JP2011012068A - Metal surface which suppresses polymerization of ethylenically unsaturated monomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for suppressing polymerization of monomers during production, purification, treatment or storage of ethylenically unsaturated monomers.SOLUTION: Undesirable polymerization which causes polymer staining inside of apparatuses used for producing, purifying, handling and preserving the monomers, e.g., acrylic acid, methacrylic acid, acrylates and methacrylates in the presence of oxygen can be suppressed by using the apparatuses including copper-containing metal in producing, purifying, handling and preserving the objective ethylenically unsaturated monomers.

Description

  The present invention relates to inhibiting polymerization during the production, purification, handling or storage of ethylenically unsaturated monomers.

Polymerization inhibitors such as hydroquinone (HQ), hydroquinone monomethyl ether (MEHQ), phenothiazine (PTZ), hindered amine radical scavenging, usually during production, including production and purification of ethylenically unsaturated monomers, and during handling and storage There is a need to add compounds or catechols, such as tertiary butyl catechol or ditertiary butyl catechol. Additional exemplary inhibitors commonly used include phenolic compounds characterized by the presence of at least one other substituent on the benzene ring. Such other substituents function to activate the phenolic inhibitor. Representative substituents include, for example, C ₁ -C ₄ alkoxy, such as methoxy or ethoxy, hydroxyl, sulfhydryl, amino, C ₁ -C ₉ alkyl group, phenyl, nitro or N- linked amide.

  In the absence of an inhibitor, unintended polymerization that results in polymer contamination can easily occur and not only affects the production, handling or storage of the desired product, but also leads to equipment failure. Furthermore, additional energy is required to operate the production equipment, for example a distillation equipment. Purification, particularly involving distillation equipment, is of great interest because it requires large amounts of energy to operate and operates at high temperatures. The elevated temperature increases the likelihood that polymerization will occur.

  Most of the inhibitors used are contained in the liquid monomer. The surface of the device that is not in contact with the liquid containing the inhibitor provides an open site for polymerization or contamination. For example, any part of a device where steam undergoes condensation. This is because the condensate no longer contains the inhibitor in the initial monomer liquid. Thus, equipment surfaces that are exposed to such monomers (which are typically metal surfaces) as well as the monomers themselves are protected during the production, purification, handling or storage of ethylenically unsaturated monomers. There is a need to control polymer formation.

  Patent Document 1 and Patent Document 2, both of Nakahara et al., Disclose a method and apparatus for producing (meth) acrylic acid, where the apparatus is used to minimize surface corrosion and pitting. Contains molybdenum, thereby minimizing the polymerization of (meth) acrylic acid and the attendant contamination of the equipment by polymerized products. These Nakahara et al. Documents have a molybdenum content of greater than 3% up to 20% or 1-4% with 0.5% -7% copper for manufacturing equipment, The use of metals made from nickel chrome iron alloys is disclosed.

US Pat. No. 6,441,228B2 US Patent Application Publication No. 2002 / 0165407A1 (published on Nov. 7, 2002)

  The present invention uses the novel material for at least a portion of the equipment in which the monomer is in contact, thereby allowing the monomer during manufacture, purification, handling or storage of the subject ethylenically unsaturated monomer. It meets the needs of the industry to inhibit polymerization.

  One aspect of the present invention is an apparatus for at least one of the production, purification, handling and storage of a subject ethylenically unsaturated monomer, the apparatus comprising an inlet for an oxygen-containing gas and at least in contact with the monomer. At least a portion of the device in the state relates to a device comprising a metal containing sufficient copper to inhibit polymerization of monomers in the device in the presence of an oxygen-containing gas.

Another aspect of the present invention is a method of inhibiting polymerization during at least one of the production, purification, handling and storage of a subject ethylenically unsaturated monomer comprising:
Equipment for the production, purification, handling and storage of this monomer, wherein at least part of the equipment in contact with this monomer inhibits polymerization of the monomer in the equipment in the presence of an oxygen-containing gas In a device comprising a metal containing sufficient copper to perform the steps of introducing said monomer and supplying a gas containing oxygen into the interior of the device containing monomer thereby comprising: A method for inhibiting the polymerization of monomers in an apparatus is provided.

FIG. 2 is a schematic flow diagram of an exemplary acrylic acid recovery and purification apparatus using components according to the present invention.

  References to the article “a” or “an” or singular object as used herein are contexts that are specifically and expressly limited to the singular or single object, or otherwise include the item. Unless stated otherwise, it is intended to include multiple or more than one object.

  As used herein, “about” means, for any numerical value, a variation from the stated value by an amount that does not significantly affect the characteristics of the product or process to which the value relates.

  As used herein, “suppressing” or variations thereof means reducing, preferably reducing, preferably preventing, the occurrence of events such as polymerization.

  As used herein, “percent” or “%” of a component means the weight percent of the component in the alloy, material or composition containing that component.

  As used herein, the term "target ethylenically unsaturated monomer" refers to any polymerizable ethylenically unsaturated monomer having an unsubstituted or substituted carboxylic acid or ester group other than methyl acrylate or 2-ethylhexyl acrylate. Means.

  The foregoing disclosure and the following detailed description will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. However, it should be understood that the invention is not limited to the precise arrangements and instrumentalities shown.

  The present invention includes the structure of at least a portion of a polymerization resistant device associated with the production, purification, handling or storage of such a monomer to inhibit polymerization of the subject ethylenically unsaturated monomer on the surface of the device. Includes the use of materials for. In particular, copper or metals containing at least about 10% copper are used in the construction of such devices. The higher the copper content of the metal used in the equipment, the better it will act to inhibit polymerization and thereby be used during the production, purification, handling or storage of the subject ethylenically unsaturated monomer. Prevent polymer contamination in equipment such as distillation towers. Unlike the Nakahara et al. Document, the present invention does not include the mechanisms associated with minimizing pitting or corrosion of the surface of the device in contact with the monomer. In the metal component necessary for inhibiting polymerization in the present invention, the molybdenum content is not considered.

  The present invention also provides for the production of the subject ethylenically unsaturated monomer by using a copper-containing metal in at least a portion of the apparatus in the presence of an oxygen-containing gas, used for any part of the aforementioned purposes, It relates to a method of inhibiting polymerization during purification, handling or storage. This method of controlling polymerization or contamination involves the migration of copper ions from the copper metal or alloy present in at least a portion of the device in contact with the subject ethylenically unsaturated monomer that occurs in the presence of an oxygen-containing gas. It is believed that leaching is involved. Copper ions that migrate from the metal are believed to inhibit polymerization.

  Although the present invention will be discussed primarily with respect to purification equipment such as distillation equipment, the invention is also useful in other types of equipment related to polymerization, such as flame arrestors. Specific non-limiting examples of equipment and components for the production of the subject ethylenically unsaturated monomers include reactors, distillation columns, distillation columns, optional distillation internal components, absorbers, adsorbers, reboilers, condensers, distribution Tanks (eg liquid and vapor), extraction towers and associated equipment or components, eg heat exchangers, packings or trays, piping, fittings, valves, pumps or tanks that are part of the equipment and A container containing a vessel is included. These devices or any part or component thereof may be part of the system or a separate item, and may be a stationary, mobile or portable device. As another non-limiting example, in the case of a distillation tray, the entire tray need not be made from a copper-containing metal. If blanking strips are used, these can be made solely from copper-containing metals. If a distillation column is used, some of the inner surface may only be covered with a copper-containing metal. It is possible to make a distillation column with a partial inner cover of copper-containing metal, which will be sufficient to provide the desired polymerization inhibition.

  Similarly, although the present invention will be discussed primarily with respect to the production of acrylic acid, the present invention is not limited to any other subject ethylenically unsaturated monomers such as, but not limited to, α-alkyl acrylics other than those described above. Acid, α-alkyl acrylate, β-alkyl acrylate, β-alkyl acrylate, methacrylic acid, methyl acrylate and acrylic acid esters other than 2-ethylhexyl acrylate, methacrylic acid ester, vinyl acetate, vinyl Useful in connection with the manufacture, purification, handling or storage of esters, polyunsaturated carboxylic acids, polyunsaturated esters, maleic acid, maleic esters, maleic anhydride and acetoxystyrene. The alkyl group of any of the above compounds is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 4 carbon atoms.

  The use of copper or copper-containing metals according to the present invention suppresses the polymerization reaction that occurs in the subject ethylenically unsaturated monomer when the monomer is in contact with the metal used in the apparatus of the present invention.

The present invention includes, together with monomers, conventional in-process polymerization inhibitors such as hydroquinone (HQ), monomethyl ether of hydroquinone (MEHQ), phenothiazine (PTZ), hindered amine radical scavenging compounds or catechols such as tertiary butyl catechol or diterpolymers. It does not eliminate the need for the use of tertiary butyl catechol or other typical polymerization inhibitors, such as phenolic compounds characterized by the presence of at least one other substituent on the benzene ring. Such other substituents function to activate the phenolic inhibitor. Representative substituents include for example C ₁ -C ₄ alkoxy, such as methoxy or ethoxy, hydroxyl, sulfhydryl, amino, C ₁ -C ₉ alkyl group, phenyl, nitro or N- linked amide.

  The structural material for the equipment that includes, or is used for, the production, purification, handling and storage of ethylenically unsaturated monomers is copper or a metal containing at least about 10% copper. It has been found that this metal exhibits self-suppressing surface properties for devices made from such metals or parts thereof.

  Preferred metals include not only metals that are about 100% copper, but also alloys that contain at least about 10% copper. The metal preferably has a composition comprising about 25% to about 75% copper, more preferably about 30% to about 50% copper. Preferred alloys include bronze (including about 90% to about 99% copper and about 1% to about 10% tin); some variants such as red brass (about 85% copper and about 15% zinc) ), Brass (about 63% to about 66% copper and about 34% to about 37% zinc), medicinal brass (containing about 67% to about 70% copper and about 30% to about 33% zinc) Admiralty brass (sometimes referred to as Admiralty metal) (about 67% to about 70% copper, about 25.8% to about 29.25% zinc and about 0.75% to about 1.2% Tin (including tin) and mantz metal (including about 60% copper and about 40% zinc), brass (alloys mainly containing copper and zinc) and copper-nickel alloys such as those from Huntington, West Virginia From Special Metals Corporation, Monel R) include those available as an alloy. Monel® alloys, such as Monel® alloys 400, 401, 404, R-405 and K-500, have their strength with respect to structural supports, the ability to be easily welded, generally about 538 ° C. Particularly preferred because of its ability to withstand temperatures below (about 1,000 ° F.) and relatively low cost.

  The above Monel (registered trademark) alloy has the following composition according to information available from Special Metals.

  This polymerization inhibition must be carried out in the presence of oxygen-containing gas, which may be substantially pure oxygen or other oxygen-containing gas (eg at least about 5% oxygen by volume), most conveniently air. Don't be. Air or other oxygen-containing gas is introduced into the equipment components of the apparatus, preferably through any suitable inlet and preferably a valved inlet located at the bottom of the equipment, more preferably from the bottom, The oxygen-containing gas can be present throughout the apparatus wherever any unwanted polymerization can occur.

Without wishing to be bound by any theory, it is believed that oxygen enhances the transfer of copper ions from the copper-containing metal by the subject ethylenically unsaturated monomer. Thus, oxygen in air or other oxygen-containing gas appears to facilitate the entry of copper ions into the liquid monomer. The inhibitory effect of copper appears to be based on the following chemical action. Very small amounts (a few per million) in copper-containing metals in the presence of ethylenically unsaturated monomers with carboxylic acid or ester functional groups and oxygen at temperatures above or above room temperature The copper metal of the order) is oxidized to cupric ions (Cu ⁺² ), which are then dissolved, for example, in a monomer that can exist as a condensed liquid. This cupric ion appears to play an important role in the suppression process. In the process of monomer polymerization, carbon-centered free radicals are present during the chain growth reaction. The cupric ion receives one electron transfer from the carbon-centered free radical, and generates cuprous ion (Cu ⁺¹ ) and carbocation (R ⁺ ) (see Formula 1).

Formula 1: Cu ⁺² + R ^* → Cu ⁺¹ + R ⁺

  By removing free radicals, chain growth (ie polymerization) is stopped. The cuprous ions are then oxidized by oxygen from the oxygen-containing gas back to cupric ions, which then remove other carbon-centered free radicals from the solution. In this formula, copper is catalytic as long as oxygen is present in the system. In the absence of oxygen, copper will slowly plate out (ie, cover the metal surface) as a result of the following reaction (Equation 2).

Equation ^{2: Cu +1 + Cu +1 →} Cu 0 + Cu +2

  The apparatus and method of the present invention is generally used in a metal facility, such as a distillation column, that does not have a process inhibitor (eg, PTZ or HQ) present uniformly, due to the poor distribution of liquid in the facility. Provides polymerization protection for condensed liquid on the surface.

  The present invention is adapted from Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A1, pp. 166-167, the disclosure of which is hereby incorporated by reference. This will be described with reference to the drawings. The apparatus shown in the figure is used for illustrative purposes only and is in no way intended to limit the application of the present invention. This figure shows a schematic flow of an acrylic acid recovery and purification apparatus 10 using a light extraction solvent in which at least some of the components are made using copper or a metal containing at least 10% copper according to the present invention. FIG.

  In apparatus 10, an acrylic acid-water mixture obtained from a manufacturing facility (not shown) is fed to extraction column 14 through inlet line 12 for recovery and purification of acrylic acid. The aqueous acrylic acid solution is introduced in countercurrent to a light organic solvent having a lower boiling point than acrylic acid, such as ethyl acetate, butyl acetate, ethyl acrylate and 2-butanone or any mixture thereof. The solvent must have a high partition coefficient for acrylic acid and a low solubility in water, and it must form an azeotrope containing a high percentage of water.

  The extract from the top of the extraction column 14 is passed through line 16 into the solvent separation column 18 where the solvent and water are distilled upwards in line 22 and in condenser / separator 24. Condensate and separate, and the solvent is passed through line 20 back to extraction column 14 and recycled. Water from overhead condenser / separator 24 passes through line 26. The bottom stream from extraction column 14 passes through line 28 and into line 26 where the bottom stream from extraction column 14 and water from solvent separation column 18 are sent to raffinate-stripping column 30. A small amount of solvent is recovered from the raffinate-stripping column 30 by distillation and sent through line 32, condenser / separator 34 and line 36 into recycle line 20 and back to extraction column 14. Wastewater from the raffinate-stripping tower 30 is drained through line 38 and biologically treated or incinerated.

  The bottom fraction from the solvent separation column 18 is fed through line 40 into a light end cut column 42 where acetic acid is distilled off through line 44, condensed and optionally recovered. To send through line 46. Crude acrylic acid from the bottom of the light end cut tower 42 is sent through line 48 to product tower 50 where high purity acrylic acid is obtained upward through line 52, condensed and stored or distributed. Through line 54 for The material from the bottom of the product column 50 containing acrylic acid and acrylic acid dimer is sent through line 56 to cracking evaporator 58 where the dimer is decomposed into monomers. The evaporator residue consisting of acrylic acid oligomer, polymer and inhibitor is discharged through line 60 and sent for component recovery, incinerated, or otherwise properly processed.

  Since acrylic acid is easily polymerized, the distillation column is operated under reduced pressure to reduce the distillation temperature in the presence of oxygen with the inhibitor as described above. The purity of acrylic acid produced by this method is usually above 99.5% and the purification yield is typically about 98%.

  An oxygen-containing gas, optionally substantially pure oxygen from any suitable source, can be used, but preferably air is directed through the inlet line 62 into the compressor 64. From the compressor 64, air or other oxygen-containing gas is passed through lines 66, 68, 70, 72, 74 and 76 through the inlet 78 into the extraction tower 14 and through the inlet 80 to the raffinate. Distribute into the stripping column 30 through the inlet 82 into the solvent separation column 16, through the inlet 84 into the light end cut column 42, and through the inlet 86 into the product column 50. . The inlets into the various towers are located at the lower part of the tower, preferably at the bottom of the lower part of the tower or at the reboiler inlet, so that oxygen can be present throughout the tower and the line leading from the tower. ing.

  The inner surface of the tower or the internal components of the tower and at least some of the fittings, lines, piping, valves (not shown for clarity), pumps (not shown for clarity) and other components, At least partially, preferably substantially all, must be made from copper or a metal containing at least about 10% copper, preferably a Monel® alloy, in accordance with the present invention. By using the metal of the present invention in an apparatus for the production, purification, handling or storage of the subject ethylenically unsaturated monomer, the liquid monomer containing all the pre-dissolved inhibitor cannot be reached. Even in this case, polymerization of the monomer is suppressed.

  The invention will now be described in more detail with reference to the following non-limiting examples.

Example 1
Twelve 10 mL DOT (US Department of Transportation) tubes were filled with 5 mL of glacial acrylic acid containing about 200 ppm MeHQ inhibitor. Three tubes were used as controls, with different pieces of metal in the other nine tubes. Place about 0.1 g of 316 stainless steel pieces in 3 tubes, about 0.1 g of Monel® alloy in 3 tubes, and about 0.1 g of copper pieces in 3 tubes. I put it in. The twelve tubes were opened and placed in a hot oil bath at about 110 ° C. (about 230 ° F.). The tube was stirred at regular intervals and mixed with air. The tube was checked periodically for polymer formation. The results of the test are included in Table VI below. In Table VI, the data represents the average of three individual experiments.

Example 2
The copper and Monel® alloy test of Example 1 was repeated using glacial acrylic acid that did not contain any MeHQ inhibitor. This experiment showed no signs of polymer in either the Monel® alloy or the DOT tube containing copper and stopped after 17 days (about 400 hours).

Example 3
In a three-neck 250 mL glass round bottom flask, Monel® alloy packing material (about 35 g and about 0.24 inch length from Cannon Instrument Company) A 30.5 cm (12 inch) long glass tube was attached. Glacial acrylic acid (about 200 g containing about 500 ppm PTZ) was placed in the round bottom flask, and the flask was then fitted with a thermowell probe to monitor temperature and flushed with air. A distillation head was attached to the top of the Monel® alloy packed tower. The contents of the flask were heated in an oil bath and magnetically stirred. A 10 mL portion of the distillate was collected and then recycled to the flask. The overhead temperature during operation was about 147 ° C. (about 297 ° F.). The run was continued for about 70 minutes during which time no polymer formed on the packing. A significant amount of polymer was observed in the glass of the distillation head above the top of the Monel® alloy packing. The acrylic acid residue in the pot had a copper content of about 52 ppm as determined by light blue and atomic absorption.

  Example 3 did not reproduce with stainless steel as the surface because it was apparent that polymerization or contamination occurred immediately.

  The data and results in each of the above examples indicate that copper and Monel® alloy functioned as an enhanced polymerization inhibitor surface when compared to glass or stainless steel surfaces. Reactions in glass or on stainless steel surfaces contaminated within 5-6 hours, while copper and Monel® alloy prevented polymerization for longer than 970 hours (greater than 40 days) Can know.

  During the experiment, some copper leached into the product, but it was observed that this copper was not a problem during the entire refining operation. This is because the product going through the additional distillation is treated to remove heavy final impurities, which also removes any residual copper metal present. Copper and copper alloy metals are not volatile and are therefore not expected to combine with heavy final impurities.

  It will be appreciated by those skilled in the art that modifications can be made to the above embodiments without departing from the broad inventive concept. Accordingly, it is to be understood that the invention is not limited to the particular embodiments disclosed, but is intended to cover modifications within the spirit and scope of the invention as defined in the claims.

The related aspects of the present invention are described below.
Aspect 1. An apparatus for at least one of the production, purification, handling and storage of the subject ethylenically unsaturated monomer, the apparatus comprising an inlet for an oxygen-containing gas, and at least a portion of the apparatus in contact with the monomer, An apparatus comprising a metal containing sufficient copper to inhibit polymerization of monomers in the apparatus in the presence of an oxygen-containing gas.
Aspect 2. The apparatus of embodiment 1, wherein the metal comprises at least 10% copper.
Aspect 3. The apparatus according to embodiment 2, wherein the metal is an alloy containing 25% to 75% copper.
Aspect 4. The apparatus of embodiment 3, wherein the alloy comprises 30% to 50% copper.
Aspect 5 The apparatus of embodiment 2, wherein the metal comprises copper and nickel.
Aspect 6 The apparatus according to embodiment 2, wherein the metal comprises copper and zinc.
Aspect 7. The apparatus according to embodiment 2, wherein the metal comprises copper and tin.
Aspect 8 The apparatus according to aspect 1, wherein the apparatus is selected from the group consisting of a distillation apparatus, a distillation internal component, a flame arrester apparatus, an extraction tower apparatus, an absorption apparatus, an adsorption apparatus, a heat exchange apparatus, a pipe, a joint, a valve, a pump, and a container.
Aspect 9. The apparatus of embodiment 1, wherein the apparatus is a distillation apparatus and a portion of the apparatus is a packing.
Aspect 10 The apparatus according to embodiment 1, wherein the apparatus is a distillation column.
Aspect 11 The apparatus according to embodiment 10, wherein the inlet for the oxygen-containing gas is present at the bottom of the distillation column.
Aspect 12 The apparatus of embodiment 1, wherein the apparatus is a distillation column, and said portion comprises a tray for a distillation column.
Aspect 13 The apparatus of embodiment 1, wherein an inlet for the oxygen-containing gas is present at the bottom of the apparatus.
Aspect 14. The apparatus according to embodiment 1, wherein the oxygen-containing gas is air.
Aspect 15 The apparatus of embodiment 1, wherein the oxygen-containing gas comprises at least 5% oxygen by volume.
Aspect 16. A method of inhibiting polymerization during at least one of the production, purification, handling and storage of a subject ethylenically unsaturated monomer, the apparatus for at least one of the production, purification, handling and storage of the monomer comprising: The monomer is introduced into a device comprising at least a portion of the device in contact with a metal containing sufficient copper to inhibit polymerization of the monomer within the device in the presence of an oxygen-containing gas. And a step of supplying a gas containing oxygen into the inside of the device containing the monomer, thereby suppressing polymerization of the monomer inside the device.
Aspect 17 Ethylenically unsaturated monomers are acrylics other than acrylic acid, α-alkyl acrylic acid, α-alkyl acrylic ester, β-alkyl acrylic acid, β-alkyl acrylic ester, methacrylic acid, methyl acrylate and 2-ethylhexyl acrylate Aspect 16 selected from the group consisting of esters of acids, esters of methacrylic acid, vinyl acetate, vinyl esters, polyunsaturated carboxylic acids, polyunsaturated esters, maleic acid, maleic esters, maleic anhydride and acetoxystyrene. the method of.
Aspect 18. The method according to embodiment 17, wherein the alkyl group is a linear or branched alkyl group having 1 to 8 carbon atoms.
Aspect 19 The method according to embodiment 18, wherein the alkyl group is a linear or branched alkyl group having 1 to 4 carbon atoms.
Aspect 20 The method of embodiment 16, wherein the ethylenically unsaturated monomer is acrylic acid.
Aspect 21. The method according to embodiment 16, wherein the ethylenically unsaturated monomer is ethyl acrylate.
Aspect 22 The method according to embodiment 16, wherein the ethylenically unsaturated monomer is butyl acrylate.
Aspect 23. Embodiment 17. The method of embodiment 16, wherein the metal comprises at least 10% copper.
Aspect 24. Embodiment 24. The method of embodiment 23, wherein the metal is an alloy comprising 25% to 75% copper.
Aspect 25 25. A method according to embodiment 24, wherein the alloy comprises 30% to 50% copper.
Aspect 26. The method of embodiment 23, wherein the metal comprises copper and nickel.
Aspect 27. Embodiment 24. The method according to embodiment 23, wherein the metal comprises copper and zinc.
Aspect 28. The method according to embodiment 23, wherein the metal comprises copper and tin.
Aspect 29 The method according to embodiment 16, wherein the apparatus is selected from the group consisting of a distillation apparatus, distillation internal components, flame arrester apparatus, extraction tower apparatus, absorption apparatus, adsorption apparatus, heat exchange apparatus, piping, fittings, valves, pumps and containers.
Aspect 30 Embodiment 17. The method of embodiment 16, wherein the apparatus is a distillation apparatus and the portion of the apparatus is a packing.
Aspect 31 The method according to embodiment 16, wherein the apparatus is a distillation column.
Aspect 32. 32. A process according to embodiment 31, wherein the oxygen-containing gas is fed through an inlet for oxygen-containing gas present at the bottom of the distillation column.
Aspect 33. Embodiment 17. The method of embodiment 16, wherein the apparatus is a distillation column and said portion comprises a tray for a distillation column.
Aspect 34. The method of embodiment 16, wherein the oxygen-containing gas is fed through an inlet for an oxygen-containing gas present at the bottom of the apparatus.
Aspect 35. The method according to embodiment 16, wherein the oxygen-containing gas is air.
Aspect 36. The method of embodiment 16, wherein the oxygen-containing gas comprises at least 5% by volume of oxygen.

Claims (18)

Acrylic acid, α-alkyl acrylic acid, α-alkyl acrylic ester, β-alkyl acrylic acid, β-alkyl acrylic ester, methacrylic acid, methyl acrylate and esters of acrylic acid other than 2-ethylhexyl acrylate, methacrylic acid Production and purification of target ethylenically unsaturated monomers selected from the group consisting of esters, vinyl acetate, vinyl esters, polyunsaturated carboxylic acids, polyunsaturated esters, maleic acid, maleic esters, maleic anhydride and acetoxystyrene A method of inhibiting polymerization during at least one of handling and storage, wherein at least a portion of the device in contact with the monomer inhibits polymerization of the monomer within the device in the presence of an oxygen-containing gas. Including a metal that is a sufficient alloy containing 25% to 75% copper That production of the monomer, purification, to handling and the apparatus for at least one for storage,
A method of suppressing the polymerization of the monomer inside the apparatus by introducing the monomer and supplying a gas containing oxygen into the inside of the apparatus containing the monomer.   The method according to claim 1, wherein the alkyl group is a linear or branched alkyl group having 1 to 8 carbon atoms.   The method according to claim 2, wherein the alkyl group is a linear or branched alkyl group having 1 to 4 carbon atoms.   The method of claim 1 wherein the ethylenically unsaturated monomer is acrylic acid.   The process of claim 1 wherein the ethylenically unsaturated monomer is ethyl acrylate.   The method of claim 1 wherein the ethylenically unsaturated monomer is butyl acrylate.   The method of claim 1 wherein the alloy comprises 30% to 50% copper.   The method of claim 1 wherein the metal comprises copper and nickel.   The method of claim 1 wherein the metal comprises copper and zinc.   The method of claim 1 wherein the metal comprises copper and tin.   The method of claim 1, wherein the apparatus is selected from the group consisting of a distillation apparatus, distillation internal components, flame arrester apparatus, extraction tower apparatus, absorption apparatus, adsorption apparatus, heat exchange apparatus, piping, fittings, valves, pumps and containers. .   The method of claim 1 wherein the apparatus is a distillation apparatus and the portion of the apparatus is a packing.   The method of claim 1 wherein the apparatus is a distillation column.   The process according to claim 13, wherein the oxygen-containing gas is fed through an inlet for an oxygen-containing gas present at the bottom of the distillation column.   The method of claim 1 wherein the apparatus is a distillation column and the portion comprises a tray for the distillation column.   The method of claim 1, wherein the oxygen-containing gas is supplied through an inlet for an oxygen-containing gas present at the bottom of the apparatus.   The method according to claim 1, wherein the oxygen-containing gas is air.   The method of claim 1 wherein the oxygen-containing gas comprises at least 5% oxygen by volume.

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