KR20020016835A - Processes for conducting equilibrium-limited reactions - Google Patents

Abstract

The present invention relates to a process for carrying out equilibrium restriction reactions such as esterification reactions and polyalcoholization reactions using acid separation columns containing a single reaction zone, rectification zone and stripping zone. The temperature and pressure of the single reaction zone are sufficient to decompose the weight, for example the Michael addition weight formed or introduced into the single reaction zone and to evaporate at least a portion of the product in the preparation of the ester product. The rate of feeding the base fraction recovered from the acid separation column to the single reaction zone can be adjusted and adjusted to provide stable and efficient operation of the acid separation column and the single reaction zone.

Description

Processes for conducting equilibrium-limited reactions

The present invention includes a process for the preparation of reaction products via equilibrium-limited reactions, such as esterification and polyalcolysis (or transesterification) reactions. The present invention is particularly useful for esterification reactions for producing carboxylic acid esters such as butyl acrylate and ethylhexyl acrylate.

Background of the Invention

Equilibrium restriction reactions generally involve the reaction of one or more products and usually two or more reactants to produce a coproduct. In order to achieve more conversion to the desired product (s), various techniques have been proposed, such as removing coproducts and / or products from the reaction solvent to maintain driving force for the product.

The equilibrium restriction reaction can be carried out in a single reactor in which the product is selectively removed from the reaction solvent or in multiple reactors in which the product is separated from the reaction solvent in each reactor stage. One form of single reactor process is described in US Pat. No. 3,700,726, wherein the reactor is about 150 such that the reaction of lower alkyl acetate and glycol ether is carried out in the presence of a catalyst selected from aluminum alkoxide, titanium alkoxide and dialkyl tin oxide. Processes for preparing glycol ether acetates that operate at temperatures between -225 [deg.] C. and pressures of about 25 to about 150 psia are described. The vapor is recovered from the reactor and distilled to recover the coproduct alcohol and the base fraction and then recycled to the reactor. The liquid is recovered from the reactor and flashed in a flash column operating at about 130-180 ° C. The overhead of the flash column contains product esters, which are distilled for purification and the base of the flash column containing the catalyst is recycled to the reactor.

Another form of single reactor process is described in US Pat. No. 4,280,010, which provides for continuous production of alkyl acrylates liberated from ethers by liquid phase reaction of acrylic acid with C1 to C4 alkanols in a molar ratio of 1: 1 to 1: 2. The method is described. This process is carried out in the presence of sulfuric acid or an organic sulfonic acid catalyst at a temperature of 80 to 130 ° C. and a pressure of 100 to 760 mmHg, and the resulting alkyl acrylate is purified by distillation. As part of the distillation, the azeotropic mixture of alkyl acrylate, reacted water and unreacted alkanol is distilled near the head of the first distillation zone installed in the reaction zone.

Another form of single reactor process is described in EP 0 733 617, in which water produced in the reaction and the resulting alkyl esters are installed above the reaction zone and head to provide pure (meth) acrylates. A continuous esterification process of alkanol and (meth) acrylic acid in a homogeneous liquid solvent free phase in the presence of a proton donor catalyst is described, which is subsequently separated as an aqueous azeotrope through the head of the rectifying zone at a pressure of 0.1 to 1 atm. have.

EP 0 779 268 discloses a vaporized mixture of acrylic acid, n-butyl acrylate, n-butanol and water from an esterification reactor and condensing the vaporized mixture to provide a first condensate of an organic phase and an aqueous phase. There is described a method for recovering n-butyl acrylate in which substantially acrylic acid is removed from the esterification reaction mixture. A portion of the organic and aqueous phases are then fed to an acrylic acid separation column. The azeotropic mixture of n-butanol, n-butyl acrylate and water is distilled from the acrylic acid separation column at an aqueous reflux ratio of 8.5: 1 to 17: 1, and the acrylic acid base stream is removed from the distillation column and recycled to the esterification reactor. Refluxing the organic phase is fatal to the operation of the acrylic acid separation column (see line 13 on page 58 to line 14 on page 5). The overhead mixture is condensed to obtain a second condensate that is separated into n-butyl acrylate rich organic and aqueous phases. Next, the n-butyl acrylate rich organic phase substantially free of acrylic acid is removed. The addition reactant is recovered and recycled after treatment in separate hydrolysis recovery apparatus and pyrolysis reactor.

Often, when the reaction is carried out in a single reactor, the residence time to ensure the desired conversion leads to a larger reactor volume per unit volume of product. Moreover, a substantial amount of steam is usually generated to remove product and coproducts, and the vaporization reactants are recovered and returned to the reactor, which results in significant energy costs. Reactant recovery itself can cause difficult problems or require sophisticated separation schemes. In some cases, in order to vaporize the product for its removal, a negative pressure may be used that requires a temperature that causes undesirable side reactions and / or further increases operating costs.

Thus, equilibrium limiting reactions reduce overall reactor volume and reactor number, minimize reactant recovery problems, and provide conversion to the product without requiring significant energy use, eg, inadequate high temperature or excess steam, in the performance of the reaction. How to do this is required.

Description of invention

The process of the invention relates to a process for producing at least one ester product in a single reaction zone by carrying out an equilibrium restriction reaction of at least one carboxylic acid with at least one alcohol, wherein the reaction zone temperature and pressure are heavy, for example However, the Michael addition weight formed in the single reaction zone or introduced into the single reaction zone should be sufficient to decompose and evaporate at least a portion of the ester product in the preparation of the ester product. An acid separation column comprising a rectifying zone and a stripping zone provides an overhead fraction comprising at least one ester product to the rectifying zone and a base fraction comprising water and at least one carboxylic acid to the stripping zone, wherein the base fraction At least a portion of is fed to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone. Normally only one ester product is ultimately obtained, but the process of the present invention may allow for the simultaneous formation of two or more ester products. For example, acrylic acid can be reacted with a mixture of ethanol and butanol to produce the corresponding ethyl and butyl acrylates.

The method of the present invention is partially

a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products),

b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introducing into a lower portion of an acid separation column comprising a zone to provide an overhead fraction comprising at least one ester product to a rectifying zone and a base fraction comprising water and at least one carboxylic acid to a stripping zone,

c. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone, and

d. Recovering the overhead fraction from the acid separation column and recovering the at least one ester product from the overhead fraction, wherein the equilibrium restriction reaction of at least one carboxylic acid and at least one alcohol is carried out to produce at least one ester product. It is about.

In this embodiment, crude equilibrium containing low purity feed streams, such as dibutyl ether, as well as heavy residue-containing streams resulting from similar equilibrium restriction reactions, e.g., other methods used in integrated equilibrium restriction methods. Butanol streams or crude acrylic acid streams containing high concentrations of acrylic acid dimers or other Michael addition weights may be used in the process of the present invention. In addition, in this embodiment, the rate of feeding the base fraction recovered from the acid separation column to a single reaction zone is controlled according to the water rate required for the formation of product / water azeotrope (e.g. butyl acrylate / water azeotrope). Can be controlled. If the rate is too low, the liquid level in the single reaction zone increases due to the deposition of the product (eg butyl acrylate) resulting in inefficient operation of the single reaction zone. If the rate is too high, excess water removes byproducts (e.g. butoxy propionate (BBP)) from the single reaction zone by BBP / water azeotropes, resulting in higher acid concentrations by increasing the concentration of BBP in the acid separation column. This leads to unstable and inefficient operation of the column.

The method of the present invention is partially

a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products),

b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introducing into a lower portion of an acid separation column comprising a zone to provide an overhead fraction comprising at least one ester product to a rectifying zone and a base fraction comprising water and at least one carboxylic acid to a stripping zone,

c. At least one alcohol, which may be the same as or different from the alcohol contained in the alcohol containing feedstock, may be used to ensure stable and efficient operation of the acid separation column in the region between the base of the acid separation column and the point at which the recovered vapor is introduced into the acid separation column. Introducing into the acid separation column in an amount sufficient to provide, for example, an amount sufficient to minimize or eliminate foaming of the acid separation column,

d. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone, and

e. Recovering the overhead fraction from the acid separation column and recovering the at least one ester product from the overhead fraction, wherein the equilibrium restriction reaction of at least one carboxylic acid and at least one alcohol is carried out to produce one or more ester products. It is about.

In this embodiment, the operational stability is determined by acid separation through the introduction of fresh or recycled alcohol into the acid separation column in the region between the base of the acid separation column and the point where steam recovered from the single reaction zone is introduced into the acid separation column. Is given to the column. In addition to operating stability and efficiency, it is important to control the foaming at the bottom of the distillation column to minimize carboxylic acid degradation at overhead. Foaming can result from unstable composition areas of the acid separation column and / or high basal circulation rates.

The method of the present invention is also partially

a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products),

b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introduced into the lower portion of the acid separation column comprising the zone providing an overhead fraction comprising one or more unsaturated ester products, low boiling by-products, high boiling by-products and one or more alcohols to the rectifying zone and comprising water and one or more carboxylic acids Providing a base fraction to the stripping zone, introducing one or more polymerization inhibitors into the acid separation column,

c. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone,

d. The overhead fraction is recovered from the acid separation column and at least a portion of the recovered overhead fraction is introduced into one or more splitter distillation columns to provide an overhead fraction comprising low boiling by-products and one or more alcohols and one or more unsaturated ester products Providing a base fraction comprising by-products and the like, introducing one or more polymerization inhibitors into one or more splitter distillation columns,

e. Recovering the overhead fraction from one or more splitter distillation columns and introducing the recovered overhead fraction into one or more alcohol recovery distillation columns to provide an overhead fraction comprising low boiling by-products and a base fraction comprising one or more alcohols; Introducing at least one polymerization inhibitor into at least one alcohol recovery distillation column,

f. Recovering the base fraction (recycling at least a portion of the base fraction) and the overhead fraction (purging at least a portion of the overhead fraction) from one or more alcohol recovery distillation columns,

g. The base fraction is recovered from one or more splitter distillation columns and the recovered base fraction is introduced into one or more ester distillation columns to provide an overhead fraction comprising one or more unsaturated ester products and a base comprising high boiling by-products and one or more polymerization inhibitors. Providing a fraction, wherein the at least one polymerization inhibitor is introduced into the recovered base fraction from at least one ester distillation column and / or at least one splitter distillation column prior to introducing the recovered base fraction into at least one ester distillation column,

h. A base fraction comprising one or more polymerization inhibitors is recovered from one or more ester distillation columns, and at least a portion of the recovered base fraction is in an amount sufficient to minimize or eliminate the polymerization of the unsaturated carboxylic acid and / or the unsaturated ester product, Feeding at least one splitter distillation column and / or at least one alcohol recovery distillation column and

i. A process for producing at least one ester product by carrying out an equilibrium restriction reaction of at least one carboxylic acid and at least one alcohol, comprising recovering an overhead fraction comprising at least one unsaturated ester product from at least one ester distillation column. .

In this embodiment, the polymerization inhibitor is returned in the process by recycling the base fraction containing the polymerization inhibitor recovered from at least one ester distillation column to an acid separation column, at least one splitter distillation column and / or at least one alcohol recovery distillation column. Used. In addition to cost effective, recycling of polymerization inhibitors to various distillation columns can control undesirable polymerization. For example, reactive monomers (such as acrylic acid and butyl acrylate), when poorly inhibited, readily form polymers via free radical polymerization. In addition, the present process, where the recycle stream returns the cracking weight to the reactor, is economically effective.

The method of the present invention is also partially

a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products),

b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introduced into the lower portion of the acid separation column comprising the zone providing an overhead fraction comprising one or more ester products, low boiling by-products, high boiling by-products and one or more alcohols to the rectifying zone and a base comprising water and one or more carboxylic acids Providing a fraction to the stripping area,

c. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone,

d. The overhead fraction is recovered from the acid separation column and at least a portion of the recovered overhead fraction is introduced into one or more splitter distillation columns to provide an overhead fraction comprising low boiling by-products and one or more alcohols and one or more unsaturated ester products. Providing a base fraction comprising by-products, and the like,

e. Recovering the base fraction from one or more splitter distillation columns and introducing the recovered base fraction into one or more ester distillation columns to provide an overhead fraction comprising one or more ester products and a base fraction comprising high boiling byproducts,

f. Recovering the base fraction (recycling at least a portion of the base fraction) and the overhead fraction (including one or more ester products) from one or more ester distillation columns,

g. The overhead fraction is recovered from one or more splitter distillation columns and the recovered overhead fraction is introduced into one or more alcohol recovery distillation columns to provide an overhead fraction comprising low boiling by-products and a base fraction comprising one or more alcohols. step,

h. The base fraction is recovered from one or more alcohol recovery distillation columns and at least a portion of the recovered base fraction is recovered in a stable and efficient manner in the acid separation column in the region between the base of the acid separation column and the point at which the recovered steam is introduced into the acid separation column. Supplying an amount sufficient to provide operation, such as an amount sufficient to minimize or eliminate foaming in the acid separation column and / or in a single reaction zone, and

i. Recovering the overhead fraction from one or more alcohol recovery distillation columns (purging at least a portion of the recovered overhead fraction) to perform an equilibrium restriction reaction of the one or more carboxylic acids and one or more alcohols to produce one or more ester products. It relates to a method of manufacturing.

In this embodiment, the unreacted alcohol comprises the recovered base fraction containing the unreacted alcohol from at least one alcohol recovery distillation column from the base of the acid separation column and steam recovered from the single reaction zone. It is used again in this process by recycling to the acid separation column in the region between the points introduced into the reaction zone. In addition to making the cost effective, recycling of the unreacted alcohol to the acid separation column may impart operational stability to the acid separation column as described above.

In another embodiment, the process also includes overhead fraction (i) recovered from an acid separation column, overhead fraction (ii) recovered from one or more splitter distillation columns and / or over recovered from one or more alcohol recovery distillation columns. Introducing at least a portion of the head fraction (iii) into the water distillation column to provide an overhead fraction comprising one or more alcohols and a base fraction comprising water, and recovering the base fraction from the water distillation column (at least a portion of the Purge), recovering the overhead fraction from the water distillation column, and evacuating at least a portion of the overhead fraction from the base of the acid separation column and from the single reaction zone into the acid separation column and / or into the single reaction zone. Feeding the acid separation column in the region between the points. In this embodiment, the unreacted alcohol is recycled and used again in the process as described above.

In another embodiment, the present invention relates to a batch or continuously produced mixture comprising at least 50.0% by weight of butyl acrylate and at most 8 ppm of acrylic acid. Such mixtures result from the practice of the present invention when the change in the carboxylic acid (eg acrylic acid) of the overhead produced from the acid separation column is minimized or eliminated. The unique form of the single reaction zone and acid separation column is as described above with high concentrations of butyl acrylate (e.g., at least 50.0% by weight) and low concentrations of acrylic acid (e.g., at most 10 ppm, preferably at most 8 ppm, more preferably at 5 ppm. Useful for enabling the preparation of overhead (from the acid separation column). Higher acrylic acid concentrations may be detrimental to obtaining the desired butyl acrylate quality. Lower concentrations of acrylic acid in the butyl acrylate stream may obviate the need for further processing, such as the need to reduce acrylic acid by neutralization.

The process of the present invention also partially reacts in the presence of an esterification catalyst in a single reaction zone wherein at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock are maintained under reaction conditions sufficient to produce at least one ester product. The reaction conditions include sufficient temperature and pressure to decompose the weight formed in or introduced into the single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products). To at least one ester product by carrying out an equilibrium restriction reaction of at least one carboxylic acid with at least one alcohol, wherein the at least one carboxylic acid containing feedstock comprises acetic acid, acrylic acid dimers and / or other Michael addition weights. Which comprises crude acrylic acid stream. In this embodiment, a low purity feed stream, such as a crude acrylic acid stream containing a high concentration (eg, at least about 0.25% or even at least about 0.5%) of acrylic acid dimers and / or other Michael addition weights, is present. It can be used in the process of the invention.

The process of the present invention has been found to be of particular use in the preparation of esters, especially esters containing ethylenically unsaturated reactive groups or other reactive groups which can induce undesired side reactions. Advantageous methods include the formation of alkyl acrylates and alkyl methacrylates from lower alkanols, usually alcohols having 1 to 12 carbon atoms and acrylic acid or methacrylic acid. Preferred aspects of the invention include a process for the preparation of butyl acrylate from butanol and acrylic acid.

1 is a simplified diagram of a process for the preparation of butyl acrylate from acrylic acid and butanol according to the present invention.

The present invention relates to a process for carrying out an equilibrium restriction reaction process. Although the present invention broadly belongs to equilibrium limiting reaction processes, this process has found the most useful applications in the preparation of organic equilibrium products, in particular esters. This process is a batch process, but preferably a continuous process in which reactants and certain auxiliaries (such as catalysts, inhibitors and solvents) are added to the reaction zone periodically or continuously and the product is removed from the reaction zone periodically or continuously. Process. The discussion below uses two or more reactants for convenience. In aspects of the invention where a single reactant is used in the equilibrium restriction reaction, it should be understood that this description applies equally. Similarly, co-products are referenced for convenience. It is to be understood that the present invention includes equilibrium limiting reactions in which no coproducts are formed.

Common equilibrium limiting reaction processes include esterification and dialcoholization reactions. The esterification reaction involves the production of esters by the reaction of alcohols with carboxylic acids. Coproducts of water are also produced. In the alcoholic reaction (ester exchange reaction), the ester reacts with the alcohol by exchange.

Carboxylic acids used in the process of the present invention are often of the formula R'C (O) OH, wherein R 'is a hydrocarbyl containing group having 1 to about 8 carbon atoms, preferably 1 to about 4 carbon atoms, and is saturated or unsaturated aliphatic Or alicyclic (including branched and straight chain aliphatic or cycloaliphatic groups which may contain saturated or ethylenically unsaturated groups), aryl, alkaryl (cyclic, straight and branched chain alkyl), aralkyl (cyclic, straight and branched chain) Alkyl) or a hetero atom such as oxygen, sulfur, nitrogen and phosphorus, and any one of the aforementioned groups, and R 'may be substituted with one or more hetero atom containing substituents such as halides. Can be displayed. In the polyalcoholization process, esters are generally of the formula R'C (O) OR "[where R 'is as defined above and R" is a hydro of 1 to about 12 carbon atoms, preferably 1 to about 8 carbon atoms. Carbyl-containing groups, saturated or unsaturated aliphatic or cycloaliphatic (including branched and straight chain aliphatic or cycloaliphatic groups which may contain saturated or ethylenically unsaturated groups), aryl, alkaryl (cyclic, straight and branched alkyl) , Aralkyl (cyclic, straight and branched chain alkyl) or hetero atom (eg, oxygen, sulfur, nitrogen or phosphorus). Alcohols are of the formula R '' 'OH [where R' '' is a hydrocarbyl containing group having from 1 to about 12 carbon atoms and is a saturated or unsaturated aliphatic or cycloaliphatic group, aryl, alkaryl, aralkyl, or hetero atom (E.g., oxygen, sulfur, nitrogen or phosphorus), and R '' 'may be substituted with one or more hetero atom-containing substituents (e.g. halides), provided that R ′ '' in the reaction may be different from R ″. The product may be represented by the formula R′C (O) OR ′ ″.

The process of the present invention can be used to simultaneously produce one or more equilibrium products. For example, one or more acids or esters may be used, or one or more alcohols may be used to form the ester mixture. For example, a product stream containing one ester product and a high boiling ester product can be recovered from a single reaction zone both in the vapor stream or in one of the vapor streams and the other in the liquid product stream. As an example involving simultaneous preparation of butyl acrylate and ethylhexyl acrylate, butyl acrylate can be recovered from a single reaction zone in a vapor stream and ethylhexyl acrylate can be recovered in a liquid stream.

The process of the invention is particularly preferably used for the preparation of acetates, acrylates, propionates and methacrylates, where R '' 'is 1 to about 12 carbon atoms, preferably 1 to 11 carbon atoms, more preferably 3 to 8 carbon atoms, most preferably 3 to 6 carbon atoms. Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, isobutanol, pentanol, hexanol, 2-ethyl hexanol, methoxypropanol, ethoxyethanol, methoxyethanol, methoxybutanol, ethoxypropanol, eth Methoxybutanol, butoxyethanol, butoxyethoxyethanol, ethoxyethoxyethanol and methoxyethoxyethanol. The carboxylic acid feed preferably contains 2 to 4 carbons, examples of which are acetic acid, acrylic acid, propionic acid and methacrylic acid.

The process of the present invention is carried out at a temperature of about 50 to about 200 ° C, preferably about 100 to about 160 ° C and more preferably about 125 or 135 ° C to about 150 ° C. If the temperature is too low, the reaction rate is lowered. If the temperature is too high, there are more by-products and the corrosion rate is faster. The reaction zone temperature (along with the pressure) should be sufficient to decompose the weight, for example the Michael addition weight formed in or introduced into the single reaction zone and to evaporate at least a portion of the ester product in its preparation. However, the reaction zone temperature should not cause excessive decomposition of the reactants, the desired product, the catalyst used or the desired side reactions. If the reactants contain unsaturated groups in the case of other reactive groups, such as acrylic and methacryl residues, the temperature should not cause undesirable side reactions. To some extent, the polymerization reaction can be controlled by the use of inhibitors as described above, so the reaction temperature can also be influenced by the inhibitor concentration.

The pressure at which the equilibrium restriction reaction can be carried out can also vary widely. Typically, the pressure is in the range of negative pressure to superatmospheric pressure, for example about 0.01 to 100 bar, most often about 0.1 to 10 or 15 bar. As set forth above, the reaction zone temperature and pressure decompose heavy weights, such as Michael addition weights formed in or introduced into a single reaction zone and evaporating at least a portion of the ester product in the preparation of the ester product. Should be enough.

The reaction can be carried out in the presence of a solvent or one or more reactants and the product, coproduct and side reaction product can comprise a liquid medium for the reaction. If a solvent is used, it is preferred that it is substantially inert and substantially nonvolatile under the reaction conditions.

Many equilibrium restriction reactions use catalysts to facilitate the exchange reaction. Catalysts suitable for equilibrium restriction reactions can be used in the process of the present invention. For esterification the catalyst is often an acid (e.g. sulfuric acid, sulfonic acid and acid exchange resins), and for the alcoholic reaction, metals such as alkali metals, alkaline earth metals, transition and rare earth metals, lead, bismuth and tin Oxides and alkoxides. The catalytic amount can vary widely. Homogeneous catalysts are often used in the range of about 0.001 to 10 or 20% by weight of the liquid solvent, and heterogeneous catalysts typically comprise about 10 to 60% of the volume of the reaction zone. The lower the catalyst concentration, the slower the rate of esterification and decomposition and the greater the purging from a single reaction zone. The higher the catalyst concentration, the more by-products and the faster the corrosion rate. When using sulfonic acid catalysts such as dodecylbenzene sulfonic acid (DBSA), small amounts, such as from about 0.5 to about 1 weight percent, preferably about 1 weight percent, to minimize the formation of sulfonate esters Less water should be present in a single reaction zone.

Other adjuvants such as antioxidants, stabilizers, buffers and polymerization inhibitors may be included in the liquid reaction medium. It is not intended that the present invention be limited to adjuvant in any way. Phenothiazine (PZ) is the preferred primary process inhibitor. Since PZ is insoluble in water, hydroquinone (HQ) is preferably used as an inhibitor for aqueous streams. Monomethyl ether of hydroquinone (MEHQ) is the preferred product shipping inhibitor and is used in ester distillation columns. Air or oxygen is used to enhance the effect of the inhibitor. In all columns except the water column, the partial pressure of oxygen is preferably about 0.05 to about 1.0 mmHg, preferably about 0.1 to about 0.8 mmHg, at the base of the column.

The single reaction zone can be a stirred tank or a shake tank. In a preferred embodiment, the overhead vapor stream is believed to drive the conversion reaction back to the desired product by removing product / coproducts (eg, esters / water resulting from esterification of alcohols and carboxylic acids). The overhead vapor stream is then subjected to a separation operation (eg distillation) to recover the crude product for further purification and to recover the reactants (eg alcohol) and auxiliaries (eg polymerization inhibitors) for recycling.

In general, the residence time of the liquid solvent in a single reaction zone is less than 50% of the theoretical equilibrium concentration, usually within about 70% and often at least about 90% or 95% of the product in the reaction solvent under the reaction conditions (to the reactant concentrations shown). It should be sufficient to produce the above concentration. The single reaction zone residence time is not narrowly stringent and usually ranges from about 1 hour or less to about 20 hours or more, preferably from about 2 to about 10 hours.

The relative amounts of reactants fed to a single reaction zone can also vary widely and are often chosen depending on economic factors. In many commercial equilibrium limiting reaction processes, the reactants are supplied in approximately stoichiometric ratios to produce the desired product and in the amounts necessary to compensate for the losses due to side reactions. Often, in esterification and dialcoholization reactions, the molar ratio of fresh alcohol to fresh acid or ester is from about 0.9: 1 to about 1.1: 1 or more. Preferably, the single reaction zone is operated such that an amount corresponding to at least about 50%, preferably at least about 70% and most preferably about 75 to 90% of the fresh feed of at least one reactant is consumed.

It can be seen that the amount of reactants and their relative concentrations in a single reaction zone may differ from the amount of fresh feed and its concentration due to the recycling of unreacted reactants. Generally, the reactants are recycled to a single reaction zone or acid separation column to enhance the driving force for the desired product. About 0-100%, preferably about 40-60% alcohol recycle is fed to a single reaction zone and the remainder is fed to the bottom of the acid separation column to stabilize the operation of the acid separation column. It is desirable to supply excess alcohol (eg butanol) to a single reaction zone to complete the carboxylic acid (eg acrylic acid) conversion. In a single reaction zone, it is desirable to maintain a molar ratio of alcohol to acid or ester of less than about 2: 1 because lower molar ratios produce less byproducts such as butyl ether, resulting in lower capital and operating costs. If the molar ratio of alcohol to carboxylic acid or ester in the reactor is too low, the acid conversion is lowered to deposit carboxylic acid in a single reaction zone, carboxylic acid breakthrough in an acid separation column, and high viscosity reactor materials and / or large amounts of reactor purge Is generated.

The conditions of the single reaction zone are maintained so that the product is preferably prepared in liquid phase and then evaporated. The reaction zone conditions should be sufficient to decompose the weight, for example the Michael addition weight formed in or introduced into the single reaction zone and to evaporate at least a portion of the ester product in the preparation of the ester product. Preferably, an azeotropic agent is present to lower the boiling point of the product, thereby avoiding the deleterious effects of high temperature or high expense and high vacuum. Examples of azeotropic esterification are shown in Tables 1a and 1b.

Water-ester azeotropes mountain nbp (℃) Alcohol nbp (℃) ester nbp (℃) Water-ester azeotropes (nbp, ° C) Water (% by weight) Acetic acid 118.5140.5 Ethanol n-propanol i-propanol n-butanol i-butanol 2-ethynol ethanol n-propanol i-propanol n-butanol i-butanol 2-ethylhexanol 78.397.282.5117.8108.0184.678.397.282.5117.8108.0184.6 EACn-PACi-PACn-BACi-BACEHACEAn-PAi-PAn-BAi-BAEHA 77.2101.688.6126.2117.2198.499.5 ---- 147 ---- 70.482.476.690.287.499.081.1 ---- 94.5 ---- 8.51410.628.716.573.515.0 ---- 40 ---- AC = acetate E = ethyl P = propyl B = butyl A = acrylate EH = 2-ethylhexyl

Water-ester azeotropes mountain nbp (℃) Alcohol nbp (℃) ester nbp (℃) Water-ester azeotropes (nbp, ° C) Water (% by weight) Propionate Methacrylic Acid 140.9160.5 Ethanol n-propanol i-propanol n-butanol i-butanol 2-ethynol ethanol n-propanol i-propanol n-butanol i-butanol 2-ethylhexanol 78.397.282.5117.8108.0184.678.397.282.5117.8108.0184.6 EPn-Pi-Pn-Pi-PEHPEMAn-MAi-MAn-MAi-MAEHMA 99.2122.1110.3146.8136.9 -------------- 81.288.985.294.892.8 -------------- 102319.94152.2 -------------- P = propionate MA = methacrylate

Preferably, under conditions of a single reaction zone involving azeotropic formation, the vapor-liquid equilibrium for one or more products is such that less than about 50%, preferably less than about 30%, of the product is present in the liquid phase in the single reaction zone. do. Good mixing of the liquid solvent in a single reaction zone should ensure uniform concentration and temperature. It may be desirable to use forced or natural circulation calandria to supply heat and mix in a single reaction zone.

Often the reaction in a single reaction zone is carried out at a temperature of about 100 to 160 ° C., more typically about 125 or 135 ° C. to about 150 ° C., but at a temperature that causes excessive decomposition of the reactant, desired product, catalyst or desired side reaction. Is carried out in less than. The reaction zone temperature (along with the pressure) should be sufficient to decompose the weight, for example the Michael addition weight formed in or introduced into the single reaction zone and to evaporate at least a portion of the ester product in the preparation of the ester product. . If the reactants contain unsaturated groups in the case of other reactive groups, for example acrylic and methacryl residues, the temperature should also be below the temperature causing an undesired side reaction (eg polymerization). Polymerization inhibitors can be used to extend the desired temperature range for the reaction. The pressure in a single reaction zone can also vary widely. Typically, the pressure ranges from negative pressure to superatmospheric pressure, for example about 0.01 to 100 bar, most often about 0.1 to 10 or 15 bar (absolute pressure).

In a single reaction zone, the reaction is

One or more reactants (A),

A product other than the actual evaporation product (B) if one or more products are to be formed,

Coproducts other than the actual evaporative coproducts (C) and

It is carried out in the presence of a liquid comprising at least one of at least one other liquid component (D), such as a solvent. The vapor is recovered from a single reaction zone and comprises at least one reactant (i), product (ii) and coproduct (iii).

When the equilibrium limiting reaction is an esterification or an alcoholic reaction, it is possible to dimerize the acid or ester or produce other weights. In the case of esterification of acrylic acid and butanol to form butyl acrylate, the weight is formed by the Michael addition reaction, shown in Scheme 1 below:

Acrylic acid + butanol + butyl acrylate ↔ heavy

Dimer or weight products are usually equilibrium products. The process of the present invention facilitates the decomposition of dimers and other weights. In particular, the single reaction zone operates at a high temperature sufficient to decompose dimers and weights, the dimers and weights being in actual amounts of liquid solvent, for example at least about 10% by weight, more typically from about 20 to 90% by weight. % Or more solvents may be included. Weight residues, including polymers and non-degradable weights, are purged through a single reaction zone tail.

In contrast to prior art processes in which an acid separation column is installed above the reactor and operating as a rectifying column (see eg EP 0 733 617), the acid separation column of the present invention is located far from a single reaction zone, It serves as an acid separation column that includes both rectification and stripping regions. The rectifying zone is located above the point at which steam recovered from the single reaction zone is introduced into the acid separation column, and the stripping zone is located below the point at which steam recovered from the single reaction zone is introduced into the acid separation column. This form offers many advantages. At least a portion of the base fraction recovered from the acid separation column may be fed to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone. The feed rate of the base fraction recovered from the acid separation column into a single reaction zone can be adjusted according to the rate of water required to form the product / water azeotrope (eg butyl acrylate / water azeotrope) as set out above. As shown above, by this configuration, the upper part of the acid separation column can act as a rectifying zone (enhancing the separation of the product / reactant, for example butyl acrylate / acrylic acid), and the lower part as a stripping area. [Reduction of product (eg butyl acrylate) and recycling to a single reaction zone].

The process of the present invention will be described again in connection with esterification of acrylic acid and butanol. This is a preferred method for preparing butyl acrylate, but is not intended to limit the broader aspects of the present invention.

In summary, butyl acrylate is prepared by acid catalyzed esterification of acrylic acid and butanol. In this process, acrylic acid is esterified by a homogeneous acidic catalyst in a single reaction zone. Butyl acrylate and by-products that are substantially free of acrylic acid are recovered in the acid separation column overhead portion. Butyl acrylate is essentially removed through the butyl acrylate / water azeotrope. This overhead structure is essentially purified to provide pure butyl acrylate. The tail stream from the acid separation column comprising water, unreacted feed and by-products is returned to the reactor to increase conversion.

Referring to the drawings, butanol and acrylic acid (including recycle) are fed to the reactor 100 in a butanol: acrylic acid molar ratio of about 1: 1 to about 2: 1. Acrylic acid and butanol supplied to the reactor 100 are usually of standard purity. However, according to the process of the present invention, higher concentrations of conventional impurities in the acrylic acid stream are well tolerated. For example, the acrylic acid feed fed to the reactor 100 may contain up to 0.2 percent by weight or more of acetic acid, which is a light component that acetic acid reacts with butanol and can be easily removed using the present invention. This is because it forms butyl acetate. Other impurities, such as acrylic acid dimers, which are usually present in the acrylic acid feed are also acceptable, and the dimers are readily decomposed by, for example, high temperature operation of the reactor 100 as discussed above. Similarly, according to the unique purification scheme, it is possible to easily remove dibutyl ether, which is the main impurity in butanol, so that low grade butanol feeds can be used. The ability to use a wide range of acids and alcohols offers significant economic advantages.

The reaction is carried out in the presence of an acid catalyst. Examples of acidic catalysts include, for example, sulfuric acid, phosphoric acid, and resins containing acid functional groups. Preferably, the catalyst is a long chain alkylbenzene sulfonic acid such as dodecylbenzene sulfonic acid (DBSA). DBSA catalysts and derivatives thereof are described in US Pat. No. 5,231,222, which is incorporated herein by reference. In contrast to other catalysts, DBSA produces significantly less dibutyl ether and weight during esterification of acrylic acid and butanol, Higher efficiency is achieved by DBSA due to the low formation of dibutyl ether and heavy weights. However, DBSA is a homogeneous catalyst and therefore entrained. Nevertheless, the reaction is carried out using DBSA, since the entrained DBSA in this process simply circulates through line 15 between reactor 100 and acid separation column 210. Reactor 100 and acid separation column 210 and feed lines 14 and 15 are composed of materials that are resistant to corrosion by acid catalysts.

Catalyst concentrations can vary widely. In reactor 100, the DBSA may vary from about 1 to 25% by weight, preferably about 3 to 20% by weight, more preferably about 5 to 15% by weight of the liquid solvent. Since the DBSA is purged, the catalyst configuration for reactor 100 may be a solution of acrylic acid, butanol, recycle liquid or other process stream and catalyst.

It is known in the art that chemical inhibitors can be used to inhibit the formation of polymers derived from acrylic acid and / or butyl acrylate. The inhibitor is provided to the acid separation column 210 via line 16. Inhibitors include phenothiazine (PZ), hydroquinone (HQ) and monomethyl ether of hydroquinone (MEHQ). In general, polymer formation is known to occur in areas of high temperature (eg reactors and distillation columns) or in areas where steam condenses on cold surfaces. PZ is used for organic streams and HQ and / or MEHQ are used for water streams. The amount of inhibitor used depends on the process. The chemical inhibitor in reactor 100 will be about 50 to 30,000 ppm by weight, for example about 10,000 ppm by weight, based on the weight of the liquid solvent.

In addition to chemical inhibitors, oxygen is added to the reactor 100 to enhance the inhibition of polymer formation. The use of oxygen is known in the art. Oxygen can be added as pure oxygen, as a mixture with an inert gas, or preferably as air. Oxygen is supplied by an air sparger (not shown) provided at the base of the reactor.

Reactor 100 is a tank reactor for the reaction of acrylic acid and butanol and removal of butyl acrylate / water azeotrope for imparting equilibrium to acrylate. The acrylic acid conversion is preferably about 90% or more. Some of the liquid in the reactor 100 is fed to calendria (not shown) to increase the temperature of the liquid. The volume conversion through the calendria should be such that the contents of the reactor are well stirred and heated more evenly. In addition, a jacketed reactor designed to generate the required heat and provided with a mechanical stirrer may be used in place of the tank reactor and calendria.

Although the temperature of the reactor 100 is in the range of 100 to 160 ° C., it is most preferred to maintain the temperature in the range of 125 or 135 ° C. to about 150 ° C. The temperature is not only easy to convert butanol and acrylic acid into the product, but very importantly it must be sufficient to decompose the weight back to butyl acrylate, acrylic acid and butanol under these conditions. The average residence time in the reactor 100 is about 4 to 10 hours. The pressure of the reactor 100 is maintained at about 200 to 600 mm Hg (absolute pressure) (about 0.3 to 0.8 bar; absolute pressure). The liquid in reactor 100 contains about 1% by weight of water and is present in a single phase. Weight residues, including catalysts, inhibitors, non-degradable weights and polymers, are purged from reactor 100 via line 13.

The reactor purge via line 13, which may contain significant amounts of acrylic acid and butyl acrylate, can be sent to a separator, such as a wipe film evaporator, to recover useful material. The recovered material may then be recycled to reactor 100 or to another suitable point in the process.

The esterification reaction is removed from the reactor 100 to produce water that is fed to the lower portion of the acid separation column 210 as an azeotrope (eg butanol / butyl acrylate / water azeotrope). As mentioned earlier, the removal of water proceeds the reaction in the butyl acrylate direction. Acid separation column 210 is a standard engineering design and may use a tray or packing. To accommodate the incorporation of the DBSA catalyst, the base tray should be made of metal capable of handling highly corrosive liquids. To prevent polymerization and other contaminating reactions in the acid separation column 210, conventional inhibitors (e.g., hydroquinone and phenothiazine) are introduced into the acid separation column 210 and diluted with butanol or some other treatment liquid. .

As mentioned above, butyl acrylate, water and lightweight are removed from the reactor 100 as vapor and fed via line 14 to an intermediate point of the acid separation column 210. The primary purpose of the acid separation column 210 is to recover butyl acrylate, essentially free of acrylic acid, from the vapor stream of the reactor 100. The secondary purpose is to recycle the water containing stream directly back to the reactor 100 or indirectly back to the reactor 100 via calendria. Acid separation column 210 acts as an acid separation column comprising both rectification and stripping regions as described above.

Separation in acid separation column 210 occurs between the low boiling water / butyl acrylate azeotrope and acrylic acid. The overhead vapor recovered from the acid separation column 210 is condensed and decanted. Part of the aqueous layer is used as reflux and part of the organic layer is also used for reflux to enhance separation. Organic reflux can be replaced from the process with a butyl acrylate containing stream. Preferably, balanced water and organic profiles can be maintained in the acid separation column 210 to achieve stable optimal operation of the acid separation column. A balanced profile can be maintained using the reflux ratio control for the organic phase and the column temperature control for the water phase. In general, from 10 to 90% by weight of the organic layer and from 50 to 100% by weight of the aqueous layer can be recycled to the upper portion of the acid separation column to obtain a balanced water and organic profile.

In certain compositional ranges, the material of the lower portion of the acid separation column 210 may foam. Foaming includes liquid from the lower portion to the upper portion of the acid separation column 210 and causes leakage of acrylic acid in the overhead portion. Operational stability is such that the new or recycled alcohol is separated from the acid separation column 210 in the region between the base of the acid separation column 210 and the point where the vapor recovered from the single reaction zone 100 is introduced into the acid separation column 210. It was found that it can be introduced into the acid separation column 210 by introducing into. Preferably, about 0.1 to about 10 weight percent alcohol is maintained in the lower portion of the acid separation column 210 to provide operational stability.

The acid separation column tail flow rate through line 15 should be adjusted according to the water flow rate required for the butyl acrylate / water azeotrope containing about 60 wt% butyl acrylate and about 40 wt% water. If the tail flow rate is too small, the liquid level in the reactor 100 will rise due to an increase in the butyl acrylate concentration. If the tail flow rate is too high, excess water removes butyl butoxy propionate (BBP) from the reactor 100 by BBP / water azeotrope, further raising the BBP concentration in the acid separation column 210, resulting in unstable operation. Will lead to.

Overhead from acid separation column 210 is removed via line 17 and fed to a condenser / separator (not shown). In the condenser / separator, the vapor is condensed and the liquid is phase separated, wherein the organic phase is supplied to line splitter distillation column 310 via line 18, and the aqueous phase is water distillation column 610 via lines 17 and 19. ) To remove dissolved organics from the aqueous phase.

Water is fed from the acid separation column 210 to the reactor 100 via recycle to maintain a liquid solvent concentration of about 1% by weight for effective catalyst operation. The DBSA concentration in the reactor 100 is about 1 to 25% by weight, preferably about 5 to 15% by weight (eg 10% by weight), based on the weight of the liquid solvent. Inhibitors are added to the reactor 100 to reduce polymerization.

The base of the acid separation column 210 is heated. The top of the acid separation column 210 may have an absolute pressure of 300 mm Hg (about 0.4 bar, absolute pressure). In order to effectively remove butyl acrylate from reactor 100, an acid separation column can be operated under vacuum to lower the boiling point of the water / butyl acrylate azeotrope. The base liquid of the acid separation column 210 contains about 20 to 60% by weight of water and 40 to 80% by weight of organic material (mostly acrylic acid). The base fraction is returned to reactor 100 via line 15. This recycling step helps to maintain the concentration of water at about 1% by weight in the reactor 100 and to supply water for the water / butyl acrylate azeotrope.

The feed of splitter distillation column 310 is an organic stream from acid separation column 210, consisting primarily of butyl acrylate, with some butanol, light weight and weight. The purpose of the splitter distillation column 310 is to convert the stream into a tail fraction containing butyl acrylate and weights, as well as butanol, butyl acrylate and lightweights such as dibutyl ether and butyl acetate. To separate overhead streams. The tail fraction is essentially all lightweight components removed. The column design is consistent with conventional technical practice and may use packing or trays. In this embodiment, the base temperature of the splitter distillation column 310 is about 120 ° C. and the base pressure is about 400 mm Hg (0.6 bar absolute).

Overhead from splitter distillation column 310 feeds to a condenser / separator (not shown). In the condenser / separator, the vapor is condensed and the liquid is phase separated, with a portion of the organic phase being fed to the alcohol distillation column 410 via line 20 and the aqueous phase through the water 19 to the water distillation column 610. Sent to remove the dissolved organics from the aqueous phase. Part of the organic layer is used as reflux for splitter distillation column 310.

The alcohol distillation column 410 comprises an overhead stream from the splitter distillation column 310, essentially a tail stream consisting of butanol and butyl acrylate and an overhead consisting essentially of lightweight, mainly dibutyl ether and butyl acetate. Separate into streams. The lightweight stream is fed to a condenser / separator (not shown). In the condenser / separator, the vapor is condensed and the liquid phase separated, with a portion of the organic phase purged and a portion of the aqueous phase sent to a water distillation column 610 to remove dissolved organics from the aqueous phase. The remainder of the organic and aqueous phases is used as reflux to form an azeotrope profile in the alcohol distillation column 410. High reflux ratios can be used to minimize efficiency losses. As indicated above, a portion of the lightweight stream may be sent, soldered or combusted to waste treatment via line 21, and the tail stream is passed through line 22 to reactor 100 and acid separation column 210. Recycled back to one or both). The design of the alcohol distillation column 410 is consistent with conventional technical practice, and packing or trays may be used. The base temperature of the alcohol distillation column 410 is about 80 ° C., and the pressure is about 300 mm Hg (0.4 bar absolute).

The tail fraction from splitter distillation column 310 is fed to ester distillation column 510 via line 23. Ester distillation column 510 separates the tail fraction into an overhead stream of butyl acrylate and a tail stream of heavy (and butyl acrylate). The tail stream is recycled through line 24 to one or both of reactor 100 and acid separation column 210 and / or to another distillation column. The tail stream also contains an inhibitor that is preferably recycled, as described above. The column design is consistent with conventional technical practice and may use packing or trays. The base temperature of the column is about 100 ° C. and the pressure is about 100 mm Hg (0.2 bar absolute). In addition, the vapor stream may be recovered and condensed from the bottom portion or bottom of the splitter distillation column 310 to form a stream of butyl acrylate, thereby eliminating the need for an ester distillation column 510.

The unique process of the present invention enables the recycling of weights and inhibitors. In a conventional process, the entire heavy stream containing the inhibitor is usually discarded. A conventional process that uses a neutralization step to remove acrylic acid instead of using an acid separation column as provided in the present invention cannot reuse the base fraction recovered from the ester distillation column as an inhibitor solution, which remains in the stream. This is because sodium or other alkali metal is deposited. Conventional processes in which the reaction conditions are not suitable for cracking the heavy weight cannot deposit the base fraction recovered from the ester distillation column again as an inhibitor solution because the heavy weight is deposited in the reactor. Thus, the process of the present invention can use fewer inhibitors and reduce the inhibitor cost as well as more efficient recovery of the weight.

Co-pending US patent filed May 20, 1997, the preferred method of purifying a butyl acrylate containing stream containing butyl acrylate, dibutyl ether, butyl acetate, heavy and butanol is incorporated herein by reference. US 08 / 859,143.

In the process of the present invention, butylacrylate of the preferred composition as described in Table 2 below can be prepared. These low levels of light weight, in particular acrylates containing dibutyl ether, have a significantly reduced odor compared to commercial acrylates, and can unexpectedly produce high quality products from low quality feedstock.

ingredient Normal range (wt%) Preferred range (% by weight) 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 0.1 0.000 to 0.02 lift 0.000 to 2 0.000 to 0.5 water 0.000 to 0.5 0.000 to 0.05

As set forth above, the process of the present invention can be used to prepare other products from equilibrium restriction reactions. The following examples are provided to further illustrate the present invention. Embodiments refer to the drawings. All parts and percentages are by weight unless otherwise indicated.

Example 1

339 g / hour acrylic acid and 348 g / hour n-butanol are continuously fed to reactor 100 along with 83 g / hour stream 22 containing recycled butanol and inhibitor. Reactor 100 contains 3.5 liters of liquid that remain in the reactor for 6-7 hours at a temperature of 137 ° C. and an absolute pressure of about 550 mm Hg. Dodecylbenzene sulfonic acid (DBSA) diluted with butyl acrylate is added at a rate of 7 g / hour. Purge stream 13 is removed from the reactor at a rate of 20 g / hour. The vapor stream is removed from the reactor and introduced into an acid separation column 210. In addition, 113 g / hr stream 22 containing recycled butanol and inhibitor are added to the lower portion of the acid separation column. The acid separation column is operated at a head temperature of 83 ° C. and a pressure of 500 mm Hg. The water rich stream 15 containing acrylic acid is removed from the bottom of the acid separation column and recycled to the reactor at a rate of 760 g / hour. The vapor is removed from the top of the acid separation column 210, then condensed and decanted. A portion of the organic phase is returned to the acid separation column and the remaining organic stream 829 g / hour is sent to a splitter distillation column, ultimately producing essentially butyl acrylate.

829 g / hour organic stream 18 is fed to the middle point of the splitter distillation column. The splitter distillation column is operated at 310 mm Hg head absolute and head temperature of 87 ° C. Butanol, butyl acrylate and light impurities are removed from overhead and butyl acrylate along with heavy impurities are removed from the bottom of the splitter distillation column. The overhead recovered 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 20) is sent to alcohol distillation column 410 at a rate of 191 g / hour. The entire aqueous phase recovered from the decanter is sent to the water distillation column 610 at a rate of 6 g / hour. From the base of the splitter distillation column, stream 23 is removed at a rate of 666 g / hour and fed to the ester distillation column 510.

The alcohol distillation column 410 is operated at 270 mm Hg head pressure and head temperature of 58 ° C. The vapor stream concentrated with light impurities is removed from the overhead of the alcohol distillation column and the butanol rich stream is removed from the base of the alcohol distillation column. The vapor stream is condensed and decanted to yield an organic phase and water. A portion of the organic phase and water is returned to the alcohol distillation column. The remaining water from the decanter is sent to the water distillation column 610 at a rate of 2 g / hour. The remaining organic phase from the decanter is purged from the system at a rate of 3 g / hour (stream 21). The butanol rich stream 22 is removed from the base of the alcohol distillation column at 196 g / hour, a portion is returned to a single reactor and the remaining amount is returned to the base of the acid separation column.

The ester distillation column is operated at 90 mm Hg head pressure and head temperature of 79 ° C. The vapor recovered from the top of the ester distillation column is condensed and refluxed back to the column under reflux at a distillate ratio of 0.2 g / hour. From the bottom of the ester distillation column, stream 24 is removed at 110 g / hour and recycled. From the top of the ester distillation column, 99.9% by weight of butyl acrylate is removed at 577 g / hour.

The composition of the main feedstock and the composition of the reactant and product streams recovered from the reactor and distillation column are shown in Tables 3a and 3b below.

ingredient AA feed (% by weight) BuOH feed (% by weight) DBSA Feed (% by weight) Stream (17) (% by weight) Stream 18 (% by weight) Stream 20 (% by weight) Stream 23 (% by weight) Water Butanol butyl acrylate BBP + HVS butyl ether butyl acetate acetic acid DBSA 0.0499.910.05 0.1099.850.05 5050 11.6513.3374.800.030.090.10 2.4014.4482.930.020.100.11 7.3058.2533.520.170.350.41 0.0299.960.02 all 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Total (g / hour) 339 348 7 919 829 191 666

ingredient Stream 21 (% by weight) Stream 22 (% by weight) Stream 25 (% by weight) Stream 24 (% by weight) Stream (13) (% by weight) Stream 19 (% by weight) Stream 15 (% by weight) Water Butanol butyl acrylate BBP + HVS butyl ether butyl acetate acetic acid DBSA 6.0331.1221.964.9818.2617.65 5.9757.8835.990.070.010.08 0.0199.980.01 0.0199.680.31 1.00.5312.259.5270.446.26 96.643.130.120.090.02 45.466.1242.790.543.09 all 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Total (g / hour) 3 196 577 110 20 98 760

Although the present invention has been described with reference to the above-described embodiments, it is not intended to be limited thereby, but rather the invention includes the general scope as described above. Various modifications and embodiments may be possible without departing from the spirit and scope thereof.

Claims (30)

a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products), b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introducing into a lower portion of an acid separation column comprising a zone to provide an overhead fraction comprising at least one ester product to a rectifying zone and a base fraction comprising water and at least one carboxylic acid to a stripping zone, c. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone, and d. Recovering the overhead fraction from the acid separation column and recovering the at least one ester product from the overhead fraction, wherein the equilibrium restriction reaction of at least one carboxylic acid and at least one alcohol is carried out to produce one or more ester products. The process of claim 1, wherein the at least one carboxylic acid containing feedstock comprises a crude acrylic acid stream containing acetic acid, acrylic acid dimers and / or other Michael addition weights and wherein the at least one alcohol containing feedstock comprises butyl ether. A crude butanol stream containing. The process of claim 1, wherein the at least one carboxylic acid containing feedstock and / or the at least one alcohol containing feedstock comprises a heavy residue containing stream resulting from another process using similar equilibrium restriction reactions. a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products), b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introducing into a lower portion of an acid separation column comprising a zone to provide an overhead fraction comprising at least one ester product to a rectifying zone and a base fraction comprising water and at least one carboxylic acid to a stripping zone, c. At least one alcohol, which may be the same as or different from the alcohol contained in the alcohol containing feedstock, may be used to ensure stable and efficient operation of the acid separation column in the region between the base of the acid separation column and the point at which the recovered vapor is introduced into the acid separation column. Introducing into the acid separation column in an amount sufficient to provide, for example, an amount sufficient to minimize or eliminate foaming of the acid separation column, d. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone, and e. Recovering the overhead fraction from the acid separation column and recovering the at least one ester product from the overhead fraction, wherein the equilibrium restriction reaction of at least one carboxylic acid and at least one alcohol is carried out to produce one or more ester products. 5. The process according to claim 4, wherein the operational stability is imparted to the acid separation column by introducing alcohol into the acid separation column in the region between the base of the acid separation column and the point where steam recovered from the single reaction zone is introduced into the acid separation column. . 6. The method of claim 5, wherein the alcohol is fresh alcohol or recycled alcohol. The process of claim 4 wherein carboxylic acid leakage of the overhead fraction recovered from the acid separation column is minimized or eliminated. a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products), b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introduced into the lower portion of the acid separation column comprising the zone providing an overhead fraction comprising one or more unsaturated ester products, low boiling by-products, high boiling by-products and one or more alcohols to the rectifying zone and comprising water and one or more carboxylic acids Providing a base fraction to the stripping zone, introducing one or more polymerization inhibitors into the acid separation column, c. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone, d. The overhead fraction is recovered from the acid separation column and at least a portion of the recovered overhead fraction is introduced into one or more splitter distillation columns to provide an overhead fraction comprising low boiling by-products and one or more alcohols and one or more unsaturated ester products Providing a base fraction comprising by-products and the like, introducing one or more polymerization inhibitors into one or more splitter distillation columns, e. Recovering the overhead fraction from one or more splitter distillation columns and introducing the recovered overhead fraction into one or more alcohol recovery distillation columns to provide an overhead fraction comprising low boiling by-products and a base fraction comprising one or more alcohols; Introducing at least one polymerization inhibitor into at least one alcohol recovery distillation column, f. Recovering the base fraction (recycling at least a portion of the base fraction) and the overhead fraction (purging at least a portion of the overhead fraction) from one or more alcohol recovery distillation columns, g. The base fraction is recovered from one or more splitter distillation columns and the recovered base fraction is introduced into one or more ester distillation columns to provide an overhead fraction comprising one or more unsaturated ester products and a base comprising high boiling by-products and one or more polymerization inhibitors. Providing a fraction, wherein the at least one polymerization inhibitor is introduced into the recovered base fraction from at least one ester distillation column and / or at least one splitter distillation column prior to introducing the recovered base fraction into at least one ester distillation column, h. A base fraction comprising one or more polymerization inhibitors is recovered from one or more ester distillation columns, and at least a portion of the recovered base fraction is in an amount sufficient to minimize or eliminate the polymerization of the unsaturated carboxylic acid and / or the unsaturated ester product, Feeding at least one splitter distillation column and / or at least one alcohol recovery distillation column and i. Recovering an overhead fraction comprising at least one unsaturated ester product from at least one ester distillation column, to perform an equilibrium limiting reaction of at least one carboxylic acid with at least one alcohol to produce at least one ester product. The method of claim 8, wherein the one or more new inhibitors are fed to the base fraction recovered from the splitter distillation column and / or the ester distillation column before introducing the acid separation column, the splitter distillation column, the recovered base fraction into the ester distillation column. How to be. The method of claim 8, wherein the new inhibitor is the same or different. The method of claim 8, wherein at least a portion of the base fraction recovered from the alcohol distillation column is recycled and at least a portion of the overhead fraction recovered from the alcohol distillation column is purged. a. Reacting at least one carboxylic acid containing feedstock and at least one alcohol containing feedstock in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce at least one ester product, wherein the reaction conditions are in a single reaction zone. A temperature and pressure sufficient to decompose the weight formed or introduced into a single reaction zone and to evaporate at least a portion of the one or more ester products in the preparation of the one or more ester products), b. Steam is recovered from a single reaction zone, and the recovered steam is stripped at a rectification zone located above the point where the recovered steam is introduced into the acid separation column and below the point where the recovered steam is introduced into the acid separation column. Introduced into the lower portion of the acid separation column comprising the zone providing an overhead fraction comprising one or more ester products, low boiling by-products, high boiling by-products and one or more alcohols to the rectifying zone and a base comprising water and one or more carboxylic acids Providing a fraction to the stripping area, c. Recovering the base fraction from the acid separation column and feeding at least a portion of the recovered base fraction to the single reaction zone in a controlled manner sufficient to provide stable and efficient operation of the acid separation column and the single reaction zone, d. The overhead fraction is recovered from the acid separation column and at least a portion of the recovered overhead fraction is introduced into one or more splitter distillation columns to provide an overhead fraction comprising low boiling by-products and one or more alcohols and one or more unsaturated ester products. Providing a base fraction comprising by-products, and the like, e. Recovering the base fraction from one or more splitter distillation columns and introducing the recovered base fraction into one or more ester distillation columns to provide an overhead fraction comprising one or more ester products and a base fraction comprising high boiling byproducts, f. Recovering the base fraction (recycling at least a portion of the base fraction) and the overhead fraction (including one or more ester products) from one or more ester distillation columns, g. The overhead fraction is recovered from one or more splitter distillation columns and the recovered overhead fraction is introduced into one or more alcohol recovery distillation columns to provide an overhead fraction comprising low boiling by-products and a base fraction comprising one or more alcohols. step, h. The base fraction is recovered from one or more alcohol recovery distillation columns and at least a portion of the recovered base fraction is recovered in a stable and efficient manner in the acid separation column in the region between the base of the acid separation column and the point at which the recovered steam is introduced into the acid separation column. Supplying an amount sufficient to provide operation, such as an amount sufficient to minimize or eliminate foaming in the acid separation column and / or in a single reaction zone, and i. Recovering the overhead fraction from one or more alcohol recovery distillation columns (purging at least a portion of the recovered overhead fraction) to perform an equilibrium restriction reaction of the one or more carboxylic acids and one or more alcohols to produce one or more ester products. How to prepare. 13. The process of claim 12 wherein at least a portion of the base fraction recovered from the ester distillation column is recycled and at least a portion of the overhead fraction recovered from the alcohol distillation column is purged. 13. The process according to claim 12, wherein the operational stability is achieved in the region between the bottom of the acid separation column and the point at which steam recovered from the single reaction zone is introduced into the acid separation column. A process imparted to the acid separation column by introducing it into the acid separation column. The method according to claim 12, wherein the overhead fraction recovered from the acid separation column (i), the overhead fraction recovered from one or more splitter distillation columns (ii) and / or the overhead fraction recovered from one or more alcohol recovery distillation columns ( introducing at least a portion of iii) into the water distillation column to provide an overhead fraction comprising one or more alcohols and a base fraction comprising water and recovering the base fraction from the water distillation column (purging at least a portion of the base fraction) And recover the overhead fraction from the water distillation column, and at least a portion of the overhead fraction between the base of the acid separation column and the point at which steam recovered from the single reaction zone is introduced into the acid separation column and / or the single reaction zone. And feeding the acid separation column in the region. The method of claim 15, wherein at least a portion of the base fraction recovered from the water distillation column is purged. 16. The zone of claim 15 wherein the operational stability is between the base of the acid separation column and the point at which steam recovered from the single reaction zone is introduced into the acid separation column from the recycled alcohol contained in the overhead fraction recovered from the water distillation column. Imparted to the acid separation column by introducing it into the acid separation column. The process of claim 1 wherein the equilibrium limiting reaction is an esterification reaction of an alcohol having 1 to 12 carbon atoms with a carboxylic acid having 2 to 4 carbon atoms. The method of claim 18, wherein the alcohol comprises n-butanol and the carboxylic acid comprises acrylic acid. The process of claim 1 wherein the ester product is represented by the formula R'C (O) OR '' ', the carboxylic acid is represented by the formula R'C (O) OH, the alcohol is represented by the formula R' '' OH, Wherein R 'is a hydrocarbyl containing group having 1 to about 8 carbon atoms and R' '' is a hydrocarbyl containing group having 1 to about 12 carbon atoms. The process of claim 1 wherein butyl acrylate and ethylhexyl acrylate are produced simultaneously. 22. The process of claim 21 wherein both butyl acrylate and ethylhexyl acrylate are recovered in a vapor stream from a single reaction zone or butyl acrylate is recovered in a vapor stream from a single reaction zone and ethylhexyl acrylate is recovered from a single reaction zone. How to recover to the stream. The method of claim 1, wherein the overhead fraction recovered from the acid separation column is condensed and decanted, and from 10 to 90% by weight of the organic layer and from 50 to 100% by weight of the aqueous layer are recycled to the upper portion of the acid separation column for reflux. The method further comprises a step. A batch produced continuously or continuously comprising at least 50.0% by weight of butyl acrylate and up to 8 ppm acrylic acid. The process of claim 1 wherein the esterification catalyst comprises sulfuric acid, sulfonic acid or an acid exchange resin. The method of claim 25, wherein less than about 1 weight percent of water is in a single reaction zone. One or more esters of at least one carboxylic acid containing feedstock, wherein the at least one carboxylic acid containing feedstock comprises a crude acrylic acid stream containing acetic acid, acrylic acid dimers and / or other Michael addition weights and at least one alcohol containing feedstock Reaction in the presence of an esterification catalyst in a single reaction zone maintained under sufficient reaction conditions to produce the product, wherein the reaction conditions decompose the weight formed in the single reaction zone or introduced into the single reaction zone to prepare one or more ester products. A temperature and pressure sufficient to evaporate at least a portion of the at least one ester product) to carry out an equilibrium limiting reaction of the at least one carboxylic acid with the at least one alcohol. The method of claim 27, wherein the crude acrylic acid stream contains at least about 0.5% by weight acetic acid, acrylic acid dimer and / or other Michael addition weights. The process of claim 1 wherein the single reaction zone contains a purge stream comprising acrylic acid and butyl acrylate, the purge stream is treated with a separator, and optionally recovered acrylic acid and butyl acrylate are subjected to a single reaction zone or process of the process. Recycling to other appropriate points. 30. The method of claim 29, wherein the separator comprises a wipe film evaporator.