WO2017114829A1 - Absorption d'acide carboxylique à partir de courants aqueux à l'état de vapeur - Google Patents

Absorption d'acide carboxylique à partir de courants aqueux à l'état de vapeur Download PDF

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Publication number
WO2017114829A1
WO2017114829A1 PCT/EP2016/082706 EP2016082706W WO2017114829A1 WO 2017114829 A1 WO2017114829 A1 WO 2017114829A1 EP 2016082706 W EP2016082706 W EP 2016082706W WO 2017114829 A1 WO2017114829 A1 WO 2017114829A1
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Prior art keywords
carboxylic acid
stream
solvent
absorbing solvent
methyl
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Inventor
Kai Jürgen FISCHER
Jean Paul Andre Marie Joseph Ghislain LANGE
Guus VAN ROSSUM
Ronald Jan Schoonebeek
Carmelo PEREZ GOLF
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Shell Internationale Research Maatschappij BV
Shell USA Inc
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Shell Internationale Research Maatschappij BV
Shell Oil Co
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation

Definitions

  • the present invention relates to a process of recovering C C6 carboxylic acids from vaporous aqueous streams by means absorption .
  • oxidative chemical conversion processes known in the art produce aqueous streams comprising carboxylic acids as a side product.
  • C 3 -C 6 alkanes such as propane or butane resulting in propylene and butylene, respectively
  • ODH oxidative dehydrogenation
  • the dehydrogenated equivalent of the alkane may be further oxidized under the same conditions into the corresponding carboxylic acid, which may or may not contain one or more unsaturated double carbon- carbon bonds, such as acrylic acid and methacrylic acid.
  • carboxylic acids thus produced are generally considered as waste products. Although they could be condensed together with water from the reactor effluent as an aqueous carboxylic acid (ca. 10 wt%) stream, the low relative volatility of carboxylic acids to water renders ordinary distillative separation of carboxylic acid and water troublesome, as this would require very large condensate recycle and/or separation trains.
  • C 3 -C 6 carboxylic acids are valuable ingredients and building blocks for use in the chemical industry. For example, the global demand for acrylic acid is around 5 million tonnes per year (Mt/a), with applications as
  • the present invention pertains to a process for the recovery of C 3 -C 6 carboxylic acid from an aqueous stream, comprising
  • the absorbing solvent is an oxygen-containing organic compound having
  • the invention further relates to a process for the recovery of C 3 -C6 carboxylic acid from a vaporous aqueous stream, comprising
  • carboxylic acid with an absorbing solvent in an absorption unit, to produce a first stream comprising absorbing solvent and C 3 -C 6 carboxylic acid and a second stream comprising water vapour,
  • the absorbing solvent is a cyclic or aromatic alcohol having 6 to 20 carbon atoms, a linear aliphatic alcohol having 6 to 14 carbon atoms or a branched aliphatic alcohol having 5 to 14 carbon atoms.
  • the invention relates to the use of an oxygen-containing organic compound having
  • Figure 1 shows an embodiment of the present invention, wherein an aqueous vapour stream comprising C3-C6 carboxylic acid is contacted with an absorbing solvent in an absorption unit, to produce a top stream comprising water vapour and a bottom stream comprising absorbing solvent and C 3 -C 6
  • the aqueous stream comprising C 3 -C 6 carboxylic acid used as feed stream for the absorption process may be any stream comprising at least 0.1, or at least 1 wt%, more preferably at least 3 wt%, even more preferably at least 5 wt%, yet even more preferably at least 10 wt% or 15 wt%, most preferably at least 20 wt% wt% of C 3 -C 6 carboxylic acid.
  • C 3 -C 6 carboxylic acid and any amounts or concentrations specified in connection therewith refers to the sum of all saturated and unsaturated carboxylic acids having 3, 4, 5 and 6 carbon atoms that are present.
  • said aqueous stream comprising one or more C 3 -C 6 carboxylic acid originates from an oxidative chemical conversion process of C 3 -C 6 alkanes and/or C 3 -C 6 alkenes, wherein the C 3 -C 6 carboxylic acid is obtained as a side product. It is preferred that the aqueous feed stream of the absorption process comprises C 3 -C 6 carboxylic acid in a concentration of at least 1 wt%, more preferably at least 3 wt%, even more preferably at least 5 wt%, yet even more preferably at least 10 wt%, most preferably at least 20 wt%.
  • the aqueous stream comprising
  • carboxylic acid originates from the oxidative dehydrogenation ("ODH”) of an alkane containing 3 to 6 carbon atoms,
  • dehydrogenation process typically produces a product stream comprising the corresponding alkene and carbon dioxide, as well as water and carboxylic acid.
  • the product of said alkane oxidative dehydrogenation process may comprise propylene and acrylic acid.
  • the product of said alkane oxidative dehydrogenation process may comprise butylene, butadiene, vinylacetic acid, crotonic acid and/or methacrylic acid.
  • the aqueous stream comprising carboxylic acid originates from the oxidation of an alkene containing 3 to 6 carbon atoms, preferably propylene, in the presence of water to produce a product stream comprising the corresponding carboxylic acids .
  • Said carboxylic acid may or may not contain one or more unsaturated double carbon-carbon bonds.
  • the alkene containing 3 to 6 carbon atoms is propylene, butylene or butadiene.
  • the product of said alkene oxidation process may comprise acrylic acid.
  • the product of said alkene oxidation process may comprise vinylacetic acid, crotonic acid and/or methacrylic acid.
  • the C 3 -C 6 carboxylic acid is a C 3 or a C 4 carboxylic acid, or a combination thereof.
  • the carboxylic acid to be recovered is acrylic acid, propionic acid, vinylacetic acid, iso-crotonic acid, n- crotonic acid, iso-butyric acid, n-butyric acid, methacrylic acid, or a combination thereof.
  • the carboxylic acid to be recovered is acrylic acid, propionic acid, vinylacetic acid, iso-crotonic acid, n- crotonic acid, iso-butyric acid, n-butyric acid, methacrylic acid, or a combination thereof.
  • the carboxylic acid to be recovered is acrylic acid, propionic acid, vinylacetic acid, iso-crotonic acid, n- crotonic acid, iso-butyric acid, n-butyric acid, methacrylic acid, or a combination thereof.
  • the carboxylic acid to be recovered is
  • methacrylic acid and/or acrylic acid most preferably acrylic acid.
  • a concentration step for example of a dilute aqueous gaseous process effluent comprising C 3 -C 6 carboxylic acid, may be applied prior to contacting the C 3 -C 6 carboxylic acid with the absorbing solvent in the absorption unit.
  • concentration step may comprise any suitable method for removing excess water from an aqueous C3-C6 carboxylic acid stream, including reverse osmosis or carboxylic acid- selective pervaporation, liquid-liquid (L/L) extraction or adsorption on a solid adsorbant .
  • a vaporous effluent comprising C 3 -C 6 carboxylic acid is treated using carboxylic acid-selective pervaporation to produce a concentrated C 3 -C 6 carboxylic acid/water vapour stream, which is subsequently separated using an absorption process as described herein.
  • a vaporous effluent comprising C 3 -C 6 carboxylic acid is concentrated by condensation followed by L/L extraction with a high-boiling solvent and distillation of the more concentrated C 3 -C 6 carboxylic acid/water vapour stream from the high boiling solvent and, finally, separation using absorption from the vapour phase as described herein.
  • a vaporous effluent comprising C 3 -C 6 carboxylic acid is concentrated by adsorption onto a solid, followed by desorption of a more concentrated C 3 -C 6
  • carboxylic acid/water vapour stream subsequently separated using absorption from the vapour phase as described herein.
  • such a concentration step yields an aqueous feed stream comprising C 3 -C 6 carboxylic acid in a concentration of at least 5 wt%, more preferably at least 10 wt%, even more preferably at least 15 wt%, most preferably at least 20 wt%.
  • the vaporous phase stream comprising water and C 3 -C 6 carboxylic acid may be the effluent stream from a gas-phase (oxidative) conversion process of C 3 -C 6 alkane and/or C 3 -C 6 alkene .
  • the gaseous aqueous stream comprising C 3 -C 6 carboxylic acid is contacted with an absorbing solvent in a suitable absorption unit in order to separate the carbocyclic acid from water.
  • a suitable absorption unit in order to separate the carbocyclic acid from water.
  • absorption methods for vaporous streams are available in the art.
  • absorption may suitably be performed in an absorption column, typically a multi-stage countercurrent packed or tray absorption column having inlets for receiving a vaporous feed stream and for absorbing solvent, wherein absorbing solvent is continuously fed at an upper stage of the absorption column, and wherein the C 3 -C 6 carboxylic acid is absorbed by the solvent via direct contact of the rising vapour stream and the falling solvent.
  • absorbing solvents can decrease the solvent ratio and/or the liquid load of the absorption unit, thus rendering an easy and more economical implementation of the absorption set-up, such as an absorption column, in a process line-up.
  • oxygen-containing solvents being characterized by (i) a short Hansen solubility parameter distance R a with respect to C 3 -C 6 carboxylic acid, (ii) a partition logPOW 3-S determined at 25 °C and pH 7 of at least 0, and (iii) a boiling point at atmospheric pressure that is at least 5 °C higher, preferably at least 10 °C higher, more preferably at least 20 °C higher than the boiling point of C 3 -C 6 carboxylic acid, are excellent absorbing solvents for use in a process for recovering C 3 -C 6 carboxylic acid from aqueous vapour streams comprising C 3 -C 6 carboxylic acid.
  • Hansen solubility parameters can be used as a means for predicting the likeliness of one compound (solvent) dissolving in another. More specifically, each compound is characterized by three Hansen parameters, each generally expressed in MPa 0"5 : 5 d , denoting the energy from dispersion forces between molecules; ⁇ ⁇ , denoting the energy from dipolar intermolecular forces between molecules; and 5 h , denoting the energy from hydrogen bonds between molecules.
  • the affinity between compounds can be described using a multidimensional vector that quantifies these solvent atomic and molecular interactions, as a Hansen solubility parameters (HSP) distance R a which is defined in Equation (1) :
  • R a distance in HSP space between compound 1 and compound 2 (MPa 0-5 )
  • the smaller the value for R a for a given solvent calculated with respect to the C 3 -C 6 carboxylic acid to be recovered i.e., the C 3 -C 6 carboxylic acid being compound 1 and the solvent being compound 2, or vice versa
  • the higher the affinity of this solvent for the C 3 -C 6 carboxylic acid to be recovered will be .
  • the Hansen solubility parameter distance R a with respect to the one or more C 3 -C 6 carboxylic acids to be recovered as determined at 25 °C is 12 MPa 1 2 or less, preferably 10 MPa 1 2 or less, more preferably 8 MPa 1 2 or less, most preferably 5 MPa or less.
  • Coctanoi concentration of the compound in 1-octanol
  • Coctanoi concentration of the compound in water
  • the partition coefficient is a measure for the hydrophobicity of an absorbing solvent.
  • solvents having a suitably high partition coefficient are effective in minimizing the absorption of water from the C 3 -C 6 carboxylic acid-water mixture .
  • Suitable absorbing solvents for use as described herein have a partition coefficient logP 0 w as determined at 25 °C and pH 7 of at least 0.
  • the absorbing solvent for use as described herein has a logP 0 w of at least 0.5
  • the absorbing solvent has a boiling point at atmospheric pressure that is at least 5 °C higher, preferably at least 10 °C higher, more preferably at least 20 °C higher than the boiling point of the C 3 -C 6 carboxylic acid(s) .
  • the absorbing solvent has a boiling point of at least 145 °C.
  • it has a boiling point of at least 150 °C, more preferably at least 160 °C, even more preferably at least 170 °C.
  • the absorbing solvent has a boiling point of at least 165 °C.
  • it has a boiling point of at least 170 °C, more preferably at least 180 °C, even more preferably at least 200 °C.
  • the absorbing solvent has a boiling point that does not exceed 300 °C, more preferably not exceeds 280 °C, even more preferably not exceeds 250 °C, most preferably not exceeds 225 °C, at atmospheric pressure, in order to avoid excessive heating expenditure and eventual thermal degradation of the solvent .
  • Suitable oxygen-containing compounds having a Hansen solubility parameter distance R a , partition coefficient and boiling point ranges as defined herein can be found in the classes of carboxylic acids, esters of carboxylic acids, ethers, aldehydes, ketones, alcohols and organic phosphates. These oxygen-containing component may be linear, branched or cyclic, saturated or unsaturated, and may be aliphatic or contain aromatic rings.
  • organic phosphates such as triethyl phosphate and tributyl phosphate
  • heterocyclic hydrocarbons such as benzofuran
  • carboxylic esters such as methyl benzoate, n-butyl butyrate, n-butyl acrylate, 2-ethylhexyl acetate, diethyl phthalate, isopropyl acetate, octyl acetate and cyclohexyl acetate, ketones such as acetophenone, dipropyl ketone and 5-ethyl-2- nonanone
  • high-boiling functionalized ethers such as anisole, diethylene glycol ethyl ether, diethylene glycol monobutyl ether, propylene glycol phenyl ether, 2-butoxy ethanol, 2- phenoxy ethanol and butyl diglycol acetate and, depending on the carboxylic acid to be recovered, higher-boiling
  • carboxylic acids such as pentanoic acid, hexanoic acid, heptanoic acid and octanoic acid.
  • Hansen solubility parameter distance R a partition coefficient and boiling point, and taking into account the boiling point of the carboxylic acid to be recovered, the skilled person will be capable of selecting suitable absorbing solvents from each of these classes of oxygen-containing organic compounds.
  • coefficient and boiling point as defined herein are selected from the class of protic oxygenates, i.e. containing hydroxyl (-OH) group such as acids and alcohols and more preferably organic alcohols.
  • hydroxyl (-OH) group such as acids and alcohols and more preferably organic alcohols.
  • organic alcohols are understood to organic compounds wherein one or more hydroxyl functional groups (-OH) are bound to a carbon atom. This includes linear, branched and cyclic alcohols, saturated and
  • the alcohol may contain one hydroxyl group, or may contain two (diol) or more (triol, etc.) hydroxyl groups, provided that any surplus of hydroxyl groups does not result in an
  • the alcohols for use according to the invention may further contain other organic compounds, such as, butyl alcohols, undesirably high affinity for water.
  • the alcohols for use according to the invention may further contain other organic compounds, such as, butyl alcohols, undesirably high affinity for water.
  • the alcohols for use according to the invention may further contain other organic compounds, such as, butyl alcohols, undesirably high affinity for water.
  • alcohols for use according to the invention are cyclic or aromatic alcohols having 6 to 20 carbon atoms, linear aliphatic alcohols having 6 to 14 carbon atoms and branched aliphatic alcohols having 5 to 14 carbon atoms.
  • the invention relates to process for the recovery of C 3 -C 6 carboxylic acid from a vaporous aqueous stream, comprising
  • the absorbing solvent is a cyclic or aromatic alcohol having 6 to 20 carbon atoms, a linear aliphatic alcohol having 6 to 14 carbon atoms or a branched aliphatic alcohol having 5 to 14 carbon atoms.
  • cyclic alcohols include unsubstituted and alkyl-substituted cyclohexanols and cyclopentanols, such as cyclohexanol, methyl cyclohexanol , methyl cyclopentanol, trimethyl cyclohexanols and (4-methylcyclohexyl) methanol;
  • aromatic alcohols include phenol, benzyl alcohol,
  • xylenols such as 2, 6-xylen-l-ol
  • guaiacol (2- methoxyfenol ) creosol, cresols such as m-cresol, phenoxy ethanol and naphthol
  • suitable linear alcohols include those having the general formula C n H n+ iOH, wherein n is in the range of 6 to 14, preferably in the range of from 8 to 12, such as 1-hexanol, 2-hexanol, 3-hexanol, 1-octanol and 2-octanol, 1-decanol, 2-decanol, 1-dodecanol and 2-dodecanol
  • suitable branched alcohols include those having in the range of 5 to 14, preferably in the range of 6 to 12 carbon atoms, such as 2-methyl-2-pentanol, 2-methyl-3- pentanol, 3-methyl-3-pentanol, 2-
  • heptanol 3-methyl-l-butanol (isopentyl alcohol) , 2-methyl-l- butanol, 2-benzyloxy-ethanol , 2-phenoxy ethanol and 2-butoxy- ethanol .
  • alcohols containing other functional groups such as oxygen-containing groups like aldehyde, ether- or ester groups
  • oxygen-containing groups like aldehyde, ether- or ester groups
  • suitable alcohols include terpene-based alcohols such as pinacol, citronellol, menthol, and isoborneol.
  • Particularly preferred absorbing solvents for use according to the invention are 1-hexanol, 1-octanol, 1- decanol, 1-dodecanol, 2-ethyl-hexanol, diisobutyl carbinol, cresols, xylenols, anisole, butyl butyrate and 2-ethyl-hexyl- acetate .
  • the oxygen-containing solvents as defined herein are characterized by having very good selectivity, as compared to water, for C 3 -C 6 carboxylic acid. Furthermore, these solvents have relatively high boiling points and low volatility, thus minimizing their loss as vapour in the top stream of an absorption unit and allowing efficient separation from C 3 -C 6 carboxylic acid as the bottom stream using in a subsequent distillation (solvent recovery) step.
  • the absorbing solvent with one or more other solvents.
  • a mixture of two or more absorbing solvents as defined herein are used.
  • an absorbing solvent as defined herein is combined with one or more solvents selected from carboxylic esters, ethers, aldehydes or ketones.
  • the one or more absorbing solvents with Hansen solubility parameter distance R a , partition coefficient and boiling point as defined herein are present in a
  • the solvent mixture contains less than 40 wt%, preferably less than 30 wt%, more preferably less than 20 wt%, even more preferably less than 10 wt% of amine.
  • the one or more absorbing solvents as defined herein are used in the absence of amine compounds. In one embodiment, the absorbing solvent is employed in the absence of any other solvent not according to the invention.
  • a mixture of solvents contains less than 20 wt%, more preferably less than 10 wt%, even more preferably less than 5 wt%, most preferably less than 2 wt%, based on total weight of the solvent mixture, of a solvent having a boiling that is less than 5 °C higher than the boiling point of C 3 -C 6
  • the solvent mixture may comprise one or more organic alcohols as defined herein and additionally one or more of the corresponding acetate esters, which may form during absorption and/or regeneration of the absorbing alcohol solvent. If this is undesirable, these esters may at least partially be hydrolyzed, for example by feeding steam to the bottom of the column in the absorption or solvent regeneration (desorption) step.
  • the invention further relates to the use of an oxygen- containing organic compound as fully defined above as a solvent for absorbing C 3 -C 6 carboxylic acid from a water- containing vapour stream.
  • an oxygen- containing organic compound as fully defined above as a solvent for absorbing C 3 -C 6 carboxylic acid from a water- containing vapour stream.
  • the amount of absorbing solvent employed in the absorption process may vary within wide ranges, for example in a ratio (wt/wt) of absorbing solvent to C 3 -C 6 carboxylic acid supplied to the absorption unit in the range of from 100:1 to 0.1:1,
  • the temperature in the absorption step may vary within wide ranges due to the selection of different mixtures of acid and solvents and operation pressures. It is within the ability of one skilled in the art to select appropriate operating temperature for a given mixture at a given
  • the temperature in the absorption unit as described herein is in the range of of from 80 to 300 °C, more preferably 90 to 260 °C, most preferably 100 to 250 °C.
  • the pressure in the absorption unit may also vary within wide ranges. Typically, the pressure in the absorption unit is in the range of of from 0.1 to 20 bar, more preferably 1 to 10 bar, most preferably 2 to 6 bar.
  • the temperature is at most 50 °C, preferably at most 20 °C, more preferably at most 10 °C, most preferably at most 5 °C higher than the condensation
  • the temperature of the C 3 -C 6 carboxylic acid(s) to be recovered at operating pressure is at least 0 °C, preferably at least 10 °C, more preferably at least 20 °C, most preferably at least 30 °C above the condensation temperature of water at operating pressure.
  • the pressure is at least 50 %, preferably at least 80 %, more preferably at least 100 %, most preferably at least 120 % of the condensation pressure of the C 3 -C 6 carboxylic acid(s) to be recovered at operating temperature. Furthermore, the pressure is typically at most 99 %, preferably at most 90 %, more preferably at most 80 %, even more preferably at most 70 %, most preferably at most 50 % of the condensation pressure of water at operating
  • the absorbing solvent entrains substantially none of the water present in the gaseous aqueous feed stream of the absorption unit.
  • the absorbing solvent effluent stream of the absorption unit comprises water and C 3 -C 6 carboxylic acid in a weight ratio of less than 1:1, more preferably less than 0.5:1, even more preferably less than 0.1:1, yet even more preferably less than 0.05:1, most preferably less than 0.01:1 or about zero .
  • C 3 -C 6 carboxylic acid is removed (desorbed) from the absorbing solvent resulting in a product stream comprising C 3 -C 6 carboxylic acid and another stream comprising the absorbing solvent now depleted of C 3 -C 6 carboxylic acid.
  • recovery of the absorbing solvent, and of optional other solvents present is typically effectuated by distilling the effluent stream of the
  • the absorption unit comprising C 3 -C 6 carboxylic acid and absorbing solvent, resulting in a top stream comprising C 3 -C 6 carboxylic acid and a bottom stream comprising the absorbing solvent.
  • Distillation may be carried out in any distillation unit known to the skilled that is suitable for separating absorbing solvent from C 3 -C 6 carboxylic acid, and it is within the ability of one skilled in the art to select appropriate operating conditions for obtaining a desired degree of product purity and/or solvent recovery.
  • the temperature in the solvent recovery unit would vary depending on the solvent/mixture of solvents selected and is in the range of of from 80 to 300 °C, more preferably 100 to 250 °C, most preferably 110 to 200 °C.
  • the pressure in the solvent recovery unit is suitably in the range of of from 0.1 to 10 bar, more preferably 0.5 to 5 bar, most preferably 1 to 3 bar.
  • the temperature in the solvent recovery unit is at least 0 °C, preferably at least 10 °C, more preferably at least 20 °C, most preferably at least 30 °C above the condensation temperature of the carboxylic acid at operating pressure. In one embodiment, the temperature in the solvent recovery unit is at most 20 °C, preferably at most 10 °C, more preferably at most 5 °C, most preferably at most 0 °C below the condensation temperature of the absorbing solvent at operating pressure.
  • the pressure is at least at least 100 %, more preferably at least 110 %, even more preferably at least 120 %, most preferably at least 130 % of the condensation pressure of the absorbing solvent at operating temperature.
  • the pressure is at most 100 %, preferably at most 90 %, more preferably at most 80 %, even more preferably at most 70 %, most preferably at most 50 % of the condensation pressure of the carboxylic acid at operating temperature.
  • steam is fed at the bottom of the solvent regeneration (desorption) unit to hydrolyze any esters that may have been formed in the C 3 -C 6 carboxylic acid/solvent mixture.
  • At least 80 wt%, more preferably at least 90 wt%, even more preferably at least 95 wt%, yet even more preferably at least 98 wt% of the C 3 -C 6 carboxylic acid present in the stream fed to the solvent recovery unit comprising C 3 -C 6 carboxylic acid and absorbing solvent is recovered.
  • At least 80 wt%, more preferably at least 90 wt%, even more preferably at least 95 wt%, yet even more preferably at least 98 wt% of the solvent present in the stream fed to the solvent recovery unit comprising C 3 -C 6 carboxylic acid and absorbing solvent is recovered .
  • the C 3 -C 6 carboxylic acid product stream of the solvent recovery unit comprises C 3 -C 6 carboxylic acid in a concentration of at least 70 wt%, preferably at least 80 wt%, more preferably at least 90 wt%, more preferably at least 95 wt%, even more preferably at least 99 wt%, yet even more preferably at least 99.5 wt%, most preferably at least 99.9 wt% .
  • At least a portion of the stream of the solvent recovery unit comprising the absorbing solvent is recirculated to the absorption unit.
  • at least 20 wt%, preferably at least 50 wt%, more preferably at least 70 wt%, most preferably at least 90 wt% of the recovered solvent stream is recirculated to the absorption unit.
  • the entire bottom stream comprising the absorbing solvent is recirculated to the absorption unit.
  • Water comprising or substantially consisting of water vapour, and optionally other gases lighter than water, is produced.
  • Water may be recovered from this top stream using a condensation step, for example by cooling down the top stream of the absorption unit to a lower temperature, for example room temperature, so that the water can be recovered as a liquid stream .
  • the water vapour top stream of the absorption unit may further comprise entrained absorbing solvent.
  • said top stream of the absorption unit comprises no more than 3 vol%, preferably at most 1 vol%, more preferably at most 0.3, even more preferably at most 0.1, most preferably at most 0.01 vol% of entrained absorbing solvent.
  • Said entrained absorbing solvent may be recovered by liquid-liquid
  • the absorbing solvent thus recovered is at least partially recirculated to the absorption unit either as a separate stream or by mixing with a recirculated absorbing solvent stream from the solvent recovery unit .
  • the top stream comprising C 3 -C 6 carboxylic acid
  • originating from the solvent recovery unit may be further treated downstream, for example to further remove water by (azeotropic) distillation, pervaporation, etc., and/or other purification methods available in the art to obtain the purity and specifications for C 3 -C 6 carboxylic acid products according to market requirements.
  • azeotropic distillation, pervaporation, etc.
  • a vapour stream 4 comprising water and C 3 -C 6 carboxylic acid is fed to an absorption column 5 to which further an absorbing solvent 6 is fed.
  • C 3 -C 6 carboxylic acid is absorbed by the absorbing solvent, which exits the absorption column as "fat" solvent stream 7.
  • a vapour stream comprising water and other gaseous compounds exits the absorption column as stream 8.
  • Stream 7 comprising fat absorbing solvent and absorbed C 3 -C 6 carboxylic acid is fed supplied to a solvent recovery (desorption) unit, comprising a distillation unit 9 equipped with condenser section 9a and reboiler section 9b.
  • Desorbed C 3 -C 6 carboxylic acid leaves distillation unit 9 as stream 10, while absorbing solvent now depleted of absorbed C 3 -C 6 carboxylic acid exits distillation unit 9 as stream 11.
  • the C 3 -C 6 carboxylic acid-depleted absorbing solvent stream 11 may be partially recirculated to absorption column 5 as absorbing solvent recirculation stream 12.
  • C 3 -C 6 carboxylic acid stream 10 may be further purified downstream.
  • vapour stream 8 comprising water and other gaseous compounds obtained as a top stream from absorption column 5 is fed to a condensation unit 13, where water is removed via stream 14.
  • a product stream comprising gaseous compounds is removed via stream 15, from where it may undergo further separation and/or purification further downstream.
  • condensation unit 13 spontaneous separation from the condensed water of absorbing solvent entrained in vapour stream 8 originating from absorption column 5 may occur.
  • This separated absorbing solvent stream 16 may at least partially be recirculated to absorption column 5 via recirculation stream 17.

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Abstract

L'invention concerne un procédé de récupération d'acide carboxylique en C3-C6 à partir d'un courant aqueux à l'état de vapeur, consistant à utiliser un courant aqueux à l'état de vapeur comprenant un acide carboxylique en C3-C6, à mettre en contact ledit courant aqueux à l'état de vapeur comprenant l'acide carboxylique en C3-C6 avec un solvant absorbant dans une unité d'absorption, pour produire un premier courant comprenant le solvant absorbant et l'acide carboxylique en C3-C6 et un deuxième courant comprenant de la vapeur d'eau, à alimenter ce premier courant comprenant le solvant absorbant et l'acide carboxylique en C3-C6 à une unité de récupération de solvant, pour produire un troisième courant comprenant l'acide carboxylique en C3-C6 et un quatrième courant comprenant le solvant absorbant, et éventuellement à recycler au moins une partie du quatrième courant contenant le solvant absorbant vers l'unité d'absorption, le solvant absorbant étant un composé organique contenant de l'oxygène ayant (i) une distance de paramètre de solubilité de Hansen Ra par rapport à l'acide carboxylique en C3-C6 telle que déterminée à 25 °C de 15 MPa1/2 ou moins, de préférence 12 MPa1/2 ou moins, plus préférablement 10 MPa1/2 ou moins ; (ii) un coefficient de partage 1-octanol/eau logPOW, tel que déterminé à 25 °C et pH 7 d'au moins 0, de préférence d'au moins 0,5, plus préférentiellement d'au moins 1,0, encore plus préférentiellement d'au moins 1,5, plus préférentiellement encore d'au moins 2,0, idéalement d'au moins 3,0 ; et (iii) un point d'ébullition à pression atmosphérique qui est supérieur d'au moins 5 °C, de préférence d'au moins 10 °C, plus préférentiellement d'au moins 20 °C supérieur au point d'ébullition de l'acide carboxylique en C3-C6.
PCT/EP2016/082706 2015-12-29 2016-12-27 Absorption d'acide carboxylique à partir de courants aqueux à l'état de vapeur Ceased WO2017114829A1 (fr)

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WO2020186102A1 (fr) * 2019-03-13 2020-09-17 The University Of Wyoming Research Corporation D/B/A Western Research Institute Procédés de modulation d'hydrocarbures à base de pétrole à l'aide d'amines

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GB1458396A (en) * 1972-12-27 1976-12-15 Degussa Process for obtaining acrylic acid and optionally acrolein

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020186102A1 (fr) * 2019-03-13 2020-09-17 The University Of Wyoming Research Corporation D/B/A Western Research Institute Procédés de modulation d'hydrocarbures à base de pétrole à l'aide d'amines
US12076663B2 (en) 2019-03-13 2024-09-03 Western Research Institute, Inc. Methods for modulating petroleum-based hydrocarbons using amines

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