WO1998052903A1 - Procedes pour realiser des reactions limitees a l'etat d'equilibre - Google Patents

Procedes pour realiser des reactions limitees a l'etat d'equilibre Download PDF

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Publication number
WO1998052903A1
WO1998052903A1 PCT/US1997/009192 US9709192W WO9852903A1 WO 1998052903 A1 WO1998052903 A1 WO 1998052903A1 US 9709192 W US9709192 W US 9709192W WO 9852903 A1 WO9852903 A1 WO 9852903A1
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Prior art keywords
product
reaction zone
reaction
reactant
reactor
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PCT/US1997/009192
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English (en)
Inventor
Fungau Ho
William Marshall Haydon
Morteza Mokhtarzadeh
Anthony Joseph Papa
Leah Ann Paterson
Richard William Wegman
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Union Carbide Chemicals & Plastics Technology Corporation
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Publication of WO1998052903A1 publication Critical patent/WO1998052903A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

  • This invention pertains to processes for producing reaction product through equilibrium-limited reactions, such as esterif ⁇ cation and alcoholysis (or transesterification) reactions, wherein the processes are conducted using two reactor stages and the desired product or products of the equilibrium-limited reactions are removed in the vapor phase from the second stage reactor.
  • the invention is particularly useful in esterification processes such as to make carboxylic acid esters, e.g., butyl acrylate.
  • Equilibrium-limited reactions generally involve the reaction of two or more reactants to produce at least one product and, typically, a coproduct.
  • various techniques have been suggested such as removing the coproduct and/or product from the reaction menstruum to maintain a driving force toward the product.
  • Equilibrium-limited reactions are often conducted in a single reactor with product being selectively removed from the reaction menstruum or in a plurality of reactors in which product is separated from the reaction menstruum in each of the reactor stages.
  • One type of multistage reactor process is disclosed in United States patent no. 3,875,212 which discloses a process for making methyl acrylate or ethyl acrylate from methanol or ethanol and acrylic acid or methyl or ethyl methacrylate from methanol or ethanol and methacrylic acid.
  • the first reactor contains the acid and alcohol reactants in a solvent, and a vapor stream is taken which contains water, ester and alcohol. Liquid from the first reactor passes to a second reactor where additional alcohol is added and a vapor stream containing the ester, water and alcohol is removed.
  • the residence time to secure the desired conversion results in a large reactor volume per unit volume of product.
  • substantial amounts of vapor are typically generated to remove product and coproduct, and vaporized reactants are recovered and returned to the reactor, resulting in significant energy costs.
  • temperatures may be required that result in undesired side reactions and/or subatmospheric pressures are employed that further increase operating costs.
  • United States patent no. 3,700,726 discloses a process for making glycol ether acetates in which a reactor operates at a temperature of about 150° to 225°C to effect the reaction of a lower alkyl acetate with a glycol ether in the presence of catalyst.
  • a vapor is withdrawn from the reactor and is distilled to recover the coproduct alcohol and a bottoms fraction which is recycled to the reactor.
  • a liquid is withdrawn from the reactor and is flashed in a flash column operating at about 130° to 180°C.
  • the overhead from the flash column contains the product ester which is subjected to distillation for purification and the bottoms from the flash column, which contains catalyst, is recycled to the reactor.
  • the processes of this invention relate to conducting an equilibrium-limited reaction in at least two reaction zones, wherein at least a portion of a liquid phase reaction menstruum containing product produced in a first reactor zone is supplied to a second reaction zone and wherein product produced in the first reaction zone is also produced in the second reaction zone and is removed from the second reaction zone in the vapor phase. While typically only one product is ultimately sought, the processes of this invention may make possible the simultaneous formation of two or more products. For instance, acrylic acid may be reacted with a mixture of ethanol and butanol to produce the corresponding ethyl and butyl acrylates.
  • the processes of this invention pertain to conducting an equilibrium-limited reaction of at least one reactant to produce at least one product, comprising: a. reacting said at least one reactant in a first reaction zone maintained under reaction conditions, including temperature and pressure, sufficient to produce at least one product and sufficient to maintain at least a portion of at least one reactant and at least one product in the liquid phase, b. withdrawing liquid containing said at least one reactant and said at least one product from the first reaction zone, c. introducing at least a portion of said withdrawn liquid into a second reaction zone maintained under reaction conditions sufficient to produce in the liquid phase said at least one product, said conditions comprising temperature and pressure such that at least a portion of the at least one product is vaporized upon production thereof, d. withdrawing gas from said reaction zone, said gas comprising at least one product, and e. recovering the at least one product from the withdrawn gas.
  • At least two reactants are supplied to the first reaction zone to produce at least one product in the liquid phase.
  • Liquid containing at least a portion of said at least two reactants and at least a portion of said at least one product is withdrawn from first reaction zone, and at least a portion of this withdrawn liquid is introduced into a second reaction zone.
  • In the second reaction at least one product is produced and at least a portion thereof is vaporized.
  • Gas is withdrawn from said at least one second reactor and comprises said at least one product. From the withdrawn gas, said at least one product is recovered and remaining reactant is preferably recycled to at least one of the reaction zones.
  • the processes of this invention find particular application in the production of esters, especially esters that contain ethylenic unsaturation or other reactive groups that can lead to unwanted side reactions.
  • Advantageous processes include the formation of alkyl acrylates and alkyl methacrylates from lower alkanols, typically alcohols of one to twelve carbon atoms, and acrylic acid or methacrylic acid.
  • a preferred aspect of this invention pertains to processes for making butyl acrylate from butanol and acrylic acid.
  • the Figure is a schematic depiction of a process for making butyl acrylate from acrylic acid and butanol in accordance with this invention.
  • This invention relates to processes for conducting equilibrium- limited reaction processes.
  • This invention pertains broadly to any equilibrium-limited reaction process; however, the processes find most useful applications in producing organic equilibrium products, especially esters.
  • the processes may be batch processes, but are preferably continuous processes in which the reactants and any adjuvants such as catalysts, inhibitors and solvents, are added periodically or uninterruptedly to, and products are removed periodically or uninterruptedly from, the reaction zones.
  • the following discussion references the use of at least two reactants for the sake of convenience. It should be understood in the aspects of this invention where a single reactant is used for the equilibrium-limited reaction, that the description applies equally. Similarly, reference is made to a co-product for the sake of convenience.
  • Typical equilibrium-limited reaction processes include esterification and alcoholysis reactions. Esterification reactions involve the production of an ester by reaction of an alcohol with a carboxylic acid. A coproduct, water, is also produced. In alcoholysis (transesterification) reactions, an ester is reacted with an alcohol with an interchange occurring.
  • the carboxylic acids used in the processes of this invention often can be represented by the formula R C(O)OH, wherein R' is a hydrocarbyl- containing group of 1 to about 8, preferably 1 to about 4, carbon atoms and may be saturated or unsaturated aliphatic or cycloaliphatic (including branched and unbranched aliphatic and cycloaliphatic which may be saturated or contain ethylenic unsaturation), aryl, alkaryl (cyclic, linear and branched alkyl), aralkyl (cyclic, linear and branched alkyl), or any of the preceding containing a hetero atom such as oxygen, sulfur, nitrogen and phosphorus, and R 1 may be substituted with one or more hetero atom- containing substituents such as halides.
  • R' is a hydrocarbyl- containing group of 1 to about 8, preferably 1 to about 4, carbon atoms and may be saturated or unsaturated aliphatic or cycloaliphatic (including branched
  • esters In alcoholysis processes, the esters generally can be represented by the formula R'C(O)OR" wherein R' is as defined above and R" is a hydrocarbyl-containing group of 1 to about 12, preferably 1 to about 8, carbon atoms and may be saturated or unsaturated aliphatic or cycloaliphatic (including branched and unbranched aliphatic and cycloaliphatic which may be saturated or contain ethylenic unsaturation), aryl, alkaryl (cyclic, linear and branched alkyl), aralkyl (cyclic, linear and branched alkyl), or any of the preceding containing a hetero atom such as oxygen, sulfur, nitrogen or phosphorus.
  • R' is as defined above and R" is a hydrocarbyl-containing group of 1 to about 12, preferably 1 to about 8, carbon atoms and may be saturated or unsaturated aliphatic or cycloaliphatic (including branched and unbranched aliphatic and cycloali
  • the alcohols can be represented by the formula R'"OH wherein R'" is a hydrocarbyl-containing group of 1 to about 12 carbon atoms and may be saturated or unsaturated aliphatic or cycloaliphatic, aryl, alkaryl, aralkyl, or any of the preceding containing a hetero atom such as oxygen, sulfur, nitrogen or phosphorus, and R 1 " may be substituted with one or more heteroatom-containing substituents such as halides, with the proviso that in an alcoholysis reaction, R" 1 is other than R".
  • the products can be represented by the formula R'C ⁇ OR'".
  • the processes of this invention can be used to simultaneously produce more than one equilibrium product. For instance, more than one acid or ester can be used or more than one alcohol can be used to form a mixture of esters.
  • a product stream containing one ester product may be recovered from the primary reaction zone and a higher boiling ester product may be recovered from the secondary reactor.
  • both products may be recovered from the secondary reaction zone, either both in a vapor stream or one in the vapor stream and the other in a liquid product stream.
  • R"' is 1 to about 12 carbons, preferably 1 to 11, more preferably 3 to 8, and most preferably 3 to 6, carbon atoms.
  • alcohols include methanol, ethanol, iso-propanol, n- butanol, isobutanol pentanol, hexanol, 2-ethyl hexanol, methoxypropanol, ethoxyethanol, methox ethanol, methoxybutanol, ethoxypropanol, ethoxybutanol, butoxyethanol, butoxyethoxyethanol, ethoxyethoxy ethanol, and methoxyethoxy ethanol.
  • the carboxylic acid feed preferably contains 2 to 4 carbons such as acetic acid, acrylic acid, propionic acid, and methacrylic acid.
  • the processes are conventionally conducted at temperatures within the range of about 0° to 200°C, preferably in the range of about 40° to 150°C, but below a temperature that causes undue degradation of reactants, desired products, any catalyst used or desired side reactions.
  • a reactant contains another reactive group, e.g., unsaturation in the case of acrylic and methacrylic moieties
  • the temperature should be below that which causes undesirable side reactions.
  • the polymerization reactions can be controlled by the use of inhibitors, and thus the temperature of the reaction will also be influenced by inhibitor concentration.
  • the pressure under which the equilibrium-limited reactions can be conducted can also vary widely. Typically, pressures range from subatmospheric to superatmospheric, e.g., from about 0.01 to 100 bar, most often from about 0.1 to 10 or 15 bar, absolute.
  • the reaction may be conducted in the presence of a solvent or one or more of the reactants, products, coproducts and side reaction products may comprise the liquid media for the reaction.
  • the reaction menstruum in the first reaction zone may be the same as or different than that in the second reaction zone. Where a solvent is used, it is preferably substantially inert and is substantially nonvolatile under reaction conditions.
  • catalysts appropriate for the equilibrium-limited reaction can be used in the processes of this invention.
  • catalysts are often acids such as sulfuric acid, sulfonic acids and acidic exchange resins, and for alcoholysis reactions, metal oxides and alkoxides such as of alkali, alkaline earth, transition and rare earth metals, lead, bismuth and tin and the like.
  • the amount of catalyst can vary widely.
  • Homogeneous catalysts are often used in the range of about 0.001 to 10 or 20 weight percent of the liquid menstruum, and heterogeneous catalysts typically comprise about 10 to 60 percent of the volume of the reaction zone.
  • liquid reaction media such as antioxidants, stabilizers, buffers, polymerization inhibitors and the like.
  • the processes of this invention are conducted in at least one first reaction zone and at least one second reaction zone.
  • the at least one first reaction zone is maintained under reaction conditions such that at least a portion of the at least two reactants and at least one product are maintained in the liquid phase.
  • the vapor-liquid equilibrium for the at least one product is such that at least about 70, preferably at least about 80, percent of the product in the first reaction zone is in the liquid phase.
  • the vapor-liquid equilibrium for the at least two reactants is such that at least about 50, preferably at least about 70, percent of each reactant in the first reaction zone is in the liquid phase.
  • the first reaction zone may be a single vessel or may comprise two or more discrete vessels, one or more of which may be a stirred or agitated tank.
  • an overhead stream may be taken to remove co-product (e.g., water, from the esterification of alcohol with carboxylic acid) and thus drive the reaction further toward conversion to the desired product.
  • co-product e.g., water
  • the overhead stream is subjected to rectification or other separation unit operation such as liquefaction, condensation and liquid phase separation, sorption and membrane separation, to recover reactants for recycle to the reaction zone.
  • no overhead stream is removed from the first reaction zone, thus permitting the use of a plug flow reactor. Because no overhead stream need be taken, savings in equipment and energy can be achieved.
  • the residence time of the liquid menstruum in the first reaction zone is sufficient to yield production in a concentration within 50, typically within about 70, and sometimes at least about 90 or 95, percent of the theoretical equilibrium concentration of the product in the reaction menstruum under the conditions of the reaction (for given reactant concentrations).
  • at least about 50, preferably at least about 70, and most preferably between about 75 and 90, percent of the total amount of product produced in the process is produced in the first reaction zone.
  • the relative amounts of the reactants fed to the first reaction zone may also vary widely and will often be selected based upon economic factors. In many commercial equilibrium-limited reaction processes, the reactants are fed in an approximately stoichiometric ratio for producing the desired product, plus any additional amounts required to make up for losses due to side reactions. Often, for esterification and alcoholysis reactions, the mole ratio of the alcohol to acid or ester is between about 0.9:1 to about 1.1:1.
  • the first reaction zone is operated such that an amount equivalent to at least about 50, preferably at least about 70, and most preferably between about 75 and 90, percent of the fresh feed of at least one of the reactants is consumed.
  • the amount of the reactants, and their relative concentrations, in the first reaction zone may be different than that of the fresh feed due to recycling of unreacted reactants.
  • any recycle of reactants is to the first reaction zone in order to enhance the driving force to the sought product.
  • Liquid is withdrawn from the first reaction zone, which liquid contains product and reactants. At least a portion of this liquid is introduced into a second reaction zone. While in many instances, essentially all of the liquid withdrawn from the first reaction zone is passed to the second reaction zone, the broad concepts of this invention contemplate, for instance, an intervening separation step to be used to remove product and/or coproduct from the liquid.
  • the separation may simply be a liquid phase separation to remove, e.g., water from an esterification, a flashing or distillation unit operation, or product or coproduct via a membrane separation or a sorption step. Also, a portion of the liquid stream may be used for other processing. Additional reactant can be provided to the second reaction zone as a fresh feed or through recycle.
  • the second reaction zone may be a single vessel or may comprise two or more discrete vessels.
  • the conditions of the second reaction zone are maintained such that the product is, preferably, produced in the liquid phase and then vaporized.
  • an azeotroping agent is present to lower the boiling point of the product to avoid deleterious effects of high temperatures or expensive, high vacuum. Examples of azeotropic esterifications are set forth in Table 1.
  • the vapor-liquid equilibrium for the at least one product is such that less than about 50, preferably less than about 30, percent of the product in the second reaction zone is in the liquid phase.
  • the vapor- liquid equilibrium for the at least two reactants results in at least one reactant being vaporized is that less than about 50, and sometimes less than about 30, percent of at least one of, sometimes both, the reactants in the second reaction zone are in the liquid phase.
  • the reactions in the second reaction zone are conducted at temperatures within the range of about 0° to 200°C, more typically about 40° to about 170°C, but below a temperature that causes undue degradation of the reactants, desired products, catalyst or desirable side reactions.
  • a reactant contains another reactive group, e.g., unsaturation in the case of acrylic and methacrylic moieties
  • the temperature should also be below that which causes undesirable side reactions such as polymerization.
  • Polymerization inhibitors may be used to extend the desirable temperature range for the reaction.
  • the pressure in the secondary reaction zone can also vary widely.
  • pressures range from subatmospheric to superatmospheric, e.g., from about 0.01 to 100 bar, most often from about 0.1 to 10 or 15 bar, absolute.
  • the reaction in the second reaction zone is conducted in the presence of liquid comprising at least one of
  • Gas is withdrawn from the secondary reactor and comprises (i) at least one of the reactants, (ii) the product, and (iii) the co-product.
  • the equilibrium-limited reaction is an esterification or alcoholysis reaction
  • the acid or ester dimerize or generate other heavies.
  • the heavies are formed by a Michael reaction and as depicted by the following equation:
  • the dimer or heavies product is typically an equilibrium product.
  • the processes of this invention facilitate cracking of the dimer and other heavies.
  • the secondary reaction zone can be operated at sufficiently high temperatures to crack the dimer and heavies, and the dimer and heavies may comprise a substantial portion of the liquid menstruum, for instance, at least about 10 or, more typically, about 20 to 90 or more, weight percent of the menstruum
  • butyl acrylate is prepared by acid catalyzed esterification of acrylic acid with butanol.
  • acrylic acid is esterified with a homogeneous acidic catalyst in two reactors run in series.
  • water is removed overhead.
  • the tails stream containing butyl acrylate, unreacted feeds, and by-product is sent to a second reactor in order to increase conversion.
  • Butyl acrylate and by-products, substantially free of acrylic acid, are recovered in the overhead make of the second reactor. This overhead make is refined to give essentially pure butyl acrylate.
  • fresh acrylic acid and butanol are fed to a first reactor 100 in approximately equimolar amounts.
  • the acrylic acid and butanol supplied to the reactor 100 are typically of standard purities. However, as a result of the processes of the present invention, higher concentrations of typical impurities in the acrylic acid stream are better tolerated.
  • the acrylic acid feed to reactor 100 may contain up to 0.2 or more weight percent acetic acid because the acetic acid can react with butanol to form butyl acetate, a light component that can be readily removed by employing the present invention.
  • dimer for example, is readily cracked by the high temperature operation of the second reactor 200, as discussed below.
  • dibutyl ether the main impurity in butanol, which allows the use of a lower grade butanol feed.
  • the ability to use a wide range of acid and alcohol leads to significant economic savings.
  • the butanol: acrylic acid molar ratio of the fresh feed to reactor 100 is approximately equimolar (1:1).
  • the reaction is carried out in the presence of an acidic catalyst.
  • an acidic catalyst examples include sulfuric acid, phosphoric acid, and resins that contain acid functional groups.
  • the catalyst is a long chain alkyl benzene sulfonic acid such as dodecylbenzene sulfonic acid (DBSA).
  • DBSA catalyst and variations of it are described in United States patent no. 5,231,222. Relative to other catalysts, DBSA generates significantly less dibutyl ether and heavies during the esterification of acrylic acid with butanol; hence, higher efficiencies are achieved with DBSA as a result of low dibutyl ether and heavies formation.
  • DBSA is a homogeneous catalyst; thus, it is subject to entrainment. Nonetheless, the reaction is carried out using DBSA because, unlike conventional processes employing DBSA, which would require catalyst reclamation steps, in the present processes DBSA is simply cycled via lines 1 and 9 between reactors 100 and 200.
  • the reactors 100 and 200 and supply lines 1 and 9 are constructed of materials resistant to corrosion by the acid catalyst.
  • the catalyst concentration can vary over a wide range.
  • the DBSA can vary from about 0.1 to 10, preferably about 0.5 to 2, weight percent of the liquid menstruum.
  • DBSA is entrained, thus, catalyst make-up to reactor 100 or 200 can be a solution of the catalyst with acrylic acid, butanol, recycle liquid or any other process stream.
  • chemical inhibitors are employed to inhibit the formation of polymers derived from acrylic acid and/or butyl acrylate. Inhibitors are provided to reactor 100.
  • the inhibitors include phenothiazine (PZ), hydroquinone (HQ), and monomethyl ether of hydroquinone (MEHQ).
  • PZ is utilized in organic streams and HQ and/or MEHQ in water streams.
  • the amount of inhibitors used depends on the process.
  • the chemical inhibitors in reactor 100 will be about 50 to 10,000, e.g., about 500, ppmw by weight based upon the weight of the liquid menstruum.
  • oxygen is added to reactor 100 to enhance the inhibition of polymer formation.
  • Use of oxygen is well known in the art.
  • the oxygen can be added as pure oxygen, as a mixture with an inert gas, or preferably as air.
  • the oxygen is supplied by an air sparger provided at the bottom of the reactor (not shown).
  • Reactor 100 is a tank type reactor for the reaction of acrylic acid with butanol and removal water in order to force the equilibrium to acrylate. A conversion of about 80 to 85 percent is desired. A portion of the liquid in reactor 100 is taken to calandria 110 for increasing the temperature of the liquid. Calandria 110 is a conventional tube in shell vessel. The volume turnover rate through calandria 110 must assure that the contents of the reactor are well agitated and more uniformly heated. Alternatively, a jacketed reactor designed to generate the requisite heat and provided with mechanical stirrers could be used in place of the tank reactor and calandria.
  • the temperature in reactor 100 can range from 80 to 170°C but it is most preferred to maintain the temperature within the range of 120-130°C.
  • the return stream from calandria 110 is therefore at a temperature about 5 to 15°C higher.
  • the average residence time in reactor 100 is about 2 to 3 hours.
  • the pressure in reactor 100 is maintained at about atmospheric pressure.
  • the liquid in reactor 100 contains about 1 weight percent water and is in a single phase.
  • the esterification reaction generates water which is removed overhead and supplied to the bottom of a distillation column 120. As stated before, removing water drives the reaction toward butyl acrylate.
  • the distillation column 120 may be attached to the top of the reactor. Column 120 is of standard engineering design and can use trays or packing. To accommodate any entrainment of the DBSA catalyst, the bottom trays may need to be constructed of a metal which can handle highly corrosive liquid. To prevent polymerization and other fouling reactions in the distillation column 120, conventional inhibitors such as hydroquinone and phenothiazine are introduced throughout the column 120, diluted by butanol or some other process liquid.
  • the overhead from the distillation column 120 is removed via line 11 and supplied to a condenser/separator 130.
  • condenser/separator 130 the vapor is condensed and the liquid is phase separated, with the organic phase being returned to the distillation column 120 and the aqueous phase being sent via line 12 to disposal or to another column (not shown) to remove residual organics from the aqueous phase.
  • reactor 200 The liquid reaction menstruum from the reactor 100 is supplied via line 1 to reactor 200.
  • Reactor 200 is a standard tank reactor equipped with an air sparger (not shown). A portion of the liquid in reactor 200 is taken to calandria 210 to increase the temperature of the liquid. The volume turnover rate through calandria 210 must assure that the contents of the reactor are well agitated and maintained at the desired temperature.
  • the operating temperature in reactor 200 is higher than reactor 100 and the preferred range is 130° to 140 °C.
  • the return stream from calandria 210 is about 5° to 15°C higher than the preferred reactor temperature.
  • the higher temperature not only facilitates the conversion of the remaining butanol and acrylic acid to product, but very importantly, under these conditions, enable the heavies to be cracked back to butyl acrylate, acrylic acid and butanol.
  • the operating pressure in reactor 200 is lower than the pressure in reactor 100, and the preferred range is about 200 to 600 mmHg absolute (about 0.3 to 0.8 bar absolute).
  • the residence time in reactor 200 is approximately 2 to 3 hours.
  • Water is fed to reactor 200 in order to maintain a concentration of about 1 weight percent of the liquid menstruum for effective catalyst operation.
  • the concentration of DBSA in the second reactor is about 1 to 20, preferably about 5 to 25, e.g., 10, weight percent based upon the weight of the liquid menstruum.
  • inhibitor is added throughout reactor 200 to reduce polymerization.
  • the liquid bottom stream from reactor 200 which contains heavies and catalyst, is recycled via line 9 to reactor 100.
  • the bottom stream from reactor 200 is richer in catalyst and heavies than reactor 100.
  • the inhibitor concentration is also greater than in the first reactor, due to the cycle of the heavies between reactors 100 and 200.
  • a purge from this recycle stream can be taken via line 10.
  • the unique reaction system of our process allows for the recycle of heavies, catalyst and inhibitors. In conventional processes the entire heavies stream containing the inhibitors is typically discarded. Thus the processes of this invention enable lower catalyst and inhibitor usage and reduced inhibitor and catalyst cost.
  • Butyl acrylate, water and lights are removed as a vapor from reactor 200 and supplied via line 14 to an intermediate point of a distillation column 220.
  • the primary purpose of distillation column 220 is to recover butyl acrylate, essentially free of acrylic acid, from the vapor stream of reactor 200.
  • a secondary purpose is to recover water which is flashed in the reactor 200 due to the heat load in the reactor 200 and the calandria 210.
  • the overhead from distillation column 220 is supplied via line 16 to a condenser/separator 230, and the water phase and a portion of the organic phase are returned to the top of the distillation column 220.
  • the remaining portion of the organic phase is sent via line 2 to splitter distillation column 310.
  • the base of column 220 is heated.
  • the top of column 220 may be at a pressure of 300 mmHg absolute (about 0.4 bar absolute).
  • the liquid at the bottom of column 220 contains about 60 weight percent water and 40 weight percent organics (mostly acrylic acid). This bottoms fraction is returned via line 15 to reactor 200. This recycle step assists in maintaining a water concentration of about 1 weight percent in reactor 200
  • the feed for splitter distillation column 310 is the organic stream from distillation column 220, which consists mainly of butyl acrylate along with some butanol, lights, and heavies.
  • the purpose of splitter distillation column 310 is, as described earlier, to separate the stream into a tails fraction containing butyl acrylate and heavies, and an overhead stream of butanol, butyl acrylate, and lights such as dibutyl ether and butyl acetate.
  • the tails fraction is essentially free of all light components.
  • the column design is consistent with conventional engineering practice and can use packing or trays.
  • the base temperature of the splitter distillation column 310 is about 120°C with a pressure of about 400 mmHg (0.6 bar absolute).
  • the overhead stream from splitter distillation column 310 is supplied via line 3 to distillation column 320.
  • Distillation column 320 separates the overhead stream into a tails stream consisting essentially of butanol and butyl acrylate and an overhead stream consisting essentially of lights, mainly dibutyl ether and butyl acetate.
  • the lights stream is sent via line 5 to waste treatment or may be sold or burned and the tails stream is recycled via line 6 back to either or both of reactors 100 and 200.
  • the design of distillation column 320 is consistent with conventional engineering practice and can use packing or trays.
  • the base temperature of distillation column 320 is about 80°C with a pressure of about 300 mmHg (0.4 bar absolute).
  • the tails fraction from splitter distillation column 310 is supplied via line 4 to distillation column 330.
  • Column 330 separates the tails fraction into an overhead stream of butyl acrylate and a tails stream of heavies.
  • the tails stream is recycled via line 8 to either or both of reactors 100 and 200 or is recycled to the distillation columns (not shown).
  • the tails stream also contains inhibitors which, as described earlier, are desirably recycled.
  • the column design is consistent with conventional engineering practice and can use packing or trays.
  • the base temperature of the column is about 100°C with a pressure of about 100 mmHg (0.2 bar absolute). Alternatively, a vapor stream can be withdrawn from the bottom portion or base of column 310 and condensed to form a stream of butyl acrylate, thus eliminating the need for distillation column 330.
  • butyl acrylate can be produced having the preferred composition as described in Table 2, below.
  • Acrylates with such low levels of lights, especially dibutyl ether exhibit significantly reduced odor as compared to commercially available acrylates and enable the production of unexpectedly high quality product from lower quality feedstock. This combination of improved quality and lower production cost has not been heretofore appreciated.
  • Butyl Acrylate 95.0 to 100 99.5 to 100 Butyl Acetate 0.000 to 0.05 0.000 to 0.01 Butanol 0.000 to 0.01 0.000 to 0.01 Acrylic Acid 0.000 to 5 0.000 to 0.01 Dibutyl Ether 0.000 to 0J 0.000 to 0.02 Heavies 0.000 to 2 0.000 to 0.5 Water 0.000 to 0.5 0.000 to 0.05
  • Kettle 1 To an electrically heated, stirred reaction kettle (Kettle 1) are added about 500 grams of a mixture containing on a weight basis 0.4 % water, 11.5 % acetic acid (glacial), 12.2 % methoxypropanol, 75.3% methoxypropyl acetate, and 0.2 % propylene glycol diacetate with about 0.1 % unknown organics and an amount of dodecylbenzene sulfonic acid calculated as 0.32 weight percent of sulfuric acid.
  • Kettle 1 has an overhead column of about 10 theoretical plates with a partial condenser having a recycle to about the middle of the column.
  • a line runs from the bottom of Kettle 1 to an upper portion of another electrically heated, stirred reaction kettle (Kettle 2).
  • a flow control pump is provided to pump liquid from Kettle 1 to Kettle 2.
  • a recycle line is provided between the base of Kettle 2 to a feed line to Kettle 1. This recycle line also has a flow control pump to pump liquid from Kettle 2 to
  • Kettle 2 is charged with a mixture of about 375 grams of methoxypropyl acetate, 65 grams of methoxypropanol, 60 grams of acetic acid (glacial) and 5 grams of dodecylbenzene sulfonic acid.
  • Kettle 1 Both kettles are heated to reaction temperature (135°C in Kettle 1 and 144°C in Kettle 2).
  • reaction temperature When reaction temperature is achieved, a mixture of 22.7 parts by weight of methoxypropanol, 28.4 parts by weight of acetic acid (glacial) and 9.7 parts by weight of a equivolume mixture of methoxypropanol and water is fed to Kettle 1 to maintain a liquid level constant in Kettle 1.
  • Kettle 1 also receives a recycle stream from refining (described below) of about 200 grams per hour and a recycle stream from Kettle 2 in an amount of about 16 grams per hour.
  • the column on Kettle 1 has an overhead temperature of about 124 to 136°C and is at ambient atmospheric pressure.
  • the partial condenser is operated such that about 100 grams per hour of liquid are refluxed to the column and 125 grams per hour are in a vapor stream sent to refining.
  • Kettle 1 From the bottom of Kettle 1 is withdrawn about 150 grams per hour of liquid and this liquid is fed to Kettle 2.
  • Kettle 2 also operates at ambient atmospheric pressure and serves, in part, as a flash tank. About 130 grams per hour of vapor are withdrawn from Kettle 2 and are sent to refining. About 16 grams per hour are taken from the bottom of Kettle 2 for recycle to Kettle 1 and the balance is used for analysis.
  • the overhead from Kettle 1 and Kettle 2 are refined by distillation and a stream containing about 45 parts of methoxypropanol, 33 parts of methoxypropyl acetate and 22 parts of acetic acid is recycled to Kettle 1. The flow of this recycle stream is about 200 grams per hour.
  • the overhead stream from Kettle 2 contained 77% of unrefined product, methoxypropyl acetate, compared to about 54% obtained by a single reactor process.
  • 576 g/h of acrylic acid and 599 g/h of n-butanol are feed continuously to a first reactor (100), along with a 137 g/h stream (Stream 6) containing recycle butanol and inhibitor, and a 156 g/h recycle stream (Stream 9) from a second reactor containing catalyst.
  • the first reactor (100) contains 3.5 L liquid resident in the reactor for a period of 2 to 3 hours at a temperature of 129 C and atmospheric pressure.
  • a vapor stream rich in water is removed from the first reactor, is sent to a first distillation column, and is then condensed and decanted. The water phase is sent to another distillation column for further treatment, and the organic phase is returned to the first distillation column.
  • a 1339 g/h liquid stream (Stream 1) is removed from the first reactor and is supplied to the second reactor.
  • the second reactor (200) contains 3.5 L liquid resident in the reactor for a period of 2 to 3 hours at a temperature of 133 C and pressure of about 350 mm Hg absolute.
  • DBSA dodecylbenzene sulfonic acid
  • a recycle stream (Stream 10) is removed from the second reactor at a rate of 27 g/h.
  • a vapor stream is removed from the second reactor and is introduced into a distillation column. The distillation column is operated at a head temperature of 72 C and pressure of 300 mm Hg.
  • a water rich stream containing acrylic acid (Stream 15) is removed from the base of the distillation column and is recycled to the second reactor at a rate of 1061 g/h. Vapor is removed from the top of distillation column, and is then condensed and decanted. A portion of the organic phase, containing about 90 wt% butyl acrylate, is returned to the distillation column. The remainder of the organic stream, 1151 g/h, is sent to a splitter distillation column to produce, ultimately, essentially pure butyl acrylate.
  • the 1151 g/h organic stream (Stream 2) is fed to the middle of the splitter distillation column.
  • the splitter distillation column is operated at 150 mm Hg absolute head pressure and 71 C head temperature. Butanol, butyl acrylate and light impurities are removed over head, and butyl acrylate with heavy impurities is removed from the base of splitter distillation column.
  • the overhead from the splitter distillation column is condensed and decanted. A portion of the organic phase is returned to the column and the remaining organic phase (Stream 3) is sent to a lights distillation column at a rate of 143 g/h.
  • the total water phase from the decanter is sent to another refining column at a rate of 3 g/h.
  • a stream (Stream 4) is removed at an 1005 g/h rate and is supplied to a bottoms distillation column 330.
  • the lights distillation column (320) is operated at 150 mm Hg head pressure and a head temperature of 55 C.
  • a vapor stream concentrated in light impurities is removed over head from the lights distillation column and a butanol rich steam is removed from the base of the lights distillation column.
  • the vapor stream is condensed and is decanted to yield an organic phase and water.
  • a portion of the organic phase and water are returned to the column.
  • the remaining water from the decanter is sent to another refining column at a rate of 2 g/h.
  • the remainder of the organic phase from the decanter is purged from the system at a rate of 4 g/h (Stream 5).
  • the butanol rich stream (Stream 6) from the bottom of the lights distillation column is removed at 137 g/h and is returned to either or both of the first or second reactors.
  • the bottoms distillation column is operated at 20 mm Hg head pressure and a head temperature of 53 C. Vapor from the top of the bottoms distillation column is condensed and is refluxed back to the column at a reflux to distillate ratio of 0.2 gig. From the bottom of bottoms distillation column a stream (Stream 8) is removed at 7 g/h and is recycled to either or both of the first or second reactors. From the top of bottoms distillation column 99.9 wt% butyl acrylate is removed at 998 g/h.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

Les procédés faisant l'objet de cette invention, qui permettent de réaliser des réactions limitées à l'état d'équilibre, telles que des réactions d'estérification et d'alcoolyse, utilisent deux zones de réaction. La première zone de réaction agit dans des conditions de réaction qui retiennent au moins une partie du produit dans une phase liquide, et au moins une partie liquide provenant de la première zone de réaction est introduit dans une seconde zone de réaction, laquelle agit dans des conditions telles qu'au moins une partie du produit obtenu dans la seconde zone de réaction est vaporisée.
PCT/US1997/009192 1997-05-20 1997-05-27 Procedes pour realiser des reactions limitees a l'etat d'equilibre WO1998052903A1 (fr)

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US08/859,142 1997-05-20

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1215194A2 (fr) * 2000-12-15 2002-06-19 mg technologies ag Procédé de préparation d'esters d'acide acrylique ou méthacrylique
US6482976B1 (en) 1999-06-17 2002-11-19 Union Carbide Chemicals & Plastics Technology Corporation Processes for conducting equilibrium-limited reactions
WO2004078679A2 (fr) * 2003-02-28 2004-09-16 Union Carbide Chemicals & Plastics Technology Corporation Procede pour la conduite de reactions a equilibre limite
FR3008971A1 (fr) * 2013-07-29 2015-01-30 Arkema France Procede de production en continu d'acrylates legers par esterification d'un acide acrylique de grade ester brut

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875212A (en) * 1972-05-23 1975-04-01 Sumitomo Chemical Co Process for continuously synthesizing acrylic acid esters
DE3308879A1 (de) * 1982-03-17 1983-09-29 Nippon Kayaku K.K., Tokyo Verfahren zur herstellung von acrylsaeure- oder methacrylsaeureestern
EP0765859A1 (fr) * 1995-09-28 1997-04-02 Basf Aktiengesellschaft Procédé et installation de préparation continue de (méth-)acrylates d'alkyle

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875212A (en) * 1972-05-23 1975-04-01 Sumitomo Chemical Co Process for continuously synthesizing acrylic acid esters
DE3308879A1 (de) * 1982-03-17 1983-09-29 Nippon Kayaku K.K., Tokyo Verfahren zur herstellung von acrylsaeure- oder methacrylsaeureestern
EP0765859A1 (fr) * 1995-09-28 1997-04-02 Basf Aktiengesellschaft Procédé et installation de préparation continue de (méth-)acrylates d'alkyle

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6482976B1 (en) 1999-06-17 2002-11-19 Union Carbide Chemicals & Plastics Technology Corporation Processes for conducting equilibrium-limited reactions
EP1215194A2 (fr) * 2000-12-15 2002-06-19 mg technologies ag Procédé de préparation d'esters d'acide acrylique ou méthacrylique
EP1215194A3 (fr) * 2000-12-15 2004-01-07 mg technologies ag Procédé de préparation d'esters d'acide acrylique ou méthacrylique
WO2004078679A2 (fr) * 2003-02-28 2004-09-16 Union Carbide Chemicals & Plastics Technology Corporation Procede pour la conduite de reactions a equilibre limite
WO2004078679A3 (fr) * 2003-02-28 2004-12-09 Union Carbide Chem Plastic Procede pour la conduite de reactions a equilibre limite
JP2006519257A (ja) * 2003-02-28 2006-08-24 ユニオン・カーバイド・ケミカルズ・アンド・プラスティックス・テクノロジー・コーポレイション 平衡制限反応の実施方法
CN100345816C (zh) * 2003-02-28 2007-10-31 联合碳化化学及塑料技术公司 用于进行平衡限制反应的方法
US7569721B2 (en) 2003-02-28 2009-08-04 Union Carbide Chemicals And Plastics Technology Corporation Process for conducting equilibrium-limited reactions
FR3008971A1 (fr) * 2013-07-29 2015-01-30 Arkema France Procede de production en continu d'acrylates legers par esterification d'un acide acrylique de grade ester brut
WO2015015100A1 (fr) * 2013-07-29 2015-02-05 Arkema France Procede de production en continu d'acrylates legers par esterification d'un acide acrylique de grade ester brut
US9796651B2 (en) 2013-07-29 2017-10-24 Arkema France Method for continuous production of light acrylates by esterification of a raw ester-grade acrylic acid

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