CA3009033C - Method for producing (meth)acrylic acid - Google Patents
Method for producing (meth)acrylic acid Download PDFInfo
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- CA3009033C CA3009033C CA3009033A CA3009033A CA3009033C CA 3009033 C CA3009033 C CA 3009033C CA 3009033 A CA3009033 A CA 3009033A CA 3009033 A CA3009033 A CA 3009033A CA 3009033 C CA3009033 C CA 3009033C
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
- C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/48—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
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Abstract
The application relates to stably producing high-quality (meth)acrylic acid, by performing an energetically advantageous operation resulting from a lowered heat load in a distillation step of a (meth)acrylic acid production process, and by preventing the occurrence of an oil-water suspension state and maintaining good separation of water in an extraction step. A method may include an oxidation reaction to obtain a reaction gas containing (meth)acrylic acid; bringing the reaction gas into gas-liquid contact with water, to yield a (meth)acrylic acid aqueous solution; bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to extract crude (meth)acrylic acid; and distilling (meth)acrylic acid from the crude (meth)acrylic acid. A solution containing a discharge solution discharged from at least one of the steps is used as a collected solution, which is held for 1-60 days, and the held collected solution is fed to the extraction step.
Description
16A00512W00 (0P-16414-PCT) TITLE OF THE INVENTION
METHOD FOR PRODUCING (METH)ACRYLIC ACID
Technical Field [0001] The present invention relates to a method for producing (meth)acrylic acid, the method including extraction of (meth)acrylic acid by an organic solvent. More particularly, the present invention relates to a method for stably producing high-quality (meth)acrylic acid, by performing an energetically advantageous operation resulting from a lowered heat load in a distillation step of a production process of (meth)acrylic acid, and by preventing the occurrence of an oil-water suspension state in an extraction step and maintaining good separation of water in the extraction step.
Background Art
METHOD FOR PRODUCING (METH)ACRYLIC ACID
Technical Field [0001] The present invention relates to a method for producing (meth)acrylic acid, the method including extraction of (meth)acrylic acid by an organic solvent. More particularly, the present invention relates to a method for stably producing high-quality (meth)acrylic acid, by performing an energetically advantageous operation resulting from a lowered heat load in a distillation step of a production process of (meth)acrylic acid, and by preventing the occurrence of an oil-water suspension state in an extraction step and maintaining good separation of water in the extraction step.
Background Art
[0002] Herein (meth)acrylic acid [acrylic acid and/or methacrylic acid] is obtained as an oxidation reaction gas through vapor-phase catalytic oxidation of propylene or propane, which is a hydrocarbon having three carbon atoms (C3), or isobutylene, butenes or tertiary butanol, which is a hydrocarbon having four carbon atoms (C4), together with air as an oxygen source and steam or nitrogen, using two types of solid catalyst. The obtained oxidation reaction gas is cooled, * CA 03009033 2018-06-18 1 *
16A00512W00 (0P-16414-PCT) and thereafter is brought into gas-liquid contact with absorbing water that contains a polymerization inhibitor, in an absorption column, as a result of which the oxidation reaction gas is separated in the form of a (meth)acrylic acid aqueous solution.
The gas not having been absorbed is introduced into a waste gas treatment step, to be rendered harmless and then disposed of, although part of the gas is recycled to an oxidation reaction step.
16A00512W00 (0P-16414-PCT) and thereafter is brought into gas-liquid contact with absorbing water that contains a polymerization inhibitor, in an absorption column, as a result of which the oxidation reaction gas is separated in the form of a (meth)acrylic acid aqueous solution.
The gas not having been absorbed is introduced into a waste gas treatment step, to be rendered harmless and then disposed of, although part of the gas is recycled to an oxidation reaction step.
[0003]
The (meth)acrylic acid aqueous solution obtained from the absorption column is ordinarily purified through extraction or azeotropic distillation, to produce (meth)acrylic acid thereby (Non-Patent document 1).
In the extraction method, the (meth)acrylic acid aqueous solution is subjected to an extraction treatment in an extraction column, using an extraction solvent selected from among ketones, alcohols, ethers, esters and hydrocarbons, to yield an extract solution which is a mixed solution of (meth)acrylic acid and the extraction solvent.
The extract solution is further introduced into a (meth)acrylic acid purification system, and is subjected to a purification treatment by distillation, crystallization or the like, to yield (meth)acrylic acid as the product.
The (meth)acrylic acid aqueous solution obtained from the absorption column is ordinarily purified through extraction or azeotropic distillation, to produce (meth)acrylic acid thereby (Non-Patent document 1).
In the extraction method, the (meth)acrylic acid aqueous solution is subjected to an extraction treatment in an extraction column, using an extraction solvent selected from among ketones, alcohols, ethers, esters and hydrocarbons, to yield an extract solution which is a mixed solution of (meth)acrylic acid and the extraction solvent.
The extract solution is further introduced into a (meth)acrylic acid purification system, and is subjected to a purification treatment by distillation, crystallization or the like, to yield (meth)acrylic acid as the product.
[0004]
In the production process of (meth)acrylic acid, contamination in the form of polymerization products and the like accumulates in equipment and piping, and accordingly the 16A00512W00 (0P-16414-PCT) equipment must be opened and cleaned periodically.
Retained solution within the various equipment items is once discharged and held in a reservoir such as a tank.
Discharge solutions are generated also during partial or complete process shutdown, upon occurrence of operational problems. These discharge solutions include large amounts of valuable products such as acrylic acid, the discarding of which is undesirable in terms of production intensity. Accordingly, it is necessary to feed the discharge solutions once more into the process, after restart of process operations once cleaning is complete. In some instances the discharge solutions may contain large amounts of water. Herein it would be ideal to feed the discharge solutions to an extraction step in which water is removed from acrylic acid. At the same time, however, these discharge solutions include also components that adversely affect oil-water separation, for causes that are not exactly clear.
Accordingly, a concern has arisen in that in cases where these discharge solutions are fed to the extraction step, separation may be defective due to the formation of an oil-water suspension state, and also operational problems may occur, depending on the content of components that impair oil-water separation and depending on operation conditions. In conventional art, therefore, these discharge solutions have been fed to a distillation process (see Patent document 1, for instance).
16A00512W00 (0P-16414-PCT) Citation List Patent Literature
In the production process of (meth)acrylic acid, contamination in the form of polymerization products and the like accumulates in equipment and piping, and accordingly the 16A00512W00 (0P-16414-PCT) equipment must be opened and cleaned periodically.
Retained solution within the various equipment items is once discharged and held in a reservoir such as a tank.
Discharge solutions are generated also during partial or complete process shutdown, upon occurrence of operational problems. These discharge solutions include large amounts of valuable products such as acrylic acid, the discarding of which is undesirable in terms of production intensity. Accordingly, it is necessary to feed the discharge solutions once more into the process, after restart of process operations once cleaning is complete. In some instances the discharge solutions may contain large amounts of water. Herein it would be ideal to feed the discharge solutions to an extraction step in which water is removed from acrylic acid. At the same time, however, these discharge solutions include also components that adversely affect oil-water separation, for causes that are not exactly clear.
Accordingly, a concern has arisen in that in cases where these discharge solutions are fed to the extraction step, separation may be defective due to the formation of an oil-water suspension state, and also operational problems may occur, depending on the content of components that impair oil-water separation and depending on operation conditions. In conventional art, therefore, these discharge solutions have been fed to a distillation process (see Patent document 1, for instance).
16A00512W00 (0P-16414-PCT) Citation List Patent Literature
[0005]
Patent document 1: Japanese Patent Application Publication No. 2003-292470 Patent document 2: Japanese Patent Application Publication No. 2013-151455 Non-Patent Literature
Patent document 1: Japanese Patent Application Publication No. 2003-292470 Patent document 2: Japanese Patent Application Publication No. 2013-151455 Non-Patent Literature
[0006]
Non-Patent document 1: Eizo OMORI, "Acrylic Acid and its Polymers [I]", 3rd edition, Shokodo Co., Ltd., April 28, 1978, pp. 10 to 13 (1.4 Purification Methods of Acrylic Acid) Summary of Invention Technical Problem
Non-Patent document 1: Eizo OMORI, "Acrylic Acid and its Polymers [I]", 3rd edition, Shokodo Co., Ltd., April 28, 1978, pp. 10 to 13 (1.4 Purification Methods of Acrylic Acid) Summary of Invention Technical Problem
[0007] As described above, components of large latent heat of vaporization, such as water, are also present in the discharge solutions that are discharged from the (meth)acrylic acid production process. When implementing the operations involved in the above methods, it has been necessary to adopt measures such as increasing the number of plates of distillation columns and increasing the heat load during operations, all of which is energetically disadvantageous. A
=
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) further concern is the increased frequency of equipment opening and cleaning derived from contamination of reboilers and draw-out piping of the distillation columns, arising from the impact of components such as oligomers and polymers of (meth)acrylic acid, maleic acid derivatives, phenolic resins and the like, contained in the discharge solutions.
It is an object of the present invention to provide a method for stably producing high-quality (meth)acrylic acid, by performing an energetically advantageous operation resulting from a lowered heat load in a distillation step of a production process of (meth)acrylic acid, and by preventing the occurrence of an oil-water suspension state in an extraction step and maintaining good separation of water in the extraction step.
Solution to Problem
=
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) further concern is the increased frequency of equipment opening and cleaning derived from contamination of reboilers and draw-out piping of the distillation columns, arising from the impact of components such as oligomers and polymers of (meth)acrylic acid, maleic acid derivatives, phenolic resins and the like, contained in the discharge solutions.
It is an object of the present invention to provide a method for stably producing high-quality (meth)acrylic acid, by performing an energetically advantageous operation resulting from a lowered heat load in a distillation step of a production process of (meth)acrylic acid, and by preventing the occurrence of an oil-water suspension state in an extraction step and maintaining good separation of water in the extraction step.
Solution to Problem
[0008]
As a result of diligent research aimed at solving the above problem, the inventors found that by feeding to the extraction step the discharge solutions having been discharged from the (meth)acrylic acid production process, the heat load in the distillation step can be eased and an energetically favorable operation can be carried out, while contamination derived from the discharge solutions can be reduced.
As described above, components that adversely affect oil-water separation may in some instances be present in the discharge = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) solutions that are discharged from the (meth)acrylic acid production process.
By being fed to the extraction step, these components may impair oil-water separation in the extraction step. If oil-water separation becomes poor in the extraction step, water flows downstream contained in the extraction solvent, which may translate into greater downstream purification load and poorer product quality. Oil-water separation may conceivably be carried out reliably by keeping a liquid load no greater than a given level, in order to prevent the above occurrence.
However, this requires imposing limitations to processing capacity during the operation, which may result in decreased production capacity.
As a result of diligent research aimed at solving the above problem, the inventors found that by feeding to the extraction step the discharge solutions having been discharged from the (meth)acrylic acid production process, the heat load in the distillation step can be eased and an energetically favorable operation can be carried out, while contamination derived from the discharge solutions can be reduced.
As described above, components that adversely affect oil-water separation may in some instances be present in the discharge = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) solutions that are discharged from the (meth)acrylic acid production process.
By being fed to the extraction step, these components may impair oil-water separation in the extraction step. If oil-water separation becomes poor in the extraction step, water flows downstream contained in the extraction solvent, which may translate into greater downstream purification load and poorer product quality. Oil-water separation may conceivably be carried out reliably by keeping a liquid load no greater than a given level, in order to prevent the above occurrence.
However, this requires imposing limitations to processing capacity during the operation, which may result in decreased production capacity.
[0009]
Further research by the inventors aimed at solving the above problem revealed that impairment of oil-water separation in the extraction step can be prevented, and high-quality (meth)acrylic acid can be produced stably, by performing the operations set forth below.
(a) A solution containing a discharge solution that is discharged from a (meth)acrylic acid production process is held as a collected solution, and the held collected solution is fed to the above extraction step.
(b) The collected solution is fed to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
=
16A00512W00 (0P-16414-PCT) (c) The concentration of Michael adducts in a mixed composition of the (meth)acrylic acid aqueous solution and the collected solution is set to lie in the range of 0.05 to 0.7 wt%.
(d) The collected solution is distilled, and the resulting distillate is thereafter fed to the extraction step.
(e) The collected solution is subjected to oil-water separation, after which the oil phase is fed to the extraction step.
(f) The extraction temperature in the extraction step is adjusted to 30 C to 90 C.
Further research by the inventors aimed at solving the above problem revealed that impairment of oil-water separation in the extraction step can be prevented, and high-quality (meth)acrylic acid can be produced stably, by performing the operations set forth below.
(a) A solution containing a discharge solution that is discharged from a (meth)acrylic acid production process is held as a collected solution, and the held collected solution is fed to the above extraction step.
(b) The collected solution is fed to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
=
16A00512W00 (0P-16414-PCT) (c) The concentration of Michael adducts in a mixed composition of the (meth)acrylic acid aqueous solution and the collected solution is set to lie in the range of 0.05 to 0.7 wt%.
(d) The collected solution is distilled, and the resulting distillate is thereafter fed to the extraction step.
(e) The collected solution is subjected to oil-water separation, after which the oil phase is fed to the extraction step.
(f) The extraction temperature in the extraction step is adjusted to 30 C to 90 C.
[0010]
The above problems are not found in conventional art.
That is, the invention has discovered and solved problems that were wholly unknown conventionally. A
person skilled in the art unaware of the above problems would not ordinarily incur a cost liability, for instance, in terms of adding, to a production process, a new step such as holding, distillation, oil-water separation and the like of the collected solution, or adding equipment associated with these steps. It is moreover a basic feature of continuous production to set constant-quantity charge amounts and charge ratios in an extraction step; by contrast, feeding to the extraction step a solution obtained as a result of operations such as holding, distillation, oil-water separation and so forth of the collected solution, may give rise to fluctuations 16A00512W00 (0P-16414-PCT) in the above charge amounts and charge ratios, and thus such feeding is ordinarily not performed. In the production of (meth)acrylic acid, specifically, it is not usual to have a discharge solution go through extra operations and thereafter feed the discharge solution to an extraction step.
The above problems are not found in conventional art.
That is, the invention has discovered and solved problems that were wholly unknown conventionally. A
person skilled in the art unaware of the above problems would not ordinarily incur a cost liability, for instance, in terms of adding, to a production process, a new step such as holding, distillation, oil-water separation and the like of the collected solution, or adding equipment associated with these steps. It is moreover a basic feature of continuous production to set constant-quantity charge amounts and charge ratios in an extraction step; by contrast, feeding to the extraction step a solution obtained as a result of operations such as holding, distillation, oil-water separation and so forth of the collected solution, may give rise to fluctuations 16A00512W00 (0P-16414-PCT) in the above charge amounts and charge ratios, and thus such feeding is ordinarily not performed. In the production of (meth)acrylic acid, specifically, it is not usual to have a discharge solution go through extra operations and thereafter feed the discharge solution to an extraction step.
[0011] The present invention is as follows.
<1> A method for producing (meth)acrylic acid, the method comprising:
an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is held for 1 day to 60 days, and the held collected solution is fed to the extraction step.
<2> A method for producing (meth)acrylic acid, the method comprising:
16A00512W00 (0P-16414-PCT) an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is subjected to oil-water separation, and an oil phase resulting from the oil-water separation is fed to the extraction step.
<3> A method for producing (meth)acrylic acid, the method comprising:
an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is distilled, and the resulting distillate is fed to the extraction step.
<4> The method for producing (meth)acrylic acid according to any one of <1> to <3>, wherein in at least one of the steps, supply of a reaction product in the step and discharge of the discharge solution in the step are carried out simultaneously.
<5> The method for producing (meth)acrylic acid according to any one of <1> to <4>, wherein the collected solution contains water.
<6> The method for producing (meth)acrylic acid according to any one of <1> to <5>, wherein the collected solution that is fed to the extraction step is supplied to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
<7> The method for producing (meth)acrylic acid according to any one of <1> to <6>, wherein the concentration of Michael adducts in a mixed composition of the collected solution and the (meth)acrylic acid aqueous solution is 0.05 to 0.7 wt%.
<8> The method for producing (meth)acrylic acid according to any one of <1> to <7>, wherein the extraction temperature in the extraction step is 30 C to 90 C.
=
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) <9> The method for producing (meth)acrylic acid according to any one of <1> to <8>, wherein the extraction solvent is a solvent having, as a main component, a water-insoluble aromatic compound having a lower boiling point than the boiling point of (meth)acrylic acid.
<10> The method for producing (meth)acrylic acid according to <9>, wherein the water-insoluble aromatic compound is at least one compound selected from the group consisting of benzene, toluene and xylene.
Advantageous Effects of Invention
<1> A method for producing (meth)acrylic acid, the method comprising:
an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is held for 1 day to 60 days, and the held collected solution is fed to the extraction step.
<2> A method for producing (meth)acrylic acid, the method comprising:
16A00512W00 (0P-16414-PCT) an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is subjected to oil-water separation, and an oil phase resulting from the oil-water separation is fed to the extraction step.
<3> A method for producing (meth)acrylic acid, the method comprising:
an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is distilled, and the resulting distillate is fed to the extraction step.
<4> The method for producing (meth)acrylic acid according to any one of <1> to <3>, wherein in at least one of the steps, supply of a reaction product in the step and discharge of the discharge solution in the step are carried out simultaneously.
<5> The method for producing (meth)acrylic acid according to any one of <1> to <4>, wherein the collected solution contains water.
<6> The method for producing (meth)acrylic acid according to any one of <1> to <5>, wherein the collected solution that is fed to the extraction step is supplied to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
<7> The method for producing (meth)acrylic acid according to any one of <1> to <6>, wherein the concentration of Michael adducts in a mixed composition of the collected solution and the (meth)acrylic acid aqueous solution is 0.05 to 0.7 wt%.
<8> The method for producing (meth)acrylic acid according to any one of <1> to <7>, wherein the extraction temperature in the extraction step is 30 C to 90 C.
=
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) <9> The method for producing (meth)acrylic acid according to any one of <1> to <8>, wherein the extraction solvent is a solvent having, as a main component, a water-insoluble aromatic compound having a lower boiling point than the boiling point of (meth)acrylic acid.
<10> The method for producing (meth)acrylic acid according to <9>, wherein the water-insoluble aromatic compound is at least one compound selected from the group consisting of benzene, toluene and xylene.
Advantageous Effects of Invention
[0012]
The present invention allows reducing heat load in a distillation step of a production process of (meth)acrylic acid, performing an energetically favorable operation, and reducing contamination derived from discharge solutions.
Further, the invention allows producing stably high-quality (meth)acrylic acid, while maintaining the performance of removal of water and other impurities at a high level, by preventing impairment of oil-water separation in an extraction step.
Brief Description of Drawing
The present invention allows reducing heat load in a distillation step of a production process of (meth)acrylic acid, performing an energetically favorable operation, and reducing contamination derived from discharge solutions.
Further, the invention allows producing stably high-quality (meth)acrylic acid, while maintaining the performance of removal of water and other impurities at a high level, by preventing impairment of oil-water separation in an extraction step.
Brief Description of Drawing
[0013]
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) Fig. 1 is a schematic diagram illustrating an example of a production facility of (meth)acrylic acid of the present invention.
Description of Embodiments
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) Fig. 1 is a schematic diagram illustrating an example of a production facility of (meth)acrylic acid of the present invention.
Description of Embodiments
[0014] Embodiment of the method for producing (meth)acrylic acid of the present invention will be explained next in detail.
The method for producing (meth)acrylic acid of the present invention has: an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein operations are carried out in such a manner that, necessarily, a solution containing a discharge solution having been discharged from at least one of the above steps is held as a collected solution, and the held collected solution is fed to the extraction step (condition (a) below), and preferably, in such a manner that the conditions below ((b) to (f)) are satisfied.
=
=
16A00512W00 (0P-16414-PCT) (a) A solution containing a discharge solution that is discharged from a (meth)acrylic acid production process is held as a collected solution, and the held collected solution is fed to the above extraction step.
(b) The collected solution is fed to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
(c) The concentration of Michael adducts in a mixed composition of the (meth)acrylic acid aqueous solution and the collected solution is set to lie in the range of 0.05 to 0.7 wt%.
(d) The collected solution is distilled, and the resulting distillate is thereafter fed to the extraction step.
(e) The collected solution is subjected to oil-water separation, after which the oil phase is fed to the extraction step.
(f) The extraction temperature in the extraction step is adjusted to 30 C to 90 C.
The method for producing (meth)acrylic acid of the present invention has: an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein operations are carried out in such a manner that, necessarily, a solution containing a discharge solution having been discharged from at least one of the above steps is held as a collected solution, and the held collected solution is fed to the extraction step (condition (a) below), and preferably, in such a manner that the conditions below ((b) to (f)) are satisfied.
=
=
16A00512W00 (0P-16414-PCT) (a) A solution containing a discharge solution that is discharged from a (meth)acrylic acid production process is held as a collected solution, and the held collected solution is fed to the above extraction step.
(b) The collected solution is fed to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
(c) The concentration of Michael adducts in a mixed composition of the (meth)acrylic acid aqueous solution and the collected solution is set to lie in the range of 0.05 to 0.7 wt%.
(d) The collected solution is distilled, and the resulting distillate is thereafter fed to the extraction step.
(e) The collected solution is subjected to oil-water separation, after which the oil phase is fed to the extraction step.
(f) The extraction temperature in the extraction step is adjusted to 30 C to 90 C.
[0015] As set forth in (a), it is a characterizing feature of the present invention to use, as a collected solution, a solution containing discharge solutions having been discharged from the (meth)acrylic acid production process, and holding the collected solution, for instance, in a storage tank. The collected solution may be collected during the production or upon discontinuation of the production of (meth)acrylic acid.
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) Supply of the reaction product and discharge of the discharge solutions in each step may be carried out simultaneously.
Through holding of the collected solution, the discharge solutions having various compositions are mixed, whereby components are homogenized, and the concentration of components that impair oil-water separation is diluted.
Moreover, an effect of facilitating removal of impairing components can be achieved through settling of solid matter and through oil-water separation. In the present invention, the term discharge solutions that are discharged from the (meth)acrylic acid production process may denote discharge solutions that are discharged from the process during non-steady operation, for instance, periodic repairs/cleaning or plant problems, and denotes specifically solutions discharged, for instance, from an absorption column, an extraction column, an evaporator, or a distillation column. The term holding in the present invention denotes the operation of keeping the solutions to a storage tank such as a buffer tank, an off-spec tank or a rundown tank, with the holding time being set to 1 day to 60 days, preferably 2 days to 40 days and more preferably 2 days to 10 days. In the present specification, the term 1 day refers to 24 hours. If this period is too short, the effect of diluting the concentration of components that impair oil-water separation, and the effects of solid matter settling and oil-water separation fail to be achieved * CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) sufficiently, whereas if the above period is too long, oil-water separability is conversely impaired due to the generation of new impurities such as Michael adducts and polymerization products.
If the solutions discharged from the (meth)acrylic acid production process are supplied quickly to the extraction step without having undergone the holding operation, oil-water separation may be impaired, and water may flow downstream contained in the extraction solvent, which may translate into greater downstream purification load and poorer product quality.
= CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) Supply of the reaction product and discharge of the discharge solutions in each step may be carried out simultaneously.
Through holding of the collected solution, the discharge solutions having various compositions are mixed, whereby components are homogenized, and the concentration of components that impair oil-water separation is diluted.
Moreover, an effect of facilitating removal of impairing components can be achieved through settling of solid matter and through oil-water separation. In the present invention, the term discharge solutions that are discharged from the (meth)acrylic acid production process may denote discharge solutions that are discharged from the process during non-steady operation, for instance, periodic repairs/cleaning or plant problems, and denotes specifically solutions discharged, for instance, from an absorption column, an extraction column, an evaporator, or a distillation column. The term holding in the present invention denotes the operation of keeping the solutions to a storage tank such as a buffer tank, an off-spec tank or a rundown tank, with the holding time being set to 1 day to 60 days, preferably 2 days to 40 days and more preferably 2 days to 10 days. In the present specification, the term 1 day refers to 24 hours. If this period is too short, the effect of diluting the concentration of components that impair oil-water separation, and the effects of solid matter settling and oil-water separation fail to be achieved * CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) sufficiently, whereas if the above period is too long, oil-water separability is conversely impaired due to the generation of new impurities such as Michael adducts and polymerization products.
If the solutions discharged from the (meth)acrylic acid production process are supplied quickly to the extraction step without having undergone the holding operation, oil-water separation may be impaired, and water may flow downstream contained in the extraction solvent, which may translate into greater downstream purification load and poorer product quality.
[0016] As described above, components that impair oil-water separation are contained in the discharge solutions that are discharged from the (meth)acrylic acid production process, with the content of substances that impair oil-water separation fluctuating depending on the timing at which the discharge solutions are discharged. Maintaining the concentrations of these components within appropriate ranges, while monitoring the concentrations, would conceivably be the most efficient operation method herein, but such monitoring has proved difficult, since there are multiple components that can imaginably impair oil-water separation but have not been identified clearly.
[0017] As a result of further research to address this problem, it was found in the present invention that Michael = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) adducts can be used as an indicator substance of oil-water separation, and that impairment of oil-water separation can be prevented by managing the concentration of Michael adducts to lie within a given range. As set forth in (c), a method for managing oil-water separability involves preferably managing oil-water separability in such a manner that the concentration of Michael adducts in a mixed composition of the (meth)acrylic acid aqueous solution and the collected solution is 0.05 to 0.7 wt%.
The concentration of Michael adducts is more preferably 0.05 to 0.6 wt%, and yet more preferably 0.1 to 0.5 wt%. If the concentration of Michael adducts is too low, the conditions in the oxidation reaction step and the absorption step become constrained, whereas if the concentration is too high, oil-water separation in the extraction step is impaired.
As used herein, the term mixed composition denotes the composition of a mixed solution in a case where the collected solution is mixed with the (meth)acrylic acid aqueous solution, within piping, while in a case where the collected solution is supplied to the extraction step through piping separate from that of the (meth)acrylic acid aqueous solution, the term mixed composition denotes an assumed composition of the resulting mixture, calculated on the basis of respective compositions and flow ratios.
The concentration of Michael adducts can be measured in accordance with known methods. For =
16A00512W00 (0P-16414-PCT) instance, the concentration of Michael adducts can be measured by gas chromatography.
The concentration of Michael adducts is more preferably 0.05 to 0.6 wt%, and yet more preferably 0.1 to 0.5 wt%. If the concentration of Michael adducts is too low, the conditions in the oxidation reaction step and the absorption step become constrained, whereas if the concentration is too high, oil-water separation in the extraction step is impaired.
As used herein, the term mixed composition denotes the composition of a mixed solution in a case where the collected solution is mixed with the (meth)acrylic acid aqueous solution, within piping, while in a case where the collected solution is supplied to the extraction step through piping separate from that of the (meth)acrylic acid aqueous solution, the term mixed composition denotes an assumed composition of the resulting mixture, calculated on the basis of respective compositions and flow ratios.
The concentration of Michael adducts can be measured in accordance with known methods. For =
16A00512W00 (0P-16414-PCT) instance, the concentration of Michael adducts can be measured by gas chromatography.
[0018] A
conceivable method for maintaining the above concentration ratio involves adjusting the flow rate of the collected solution, or adjusting the concentration of Michael adducts by separately supplying high-purity acrylic acid.
However, the treatment throughput is constrained in such a case.
Accordingly, it is preferable to perform the distillation operation before feeding of the collected solution to the extraction step, as described in (d). By performing the distillation operation and feeding then the distillate to the extraction step it becomes possible to prevent impairment of oil-water separation in the extraction step. In a case where the distillation operation is accomplished using a distillation column, the term distillate denotes herein a condensate of components obtained from the top of a distillation column. There are conceivably multiple components that impair oil-water separation in the extraction step.
Although not clearly identified, these components are deemed to include Michael adducts of (meth)acrylic acid, polymerization products of (meth)acrylic acid, as well as other high-boiling point compounds and solid matter.
Accordingly, it is estimated that removal of these components by distillation should contribute to preventing impairment of oil-water separation.
16A00512W00 (0P-16414-PCT)
conceivable method for maintaining the above concentration ratio involves adjusting the flow rate of the collected solution, or adjusting the concentration of Michael adducts by separately supplying high-purity acrylic acid.
However, the treatment throughput is constrained in such a case.
Accordingly, it is preferable to perform the distillation operation before feeding of the collected solution to the extraction step, as described in (d). By performing the distillation operation and feeding then the distillate to the extraction step it becomes possible to prevent impairment of oil-water separation in the extraction step. In a case where the distillation operation is accomplished using a distillation column, the term distillate denotes herein a condensate of components obtained from the top of a distillation column. There are conceivably multiple components that impair oil-water separation in the extraction step.
Although not clearly identified, these components are deemed to include Michael adducts of (meth)acrylic acid, polymerization products of (meth)acrylic acid, as well as other high-boiling point compounds and solid matter.
Accordingly, it is estimated that removal of these components by distillation should contribute to preventing impairment of oil-water separation.
16A00512W00 (0P-16414-PCT)
[0019] As set forth in (e), impairment of oil-water separation in the extraction step can be prevented also by performing an oil-water separation operation on the collected solution. Although the underlying reasons are unclear, it is deemed that impairment of oil-water separation in the extraction step can be prevented by feeding to the extraction step an oil phase after oil-water separation, since components having solubility in water are present among the components that impair oil-water separation.
[0020] The collected solution is preferably fed to the extraction step during production of (meth)acrylic acid, and ,more preferably is fed to the extraction step during continuous production, after having undergone at least one step selected from the group consisting of holding, distillation and oil-water separation. As set forth in (b), the site to which the collected solution is fed is preferably identical to the site of supply of the (meth)acrylic acid aqueous solution in the extraction step. Conceivable methods to that end include mixing the collected solution into a pipe through which the (meth)acrylic acid aqueous solution flows, or a method of supplying the collected solution, through separate piping, to the site to which the (meth)acrylic acid aqueous solution is supplied. In a case where an extraction column is used as the extraction step and the (meth)acrylic acid aqueous solution is supplied to the top of the column, a = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) conceivable example of the latter method involves supplying a collected solution to the top of the column through separate piping. The extraction efficiency of (meth)acrylic acid is lowered in a case where this method is not implemented and the collected solution is instead supplied, for instance, to the same site as that of the extraction solvent.
[0021] The temperature during extraction is ordinarily a low temperature, of about 20 C to 30 C, since the mutual solubility of oil and water increases with rising temperature at the time of oil-water separation (see Patent document 2, for instance).
However, the extraction temperature is preferably not excessively low, from the viewpoint of preventing an oil-water suspension state, since the oil-water separation rate is low at low temperatures. An optimal temperature in terms of the best balance between oil-water mutual solubility and oil-water separation rate, and in terms of suppressing, for instance, new generation of components that impair oil-water separability, lies preferably in the range of 30 C to 90 C, more preferably 40 C to 80 C and yet more preferably 40 C to 60 C, as set forth in (f). As a method for adjusting the temperature, it is most efficient herein to adjust the temperature of the collected solution or the (meth)acrylic acid aqueous solution supplied to the extraction step, or the temperature of a mixed solution of the foregoing, so as to lie in an appropriate range.
16A00512W00 (0P-16414-PCT)
However, the extraction temperature is preferably not excessively low, from the viewpoint of preventing an oil-water suspension state, since the oil-water separation rate is low at low temperatures. An optimal temperature in terms of the best balance between oil-water mutual solubility and oil-water separation rate, and in terms of suppressing, for instance, new generation of components that impair oil-water separability, lies preferably in the range of 30 C to 90 C, more preferably 40 C to 80 C and yet more preferably 40 C to 60 C, as set forth in (f). As a method for adjusting the temperature, it is most efficient herein to adjust the temperature of the collected solution or the (meth)acrylic acid aqueous solution supplied to the extraction step, or the temperature of a mixed solution of the foregoing, so as to lie in an appropriate range.
16A00512W00 (0P-16414-PCT)
[0022] The present invention will be explained next by illustrating the production of acrylic acid using propylene as a starting material, as a typical example of the production of (meth)acrylic acid, with reference to Fig. 1 that depicts schematically an example of a production facility of (meth)acrylic acid.
However, the present invention is not limited to the production of acrylic acid using propylene as a starting material, and can be utilized in the production of acrylic acid or methacrylic acid in general, using starting materials in the form of hydrocarbons having three carbon atoms or hydrocarbons having four carbon atoms.
However, the present invention is not limited to the production of acrylic acid using propylene as a starting material, and can be utilized in the production of acrylic acid or methacrylic acid in general, using starting materials in the form of hydrocarbons having three carbon atoms or hydrocarbons having four carbon atoms.
[0023] 1) Oxidation reaction step Air (11), steam and/or nitrogen as a diluent (12), and further propylene (10) as a reaction starting material, are mixed and supplied to an oxidation reactor (first-stage reactor) (1). The first-stage reactor (1) is packed with a solid catalyst made up of a molybdenum (Mo)-bismuth (Bi)-based composite metal oxide, the temperature of the reactor being controlled through circulation of a heat medium. The structure of the first-stage reactor (1) is ordinarily that of a multi-tubular heat exchanger type or of a plate heat exchanger type. The reaction product gas resulting from conversion of propylene to acrolein in the first-stage reactor (1) is next supplied to an oxidation reactor (second-stage reactor) (2). The air (11) and so forth may be added to the = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) second-stage reactor (2). The second-stage reactor (2) is packed with a molybdenum (Mo)-vanadium (V)-based composite metal oxide catalyst, the temperature of the reactor being controlled through circulation of a heat medium. A structure similar to that of the first-stage reactor (1) is adopted as the structure of the second-stage reactor (2). Acrolein is converted to acrylic acid in the second-stage reactor (2), and there is obtained an oxidation reaction gas (13).
[0024] 2) Absorption step The oxidation reaction gas (13) is cooled to 150 C to 200 C using a heat exchanger (9-1), and thereafter is introduced to an absorption column (3), to yield an acrylic acid aqueous solution, with the temperature being controlled by a heat exchanger (9-3).
Specifically, the oxidation reaction gas having been cooled in the heat exchanger (9-1) is introduced into the absorption column (3), and the oxidation reaction gas and absorbing water (17) containing a polymerization inhibitor (15), and supplied from the column top of the absorption column (3), are brought into gas-liquid contact, as a result of which acrylic acid and so forth in the oxidation reaction gas is absorbed to yield an acrylic acid aqueous solution (14). A packed column or plate column having to 20 theoretical plates is ordinarily used as the absorption column (3).
The temperature of the top of the absorption column (3) is ordinarily 30 C to 70 C, while the = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) temperature of the bottom is ordinarily 35 C to 85 C, the foregoing temperatures being controlled using the heat exchanger (9-3).
Specifically, the oxidation reaction gas having been cooled in the heat exchanger (9-1) is introduced into the absorption column (3), and the oxidation reaction gas and absorbing water (17) containing a polymerization inhibitor (15), and supplied from the column top of the absorption column (3), are brought into gas-liquid contact, as a result of which acrylic acid and so forth in the oxidation reaction gas is absorbed to yield an acrylic acid aqueous solution (14). A packed column or plate column having to 20 theoretical plates is ordinarily used as the absorption column (3).
The temperature of the top of the absorption column (3) is ordinarily 30 C to 70 C, while the = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) temperature of the bottom is ordinarily 35 C to 85 C, the foregoing temperatures being controlled using the heat exchanger (9-3).
[0025]
Waste gas from the top of the absorption column (3) contains nitrogen as a main component, water, as well as unreacted oxygen and propylene. The waste gas contains carbon dioxide (CO2), acetic acid, formaldehyde and the like, as by-products of the oxidation reaction, and also small amounts of acrylic acid that failed to be absorbed.
Part of the waste gas may be recycled as-is to the oxidation reaction step.
Ordinarily, however, the waste gas is rendered harmless in a waste gas treatment step (4), after which the gas is recycled (23) to the oxidation reactor (1) or (2), and the rest is discarded as waste gas (22).
Waste gas from the top of the absorption column (3) contains nitrogen as a main component, water, as well as unreacted oxygen and propylene. The waste gas contains carbon dioxide (CO2), acetic acid, formaldehyde and the like, as by-products of the oxidation reaction, and also small amounts of acrylic acid that failed to be absorbed.
Part of the waste gas may be recycled as-is to the oxidation reaction step.
Ordinarily, however, the waste gas is rendered harmless in a waste gas treatment step (4), after which the gas is recycled (23) to the oxidation reactor (1) or (2), and the rest is discarded as waste gas (22).
[0026] The concentration of acrylic acid in the acrylic acid aqueous solution (14) of the column bottoms is about 30 to 70 wt%. The acrylic acid aqueous solution (14) contains, for instance, by-products such as formaldehyde, acetic acid, maleic acid and phthalic acid, as well as, for instance, the polymerization inhibitor that is added to the top of the absorption column (3).
[0027]
Various substances have been proposed for use as the polymerization inhibitor in the production process of acrylic acid. Examples thereof include phenol compounds such as hydroquinone and hydroquinone monomethyl ether, and also 16A00512W00 (0P-16414-PCT) phenothiazine compounds, copper salt compounds, manganese salt compounds, amine compounds, nitroso compounds, and N-oxyl compounds.
Various substances have been proposed for use as the polymerization inhibitor in the production process of acrylic acid. Examples thereof include phenol compounds such as hydroquinone and hydroquinone monomethyl ether, and also 16A00512W00 (0P-16414-PCT) phenothiazine compounds, copper salt compounds, manganese salt compounds, amine compounds, nitroso compounds, and N-oxyl compounds.
[0028]
Examples of the foregoing compounds include phenothiazine and bis-(a-methylbenzyl)phenothiazine as the phenothiazine compound.
The copper salt compound, which is not particularly limited, may be an inorganic salt, or an organic salt, and numerous compounds can be used.
Examples thereof include copper dialkyldithiocarbamate, copper acetate, copper acrylate, copper naphthenate, copper sulfate, copper paratoluenate, copper nitrate and copper carbonate. However, the solution in the absorption column (3) is an aqueous solution, and hence the copper salt compound is preferably a water-soluble compound, for instance, copper acetate, copper acrylate, copper carbonate, copper sulfate or copper paratoluenate.
Examples of suitable manganese salt compounds include manganese acetate, manganese formate, manganese acrylate, manganese naphthenate, manganese sulfate and manganese carbonate.
Examples of nitroso compounds and amine compounds include p-nitrosophenol, N-nitrosophenylhydroxylamine and ammonium salts thereof, and N-nitrosodiphenylamine and ammonium salts thereof.
16A00512W00 (0P-16414-PCT) Examples of N-oxyl compounds include tertiary butyl nitrooxide, 2,2,6,6-tetramethylpiperidine-1-oxyl, 2,2,6,6-tetramethy1-4-hydroxypiperidine-l-oxyl, and 4,4',4"-tris(2,2,6,6-tetramethylpiperidinooxyl)phosphite.
Examples of the foregoing compounds include phenothiazine and bis-(a-methylbenzyl)phenothiazine as the phenothiazine compound.
The copper salt compound, which is not particularly limited, may be an inorganic salt, or an organic salt, and numerous compounds can be used.
Examples thereof include copper dialkyldithiocarbamate, copper acetate, copper acrylate, copper naphthenate, copper sulfate, copper paratoluenate, copper nitrate and copper carbonate. However, the solution in the absorption column (3) is an aqueous solution, and hence the copper salt compound is preferably a water-soluble compound, for instance, copper acetate, copper acrylate, copper carbonate, copper sulfate or copper paratoluenate.
Examples of suitable manganese salt compounds include manganese acetate, manganese formate, manganese acrylate, manganese naphthenate, manganese sulfate and manganese carbonate.
Examples of nitroso compounds and amine compounds include p-nitrosophenol, N-nitrosophenylhydroxylamine and ammonium salts thereof, and N-nitrosodiphenylamine and ammonium salts thereof.
16A00512W00 (0P-16414-PCT) Examples of N-oxyl compounds include tertiary butyl nitrooxide, 2,2,6,6-tetramethylpiperidine-1-oxyl, 2,2,6,6-tetramethy1-4-hydroxypiperidine-l-oxyl, and 4,4',4"-tris(2,2,6,6-tetramethylpiperidinooxyl)phosphite.
[0029] 3) Waste gas treatment step The waste gas discharged from the top of the absorption column (3) ordinarily contains organic substances such as acetic acid, formaldehyde and acrylic acid, together with water, oxygen (02) and carbon dioxide (002). The treatment for rendering the waste gas harmless is ordinarily carried out in accordance with a catalytic combustion scheme.
Examples of the catalyst include honeycomb-like catalysts.
Examples of the catalyst include honeycomb-like catalysts.
[0030] 4) Extraction step The acrylic acid aqueous solution (14) from the bottom of the absorption column (3) undergoes heat exchange in a heat exchanger (9-2), the temperature of the solution is adjusted to about 20 C to 90 C, the solution is supplied to an extraction column (5), and undergoes a liquid-liquid contact treatment with an extraction solvent (16), to be separated into an extract solution (18) of acrylic acid and into raffinate water (19).
[0031] If the extraction temperature in the extraction column (5) is excessively high, the mutual solubility between water and the extraction solvent increases, whereas if the extraction temperature is too low, oil-water separation takes 16A00512W00 (0P-16414-PCT) some time. Accordingly, the extraction temperature is preferably set to about 30 C to 90 C.
[0032] The water-insoluble solvents described below are preferably used as the extraction solvent (16). The water concentration in the extract solution (18) after extraction decreases as a result of extraction using the water-insoluble solvent, and accordingly it becomes possible to prevent, for instance, clogging due to polymerization of acrylic acid in a subsequent acrylic acid purification step (7); at the same time, it becomes possible to reduce the heat load in the purification step (7). By using a water-insoluble solvent, moreover, there can be reduced the concentration of impurities such as acetic acid and maleic acid in the extract solution (18) after extraction. It is likewise preferable to use a water-insoluble solvent, in order to treat discharge solutions from the various equipment items, containing such impurities, in the extraction step.
[0033] For instance, a water-insoluble aromatic compound solvent can be used as the water-insoluble solvent that is utilized for extracting acrylic acid. A
compound the main component of which has a lower boiling point than the boiling point of acrylic acid is preferably used as the solvent, in terms of separation efficiency of the solvent during acrylic acid purification. The above main component is herein a water-insoluble aromatic compound having a boiling point lower 16A00512W00 (0P-16414-PCT) than the boiling point of acrylic acid and being 50 wt% or more, preferably 60 wt% or more, and more preferably 80 wt% or more of the extraction solvent.
Typical types of the water-insoluble aromatic compound solvent include water-insoluble aromatic hydrocarbon solvents.
Water-insoluble aromatic hydrocarbon solvents are advantageous in the extraction operation in that the ratio of the distribution coefficients in a ratio of extraction agent /
water for acrylic acid and acetic acid is high, and acrylic acid selectivity is thus high. A solvent having a solubility in water at 20 C of 1.5 wt% or less is selected as the above water-insoluble aromatic hydrocarbon solvent, but the solubility in water is more preferably 0.5 wt% or less, yet more preferably 0.1 wt% or less, and most preferably 0.06 wt%
or less.
Examples of water-insoluble aromatic hydrocarbon solvents include benzene, toluene, xylene, ethyl benzene and mesitylene, preferred among the foregoing are benzene, toluene and xylene, since these boast high extraction efficiency and low solubility in water. The water-insoluble aromatic hydrocarbon solvent may be used singly or in the form of a mixed solvent of two or more types.
Although the water-insoluble aromatic hydrocarbon solvent can be used in the form of a mixed solvent with other water-insoluble solvents, in this case the water-insoluble aromatic hydrocarbon solvent is preferably 70 wt% or more of the mixed 16A00512W00 (0P-16414-PCT) solvent.
Toluene is most preferred herein as the water-insoluble aromatic hydrocarbon solvent, by virtue of having high extraction efficiency and low solubility in water.
compound the main component of which has a lower boiling point than the boiling point of acrylic acid is preferably used as the solvent, in terms of separation efficiency of the solvent during acrylic acid purification. The above main component is herein a water-insoluble aromatic compound having a boiling point lower 16A00512W00 (0P-16414-PCT) than the boiling point of acrylic acid and being 50 wt% or more, preferably 60 wt% or more, and more preferably 80 wt% or more of the extraction solvent.
Typical types of the water-insoluble aromatic compound solvent include water-insoluble aromatic hydrocarbon solvents.
Water-insoluble aromatic hydrocarbon solvents are advantageous in the extraction operation in that the ratio of the distribution coefficients in a ratio of extraction agent /
water for acrylic acid and acetic acid is high, and acrylic acid selectivity is thus high. A solvent having a solubility in water at 20 C of 1.5 wt% or less is selected as the above water-insoluble aromatic hydrocarbon solvent, but the solubility in water is more preferably 0.5 wt% or less, yet more preferably 0.1 wt% or less, and most preferably 0.06 wt%
or less.
Examples of water-insoluble aromatic hydrocarbon solvents include benzene, toluene, xylene, ethyl benzene and mesitylene, preferred among the foregoing are benzene, toluene and xylene, since these boast high extraction efficiency and low solubility in water. The water-insoluble aromatic hydrocarbon solvent may be used singly or in the form of a mixed solvent of two or more types.
Although the water-insoluble aromatic hydrocarbon solvent can be used in the form of a mixed solvent with other water-insoluble solvents, in this case the water-insoluble aromatic hydrocarbon solvent is preferably 70 wt% or more of the mixed 16A00512W00 (0P-16414-PCT) solvent.
Toluene is most preferred herein as the water-insoluble aromatic hydrocarbon solvent, by virtue of having high extraction efficiency and low solubility in water.
[0034] The weight ratio (S/F ratio) of the extraction solvent (16) with respect to the acrylic acid aqueous solution (14) is ordinarily set to lie in the range of 1 to 5. When the S/F ratio is lower than 1, the concentration of acrylic acid in the extract solution (18) increases, but the extraction rate of acrylic acid decreases while the water concentration in the extract solution (18) increases, which is undesirable. When the S/F ratio excesses 5, the extraction rate increases but the concentration of acrylic acid in the extract solution (18) decreases, and thereby large amounts of separation equipment and energy are required in the subsequent purification step (7), which is undesirable.
Preferably, the S/F ratio is set to lie in the range of 1 to 3.5, in order to reduce the water concentration in the extract solution (18) as much as possible.
Preferably, the S/F ratio is set to lie in the range of 1 to 3.5, in order to reduce the water concentration in the extract solution (18) as much as possible.
[0035] The theoretical plate number of the extraction column (5) is ordinarily 4 or greater, preferably 6 or greater and most preferably 7 or greater. The extraction rate of acrylic acid increases with a rising theoretical plate number.
The upper limit of the theoretical plate number of the extraction column (5) is not particularly restricted, but is ordinarily of 20 or smaller. The extraction rate of acrylic 16A00512W00 (0P-16414-PCT) acid is ordinarily 95% or higher, preferably 98% or higher and most preferably 99% or higher.
The upper limit of the theoretical plate number of the extraction column (5) is not particularly restricted, but is ordinarily of 20 or smaller. The extraction rate of acrylic 16A00512W00 (0P-16414-PCT) acid is ordinarily 95% or higher, preferably 98% or higher and most preferably 99% or higher.
[0036] As the extraction column (5) there is used a plate extraction column, a rotating disc extraction column (RDC
column) or a reciprocating plate extraction column (for instance, a Karr column). A
reciprocating plate extraction column is preferred herein, for instance, in terms of theoretical plate number and treatment throughput.
column) or a reciprocating plate extraction column (for instance, a Karr column). A
reciprocating plate extraction column is preferred herein, for instance, in terms of theoretical plate number and treatment throughput.
[0037] The concentration of acrylic acid in the extract solution (18) obtained in the extraction column (5) is ordinarily 10 to 40 wt%, with small amounts of acetic acid and water being provided in the extract solution (18). The raffinate water (19) contains oxidation reaction by-products such as acetic acid, formaldehyde and maleic acid, and also a polymerization inhibitor and the like. The composition of the extract solution (18) and the raffinate water (19) is determined by, for instance, the liquid-liquid equilibrium composition, the S/F ratio, and the theoretical plate number of the extraction column (5).
[0038] 5) Acrylic Acid purification step The present step includes a distillation step of separating acrylic acid from crude acrylic acid by distillation.
Impurities such as the extraction solvent and acetic acid in the extract solution (18) obtained from the column top of the extraction column (5) are separated by =
16A00512W00 (0P-16414-PCT) purification means, such as the above distillation separation, in the acrylic acid purification step (7). Acrylic acid (20) is thus produced. The extraction solvent (16) separated by distillation is recycled to the extraction column (5). The concentration of acrylic acid in the extraction solvent (16) affects significantly the acrylic acid extraction rate in the extraction column (5). The concentration of acrylic acid in the extraction solvent (16) is preferably 1 wt% or less, more preferably 0.5 wt% or less, since the lower the concentration the higher the extraction rate is. In order to bring the concentration of acrylic acid in the extraction solvent (16) to 0.4 wt% or less it is necessary to increase the number of plates in the distillation column, and to increase reflux, for the purpose of separating the solvent and acrylic acid by distillation. This entails a significant energy demand, and accordingly the foregoing conditions are controlled to appropriate conditions based on a relationship between the extraction rate of acrylic acid and the distillation load.
Impurities such as the extraction solvent and acetic acid in the extract solution (18) obtained from the column top of the extraction column (5) are separated by =
16A00512W00 (0P-16414-PCT) purification means, such as the above distillation separation, in the acrylic acid purification step (7). Acrylic acid (20) is thus produced. The extraction solvent (16) separated by distillation is recycled to the extraction column (5). The concentration of acrylic acid in the extraction solvent (16) affects significantly the acrylic acid extraction rate in the extraction column (5). The concentration of acrylic acid in the extraction solvent (16) is preferably 1 wt% or less, more preferably 0.5 wt% or less, since the lower the concentration the higher the extraction rate is. In order to bring the concentration of acrylic acid in the extraction solvent (16) to 0.4 wt% or less it is necessary to increase the number of plates in the distillation column, and to increase reflux, for the purpose of separating the solvent and acrylic acid by distillation. This entails a significant energy demand, and accordingly the foregoing conditions are controlled to appropriate conditions based on a relationship between the extraction rate of acrylic acid and the distillation load.
[0039] 6) Raffinate water treatment step The raffinate water (19) from the extraction column (5) is discharged as a waste solution that must be treated.
Combustion treatments and activated sludge treatments are herein ordinary instances of waste solution treatment methods, but a combustion treatment of large amounts of raffinate water requires significant energy input, while an activated sludge = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) treatment is difficult, since the raffinate water (19) contains formaldehyde. Accordingly, the raffinate water (19) is preferably recycled to the absorption column (3) and is re-used as absorbing water.
By-products (for instance, maleic acid and phthalic acid) from the oxidation reaction step that remain without having been extracted by the extraction solvent in the extraction column (5) become concentrated in the raffinate water (19).
Accordingly, it is necessary to separate the by-products from the raffinate water (19) and to discharge the separated by-products out of the system in the form of a waste solution, in order to prevent accumulation of such by-products in the system, and for the purpose of recycling to the absorption column (3).
To treat the raffinate water (19), part thereof is recycled (24) as-is, in the form of absorbing water, to the absorption column (3), and just the rest alone is subjected to a heating concentrating treatment, to separate thereby the waste solution.
As a result, it becomes possible to reduce the size of the equipment for the heating concentrating treatment, while optimizing energy.
Combustion treatments and activated sludge treatments are herein ordinary instances of waste solution treatment methods, but a combustion treatment of large amounts of raffinate water requires significant energy input, while an activated sludge = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) treatment is difficult, since the raffinate water (19) contains formaldehyde. Accordingly, the raffinate water (19) is preferably recycled to the absorption column (3) and is re-used as absorbing water.
By-products (for instance, maleic acid and phthalic acid) from the oxidation reaction step that remain without having been extracted by the extraction solvent in the extraction column (5) become concentrated in the raffinate water (19).
Accordingly, it is necessary to separate the by-products from the raffinate water (19) and to discharge the separated by-products out of the system in the form of a waste solution, in order to prevent accumulation of such by-products in the system, and for the purpose of recycling to the absorption column (3).
To treat the raffinate water (19), part thereof is recycled (24) as-is, in the form of absorbing water, to the absorption column (3), and just the rest alone is subjected to a heating concentrating treatment, to separate thereby the waste solution.
As a result, it becomes possible to reduce the size of the equipment for the heating concentrating treatment, while optimizing energy.
[0040]
The equipment used for heat-concentrating the raffinate water (19) is generally an evaporator (6) such as the one illustrated in Fig. 1.
The evaporator (6) has an evaporation tank, a reboiler for heating distillation and a condenser for condensing evaporated vapor. A mist separator =
. CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) for preventing entrainment may be provided in the tank, or distillation parts such as trays may be provided at the top section of the tank.
The heating concentrating equipment is not limited to an evaporator, and, for instance, there can be used a multiple effect evaporator, a stirring tank equipped with a heating jacket or with a heat exchanger, a membrane separation apparatus, a stripping column, a thin-film evaporator or a centrifugal thin-film evaporator (for instance, Kontro).
The equipment used for heat-concentrating the raffinate water (19) is generally an evaporator (6) such as the one illustrated in Fig. 1.
The evaporator (6) has an evaporation tank, a reboiler for heating distillation and a condenser for condensing evaporated vapor. A mist separator =
. CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) for preventing entrainment may be provided in the tank, or distillation parts such as trays may be provided at the top section of the tank.
The heating concentrating equipment is not limited to an evaporator, and, for instance, there can be used a multiple effect evaporator, a stirring tank equipped with a heating jacket or with a heat exchanger, a membrane separation apparatus, a stripping column, a thin-film evaporator or a centrifugal thin-film evaporator (for instance, Kontro).
[0041]
7) Step of collecting discharge solutions from various equipment items The matter described above applies, for instance, to preferred conditions of holding, distillation and oil-water separation of the collected solution, and to feeding of the collected solution, set out in the present section.
In anticipation of non-steady operation, for instance, due to problems or during periodic inspection, the production method of the present invention involves holding the discharge solutions from the various equipment items once in a storage tank (8) such as a buffer tank or an off-spec tank during non-steady operation.
The discharge solutions having various compositions are mixed through such holding, whereby components are homogenized, and the concentration of components that impair oil-water separation is diluted.
Through settling of solid matter and through oil-water =
16A00512W00 (0P-16414-PCT) separation it becomes possible to achieve moreover the effect of facilitating removal of impairing components. These discharge solutions are preferably supplied, in the form of a collected solution (25), to the same site as a site to which the acrylic acid aqueous solution (14) is supplied in the extraction step.
Conceivable methods to that end include mixing the collected solution into a pipe through which the acrylic acid aqueous solution (14) flows, or a method of supplying collected solution through separate piping, to the site to which the acrylic acid aqueous solution is supplied.
In a case where the extraction column (5) is used as the extraction step and the acrylic acid aqueous solution is supplied to the top of the column, a conceivable example of the latter method involves supplying the collected solution to the top of the extraction column (5) through separate piping.
The extraction efficiency of acrylic acid may drop in a case where this method is not implemented and the collected solution is instead supplied, for instance, to the same site as that of the extraction solvent (16).
The collected solution may be fed as-is to the extraction step, but is preferably distilled using distillation equipment, with the resulting distillate after distillation being then fed to the extraction step, in order to prevent the occurrence of an oil-water suspension state in the extraction step. An evaporator can be used as the distillation equipment. The 16A00512W00 (0P-16414-PCT) evaporator has an evaporation tank, a reboiler for heating distillation and a condenser for condensing evaporated vapor.
A mist separator for preventing entrainment may be provided in the tank, or a distillation part such as a tray may be provided at the top section of the tank. The distillation equipment is however not limited to an evaporator, and, for instance, there can be used a multiple effect evaporator, a stirring tank equipped with a heating jacket or with a heat exchanger, a stripping column or a thin-film evaporator.
Steam or a heat medium is used as heat source for heating in the evaporator and so forth. A high temperature process fluid or the like can also be used alternatively.
In some instances an oil-water separation operation of the collected solution may be performed, with feeding of the oil phase alone, with a view to suppressing the occurrence of an oil-water suspension state in the extraction step.
Preferably, the extraction temperature in the extraction step is set to 30 C to 90 C. More preferably, the temperature is set to 40 C to 80 C, and yet more preferably to 40 C to 60 C.
As a method for adjusting the temperature, it is most efficient to adjust the temperature of the collected solution or the acrylic acid aqueous solution that is supplied to the extraction step, or the temperature of a mixed solution of the foregoing, so as to lie in an appropriate range. An = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) appropriate range denotes herein a range of 20 C to 90 C, more preferably 30 C to 90 C and yet more preferably 30 C to 70 C.
7) Step of collecting discharge solutions from various equipment items The matter described above applies, for instance, to preferred conditions of holding, distillation and oil-water separation of the collected solution, and to feeding of the collected solution, set out in the present section.
In anticipation of non-steady operation, for instance, due to problems or during periodic inspection, the production method of the present invention involves holding the discharge solutions from the various equipment items once in a storage tank (8) such as a buffer tank or an off-spec tank during non-steady operation.
The discharge solutions having various compositions are mixed through such holding, whereby components are homogenized, and the concentration of components that impair oil-water separation is diluted.
Through settling of solid matter and through oil-water =
16A00512W00 (0P-16414-PCT) separation it becomes possible to achieve moreover the effect of facilitating removal of impairing components. These discharge solutions are preferably supplied, in the form of a collected solution (25), to the same site as a site to which the acrylic acid aqueous solution (14) is supplied in the extraction step.
Conceivable methods to that end include mixing the collected solution into a pipe through which the acrylic acid aqueous solution (14) flows, or a method of supplying collected solution through separate piping, to the site to which the acrylic acid aqueous solution is supplied.
In a case where the extraction column (5) is used as the extraction step and the acrylic acid aqueous solution is supplied to the top of the column, a conceivable example of the latter method involves supplying the collected solution to the top of the extraction column (5) through separate piping.
The extraction efficiency of acrylic acid may drop in a case where this method is not implemented and the collected solution is instead supplied, for instance, to the same site as that of the extraction solvent (16).
The collected solution may be fed as-is to the extraction step, but is preferably distilled using distillation equipment, with the resulting distillate after distillation being then fed to the extraction step, in order to prevent the occurrence of an oil-water suspension state in the extraction step. An evaporator can be used as the distillation equipment. The 16A00512W00 (0P-16414-PCT) evaporator has an evaporation tank, a reboiler for heating distillation and a condenser for condensing evaporated vapor.
A mist separator for preventing entrainment may be provided in the tank, or a distillation part such as a tray may be provided at the top section of the tank. The distillation equipment is however not limited to an evaporator, and, for instance, there can be used a multiple effect evaporator, a stirring tank equipped with a heating jacket or with a heat exchanger, a stripping column or a thin-film evaporator.
Steam or a heat medium is used as heat source for heating in the evaporator and so forth. A high temperature process fluid or the like can also be used alternatively.
In some instances an oil-water separation operation of the collected solution may be performed, with feeding of the oil phase alone, with a view to suppressing the occurrence of an oil-water suspension state in the extraction step.
Preferably, the extraction temperature in the extraction step is set to 30 C to 90 C. More preferably, the temperature is set to 40 C to 80 C, and yet more preferably to 40 C to 60 C.
As a method for adjusting the temperature, it is most efficient to adjust the temperature of the collected solution or the acrylic acid aqueous solution that is supplied to the extraction step, or the temperature of a mixed solution of the foregoing, so as to lie in an appropriate range. An = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) appropriate range denotes herein a range of 20 C to 90 C, more preferably 30 C to 90 C and yet more preferably 30 C to 70 C.
[0042]
Preferably, the operation of the extraction step, including supply of the collected solution, is managed using Michael adducts as an indicator substance. The concentration of Michael adducts in a mixed composition of the acrylic acid aqueous solution and the collected solution is preferably set to 0.05 to 0.7 wt%, more preferably 0.05 to 0.6 wt% and yet more preferably 0.1 to 0.5 wt%. If the concentration of Michael adducts is too low, the conditions in the oxidation reaction step and the absorption step become constrained, whereas if the concentration is too high, oil-water separation in the extraction step may be impaired. Herein it is effective to perform the above-described distillation or oil-water separation operation of the collected solution, as a method for maintaining the above concentration ratio.
Conceivable alternative methods include, for instance, adjusting the flow rate of the collected solution, and adjusting the concentration of Michael adducts by separately supplying high-purity acrylic acid.
Preferably, the operation of the extraction step, including supply of the collected solution, is managed using Michael adducts as an indicator substance. The concentration of Michael adducts in a mixed composition of the acrylic acid aqueous solution and the collected solution is preferably set to 0.05 to 0.7 wt%, more preferably 0.05 to 0.6 wt% and yet more preferably 0.1 to 0.5 wt%. If the concentration of Michael adducts is too low, the conditions in the oxidation reaction step and the absorption step become constrained, whereas if the concentration is too high, oil-water separation in the extraction step may be impaired. Herein it is effective to perform the above-described distillation or oil-water separation operation of the collected solution, as a method for maintaining the above concentration ratio.
Conceivable alternative methods include, for instance, adjusting the flow rate of the collected solution, and adjusting the concentration of Michael adducts by separately supplying high-purity acrylic acid.
[0043] 8) Waste solution treatment step The waste solution (21) discharged from the evaporator (6) contains, for instance, polymerization inhibitor; high-boiling point components and formaldehyde that are generated in the oxidation reaction step and that remain within the 16A00512W00 (0P-16414-PCT) raffinate water (19) in the extraction column (5). The waste solution (21) is treated, for instance, by being incinerated.
Examples
Examples
[0044] The present invention will be explained next more specifically by way of examples, but the invention is however not meant, within the gist thereof, to be limited to the examples.
[0045] [Analysis of a sampling solution]
The substances contained in a sampling solution were identified, and the substances were quantified, through analysis by gas chromatography. Gas chromatography was conducted using GC-14A, by Shimadzu Corporation. A capillary column (HP-FFAP) by Agilent Technologies, Inc. was used as a separation column, and FID and TCD were used as detectors.
The substances contained in a sampling solution were identified, and the substances were quantified, through analysis by gas chromatography. Gas chromatography was conducted using GC-14A, by Shimadzu Corporation. A capillary column (HP-FFAP) by Agilent Technologies, Inc. was used as a separation column, and FID and TCD were used as detectors.
[0046] (Reference example 1) Acrylic acid was produced in the steps below using the acrylic acid production facility described in Fig. 1.
Specifically, acrylic acid was produced as a result of: an oxidation reaction step of obtaining an oxidation reaction gas derived from a vapor-phase catalytic oxidation reaction of propylene; an absorption step of bringing the oxidation reaction gas and absorbing water, containing a polymerization inhibitor, into gas-liquid contact, to yield thereby an acrylic acid aqueous solution; an extraction step of obtaining 16A00512W00 (0P-16414-PCT) an extract solution from the acrylic acid aqueous solution, using toluene as an extraction solvent; and an acrylic acid purification step of obtaining acrylic acid through purification of the extract solution by distillation.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of an acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step. Next, 67 mL of toluene used in the extraction step were charged into the colorimetric tubes. The colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 21 C room-temperature environment, at 30 rpm, for 1 minute. The tube was thereafter allowed to stand, whereupon the oil-water separation state was checked visually. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
Specifically, acrylic acid was produced as a result of: an oxidation reaction step of obtaining an oxidation reaction gas derived from a vapor-phase catalytic oxidation reaction of propylene; an absorption step of bringing the oxidation reaction gas and absorbing water, containing a polymerization inhibitor, into gas-liquid contact, to yield thereby an acrylic acid aqueous solution; an extraction step of obtaining 16A00512W00 (0P-16414-PCT) an extract solution from the acrylic acid aqueous solution, using toluene as an extraction solvent; and an acrylic acid purification step of obtaining acrylic acid through purification of the extract solution by distillation.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of an acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step. Next, 67 mL of toluene used in the extraction step were charged into the colorimetric tubes. The colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 21 C room-temperature environment, at 30 rpm, for 1 minute. The tube was thereafter allowed to stand, whereupon the oil-water separation state was checked visually. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
[0047] (Example 1) In Example 1, the extraction step in Reference example I
was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) obtained in the absorption step and a collected solution obtained by holding the discharge solution having been discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above absorption step in a simple manner.
Colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing, at a ratio by weight of 10:1, the acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 and a collected solution (acrylic acid: 63.3 wt%, acrylic acid dimer: 2.1 wt%, acrylic acid trimer: 0.022 wt%, water: 11.4 wt%, acetic acid: 0.030 wt%) after holding of the discharge solution having been discharged from the acrylic acid production process, for 4 days, in a storage tank.
Next, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) obtained in the absorption step and a collected solution obtained by holding the discharge solution having been discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above absorption step in a simple manner.
Colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing, at a ratio by weight of 10:1, the acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 and a collected solution (acrylic acid: 63.3 wt%, acrylic acid dimer: 2.1 wt%, acrylic acid trimer: 0.022 wt%, water: 11.4 wt%, acetic acid: 0.030 wt%) after holding of the discharge solution having been discharged from the acrylic acid production process, for 4 days, in a storage tank.
Next, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
[0048] (Comparative example 1) 16A00512W00 (0P-16414-PCT) In Comparative example 1, the extraction step in Reference example 1 was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution obtained in the absorption step and the discharge solution (without holding) discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing, at a ratio by weight of 10:1, the acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 and the discharge solution (without holding) (acrylic acid: 73.3 wt%, acrylic acid dimer: 5.9 wt%, acrylic acid trimer: 0.052 wt%, water: 20.4 wt%, acetic acid: 0.16 wt%) discharged from the acrylic acid production process. Next, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. The oil-water suspension phase persisted even at the time of lapse of 90 seconds, and the oil phase and the aqueous phase failed to separate.
*
= = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT)
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing, at a ratio by weight of 10:1, the acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 and the discharge solution (without holding) (acrylic acid: 73.3 wt%, acrylic acid dimer: 5.9 wt%, acrylic acid trimer: 0.052 wt%, water: 20.4 wt%, acetic acid: 0.16 wt%) discharged from the acrylic acid production process. Next, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. The oil-water suspension phase persisted even at the time of lapse of 90 seconds, and the oil phase and the aqueous phase failed to separate.
*
= = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT)
[0049] (Example 2) In Example 2, the extraction step in Reference example 1 was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution obtained in the absorption step and a distillate obtained through simple distillation of a collected solution resulting from holding of the discharge solution having been discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 was sampled.
Then a 200 cc flask was charged with 100 g of a collected solution resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process, and a distillate obtained through simple distillation at 80 C and 10 kPa was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the distillate at a ratio by weight of 10:1.
Further, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric = = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) tubes. The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 was sampled.
Then a 200 cc flask was charged with 100 g of a collected solution resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process, and a distillate obtained through simple distillation at 80 C and 10 kPa was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the distillate at a ratio by weight of 10:1.
Further, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric = = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) tubes. The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
[0050] (Example 3) In Example 3, the extraction step in Reference example 1 was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution obtained in the absorption step and an oil phase obtained through oil-water separation of a collected solution obtained by holding the discharge solution having been discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 was sampled. Then a collected solution resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process was collected in calorimetric tubes, toluene was added in a ratio = = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) by weight of 1:1, the colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 21 C
room-temperature environment, at 30 rpm, for 1 minute.
The tube was thereafter allowed to stand, to elicit oil-water separation, and the oil phase was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the oil phase at a ratio by weight of 10:1. Further, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric tubes.
The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.0 wt%, acrylic acid dimer: 0.31 wt%, acrylic acid trimer: 0.0013 wt%, water: 38.3 wt%, acetic acid: 2.6 wt%, maleic acid: 0.44 wt%) obtained in the absorption step of Reference example 1 was sampled. Then a collected solution resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process was collected in calorimetric tubes, toluene was added in a ratio = = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) by weight of 1:1, the colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 21 C
room-temperature environment, at 30 rpm, for 1 minute.
The tube was thereafter allowed to stand, to elicit oil-water separation, and the oil phase was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the oil phase at a ratio by weight of 10:1. Further, 67 mL of toluene used in the extraction step of Reference example 1 were charged into the colorimetric tubes.
The same mixing operation as that of Reference example 1 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
[0051] (Reference example 2) Acrylic acid was produced in the steps below using the acrylic acid production facility described in Fig. 1.
Specifically, acrylic acid was produced as a result of: an oxidation reaction step of obtaining an oxidation reaction gas derived from a vapor-phase catalytic oxidation reaction of propylene; an absorption step of bringing the oxidation reaction gas and absorbing water, containing a polymerization inhibitor, into gas-liquid contact, to yield thereby an acrylic acid aqueous solution; an extraction step of obtaining = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) an extract solution from the acrylic acid aqueous solution, using toluene as an extraction solvent; and an acrylic acid purification step of obtaining acrylic acid through purification of the extract solution by distillation.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of an acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step. Next, 67 mL of toluene used in the extraction step were charged into the colorimetric tubes. The colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 2100 room-temperature environment, at 50 rpm, for 1 minute. The tube was thereafter allowed to stand, whereupon the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 40 seconds.
Specifically, acrylic acid was produced as a result of: an oxidation reaction step of obtaining an oxidation reaction gas derived from a vapor-phase catalytic oxidation reaction of propylene; an absorption step of bringing the oxidation reaction gas and absorbing water, containing a polymerization inhibitor, into gas-liquid contact, to yield thereby an acrylic acid aqueous solution; an extraction step of obtaining = CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT) an extract solution from the acrylic acid aqueous solution, using toluene as an extraction solvent; and an acrylic acid purification step of obtaining acrylic acid through purification of the extract solution by distillation.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of an acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step. Next, 67 mL of toluene used in the extraction step were charged into the colorimetric tubes. The colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 2100 room-temperature environment, at 50 rpm, for 1 minute. The tube was thereafter allowed to stand, whereupon the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 40 seconds.
[0052] (Comparative example 2) In Comparative example 2, the extraction step in Reference example 2 was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution obtained in the absorption step and the 16A00512W00 (0P-16414-PCT) discharge solution (without holding) discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing, at a ratio by weight of 10:1, the acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 2 and the discharge solution (without holding) (acrylic acid: 73.3 wt%, acrylic acid dimer: 5.9 wt%, acrylic acid trimer: 0.052 wt%, water: 20.4 wt%, acetic acid: 0.16 wt%) discharged from the acrylic acid production process. Next, 67 mL of toluene used in the extraction step of Reference example 2 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 2 was carried out, and the oil-water separation state was checked. The oil-water suspension phase persisted even at the time of lapse of 90 seconds, and the oil phase and the aqueous phase failed to separate.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing, at a ratio by weight of 10:1, the acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 2 and the discharge solution (without holding) (acrylic acid: 73.3 wt%, acrylic acid dimer: 5.9 wt%, acrylic acid trimer: 0.052 wt%, water: 20.4 wt%, acetic acid: 0.16 wt%) discharged from the acrylic acid production process. Next, 67 mL of toluene used in the extraction step of Reference example 2 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 2 was carried out, and the oil-water separation state was checked. The oil-water suspension phase persisted even at the time of lapse of 90 seconds, and the oil phase and the aqueous phase failed to separate.
[0053] (Example 4) In Example 4, the extraction step in Reference example 2 was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution 16A00512W00 (0P-16414-PCT) obtained in the absorption step and a distillate from simple distillation of a collected solution resulting from holding of the discharge solution having been discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 2 was sampled. Then a 200 cc flask was charged with 100 g of a collected solution used in Comparative example 2 and resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process, and a distillate obtained through simple distillation at 80 C and 10 kPa was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the distillate at a ratio by weight of 10:1.
Further, 67 mL
of toluene used in the extraction step of Reference example 2 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 2 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth 16A00512W00 (0P-16414-PCT) and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 40 seconds.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 2 was sampled. Then a 200 cc flask was charged with 100 g of a collected solution used in Comparative example 2 and resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process, and a distillate obtained through simple distillation at 80 C and 10 kPa was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the distillate at a ratio by weight of 10:1.
Further, 67 mL
of toluene used in the extraction step of Reference example 2 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 2 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth 16A00512W00 (0P-16414-PCT) and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 40 seconds.
[0054] (Example 5) In Example 5, the extraction step in Reference example 2 was modified to an extraction step that involved obtaining an extract solution, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution obtained in the absorption step and an oil phase from oil-water separation of a collected solution resulting from holding the discharge solution discharged from the acrylic acid production process.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 2 was sampled. Then a collected solution resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process was collected in colorimetric tubes, toluene was added in a ratio by weight of 1:1, the colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 21 C
room-temperature environment, at 30 rpm, for 1 minute. The tube was thereafter allowed to stand, to elicit oil-water 16A00512W00 (0P-16414-PCT) separation, and the oil phase was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the oil phase at a ratio by weight of 10:1. Further, 67 mL of toluene used in the extraction step of Reference example 2 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 2 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 40 seconds.
The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 2 was sampled. Then a collected solution resulting from holding, for 2 days in a storage tank, the discharge solution having been discharged from the acrylic acid production process was collected in colorimetric tubes, toluene was added in a ratio by weight of 1:1, the colorimetric tubes were set in a rotator (Taitec RT50), and rotary mixing was carried out in a 21 C
room-temperature environment, at 30 rpm, for 1 minute. The tube was thereafter allowed to stand, to elicit oil-water 16A00512W00 (0P-16414-PCT) separation, and the oil phase was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the oil phase at a ratio by weight of 10:1. Further, 67 mL of toluene used in the extraction step of Reference example 2 were charged into the colorimetric tubes. The same mixing operation as that of Reference example 2 was carried out, and the oil-water separation state was checked. It was seen that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 40 seconds.
[0055] (Reference example 3) Acrylic acid was produced in the steps below using the acrylic acid production facility described in Fig. 1.
Specifically, acrylic acid was produced as a result of: an oxidation reaction step of obtaining an oxidation reaction gas derived from a vapor-phase catalytic oxidation reaction of propylene; an absorption step of bringing the oxidation reaction gas and absorbing water, containing a polymerization inhibitor, into gas-liquid contact, to yield thereby an acrylic acid aqueous solution; an extraction step of obtaining an extract solution from the acrylic acid aqueous solution, using toluene as an extraction solvent; and an acrylic acid purification step of obtaining acrylic acid through purification of the extract solution by distillation.
16A00512W00 (0P-16414-PCT) The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of an acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step. Next, 67 mL of toluene used in the extraction step were charged into the colorimetric tubes. The colorimetric tubes were immersed for 10 minutes in a hot water bath at 42 C, and thereafter were set in a rotator (Taitec RT50), where rotary mixing was carried out at 50 rpm for 1 minute. The tube was thereafter allowed to stand, whereupon the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
Specifically, acrylic acid was produced as a result of: an oxidation reaction step of obtaining an oxidation reaction gas derived from a vapor-phase catalytic oxidation reaction of propylene; an absorption step of bringing the oxidation reaction gas and absorbing water, containing a polymerization inhibitor, into gas-liquid contact, to yield thereby an acrylic acid aqueous solution; an extraction step of obtaining an extract solution from the acrylic acid aqueous solution, using toluene as an extraction solvent; and an acrylic acid purification step of obtaining acrylic acid through purification of the extract solution by distillation.
16A00512W00 (0P-16414-PCT) The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
Colorimetric tubes were charged with 33 mL of an acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step. Next, 67 mL of toluene used in the extraction step were charged into the colorimetric tubes. The colorimetric tubes were immersed for 10 minutes in a hot water bath at 42 C, and thereafter were set in a rotator (Taitec RT50), where rotary mixing was carried out at 50 rpm for 1 minute. The tube was thereafter allowed to stand, whereupon the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
[0056) (Example 6) In Example 6, the extraction step in Reference example 2 was modified to an extraction step that involved obtaining an extract solution at a temperature of 42 C, using toluene, from a mixed solution resulting from mixing of the acrylic acid aqueous solution obtained in the absorption step and a collected solution obtained by holding the discharge solution having been discharged from the acrylic acid production process.
16A00512W00 (0P-16414-PCT) The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 3 was sampled. The temperature of the discharge solution (acrylic acid: 73.3 wt%, acrylic acid dimer: 5.9 wt%, acrylic acid trimer: 0.052 wt%, water: 20.4 wt%, acetic acid: 0.16 wt%) discharged from the acrylic acid production process was measured, whereupon a value of 20 C was obtained. A collected solution resulting from holding the discharge solution for 2 days in a storage tank was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the collected solution at a ratio by weight of 100:6.
Further, 67 mL of toluene used in the extraction step of Reference example 3 were charged into the colorimetric tubes. In the same way as in Reference example 3, the colorimetric tubes were immersed for 10 minutes in a hot water bath at 42 C, after which a mixing operation was carried out, and the oil-water separation state was checked. It was found that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
=
=
=
16A00512W00 (0P-16414-PCT)
16A00512W00 (0P-16414-PCT) The extraction test below was carried out in order to monitor the above extraction step in a simple manner.
The acrylic acid aqueous solution (acrylic acid: 57.5 wt%, acrylic acid dimer: 0.25 wt%, acrylic acid trimer: 0.0014 wt%, water: 37.7 wt%, acetic acid: 2.6 wt%, maleic acid: 0.46 wt%) obtained in the absorption step of Reference example 3 was sampled. The temperature of the discharge solution (acrylic acid: 73.3 wt%, acrylic acid dimer: 5.9 wt%, acrylic acid trimer: 0.052 wt%, water: 20.4 wt%, acetic acid: 0.16 wt%) discharged from the acrylic acid production process was measured, whereupon a value of 20 C was obtained. A collected solution resulting from holding the discharge solution for 2 days in a storage tank was sampled. Next, colorimetric tubes were charged with 33 mL of a mixed solution resulting from mixing the acrylic acid aqueous solution and the collected solution at a ratio by weight of 100:6.
Further, 67 mL of toluene used in the extraction step of Reference example 3 were charged into the colorimetric tubes. In the same way as in Reference example 3, the colorimetric tubes were immersed for 10 minutes in a hot water bath at 42 C, after which a mixing operation was carried out, and the oil-water separation state was checked. It was found that the oil phase containing acrylic acid, toluene and so forth and the aqueous phase containing water, acetic acid, maleic acid and so forth separated quickly, within 50 seconds.
=
=
=
16A00512W00 (0P-16414-PCT)
[0057]
[Table 1]
-, Feeding of solution discharged from acrylic acid Concentration (wt%) Extraction production process to extraction step Rotational speed Oil-water separation of Michael adducts temperature of rotator (rpm) time .
Discharge Collected in mixed solution CC) No feeding solution fed , solution fed _ Reference 030 21 Within 50 seconds example 1 0.31*1 _ Example 1 0 0.47 30 21 Within 50 seconds Comparative No separation 0 0.82 example 1 within 90 seconds _ Example 2 0 0.33 30 21 Within 50 seconds Example 3 0 0.43 30 21 Within 50 seconds Reference 0 0.25*1 50 21 Within 40 seconds example 2 P
.
,..
Comparative No separation .
.
0 0.77 50 21 ,0 example 2 within 90 seconds ,..
u-i -,..
o Example 4 0 0.28 50 21 Within 40 seconds 10 , Example 5 0 0.38 50 21 Within 40 seconds 0 , .
.
, Reference, 0 0.25*/
50 42 Within 50 seconds 03 example 3 i--, cs, Example 6 0 0.77 50 42 Within 50 seconds >
CD
*1 The "concentration of Michael adducts" in reference examples denotes concentration in the acrylic acid aqueous solution. o c_n 1-µ
N) D
¨
1--s 0-) az, 1--, ,I.
H
*
* CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT)
[Table 1]
-, Feeding of solution discharged from acrylic acid Concentration (wt%) Extraction production process to extraction step Rotational speed Oil-water separation of Michael adducts temperature of rotator (rpm) time .
Discharge Collected in mixed solution CC) No feeding solution fed , solution fed _ Reference 030 21 Within 50 seconds example 1 0.31*1 _ Example 1 0 0.47 30 21 Within 50 seconds Comparative No separation 0 0.82 example 1 within 90 seconds _ Example 2 0 0.33 30 21 Within 50 seconds Example 3 0 0.43 30 21 Within 50 seconds Reference 0 0.25*1 50 21 Within 40 seconds example 2 P
.
,..
Comparative No separation .
.
0 0.77 50 21 ,0 example 2 within 90 seconds ,..
u-i -,..
o Example 4 0 0.28 50 21 Within 40 seconds 10 , Example 5 0 0.38 50 21 Within 40 seconds 0 , .
.
, Reference, 0 0.25*/
50 42 Within 50 seconds 03 example 3 i--, cs, Example 6 0 0.77 50 42 Within 50 seconds >
CD
*1 The "concentration of Michael adducts" in reference examples denotes concentration in the acrylic acid aqueous solution. o c_n 1-µ
N) D
¨
1--s 0-) az, 1--, ,I.
H
*
* CA 03009033 2018-06-18 16A00512W00 (0P-16414-PCT)
[0058]
The results of Comparative example 1 revealed impairment of oil-water separability in the case of addition of the discharge solution having been discharged from the acrylic acid production process. The concentration of Michael adducts at this time, encompassing acrylic acid dimers and acrylic acid trimers, exceeded 0.7 wt%.
When holding, distillation and the oil-water separation operation were carried out, in Examples 1, 2 and 3, there was by contrast no impairment of oil-water separability, and the Michael adduct concentration was 0.7 wt% or less. A comparison between the results of Comparative example 2 and the results of Examples 4 and 5 reveals that the above tendency holds even when mixing intensity is increased through an increase in rotational speed.
The results of Reference example 3 and Example 6, meanwhile, revealed that oil-water separability was not impaired in a case where the extraction temperature was set to 42 C, even when the concentration of Michael adducts exceeded 0.7 wt%, upon addition of discharge solution having been discharged from the acrylic acid production process.
Reference Signs List
The results of Comparative example 1 revealed impairment of oil-water separability in the case of addition of the discharge solution having been discharged from the acrylic acid production process. The concentration of Michael adducts at this time, encompassing acrylic acid dimers and acrylic acid trimers, exceeded 0.7 wt%.
When holding, distillation and the oil-water separation operation were carried out, in Examples 1, 2 and 3, there was by contrast no impairment of oil-water separability, and the Michael adduct concentration was 0.7 wt% or less. A comparison between the results of Comparative example 2 and the results of Examples 4 and 5 reveals that the above tendency holds even when mixing intensity is increased through an increase in rotational speed.
The results of Reference example 3 and Example 6, meanwhile, revealed that oil-water separability was not impaired in a case where the extraction temperature was set to 42 C, even when the concentration of Michael adducts exceeded 0.7 wt%, upon addition of discharge solution having been discharged from the acrylic acid production process.
Reference Signs List
[0059]
1, 2 Oxidation reactor 3 Absorption column 4 Waste gas treatment step 16A00512W00 (0P-16414-PCT) Extraction column 6 Evaporator 7 Acrylic acid purification step 8 Storage tank 9-1, 9-2, 9-3 Heat exchanger Propylene 11 Air 12 Diluent (steam or nitrogen) 13 Oxidation reaction gas 14 Acrylic acid aqueous solution Polymerization inhibitor 16 Extraction solvent 17 Absorbing water 18 Extract solution 19 Raffinate water Acrylic acid 21 Waste solution 22 Waste gas 23 Recycled gas 24 Raffinate water recycling Discharge solution / collected solution from acrylic acid production process
1, 2 Oxidation reactor 3 Absorption column 4 Waste gas treatment step 16A00512W00 (0P-16414-PCT) Extraction column 6 Evaporator 7 Acrylic acid purification step 8 Storage tank 9-1, 9-2, 9-3 Heat exchanger Propylene 11 Air 12 Diluent (steam or nitrogen) 13 Oxidation reaction gas 14 Acrylic acid aqueous solution Polymerization inhibitor 16 Extraction solvent 17 Absorbing water 18 Extract solution 19 Raffinate water Acrylic acid 21 Waste solution 22 Waste gas 23 Recycled gas 24 Raffinate water recycling Discharge solution / collected solution from acrylic acid production process
Claims (9)
1. A method for producing (meth)acrylic acid, the method comprising:
an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is held for 1 day to 60 days, and the held collected solution is fed to the extraction step; and the concentration of Michael adducts in a mixed composition of the collected solution and the (meth)acrylic acid aqueous solution is 0.05 to 0.7 wt%.
an oxidation reaction step of obtaining a reaction gas containing (meth)acrylic acid, through vapor-phase catalytic oxidation; an absorption step of bringing the reaction gas into gas-liquid contact with water, to thereby yield a (meth)acrylic acid aqueous solution; an extraction step of bringing the (meth)acrylic acid aqueous solution and an extraction solvent into contact with each other, to thereby extract crude (meth)acrylic acid; and a distillation step of distilling (meth)acrylic acid from the crude (meth)acrylic acid, wherein a solution containing a discharge solution that is discharged from at least one of the steps is used as a collected solution, the collected solution is held for 1 day to 60 days, and the held collected solution is fed to the extraction step; and the concentration of Michael adducts in a mixed composition of the collected solution and the (meth)acrylic acid aqueous solution is 0.05 to 0.7 wt%.
2. The method for producing (meth)acrylic acid according to claim 1, Date Recue/Date Received 2022-1 0-1 3 wherein the held collected solution is subjected to oil-water separation, and an oil phase resulting from the oil-water separation is fed to the extraction step.
3. The method for producing (meth)acrylic acid according to claim 1, wherein the held collected solution is distilled, and the resulting distillate is fed to the extraction step.
4. The method for producing (meth)acrylic acid according to any one of claims 1 to 3, wherein in at least one of the steps, supply of a reaction product in the step and discharge of the discharge solution in the step are carried out simultaneously.
5. The method for producing (meth)acrylic acid according to any one of claims 1 to 4, wherein the collected solution contains water.
6. The method for producing (meth)acrylic acid according to any one of claims 1 to 5, wherein the collected solution that is fed to the extraction step is supplied to the same site as a site to which the (meth)acrylic acid aqueous solution is supplied in the extraction step.
Date Recue/Date Received 2022-1 0-1 3
Date Recue/Date Received 2022-1 0-1 3
7. The method for producing (meth)acrylic acid according to any one of claims 1 to 6, wherein the extraction temperature in the extraction step is 30 C to 90 C.
8. The method for producing (meth)acrylic acid according to any one of claims 1 to 7, wherein the extraction solvent is a solvent having 50 wt% or more of a water-insoluble aromatic compound having a lower boiling point than the boiling point of (meth)acrylic acid.
9. The method for producing (meth)acrylic acid according to claim 8, wherein the water-insoluble aromatic compound is at least one compound selected from the group consisting of benzene, toluene and xylene.
Date Regue/Date Received 2022-1 0-1 3
Date Regue/Date Received 2022-1 0-1 3
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