] The separation occurred on two reversed-phase Acquity Premier HSS T3 1.8 pm (2. 1 x 150mm, Waters P / N 186009469) columns in series. Mobile phase A was 50 mM potassium phosphate, whereas acetonitrile was used for Mobile phase B. The temperature of the columns and the autosampler were held at 25°C and 10°C, respectively. Absorption at three different wavelengths (210 nm, 240 nm, and 276 nm) was measured by diode array detector. Lactic acid and its oligomers, acetol, and acetic acid were all quantified at 240nm. Acetaldehyde is quantified at 276nm. The gradient of the 60-minute run is listed in Table 5.Table. 5 HPLC GradientA flow rate of 0. 150 rnL / min was maintained throughout the run.Experiment 1 - Solvent Screening, 0.2 S / F

[0072] Solvent screening extractions were conducted to determine which extraction solvent(s) would be best for separating acrylic acid from the aqueous feedstock. These experiments were conducted with Test Solution 1 (Table 2).

[0073] Following each solvent screening, solvent performance was preliminarily assessed according to the following factors:(i) the amount of acrylic acid and other byproducts that were extracted into the organic solvent layer (extractant) after 5 extraction stages; and(ii) the amount of these compounds that remained in the aqueous layer (raffinate).

[0074] This was determined by comparing the starting aqueous feedstock composition (weight basis), then comparing that to both the composition of the raffinate and the total combined organic solvent phase after 5 extractions that was employed in the experiment. A summary of extraction performance is provided in Table 6.Table 6. Solvent Performance at 0.2 S / F (wt %) - Initial ScreeningData here reflects the total amount (wt %) of each component that partitioned into the organic solvent phase after the 5 extraction stages. All values are reported based on GC analysis, except for lactic acid that was quantified via HPLC.

[0075] As shown in Table 6, o-xylene, toluene, and the biphenyl / diphenyl ether (25:75 weight ratio) mixture did not show suitable extraction of acrylic acid, having <50 wt% of acrylic acid partitioning into the organic solvent phase. In addition, ethyl acetate extracted over 80 wt % of the acrylic acid from the aqueous feedstock, but ethyl acetate also partitioned greater than 60 wt% of lactic acid into the organic solvent phase. Thus, ethyl acetate was determined to be unsuitable for use as an extractant for acrylic acid from the aqueous feedstock containing acrylic acid and lactic acid.

[0076] In view of the results described above in Table 6, Kd. acrylic acid values were calculated for the remaining solvents as shown in Table 7.Table 7. Kd, acrylic acid ValuesThe Kd, acrylic acid values were calculated from the 1st extraction stage. Each solvent was tested in triplicate to determine the performance, and the average Kd, acrylic acid has been reported.

[0077] As shown in Table 8, selectivity of acr lic acid against acetaldehyde, acetol, and acetic acid was favorable across the organic solvents. 2,3-pentanedione and propionic acid data showed how readily each respective byproduct partitioned into the organic solvent phase along with the acrylic acid.Table 8. Selectivity, 0.2 S / F (wt %)

[0078] Based on the performance of each organic solvent relative to the criteria of a successful extractive process, MTBE, MIBK, and DiPE were selected for evaluation in experiment 1.2, along with iPAc.Experiment 2.1: Solvent Selection, 0.2 S / F

[0079] The aqueous feedstock for this phase of the workstream was Test Solution 2. The composition of Test Solution 2 is detailed in Table 2. A summary' of extraction performance is in Table 9. Lactic acid, acetaldehyde, acetic acid, and acetol data are reported based on LC data. All other components were quantified via GC.Table 9. Solvent Performance, 0.2 S / F (wt %)*Values reported at approximately 100% are within the margin for analytical variation.**iPAc undergoes hydrolysis, which contributes to the formation of more acetic acid.

[0080] As shown in Table 10, the distribution coefficients were calculated for the three solvents evaluated in Experiment 1 in keeping with the present invention. iPAc was also evaluated and showed favorable performance as an extraction solvent.Table 10. Distribution Coefficient (Ka, acrylic acid)

[0081] As shown in Table 11, selectivity values for acrylic acid against other byproducts in the aqueous feedstock provided comparable results as observed in Experiment 1.Table 11. Selectivity7, 0.2 S / F (wt %)*Due to the hydrolysis of iPAc, other extraction criteria are difficult to assess for acetic acid.Experiment 2.2: Solvent Selection, 0.3 S / F

[0082] After confirming the performance of DIPE, MIBK, MTBE, and iPAc in Experiment 2.1, testing with the aforementioned extraction solvents was repeated at a 0.3 S / F ratio. The 0.3 S / F was applied during each extraction within the experiment using the weight of the aqueous feedstock that was being charged during that stage.Table 12. Solvent Performance, 0.3 S / F (wt %)Data for acetol, acetaldehyde and lactic acid were reported based on LC data. The amount of these 3 compounds that partitioned into the organic phase of each extractive stage was reported as the difference between the starting aqueous material concentration and the raffmate. *2,3-Pentanedione data is within the margin for analytical variation.**iPAc undergoes hydrolysis, which contributes to the formation of more acetic acid.

[0083] As shown in Table 13, the distribution coefficients (Kd, acrylic acid) at the 0.3 S / F ratio were comparable to values measured at 0.2 S / F ratio. Of the four solvents, MTBE exhibited the highest affinity for acrylic acid.Table 13. Distribution Coefficients (Kd, acrylic acid), 0.3 S / F (wt %)*MIBK was not analyzed at the 0.3 S / F.

[0084] Table 13 provides the selectivity values of each solvent at 0.3 S / F ratio, which were consistent with the values obtained in Experiment 2.2.Conclusions

[0085] As demonstrated in the above experimental examples, the separation of acrylic acid from other byproducts of lactic acid dehydration utilizing polar organic solvents as extractants. Solvent performance was determined via liquid-liquid extraction (LLE) and compared regarding extraction criteria before potential solvents were identified. MTBE, iPAc, DIPE exhibited the most preferable performance as extractants for acrylic acid, where solvents showing >50% partitioning of acry lic acid into the organic solvent phase and <50% of lactic acid with a minimum Kd, acrylic acid of 1.2 being suitable for use in the present invention.Exemplary7Aspects

[0086] The following exemplary aspects are provided, the numbering of which is not to be construed as designating levels of importance:

[0087] Paragraph (Para.) A: A process for extracting acrylic acid from an aqueous feedstock comprising acrylic acid and acetol, the process comprising: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (Kd. acrylic acid) from 1.2 to 10.0 (weight basis), andthe extractant has an acrylic acid selectivity of 1.2 to 50.0 over acetol.

[0088] Para. B: A process for extracting acrylic acid from an aqueous feedstock comprising acrylic acid and 2,3-pentanedione, the process comprising: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (Kd, acrylic aeid) from 1.2 to 10.0 (weight basis), the extractant has an acry lic acid selectivity of 0.2 to 2.0 over 2,3-pentanedione.

[0089] Para. C: The process of Para. A or B, wherein the aqueous feedstock is a product of a lactic acid to acrylic acid reaction.

[0090] Para. D: The process of any one of Paras. A-C. wherein the aqueous feedstock further comprises one or more of acetaldehyde, acetic acid, propionic acid, and / or optionally lactic acid.

[0091] Para. E: The process of any one of Paras. A-D, wherein the contacting occurs at a solvent to feedstock (S / F) ratio of 0.1 (w / w) to 0.5 (w / w).

[0092] Para. F: The process of any one of Paras. A-E. wherein the contacting occurs at a S / F of 0.15 (w / w) to 0.35 (w / w).

[0093] Para. G: The process of any one of Paras. A-F, wherein the contacting occurs at a S / F of greater than or equal to 1.0 (w / w).

[0094] Para. H: The process of any one of Paras. A-G, wherein the S / F ratio is for a single stage in a batchwise multistage extraction process or a continuous extraction process.

[0095] Para. I: The process of any one of Paras. A-H, wherein the extraction product is acry lic acid having a purity7of at least 90%.

[0096] Para. J: The process of any one of Paras. A-I. wherein the extraction product is acrylic acid having a purity of at least 95%.

[0097] Para. K: The process of any one of Paras. A- J, wherein the extractant has a Kd, acrylic acid of 1.5 to 8.0.

[0098] Para. L: The process of any one of Paras. A-K, wherein the extractant is an oxygencontaining polar organic solvent having a molecular weight in range of about 40 g / mol to about 400 g / mol.

[0099] Para. M: The process of any one of Paras. A-L, wherein the extractant is an oxygencontaining polar organic solvent comprising C2-C12 ethers, C2-C12 ketones, C2-C12 esters, or mixtures thereof.

[0100] Para. N: The process of any one of Paras. A-M. wherein the extractant is selected from the group consisting of diisopropyl ether (DIPE), methyl isobutyl ketone (MIBK), methyl tertbutyl ether (MTBE), ethyl tert-butyl ether (ETBE), ethyl acetate, 2-ethylhexanol, 2-ethylhexanoic acid, isopropyl acetate, and mixtures thereof.

[0101] Para. O: The process of any one of Paras. A-N, wherein the acry lic acid selectivity of the extractant comprises 4.0 to 50.0 compared to acetol.

[0102] Para. P: The process of any one of Paras. A-O, wherein the acrylic acid selectivity of the extractant comprises 1.0 to 7.5 compared to acetic acid.

[0103] Para. Q: The process of any one of Paras. A-P, wherein the acrylic acid selectivity of the extractant comprises 1.2 to 10.0 compared to acetaldehyde.

[0104] Para. R: The process of any one of Paras. A-Q, wherein the acrylic acid selectivity of the extractant comprises 0.25 to 1.00 compared to 2,3-pentanedione.

[0105] Para. S: The process of any one of Paras. A-R, wherein the acrylic acid selectivity of the extractant comprises 0.5 to 2.0 compared to propionic acid.

[0106] Para. T : The process of any one of Paras. A-S. wherein after separating the raffinate and the solvent phase, the process further comprises: contacting the raffinate with the extractant to form an additional solvent phase; separating the additional solvent phase from the raffinate; optionally repeating the contacting and separating steps: and combining each solvent phase prior to removing the extractant.

[0107] Para. U: The process of any one of Paras. A-T further comprising repeating the contacting and separating steps wherein at least three additional solvent phases are obtained.

[0108] Para. V: The process of Para. U further comprising repeating the contacting and separating steps wherein at least three additional solvent phases and up to 20 additional solvent phases are obtained.

[0109] Para. W: The process of any one of Paras. A-V, wherein at least 50% of the acrylic acid present in the aqueous feedstock is partitioned into the solvent phase.

[0110] Para. X: The process of any one of Paras. A-W, wherein at least 60% of the acrylic acid present in the aqueous feedstock is partitioned into the solvent phase.

[0111] Para. Y : The process of any one of Paras. A-X, wherein at least 70% of the acrylic acid present in the aqueous feedstock is partitioned into the solvent phase.

[0112] Para. Z: The process of any one of Paras. A-Y, wherein at least 85% of the acrylic acid present in the aqueous feedstock is partitioned into the solvent phase.

[0113] Para. AA: The process of any one of Paras. A-Z, wherein at least 90% of the acrylic acid present in the aqueous feedstock is partitioned into the solvent phase.

[0114] Para. AB: The process of any one of Paras. A-AA, wherein greater than 50% to 99% of the acrylic acid in the aqueous feedstock is partitioned into the solvent phase.

[0115] Para. AC: The process of any one of Paras. A-AB further comprising purifying the extraction product to obtain a substantially pure acrylic acid.

[0116] Para. AD: The process of Para. AC, wherein purifying the extraction product comprises distillation, crystallization, or combinations thereof.

[0117] Para. AE: The process of any one of Paras. A-AD further comprising distilling the extraction product to obtain substantially pure acrylic acid.

[0118] Para. AF: The process of any one of Paras. A-AE further comprising crystallizing the extraction product to obtain substantially pure acrylic acid.

[0119] Para. AG: The process of any one of Paras. AC-AF, wherein the substantially pure acrylic acid has a purity of greater than 99.0%.

[0120] Para. AH: The process of any one of Paras. A- AG, wherein the aqueous feedstock is the reaction product of a catalytic dehydration of lactic acid to acrylic acid.

[0121] Para. Al: The process of any one of Paras. A-AH, wherein extracting acrylic acid from the aqueous feedstock comprises an extraction stage of a batchwise multistage extraction process or a continuous extraction process for producing acrylic acid.

[0122] Para. AJ: A process for extracting acrylic acid from an aqueous feedstock comprising acrylic acid, acetol, 2,3-pentanedione, acetaldehyde, propionic acid, acetic acid, and optionally lactic acid, the process comprising: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid 0.0 (weight basis), andthe extractant has an acrylic acid selectivity of: about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.5, preferably 2.0 to 6.0, compared to acetic acid; about 1.2 to about 10.0, preferably 1.2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2.3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1 .6, compared to propionic acid.

[0123] Para. AK: A process for producing acry lic acid comprising: converting lactic acid to acrylic acid via catalytic dehydration to obtain an aqueous feedstock; and extracting acrylic acid from the aqueous feedstock, wherein the extracting comprises: contacting the aqueous feedstock with an extractant to obtain a raffinate and solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (Kd acrylic acid) from 1.2 to 10.0 (weight basis), the extractant has an acrylic acid selectivity of 1.2 to 50.0 over acetol, acetaldehyde, and / or acetic acid; and the extraction product is acrylic acid having a purity of at least 90%.

[0124] Para. AL: The process of Para. AK, wherein acrylic acid is extracted from the aqueous feedstock according to the process of any one of Paras. A-AJ.

[0125] Para. AM: The process of Para. AK or AL, wherein the extraction product is acrylic acid having a purity of at least 95%.

[0126] Para. AN: The process of any one of Paras. AK-AM, wherein after separating the raffinate and the solvent phase, extracting acrylic acid from the aqueous feedstock further comprises: contacting the raffinate with the extractant to form an additional solvent phase; separating the additional solvent phase from the raffinate; optionally repeating the contacting and separating steps one or more times; and combining each solvent phase prior to removing the extractant.

[0127] Para. AO: The process of any one of Paras. AK-AN, wherein the extraction product is acrylic acid having a purity of at least 95%.

[0128] Para. AP: The process of Para. AN further comprising repeating the contacting and separating steps until at least 70% of the acrylic acid present in the aqueous feedstock has partitioned into the solvent phase.

[0129] Para. AQ: The process of any one of Paras. AK-AP further comprising purifying the extraction product to obtain a substantially pure acrylic acid.

[0130] Para. AR: The process of Para. AQ, wherein purifying the extraction product comprises distillation, crystallization, chromatography, or combinations thereof.

[0131] Para. AS: The process of Para. AQ or AR, wherein the substantially pure acry lic acid has a purify of greater than 99.0%.

[0132] Para. AT: The process of any one of Paras. AK-AS, wherein the process is a batchwise multistage extraction process or a continuous extraction process.

[0133] Para. AU: Use of an extractant for liquid-liquid extraction of acry lic acid from an aqueous feedstock comprising acrylic acid and acetol, wherein the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Ka, acrylic acid) from 1.2 to 10.0 and has an acrylic acid selectivity of 1.2 to 50.0 over acetol.

[0134] Para. AV: The use ofPara. AU, wherein the liquid-liquid extraction comprises the steps of: contacting the aqueous feedstock with the extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; and removing the extractant from the solvent phase to obtain acrylic acid.

[0135] Para. AW: The use according to Para. AU or AV, wherein the acrylic acid has a purify’ of at least 90%.

[0136] Para. AX: A process for producing acry lic acid comprising: converting lactic acid to acrylic acid via catalytic dehydration to obtain an aqueous feedstock comprising acrylic acid and 2,3-pentanedione; and extracting acrylic acid from the aqueous feedstock, wherein the extracting comprises: contacting the aqueous feedstock with an extractant to obtain a raffinate and solvent phase; separating the raffinate form the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein:the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Kd, acrylic acid) from 1.2 to 10.0 (weight basis), the extractant has an acrylic acid selectivity of 0.25 to 2.0 over 2,3- pentanedione; and the extraction product is acrylic acid having a purity of at least 90%.

[0137] Para. AY : The process of Para. AX, wherein acry lic acid is extracted from the aqueous feedstock according to the process of any one of Paras. A-AJ.

[0138] Para. AZ: The process of Para. AX or AY. wherein the extraction product is acrylic acid having a purity of at least 95%.

[0139] Para. BA: The process of any one of Paras. AX- AZ, wherein after separating the raffinate and the solvent phase, extracting acry lic acid from the aqueous feedstock further comprises: contacting the raffinate with the extractant to form an additional solvent phase; separating the additional solvent phase from the raffinate; optionally repeating the contacting and separating steps one or more times; and combining each solvent phase prior to removing the extractant.

[0140] Para. BB: The process of Para. BA further comprising repeating the contacting and separating steps until at least 70% of the acrylic acid present in the aqueous feedstock has partitioned into the solvent phase.

[0141] Para. BC: The process of any one of Paras. AX-BB further comprising purifying the extraction product to obtain a substantially pure acrylic acid.

[0142] Para. BD: The process of Para. BC, wherein purifying the extraction product comprises distillation, crystallization, chromatography, or combinations thereof.

[0143] Para. BE: The process of Para. BC or BD, wherein the substantially pure acry lic acid has a purify of greater than 99.0%.

[0144] Para. BF: The process of any one of Paras AX-BE. wherein the process is a batchwise multistage extraction process or a continuous extraction process.

[0145] Para. BG: Use of an extractant for liquid-liquid extraction of acrylic acid from an aqueous feedstock comprising acrylic acid and 2,3 -pentanedione, wherein the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Kd, acrylic acid) from 1.2 to 10.0 and has an acrylic acid selectivity of 0.25 to 2.0 over 2,3-pentanedione.

[0146] Para. BH: The use according to Para. BG, wherein the liquid-liquid extraction comprises the steps of: contacting the aqueous feedstock with the extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; and removing the extractant from the solvent phase to obtain acrylic acid.

[0147] Para. BI: The use according to Para. BH or BI, wherein the acrylic acid has a purity of at least 90%.

[0148] Para. BJ: A process for extracting acrylic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to acrylic acid, the process comprising: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and a raffinate, wherein the aqueous feedstock comprises acry lic acid and acetol; ii) separating the raffinate from the solvent phase; iii) contacting the raffinate with the extractant to obtain an additional solvent phase; iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases; vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acrylic acid having a purity of at least 90%; wherein: the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Ka, acrylic acid) from 1.2 to 10.0, the extractant has an acrylic acid selectivity of 1.2 to 50.0 over acetol; and the extraction product is acrylic acid having a purity of at least 90%.

[0149] Para. BK: A process for extracting acrylic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to acrylic acid, the process comprising: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and a raffinate, wherein the aqueous feedstock comprises acrylic acid and 2,3- pentanedione; ii) separating the raffinate from the solvent phase; iii) contacting the raffinate with the extractant to obtain an additional solvent phase; iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases;vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acrylic acid having a purity of at least 90%; wherein: the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Kd. acrylic acid) from 1 .2 to 10.0, the extractant has an acry lic acid selectivity7of 0.25 to 2.0 over 2,3-pentanedione.

[0150] Para. BL: A process for extracting acrylic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to acrylic acid, the process comprising: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and a raffinate, wherein the aqueous feedstock comprises acrylic acid, acetol, 2,3- pentanedione, acetic acid, acetaldehyde, propionic acid, and optionally lactic acid; ii) separating the raffinate from the solvent phase; hi) contacting the raffinate with the extractant to obtain an additional solvent phase; iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases; vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acrylic acid having a purity of at least 90%; wherein: the extractant is a water-immiscible solvent having a distribution coefficient for acrylic acid (Ka, acrylic acid) from 1.2 to 10.0, the extractant has an acrylic acid selectivity of: about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.5, preferably 2.0 to 6.0, compared to acetic acid; about 1.2 to about 10.0. preferably 1.2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid.

[0151] Each of the non-limiting aspects above can stand on its own or can be combined in various permutations or combinations with one or more of the other aspects or other subject matter described in this document. While certain embodiments have been illustrated and described a person with ordinary skill in the art, after reading the foregoing specification can effect changes, substitutions of equivalents and other types of alterations to the present technology as set forthherein. Each aspect and embodiment described above can also have included or incorporated therewith such variations or aspects as disclosed in regard to any or all of the other aspects and embodiments.

[0152] The present technology is also not to be limited in terms of the particular aspects described herein, which are intended as single illustrations. Many modifications and variations of this present technology can be made without departing from its spirit and scope, as will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. It is to be understood that this present technology is not limited to particular methods, reagents, compounds, or compositions, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. Thus, it is intended that the specification be considered as exemplary only with the breadth, scope and spirit of the present technology indicated only by the appended claims, definitions therein and any equivalents thereof.

[0153] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitations. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase “consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of’ excludes any element not specified.

Claims

CLAIMSWhat is claimed is:

1. A process for extracting acrylic acid from an aqueous feedstock comprising acrylic acid and acetol the process comprising: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffmate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (K<i, acrylic acid) from 1.2 to 10.0 (weight basis), and the extractant has an acrylic acid selectivity of 1.2 to 50.0 over acetol.

2. A process for extracting acrylic acid from an aqueous feedstock comprising acrylic acid and 2,3 -pentanedione the process comprising: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein: the extractant is water-immiscible having a distribution coefficient for acrylic acid (Kd. acrylic acid) from 1.2 to 10.0 (weight basis), the extractant has an acrylic acid selectivity of 0.2 to 2.0 over 2,3 -pentanedione.

3. The process of claim 1 or 2, wherein the aqueous feedstock is the reaction product of a catalytic dehydration of lactic acid to acrylic acid.

4. The process of any one of claims 1-3, wherein the aqueous feedstock further comprises acetic acid, acetaldehyde, and optionally lactic acid.

5. The process of any one of claims 1-4, wherein the aqueous feedstock further comprises propionic acid.

6. The process of any one of claims 1-5, wherein the contacting occurs at a solvent to feedstock (S / F) ratio of 0. 1 (w / w) to 0.5 (w / w), wherein the S / F ratio is for a single stage in a batchwise multistage extraction process.

7. The process of any one of claims 1 -6, wherein the contacting occurs at a S / F of 10: 1 , preferably 5: 1, and most preferably 1: 1, wherein the S / F ratio is for a batchwise multistage extraction process or a continuous extraction process.

8. The process of any one of claims 1-7, wherein the extraction product is acrylic acid having a purity of at least 95%.

9. The process of any one of claims 1-8, wherein the extractant has a Ka, acrylic acid of 1.5 to 6.0.

10. The process of any one of claims 1-9, wherein the extractant is an oxygen-containing polar organic solvent having a molecular weight in range of about 40 g / mol to about 400 g / mol.

11. The process of any one of claims 1-10, wherein the extractant is selected from the group consisting of diisopropyl ether (DIPE), methyl isobutyl ketone (MIBK), methyl tertbutyl ether (MTBE), ethyl tert-butyl ether (ETBE), ethyl acetate, 2-ethylhexanol, 2- ethylhexanoic acid, isopropyl acetate, and mixtures thereof.

12. The process of any one of claims 1-11, wherein the acrylic acid selectivity7of the extractant comprises one or more of:4.0 to 50.0 compared to acetol:1 .0 to 7.5 compared to acetic acid;1.2 to 10 compared to acetaldehyde;0.25 to 1.00 compared to 2,3-pentanedione; or0.5 to 2.0 compared to propionic acid.

13. The process of any one of claims 1-12, wherein after separating the raffinate and the solvent phase, the process further comprises: contacting the raffinate with the extractant to form an additional solvent phase; separating the additional solvent phase from the raffinate; optionally repeating the contacting and separating steps: and combining each solvent phase prior to removing the extractant.

14. The process of claim 13 further comprising repeating the contacting and separating steps wherein at least three additional solvent phases and up to 20 additional solvent phases are obtained.

15. The process of any one of claims 1-14, w herein greater than 50% to 99% of the acry lic acid in the aqueous feedstock is partitioned into the solvent phase.1 . The process of any one of claims 1-15 further comprising purifying the extraction product to obtain a substantially pure acrylic acid.

17. The process of claim 16, wherein the substantially pure acrylic acid has a purity of greater than 99.0%.

18. The process of any one of claims 1-17, wherein extracting acrylic acid from the aqueous feedstock comprises an extraction stage of a continuous process for producing acrylic acid.

19. A process for extracting acrylic acid from an aqueous feedstock comprising acrylic acid, acetol, 2,3-pentanedione. acetaldehyde, propionic acid, acetic acid, and optionally lactic acid, the process comprising: contacting the aqueous feedstock with an extractant to obtain a raffinate and a solvent phase; separating the raffinate from the solvent phase; removing the extractant from the solvent phase to obtain an extraction product; wherein:the extractant is water-immiscible having a distribution coefficient for acrylic acid (Ka,from 1.2 to 10.0 (weight basis), and the extractant has an acry lic acid selectivity7of: about 4.0 to about 50.0, preferably 4.0 to 35.0, compared to acetol; about 1.0 to about 7.

5. preferably 2.0 to 6.

0. compared to acetic acid; about 1 .2 to about 10.0, preferably 1 .2 to 7.5, compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0, preferably 0.6 to 1.6, compared to propionic acid.

20. A process for extracting acrylic acid from an aqueous feedstock obtained from catalytic dehydration of lactic acid to aery lie acid, the process comprising: i) contacting the aqueous feedstock with an extractant to obtain a solvent phase and a raffinate, wherein the aqueous feedstock comprises acrylic acid, acetol, 2,3- pentanedione, acetic acid, acetaldehyde, propionic acid, and optionally lactic acid; ii) separating the raffinate from the solvent phase; iii) contacting the raffinate with the extractant to obtain an additional solvent phase; iv) separating the additional solvent phase from the raffinate; and v) optionally repeating steps iii) and iv) to obtain two or more additional solvent phases; vi) combining the solvent phases of steps ii)-v); and vi) removing the extractant from the solvent phase to obtain acry lic acid having a purity7of at least 90%; wherein: the extractant is a water-immiscible solvent having a distribution coefficient for acry lic acid (Ka.from 1.2 to 10.0, the extractant has an acrylic acid selectivity of: about 4.0 to about 50.0 compared to acetol; about 1 .0 to about 7.5 compared to acetic acid; about 1.2 to about 10.0 compared to acetaldehyde; about 0.25 to about 1.00 compared to 2,3-pentanedione; and about 0.5 to about 2.0 compared to propionic acid.

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