SA06270447B1 - Method for Producing Acrylic Acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing acrylic acid in high yield by efficiently promoting, in a recovery step of acrylic acid, decomposition of Michael adducts while suppressing precipitation of maleic acid.SOLUTION: A method for producing acrylic acid includes: (a) the collection step of collecting an acrylic acid-containing gas obtained by catalytically reacting a raw gas in a gas phase as an acrylic acid solution; (b) a crystallization and purification step of separating crystals obtained by crystallizing acrylic acid in the acrylic acid solution from a residual mother liquid; and (c) the step of decomposing at least a part of the Michael adducts included in the residual mother liquid in the form of a reaction distillation. An acrylic acid-containing distillate produced by decomposing the Michael adducts in the decomposition step (c) is supplied to the collection step (a).

Description

1 = The Method for producing acrylic acid Full Description BACKGROUND: This invention relates to a method for producing “acrylic acid” and more specifically to a method for producing acrylic acid from a solution of acrylic acid at a high level of productivity. In the process of producing acrylic acid that is carried out by oxidation of the gas phase of propylene and/or acrolein © Implementation of the catalytic gas oxidation stage of propylene and/or acrolein in the process of producing acrylic acid Jie compounds Michael compounds with dimers (dimers) up to pentamers) and compounds with oligomers (oligomers) of acrylic acid are produced as a by-product due to heat and catalyst (catalyst) in the purification step. On water and acids during the reaction of gas oxidation by catalysis, maleic acetic acids «propionic acid: Jie acetone ¢acid 0» and aldehydes such as acrolein and formaldehyde 5 furfural. These by-products become a reason for preventing the continuation of the stability of the acrylic acid production process and reducing the yield of production from it as a desirable compound. Moreover, considering that acrylic acid is a material that polymerizes easily, problems were found resulting from the acid 801:6 polymer in the manufacturing step associated with heat and the purification step (Jie distillation), which leads to clogging of the device and a reduction in the yield. Several techniques have been proposed to solve the problem in order to produce acrylic acid in a stable and effective way. in patent publications 1 to; Described later, there is a description of the production processes of acrylic acid ov _ using the purification process by distillation, where acrylic acid is obtained in the form of a solution after it was in the gaseous state by catalytic oxidation of the gas, then the by-products present in the solution are removed by distillation. Z in US Patent Application No. 00054018014 and Japanese Patent Application No. 2514449 - © Yeas -1 . As an example, which was referred to here and later (which was referred to as No. 1), a polymerization inhibitor was described that is fed from a specific location of the absorption column and the distillation column so that the polymerization inhibitor is distributed homogeneously, and there is a description of the cooling process during these steps Reducing the generation of polymers by cooling the feed solution and dissociating the acrylic oligomer 40 (Michael compounds) using a thin layer evaporator and a thermal dissociation vessel to collect the acrylic 0 to make it. In European Standard No. 874 and Japanese No. 1777 - 11 - a) Gls (patent priority claimed?) and Japanese No. 7007 - 160637 T = (claiming patent priority 7) it is proposed to disassemble Michael compounds using Distillation reactor apparatus and distillation column equipped with an .acrylic acid layer of evaporator and a thermal decomposition vessel to collect DAD, and more in 31765 - 70073 - YR - JP (patent priority claimed); where a VO process for the decomposition of multiple acryl compounds is described Compounds (Michael) present at the bottom of the solution in an acrylic acid-to-acrylic acid column and collected to improve the yield ratio of -acrylic acid General description of the invention

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_ It was indicated in the patent publications mentioned above that the preparation of maleic acid as a by-product in the acrylic acid production step reduces the acrylic acid yield and prevents the continuity of the production process level stability. Maleic acid is present as a by-product of the manufacture of acrylic acid and is found as maleic anhydride (in water-existing conditions) or dry maleic acid (in db© conditions without water at high temperature) and it depends on the installation process. In particular, since the solubility of maleic acid within acrylic acid is low, it is easy to precipitate and thus facilitate the formation of an acid conjugate polymer with -acrylic acid. On all ah (Ja), it is difficult to remove water from WS by an industrial method or to remove The water used in the absorption step from the device in the aforementioned production step for acrylic acid, therefore, it is difficult to dry maleic acid under conditions in which water is present, and therefore it becomes easier to obtain it in a precipitated state. When maleic acid is heated, this facilitates its conversion into fumaric acid, but it facilitates the precipitation of fumaric acid, maleic acid, compared to anhydrous maleic acid, as this increases the viscosity of the acrylic acid solution and reduces Ineffective dissolution of Michael compounds and Vo leads to pipe closures and contamination in Beal production.Considering the problem related to maleic acid described in Patent 1, a maleic acid separating column is used to reduce its amount in solution Decomposition after thermal decomposition (by the decomposition of Michael compounds) And in the patents ?and? it was described that the amount of maleic acid combined with acrylic acid simultaneously decreases by controlling the reaction temperature and pressure at the reaction of dissociation of Michael compounds, and this is done Yo prevent the accumulation of maleic acid or anhydrous maleic acid anhydride in the collection process. Anyway Z Yeov

There is a limit to reducing the amount of maleic anhydride s maleic acid by adjusting the dissociation conditions

decomposition and aggregation There are concerns that the accumulation of the amount of maleic acid in the system increases during

continuous process.

in innocence; A method for positively adding water and other water-insoluble solutions © has been previously described from the dissociation process of Michael compounds or to the collection solution after dissociation of the admixtures and precipitation of maleic

acid to be separated. In any case, the establishment of a new step requires investment in facilities and results

To raise the cost of producing -acrylic acid

as well; Increasing the amount of solution used is not preferable from an economic and environmental point of view.

The present invention has been implemented to focus attention on the aforementioned circumstances. It is the objectives of this

0 The invention provides a pid method for the problems arising from maleic acid (such as closing pipes and devices and increasing pressure in devices) and problems from damaging the properties of the solution that contains components with a high boiling point. The effective decomposition of Michael compounds and the production of acrylic acid was improved with a high production rate when acrylic acid was collected from high-boiling components containing Michael additives that could be separated from the acrylic acid in the purification step.

0 and as a result of extensive studies to find a solution by focusing attention on the problems mentioned above. The current inventors found through the process of manufacturing acrylic acid in particular when the Michael compounds present in the components of a high boiling point separated from the acrylic acid are decomposed and then collected in the form of acrylic acid and problems such as precipitation of maleic acid at The step of dissociation and dyes resulting from the formation of polymers associated with acrylic acid, viscosity raising, and pressure loss in the column are suppressed.

Yo by reducing the amount of water-containing maleic acid present at high temperatures to a specified amount or

11 _ less. That is, it is difficult to reduce the total amount of maleic acid formed as a by-product at the reaction step, but it was found that the amount of maleic acid present with water in the purification step decreases and thus dries up, and the problems derived from maleic acid in the decomposition step are stopped. And combines acrylic and m effectively. © The process of producing acrylic acid from the invention, Mall, solved the problems mentioned above, and it includes: (a) an adsorption step to absorb the gas containing acrylic acid obtained from the oxidized raw material gas in the gaseous state as a solution containing acrylic acid (b1) a separation step for the components at a high boiling point separating the components at the distillation column, (b) the purification step of the solution containing acrylic acid, and (c) the dissociation step 01 of the compounds Michael existing at a boiling point of dle to give acrylic acid (D) the step of adding acrylic 0 generated from the dissociation step where the ratio of late maleic acid to the sum of maleic acid and anhydrous maleic acid anhydride In the high boiling point components fed into separation step (b1) to dissociation step (c) it is 7970 or less (which is a value calculated from the following equation to the sum of maleic acid and anhydrous maleic acid anhydride as 6 \ o [Maleic acid (mass)] “100 < 70% (1) _ [Maleic acid (mass)] + [Maleic anhydride (mass)] = and as described above since the solubility of maleic acid into Acrylic acid is low and easy to precipitate compared to anhydrous maleic acid anhydride, it is difficult to precipitate the copolymer of maleic

_ No acid with maleic acid acrylic acid in the dissociation step when the amount of nutrient maleic acid is reduced in the dissociation step. Also, since components with a low boiling point such as water are easily removed from the components of a high boiling point that are fed into the dissociation step, the water is removed from the maleic acid during the dissociation treatment and dries up to 0, and since the melting point of the anhydrous maleic acid is the anhydride formed At that time they are low, they can be found in high boiling point components in melting state.” As a result, the stable dissolution of Michael compounds and effective aggregation of acrylic acid can be performed without closing the tubes or increasing the pressure in the devices according to the above mentioned process. of the present invention by placing the amount of maleic acid containing Wl in the components of high boiling point and the amount of aqueous maleic acid with anhydrous maleic acid anhydride as a specified amount or less. 0 | Also in the present invention 'sald' means a substance whose boiling point is lower than acrylic acid at standard conditions (YO C and atmospheric pressure) and 'high boiling point substance' means a substance whose boiling point is higher of acrylic acid at standard conditions. as well; “Michael cil ya” means acrylic acid polymer in the general formula (I) given below. acrylic acid and its salt in B-acryloxypropionic acid and Michael and includes example VO -dimer compounds [Chem 1] CH;=CHCOO~{X—COO}-H (1)

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d A — so that in form 0 is “ an integer from 1 to © and =x- is ~CH,CH,— or -1 07 and Lexie is “ equal to 1 or more X can be the same or different. "Purification" also includes distillation, diffusion, crystallization, extraction, absorption, and so on. Therefore, "distillation" is the process of heating a solution to a boiling point and separating the vaporized components from it. And “erystallization” means that the desired substance separates as crystals, as well as in the current description; “maleic acid” means aqueous maleic acid unless otherwise stated and used separately from maleic anhydride. For the drawings Figure 1: is a step drawing showing one example of an acrylic acid production process step of the present invention Figure ?: is a step drawing showing an example AT of an acrylic acid production step of the present invention Figure iT is a step drawing showing an example AT of an acrylic acid production process step of the present invention Fig. 4: A step drawing showing another example of an acrylic acid production step of the present invention Yéov

Figure to is a step drawing showing another example of an acrylic acid production process step related to the present invention. Figure 76: A drawing of a step showing another example of acrylic acid production approved in example AY: 1 JRA is a drawing of an acrylic acid production process approved in example NE © Detailed description The acrylic production process is characterized acid in the present invention that it has characteristics that include: (a) the absorption step of Hall containing acrylic acid obtained by oxidizing the gas of the raw material in the gaseous phase as a solution containing crude acrylic acid (B1) The step of separating the components of the high boiling point at the Jie distillation column (b) the step of purifying the crude solution containing acrylic acid, as well as (c) the step of dissociating the Michael compounds present in the components of the high boiling point to generate acrylic acid And (d) a collection step for the acrylic acid generated in the dissociation step (z) where the ratio of the amount of maleic acid to the sum of maleic acid and the anhydrous maleic 420 in the high boiling point components The feed from the high boiling point separation step (b1) to the dissociation step (c) is 7970 or less (which is the value calculated from the following equation (1) and also the ratio of the amount of maleic acid when the sum of maleic anhydrous maleic acid anhydride denoted as JY eo [Equation] 1 [Maleic acid (mass)] «100 > 70% (1) _[Maleic acid (mass)] + [Maleic anhydride (mass)] = Yeov

A 01 - and as described above when the ratio (the ratio of the amount of water present with maleic anhydride to maleic acid + maleic anhydride) ( maleic acid ) to the amounts of maleic acid in the high boiling point components fed is determined by the range mentioned above; sedimentation at the dissociation step and an increase in pressure generation in the device can be prevented, and thus (Say) performs the dissolution of Michael compounds with the effectiveness of acrylic acid gly © in a constant manner. Calculated from the above equation (1) 750 or less and preferably 740 or less. No dala to say that it is preferable to have the ratio of the amount of maleic acid in the proportion of zero 7. ey in any case; to obtain the percentage of maleic acid It reaches 70 Severe working conditions must be adopted for a specific step (often the integrity of the entire production process is affected) and therefore 0 | the effectiveness of acrylic acid production must be sacrificed sometimes. From equation (1) mentioned above and as it is 70 and this does not favor an economic point of view. Also, the minimum proportion of the amount of maleic acid calculated from the mentioned equation (1) is usually a value greater than .70 and usually Preferably, the ratio is 75, the best is 701, and the most preferred is JX Vo The components of the high boiling point mentioned above are components that contain a substance that has a boiling point higher than acrylic acid and contain side products when producing acrylic acid, including compounds Michael. Likewise, one of the objectives of the present invention is to improve the efficiency of acrylic acid production by collecting it from high-boiling components. Also, as described above, the invention al has a property in that the amount of maleic acid in the high boiling point components fed in the disintegration step is reduced to a specified amount or 0 less. Thus, in the invention, Jal, the step of manufacturing acrylic acid is not limited at all to M

111 - Production of acrylic acid, which is known to be used. Sie as a solution containing components of a high boiling point, those components separated in the purification step (such as distillation, diffusion, crystallization, extraction, absorption, and so on) or those components separated from acrylic acid as a product in the available purification step Arbitrarily © if necessary after skipping the purification step. Needless to say, acrylic acid can be contained in a solution containing high-boiling components. An ideal example of this is the bottom solution of the distillation column; Residues of the liquid generated by crystallization purification and the like. in addition to; Ly that the process of industrial production of acrylic acid; It is a catalytic process for the oxidation of propylene and/or acrolein in the gas phase in general. Therefore, in the current specifications, for example, the use of a method in which the oxidation is the catalyst in the gaseous state, as in the process of manufacturing acrylic acid. The sequential steps are explained later, referring to the drawings in agreement. manufacture of acrylic acid [ The raw materials for propylene is acrylic acid and/or acrolein are blended with gas containing oxygen | 0 Like air and dilute gas to prepare raw materials in gaseous form. The raw materials are fed in the gaseous form to the reactor filled with the oxidation catalyst in the gaseous phase and the gas containing acrylic acid which is obtained through the oxidation reaction with the catalyst in the gaseous phase. Br i - 11 - The conditions for the reaction of the oxidation phase reaction of the catalyst are not strictly limited to the gaseous state and recycle gas can apply the usual operations. In addition, the cyclic gas described later can be used as a raw material for the acrylic acid pas gas (described later) generated on the step previously described. The reactor in the oxidation phase is not specifically defined by the catalyst in the gaseous state; However, it is preferable to use a multi-tube reactor because of the superiority of the reaction efficiency. The oxidation catalyst known in the gaseous state is traditionally filled in the aforementioned reactor and oxygen is carried out by oxidation by making the raw gaseous material in contact with the containing gas as raw gas; It is preferable to have a concentration of propylene and air. When using the oxygen Jie is the rate of oxygen by volume and 701 to 0 by volume; and water from Ve from 7 to propylene 0 as can Yee to (1:0.1) aaa ratio (molecular oxygen: propylene in addition to that; at . molecular oxygen Using air as a feed source for partial oxygen Air contains moisture, it is preferable to remove moisture before feeding air to the reactor The reason for reducing the moisture content entering the reactor is to reduce the moisture content in the absorption step of pure oxygen s « a). in addition to; Air rich in (acrylic) can be used as VO; other gases other than carbon dioxide + nitrogen “aad” analogues can be used instead of air as active gases and their analogues can also be used. After being discharged from the absorption column? In this invention, the circulating gas described later in the present invention is cooled, and the evaporative materials (1 with reference to the figure) are condensed for condensation, so that they can be introduced into the reactor (not shown in the figure); the reason is that the materials contain Ye

1 “- Unreacted crude and its counterparts sometimes in recycle gas. When using 0 recycle gas, it is preferable to have Al moisture in principle than recycle gas so that the concentration of moisture in the raw material fed into the reactor ranges from zero to 701 by volume. And the most preferred is from 0 to 79 of the magnitude and the most preferred also from zero to 776 of the magnitude; © The loss rate of acrylic acid can be increased when the moisture fed into the absorption column through the reactor is increased. In addition, it is preferable that the total concentration of the acid in the recycle gas be from 0 to 707 vol and most preferably from 0 to 7001 vol. When the total concentration of the acid is within the mentioned range. The hydrolysis of the cofactor approximates generation and the Jeli continues oxidation in the gaseous state of the cofactor steadily. Unreacted propylene 0 coxygen ¢ acrolein, dilution gas and similar recycle gas are also included in addition to moisture and acid component. oxygens » propylene can be modified; And the total concentration of moisture mentioned above is easily contained when the moisture content is contained in the recycle gas. The blending quantity is calculated from the aerated raw material; And the concentration of propylene and the concentration of oxygen content in the recycle gas so that the VO moisture concentration and the total acid concentration in the gaseous raw material are within the aforementioned range, and the concentration of propylene and the concentration of the newly fed air to the reactor are determined. in addition to; "die total acid" compounds that contain carboxyl group, acrylic acid, formic acid, acetic acid, and similar ones contained in recycle gas, the oxidation reaction is carried out by the catalyst in the gas phase in Alla The use of propylene as pla material Ye is usually in two phases and two types of auxiliary oxidation materials in the gaseous state. The catalyst generates Yiov

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In the first stage, an auxiliary substance is used to oxidize the gaseous raw materials containing propylene in the state

gaseous in general acrolein; The adjuvant oxidizes the gaseous raw material on the second stage

Containing acrolein in the gaseous state and mainly alg -acrylic acid

The oxide complex containing iron, bismuth 5 molybdenum 6 iron ©, can also be mentioned as a catalyst in the first stage, and vanadium is a major component of the material as a catalyst in the second stage.

In addition, the catalyzed gas-phase oxidation reaction can be a mode of conducting the reaction from

The aforementioned two phases are in one reactor, and it can be a pattern to conduct it in harmony between the two reactors

the different.

The gas containing acrylic acid which is obtained by the oxidation reaction of the catalyst agent 0 in the gaseous state contains unreacted components in the gas in the raw material and secondary compounds Jie formaldehyde s « furfural y acrolein s acetone s » propionic maleic acids acid it; and similar ones) with each other with © to carbon dioxide » carbon monoxide (COx).

From 0.10 “acrylic acid” to 77.5” vio “acetic acid” to 727 “volume”

For molecular oxygen * to 7776 vol of water.

[ (a) acrylic acid [absorption step 0] In contact with an acrylic acid solvent, the gas obtained from the acrylic-containing gas is placed as an adsorbent and fed to the absorption column? To be absorbed as a solution containing absorption step (a)). The distillate can be introduced from the reaction distillate - 7 (data ( 40 ) (dissociation step (c)) to the absorption column ? Michael reaction) that performs the decomposition to i — 101 _ compounds as an acrylic acid product that includes the distillate «acrylic acid In addition to the gas containing acrylic acid at a high concentration, the high yield is obtained from Michael dissociation of compounds by collecting distillate products. In addition to that, the details are described later, but it is preferable that The clear from a 7-distillation reaction apparatus is the one that passes through the component separation steps that separate the high-boiling components (Yo high-boiling column © 1 distillation column). The absorption column is not limited. The aforementioned in particular, so that it can be used to create an acrylic absorption solvent with the acrylic acid. The contact between the ¢ plate column gas and the Jie column can be used. The well-known absorption columns Mie acid can be used.

jl; and a wetted-wall column » packed column | The aforementioned 0 from the lower side, acrylic acid, the gas containing . spray column on one side, absorption solvent and on the other hand; The absorption solvent is fed to the top of the absorption column. With the absorption solvent acrylic acid at this time the contact process is not limited to the containing gas All of the contact processes known as flow contact can be applied Mie 0 absorption solvent | 0 monoflat ¢ bubble tray using cross flow contact; bubble tray jet tray extrusion plate “porous plate tray” porous plate tray ¢ uniflat tray gle Jb flow direction connection using “venturi tray and bubble tray” flow plate ¢ turbo grid tray _for particle tray irregular filler gle and a regular filler

Yeov

A 11 - -

“gause” type “Kittel tray”; ripple tray; Dual flow tray Sl

layer type; and granule type.

The aforementioned absorbent solution is not particularly limited as it can absorb and dissolve acrylic

140 But Say (say) the use of known solvents such as organic solvents with a high boiling point dimethyl phthalate » diphenyl » diphenyl ether | ©. and a mixture of diphenyl s diphenyl ether;

Water and water containing organic acid generated from the process of purifying acrylic acid and solution

acrylic and spent water after removing it. In addition, among the current specifications; He is

The aforementioned “high boiling point organic solvent”.

Previously an organic solvent with a boiling point higher than “acrylic acid” or a solvent mixture containing the organic solvent 0

to (d) after the oxidation step with the catalyst in the gas phase. Corresponding to that includes water

containing the organic acid generated from the acrylic acid purification process and the acrylic acid solution

Oli the bottom solution of the absorbent column and its analogues; Reflux liquid ¢ Components of a gas

Condensate cooling disposed of from the upper side of the absorption column and similar to the absorption column in the absorption process 00 Waste that is separated from acrylic acid and is produced by

different purification processes and their analogues for the purification step (b); bottom solution of the column; extracted solution

from the middle of the column; reflux liquid ¢ distillate and equivalents from the decomposition step (c)

And the step of separating the components with a high boiling point (B1).

The amount of absorption solvent cule fed to the absorption column can be determined appropriately depending on the desired concentration of the solution containing “acrylic acid” in addition to that

Yiov

— \Vv —

The concentration of acrylic acid for the solution containing acrylic acid is appropriate when it is as high as possible in terms of the effectiveness of the purification step (b). The ratio of the mass flow rate of the absorption solvent to the view in the absorbent column is 0.1 to 0.8 times the mass flow rate of the acrylic acid content in the solution containing the acrylic acid; preferably © The ratio should be from 0.1 to 0000 times, and the most preferred (M010) is 0.8 times. It is preferable to collect acrylic acid by making the acrylic acid in the direction of flow in contact with the gas containing acrylic acid The reduction of the adsorption efficiency of the acrylic acid adsorption column is inhibited by making the mass flow rate ratio within the aforementioned range, and the containing solution is obtained.

On acrylic acid with a high concentration.

0 A polymerization inhibitor can be added to the previously mentioned absorption solvent to prevent the polymerization of acrylic acid Jie in the absorption column. The polymerization inhibitor includes one or more compounds selected from the group consisting of 0-27 (1” phenol compound; manganese acetate salt (Jie manganese), copper copper and salt from:

amine and nitroso compound + dibutylthiocarbamate like dialkyldithiocarbamate

Description: All phenothiazines 0

JP-A-2001- 348358, JP-A- 2001-9, 348360 .15-2-2001 and the like. It is recommended to operate an acrylic acid absorption column at the highest pressure of the column (pressure gauge) from 0 to Mpa c.f, preferably from 0 to 000 Mpa, and the most spain from zero to 0.05 Mpa When the upper shaft pressure is too low, a pressure reducer is needed

0 and the cost of the facility and utilities becomes high. On the other hand, when the upper pressure is higher than

VA — - desired”; There is a need to raise the temperature of the absorption column to get rid of low-boiling substances from the upper side of the absorption column, thus reducing the effectiveness of acrylic acid absorption. Acrylic acid can be effectively absorbed by preparing the upper pressure of the column with the aforementioned range. In addition to that, it is preferable that the temperature of the absorption column be from 01 © to 85 degrees C, and the most preferable is from 46 to ca Av. In addition to that, AES materials are obtained in methods within the present invention; By cooling the part (recycle gas) of the discarded gas coming out from the top of the absorbent column, which can be used as part of the absorbent solution. Since the condensate usually contains acrylic acid, the acrylic product can be raised. acid by using the absorption solvent Ve.In addition to that when using thickening materials, it is preferable to introduce the thickening materials into the absorption column by adjusting it from zero to #0m and the most preferable from 01 to Eo mm Lay can use the recycle gas after separating the condensate as part of the raw material gas for the manufacture of 0. acrylic acid in addition to that the disposed gas is recycled; in methods within the present invention; between Vo The gas disposed from the upper side of the absorption column to the reactor (acrylic acid manufacturing) is referred to as “recycle gas”, and the gas disposed from the upper side of the absorption column to the outside of the system is referred to as “waste”. gas The refrigeration process is not limited to the circulating gas and the condensing sala condensing device contained in the circulating gas can be used Mie . recycle gas a multi-tube heat exchanger can be used; 0 . double-pipe heat exchanger » wha coil type Yeov

{ ya — coil type heat exchanger ¢ direct contact type heat exchanger ¢ plate type heat exchanger and the like. in addition to; It is preferred that the amount of condensate entering the absorption column be from 0 to IV in the absorption solvent. Most preferred from 010 to © Joo The solution containing the crude acrylic acid obtained by the present step is fed from the lower side of the absorption column? Through the line WAL the purification tool © that performs the separation and purification of acrylic acid (purification step (B)). In addition, acrylic acid can be contained as a product ¢ and acrolein as a raw material; And similar ones, in addition to the by-products of the oxidation reaction with the catalyst in the gaseous state in the lower solution of the absorption column? As a result Ve can provide an acrolein separation step to remove the acrolein before feeding to the scrubber©; if necessary. Purification step (b)] Then the solution containing acrylic acid obtained from the absorption column is extracted? from the bottom side of the absorption column? It is fed to the purifier © (purification step) through line A-L (Fig. 1). Adee purification is not particularly limited and Vo purification processes known as Sle adi can be used as distillation purification; The crystal purification process “crystallization” the purification process using membrane separation 0 and the chemical treatment process alone or several methods can be used with it. (Dla) when using the distillation purification process; an azeotropic cus separation process can be used. The purification is performed in the presence of an azeotropic solvent and a Yeo-containing solution

71. On pure acrylic acid obtained from a solution containing crude acrylic acid. Just as (Say) uses the distillation column for the zeotropic separation process, it is possible to use well-known columns such as the flat column, the compact column, the wet-walled column, and the spray column. The zeotropic solvent includes: toluene, heptane, dimethylcyclotoluene, methyl isobutyl ketone, ethyl acrylate, methyl © methacrylate, hexane, butyl acetate Lia 9 latte.In addition, the treatment temperature of the crystal purification process, crystallization, among the aforementioned purification processes, is low compared to Adee distillation purification And the generation of acrylic gacid |0 Michael compounds is also low. In accordance with that, the use of the crystal purification process is one of the preferred modes in the present invention as the purification step. Then the case of using the crystal purification process is explained later ( Refining step (Yo) for an acid s.) [ Refining step (Yo) for acrylic acid [ VO when using a purification step (Ib") as a purification step (b); The solution containing the crude acrylic acid obtained in the absorption step (00) is fed to the crystallizer (purifier ©) and the acrylic acid is separated as crystals to be purified (step crystal purification (Yo) is supplied by crystallizing the acrylic acid obtained from the crystallization step (Yo) in the Yéov process.

For the production of acrylic acid related to the invention (Jl) to the purification step to carry out washing; filtration and the like if necessary. It is considered one of the most preferred methods for producing acrylic acid of higher purity. The crystallization process adopted in the crystal purification step is not (Yo ) confined, either it is a continuous process or this process can be performed in the form of batches and can be conducted in one or two stages © or more. As in the case of the continuous crystallizer, it is possible to use a crystallizer of type (BMC)

Nippon Steel Chemical manufactured by (Backmixing Column Crystallizer Limited Shareholding Company) where the Led is the part of the crystal; part of the solid-liquid separation and part of 480 crystals are integrated from the same crystallizer of the crystallizer so that part of the crystal is, for example, Coolind «CDC Disk Crystallizer | 0 The crystallizer manufactured by GMF GOUDA Company; Solid-liquid separation part, for example, filter belt; AT centrifuge and similar parts, and crystal purification part (for example: KCP)

Kureha Techno Engineering manufactured by (Kureha Crystal Purifier) Limited Shareholding Company and similar ones) and are combined. And there Alla is particularly indicated when the continuous crystal device that collects the crystallizer is the crystallizer | 0 where the two crystallizers (CDC) are described in “5017011 KAGAKU (Chemical Instrument) Jul 9011 p.7 no to VA” which is arranged as a crystallizer (KCP described in “40671” and YY p6 no to Yo) Chemical Apparatus (July) KAGAKU SOUCHI -13-47 for a fraction used in crystal purification. The two (1) and (1) constituting the crystal fraction are equipped with a transversal pattern of the crystal bowl and inside the crystal bowl divided with multiple cooling plates vertically against the horizontal surface The size of the Will sheets is a

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Cooling plates so that the gaps are suitable for the passage of the solution, which can form on the part

The bottom of the crystal vessel and the stirring column equipped with stirring blades and the wiper

To maintain the cooling surface within the center of the successive cooling plates. Especial; Complete

Ji acrylic acid solution fed from the feed inlet of the raw material solution that is located in the edge of a container © crystallization JI crystallization the other edge through the bottom of the cooling plates cooling plates

Lay is moved by timing blades. At this time cooling is performed

Crystallization of an acrylic acid solution through cooling plates.

Laie an acrylic acid solution is fed to the crystallizer (1); the acrylic acid is crystallized in

The crystal container, and then the aforementioned solution is discharged with the crystallization mother liquid | 0 of the crystallizer hs; (1) crystallizer that separates the crystals and the means of the mother crystal crystallization

mother liquid remaining using the belt filter as the mentioned filter as a means

Separate the solid part from the liquid part.

This is followed by the introduction of the JW crystallization mother liquid (1) crystallizer, then

crystallizing acrylic acid and then separating the crystals and the remaining mother crystal liquid using a belt filter | 0 .

Then the crystals obtained in crystallizers (1) and (Y) are introduced into the crystal purification part.

Then the crystal dil device (KCP) described in “KAGAKU SOUCHI (KCP)

Chemist) July (Yeo) Page VT to 1/7 18-47-40571 with screw-on center

The tube made of metal (purification column) and is equipped with a Ye dissolving tool to dissolve the crystals and an opening to remove the remnants of the dissolved product on the upper part of the purification column; the surplus comes out

A-7 of the residual solution (residual mother liquid) from an opening on the lower part of the purification column and feeding the overflow of crystals onto the lower side part of the column. The crystals entering into the AA crystallizer are transferred to the upper part of the The purification column via a moving conveyor with purification by filtration.The crystals entering the upper part of the purification column © are dissolved by the dissolving device and the bulk of the surplus of the solute for the crystals is taken out from the outlet hole.At this time, a large part of the solute for the crystals is thrown out from the orifice The output is at the top of the purification column.The solute from the crystals comes into contact with the crystals entering via a spiral jib.The surface of the crystals is finally washed from the residue emerging from an opening in the lower part of the purification column (residual mother liquid). acrylic acid The amount of solute dropped from the crystals can be suitably selected by purity 0 to 710 by mass of the amount of solute for the crystals; most preferably 1 for topical; but preferably from 7460 by weight and most preferably from © to 775 by weight.The effect is obtained by filtration such as washing the crystals with the effectively falling solute and the crystal purification column is operated in the form of the extracted (residual mother liquid is fixed. The residual liquid (residual mother liquor and/or residual mother liquor crystallization) can be recycled from the bottom of the clarification column to the VO crystallizer but at least a portion is fed to decomposition step (c) of the ¢ 35500 compounds. mother liquid . Michael can use, for example, a layer crystallizer (a dynamic crystallizer) manufactured by: a static crystallizer manufactured by «Sulzer Chemtech GmbH

BEFS PROKEM 106 00 and similar devices can be used.

Yeo

[ 1 — — if the case relates to the purification step by polymerization (Yo) on the batch system which is specifically illustrated by reference to the procedure case with reference to a multistage fractional crystallization process as an example. in addition to; No yeast the purification step (Yo) related to the present invention (Sas) can be performed according to other crystallization processes. : © Adee Fractional crystallization can be performed by the dynamic crystallizatio step or the static crystallization step With the dynamic crystallization step, the dynamic crystallization step is performed, in which the crystallization is carried out using a dynamic crystallizer with a tubular crystallizer equipped with a temperature control mechanism to conduct crystallization, filtration and dissolution, a tank to collect the source liquid after filtration, and an acrylic acid pump to feed to a device crystallizer” and the dynamic “Ve” crystallizer which can transfer the acrylic acid solution from the storage device on the lower part of the crystallizer to the upper part of the crystallizer by means of a circulating pump. A static crystallizer as it is equipped with a temperature control mechanism to conduct crystallization, filtration and dissolution which has an extraction valve on the lower end of the crystallizer and is provided with a tank that collects the source liquid after filtration. VO, in particular, the solution containing raw acrylic acid obtained from the absorption step is introduced into the crystallizer in the liquid state, and the acrylic acid coagulates in the liquid state on the cooling surface (the surface of the tubular wall). When entering a quantity in the solid state generated on the surface of the cooling, it is 40 to 798 of the weight of the solution containing acrylic acid into the crystallizer, and preferably 00 to 280 of the weight, then the liquid state is immediately disposed of from the crystallizer and is separated Ye solid state and liquid state. Yeo

A Yo _ -

Elimination of the liquid state can be either on the pumping mode (dynamic crystallization step); and the flow pattern of the crystallization tool (static crystallization step). On the other hand; After taking out the solid state from the crystallizer; It can be fed to the purification step to perform washing or filtration to improve its purity.

© When the aforementioned dynamic crystallizatio and static crystallization are performed by the multistage step; It can be preferably conducted by adopting the counter flow principle. In this case; The crystalline materials are separated in sequential steps of high purity. On the other hand, the source liquid of the residue (crystallization residue) is fed to the sequential steps of lower purity.

0 In addition, when the purity of acrylic acid is low; Crystallization is difficult in the dynamic crystallization step; However, the contact time with the cooling surface of the source residue liquid is long in the static crystallization step compared to the dynamic crystallization step, and the effect of heat is transferred easily; Therefore, even if the purity of acrylic acid decreases; Crystallization is easy. In accordance with this, the final source liquid of the dynamic crystallization step is fed to the static crystallization step to improve the collection rate of acrylic acid.

VO crystal can be made as well. (Ka) Determine the number of crystallization steps appropriately in accordance with the required purity; but the purification step is performed from 1 to + times to obtain acrylic acid of the desired purity (dynamic crystallization step); preferably from * to 0 times and Most preferred from to 4 times; the stripping step (dynamic crystallization step and/or crystallization step (ASL) is performed from 0 to 0 times and more

Yes is preferred from 0 to 7 times. Know the complete steps by which acid is obtained

{ - 1 - The higher purity of the acrylic acid solution fed sole by the punctuation step, and the complete steps are known by the stripping step. A stripping step is performed to collect the acrylic acid in the source liquid from the Ail step in addition to that the stripping step Wily is not provided for example (JE) when the separation step of high boiling components (B1) is used; That the aforementioned stripping step © be brief, and the reason for that is the collection of acrylic acid in the residue of the source liquid in the separation step of the high boiling point components (B1). static crystallization mentioned above, acrylic acid crystals are obtained by the step of crystal purification (Yo) that can be used as a product of Lady after purification (0 washing; filtration and similar) that is carried out when necessary to be prepared as output. The residue (residue of the source liquid) extracted from the crystallization step that can be extracted out of the system to produce acrylic acid may be fed to the adsorption step (a); However, in the present invention at least one part of the source fluid of the segment is fed to the dissociation step (c) of the Michael compounds. The operating conditions of acrylic acid ¢ manufacturing step, acrylic acid gas adsorption step ¢ azeotropic separation step and purification step are not particularly limited and can be performed while being appropriately adjusted; According to the components of acrylic acid and the components of the solution containing acrylic acid The raw acrylic acid solution; etc. [Separation step for high-boiling components (HB1)] Yeov

A - for 7 a? In the present invention, in addition to the previously mentioned steps, the step of separating the components with a high boiling point (Vo) is to separate the components in the distillation column; dissociation step (c) to decompose the Michael compounds contained in the high-boiling components to generate acrylic acid; A collection step (d) is generated to collect the acrylic acid in the dissociation step that can be used. The collection step (d) could be a step capable of collecting the acrylic acid generated in the dissociation step (c) and for example » the previous steps such as the absorption step (a). The purification step (b) and its counterparts can be prepared as a collection step (d). In addition, it is desirable to separate the separation step for the high boiling point (Vo) components over the previous step being prepared as a collection step. The separation step of high-boiling components (B1) may be included in the purification step (B). 0 In addition, it may include a dissociation step (c) and a combination step (d) in the purification step (d) and may be provided as a different step than the purification step (b). In addition as a preferred mode of the present invention; A pattern has been mentioned in which acrylic acid aes by providing a solution containing the high-boiling components (obtained after the high-boiling components separation step (B1)) that were separated from the acrylic acid as a desired product . VO was eliminated in the purification step (b); to the dissociation step (c) and the combination step (d). Then the preferred mode of the present invention is made particularly clear when referring to the process shown in Figure ?. The high-boiling components containing the nutrient solution are fed to the purification step (b) (not shown in the figures) during the manufacturing step and the absorption step () and are separated from 0 | Acrylic acid in the purification step that was fed to 1 distillation column shill

[ - YA -

(High-boiling point separation column) through line 1-1. Which separates high-boiling components (High-boiling-point separation step (B1)). The high-boiling component separation step can be either a separation step Acrylic acid is from the components with a high boiling point to separate the acrylic acid from the components with a high boiling point on the purification step © (not shown in the figures) and it can be a step to separate the acrylic acid and the components with a low boiling point from the components of the boiling point The low levels that are contained in the solution containing the components with a high boiling point by separating the acrylic acid in the purification step. The separated acrylic acid is distilled from the top of 1 distillation column condensed on condenser 1-12 through line 1-7; It is then collected as a product or as a feed for the subsequent purification step and Ye similar. In addition, the acrylic acid part and the boiling point component can be recycled

Low to line A-? to a distillation column and used as a reflux fluid. On the other hand, the lower solution (components with high boiling point) of distillation column 1 is fed to the reaction distillation ¥ (distillation column) (dissociation step (c)) through Lal) ,1-”. In addition, all components with a high boiling point can be introduced into the line Vo a-? to step All, but part of it can pass the heat source 1-? On line A7-1, then it can be recycled back to distillation column 1. In addition, the insoluble components contained in the distillate or the bottom solution of distillation column 1 can be removed from the distillate separated from distillation column 1 and the solution is discarded bottom of the distillation column (0) through position 2-7 before being fed to the next step. The components with the highest boiling point here mean a by-product of the production of acrylic acid 00 or the raw materials with which it begins to manufacture and which contain components with a boiling point of le! of acrylic acid in the standard state. Components with a higher boiling point include:

A — 789 dimer of acrylic acid ) Michael compounds and their analogues ( maleic ¢ protoanemonin 0 furfural 0 40 + and anhydrous maleic acid anhydride and their analogues.

and as a device that can be used as a distillation column (high-boiling-point separator column) for the high-boiling-point component separation step (B1); compact column; Shelf plate column (© plate column) and similar ones have been mentioned and any of these materials can be used as a filler in the formation of the disintegration step described later as a filler in the compact column. In addition, the plates represented in the dissociation step described below can be used for the plate supplied in the rack plate column. It can be said that Alla materials and dishes can be used in combination with each other. In addition, the ald plate rack column can be preferentially used from the point of view of reducing Salle Ve acid contamination to the distillate (acid 8116). In this cyl the theoretical number of steps of the shelf plate column is preferential between ? to Yo stage and the most preferred of; to 11 stages. be proportion

favorite retracement from 1.17 to; and most preferably from 0.4 to ?. The operating conditions of the distillation column can be such that Linh can separate the acrylic acid from the components with a high boiling point of 0 and can be appropriately selected to concentrate the acrylic acid for the components The highest boiling point and it is introduced into (crude acrylic acid solution); water concentrate; The concentration of acetic acid and its analogues. For example; The preferred bottom temperature of the separating column for high-boiling components is 0 °C or more; the most favorable is 95 degrees C or more and the most favorable is 11 degrees C or less; The most preferred is 1705 degrees C or less; the most preferred is also 171 degrees C or less.

The high (purification column) is from Ee to 90 degrees C, and the most preferred is between 0 * to Ae, then . In addition, the residence time of the lower solution of the column separating components with a preferably lower boiling point is between ? to Yo hour and the most preferred of; to Yo hour. In addition, the 773 ratio (F/B here later called condensation amplifier) which represents the ratio of the amount of © feed solution to the distillation column to the amount of extraction solution (lower solution) from the column Distillation (B), which is preferably from 010 Jo and most preferably from +6 to V0 In addition to that, the upper pressure of the column separating components with a higher boiling point (absolute pressure) is preferably from 001 to 460 KPa and SY preferably also from 0.9 to 710 KPa; most preferable bag from Yoo to KPa Yo when 0 is the shaft top pressure of the component separator With a high boiling point within the aforementioned range, the large size of the distillation column, the condenser, and the suction device are not necessary, and there is little fear of acrylic acid polymerization.Heat exchangers can be used as heat exchangers of the multi-tube type; heat exchangers Plate type “screw type heat exchangers” rotary type heat exchangers; 0 thin film type heat exchanger and re-boiler as heat source for OY-18 distillation column 1 (high boiling point separator column). In addition, the polymerization inhibitor can be added to the reflux liquid to prevent the polymerization of polymerizable materials such as acrylic acid. The polymerization inhibitor includes one or more compounds that are selected from the group consisting of compounds: N-oxyl compounds ¢ Jie manganese salt + phenol ‎E manganese acetate, a copper salt of dialkyldithiocarbamate Ye : Yeo

- 11 - copper dibutylthiocarbamate, a nitroso compound, an amine compound and phenothiazine. described in Japanese Patents No. 6854 ?-00- or mY EAT or similar. © The distillate obtained from the high-boiling components separation step can be used as a product (acrylic acid) and it can also be fed to the purification step. Without needing to say that the distillate can be fed from the distillation column) a separation column Components with a high boiling point) to the absorption step () which is on the upper side of the component separation step with a high boiling point (B1) and the purification step (B) as the water removal step. On the Ve column (1 on the other hand; the bottom solution of the distillation column .A-1? and the decomposition of the reaction distillation column (through JY high boiling) is fed to the reaction distillation apparatus The dissociation step (acrylic acid) the valuable components contained in the bottom solution of the distillation column to prepare (()

WM maleic acid and maleic acid In addition to that; When the total amount of 1 contained in the high-boiling components of the present invention is fed into a maleic anhydride the proportion of the amount of Al by weight is prepared; 7001 dissociation step (c) which is prepared as to be 270 or less. It is preferable that the total concentration at this time be (total concentration of 0 out of 7000 by weight in IYO (NY) of (anhydrous maleic acid anhydride) and maleic acid

Yeo

E 017 -

Weight of the nutrient solution to the dissociation step (the solution containing components with a boiling point

elevated). It is most preferred to be from 1 to 714 by weight.

In addition, it is preferred that the concentration be (depending on 7000 by weight of the solution.

containing components with a high boiling point) for Michael compounds contained in the components © with a high boiling point fed to the dissociation step (c) preferably from 010 to

0 by weight. It is most preferred to be from Yo to 755 in weight and the most preferred

It should also be from Fe to 0 75 by weight. In addition, the working conditions can be controlled

As the temperature of the Jind column of the distillation column in the component separation step

The high boiling point (B1); the residence time, the number of theoretical stages of the distillation tool used, and the ratio of 0 reflex as previously described so that the amount of maleic acid is prepared in the ingredients with a degree of

The high boil in the aforementioned range. In addition, the amount of maleic acid can be adjusted

The water content in the components with a high boiling point fed to the distillation column and the amount of

Michael compounds by controlling conditions such as the decomposition temperature (bottom of the column) for a step

disintegration (c) described by later and residence time; condenser and reverberation amplifiers; And the temperature of the internal column 10, and the use of distilled (cycling solution) from the dissociation step (c).

Therefore, it is one of the preferred compounds within this current invention to adjust the amount of compounds

Michael over a specified range; In addition to adjusting the amount of maleic acid contained in the solution

Contains ingredients with a high boiling point. Reducing the problems Jie blockage of the pipes

from maleic acid ¢ sticky substances; and the high viscosity of the waste oil in the dissociation step (©) 0 also described later.

rang i - rr -

Acrylic acid is also collected in the high-temperature component separation step (EP1) in addition

To separate components with a high boiling point. as a result; when using the component separation step

With high temperature (Yo), it (Ka) is an abbreviation of the stripping step for crystalline purification (Yo) at

Crystallographic purification procedure (b) and the acrylic acid production step becomes more suitable. in addition to; Since the distillate dispersed from the high-boiling component separation step (B1) into a step

Absorption (a) Simultaneously reduce the high boiling point components maleic acid jie which

feared crystallization by heat; The acrylic acid yield is improved without damaging the process properties

for the absorption step (a).

[dissociation step (c)]

0 Steps to separate the compound at a high temperature B1 The compounds that have a high boiling point are separated from the bottom of the distillation column 1 01501121100 column (compounds with high boiling points are separated from the column) and they feed the reaction to the distillation device 7 (the distillation reaction column “ ) in which the destruction of Michael's compounds occurs during line 1a-? The compounds that have high boiling points are among the compounds (double acrylic acid, Jie Michael, triple acrylic acid, and acrylic acid).

,. Michael when destroying acrylic acid compounds in the form of multiple Michael; It is possible to collect compounds of 0 means the smashing steps related to this invention; valuable ingredients; Heating compounds with Michael boiling points, Jie compounds with high boiling points, and at any step shown in the figure “The best WS decomposition steps (C)) (high acrylic acid) are destroyed to produce It is distilled from the top of the column in a reaction apparatus 1 - in an acrylic acid distillation reaction apparatus for zl

‎Ye distillation - ? and in Gila with distillation in column 1 through line .1-; And line 1-1 connected with

A ove _ distillation column 1 (compounds with high boiling atoms separated vertically) or from line A-; Directly (not shown in the drawings) On the other hand, the remaining solution from the distillation reaction apparatus ¥ is emptied out of the acrylic acid production system through line .50-1 and line ,A-1; without having to say. Part of the remaining solution can be circulated in Jalal heat exchanger 1-? To go back to the distillation reaction apparatus? © In addition, figure ¥ shows an example of which type of forced heat exchange uses heat exchange. It is preferable to use a sufficient disintegration process and sufficient retention time to process Jal fracture materials to increase the crushing efficiency of Michael compounds in the disintegration steps. Among this invention such as the decomposition steps (c) the distillation reaction process - in which the breakdown of Michael compounds or evaporation or distillation of the continuous decomposition products ol (acrylic acid) 0 - means the process of distillation of the products The reaction in which Michael "lS yo" is produced from acrylic acid is a balanced reaction, and accordingly, when using the distillation reaction process, the acrylic acid is destroyed, and evaporation and distillation occur Simultaneously with the occurrence of the degradation reaction of Michael's compounds, the degradation reaction is accelerated because the distillation of the degradation product (acrylic acid) pulls the balance of the reaction in a better direction to produce acrylic acid, and the effectiveness of the degradation of Michael's compounds increases. Examples are not limited and distillation can be carried out in batches There are the semi-continuous type and the continuous type, but the continuous type is preferred, so the shape of the reaction device is not specified, and in general, the reaction device of the distillation is similar to a simple reactor such as a boiler distiller, a distillation column, and a reflux column. The distillation column (distillation column) is protected from

A Yo type plate) supplied with (plates in stages). In the reactor there is a device that combines the reactor with the distillation column and the reactor is protected with a motor that can be used. Generally, the distillation reaction device means the distillation reaction device which can destroy Michael compounds by Adee distillation reaction with suitable sufficient retention time. © A well-known conventional source can be used as a Bln source for the distillation reaction apparatus; However, it is preferable to use a type that guarantees diffusion; To create a heat exchange (all heat exchanger) a sufficient retention time is appropriate. And the use of heating with exchange heat exchangers is suitable as a heat source in the material to destroy Michael compounds in the distillation reaction process. Therefore, when using the cyclic heat exchange, the crushed material in the solution returns to the distillation reaction device quickly Accordingly, the excess heat is transferred to the oil waste, and the problems of polymer formation and sticky spots on the device can be reduced, accordingly, the stability of the smashing process increases in long cycles; accordingly, the cyclic heat exchange process can be performed with membrane evaporation It is the best heat source, but its effectiveness is less than or slightly less in terms of providing the amount of heat and sufficient retention time for the shattered material, and care must be taken when using it and providing the necessary resources.Accordingly, when the membrane evaporator is used as a hal source, it is preferable to use exchange heat exchangers With each other, therefore, the type of plates in the distillation column is the best use for protection from stains in the distillation column.The separation efficiency of by-products that have a boiling point close to acrylic acid increases; An example is furfural ¢ benzaldehyde. At this time stage number 1 or more is theoretically the best and most preferable stage? Or more ; The most preferred one is 11 stages or less or more, and the most preferred one is 01 stages or less, and the ratio of the output is better than vio to 1 or more, and the most preferred one.

9 01 to 4; The volatilization of furfural and benzaldehyde can be reduced by adjusting the phases and the rebound ratio as mentioned in the previous ratios to maintain the quality of the product; The condensation and deposition of acrylic maleic acid 5 acid in the column (components of the remaining solution on the column plates) and the depth of the liquid in each plate can be inhibited; problems such as spotting; The lower the pressure in the column and the higher the operating cost of the utilities. If the distillate is fed into the previous Jie steps such as the manufacturing steps and the absorption steps (a) in the solution cycle; If the solution cycle contains maleic acid; It is possible that maleic acid contains water from the previous steps. In similar cases the amount of water-containing maleic acid is increased in the nutrient solution of the cracking step. Accordingly, he wants to reduce the concentration of maleic acid when feeding to reduce the amount of water contained in maleic acid. Accordingly, the best 0 theoretical number for the stage and the bounce rate are as mentioned in the previous range. For example, the plate array (dish) provided in the shattering reaction process within the Bia bubbling dish; ce plate molded plate; sparkling dish for water; bubble tray; The dish used for overlapping the communication channel (Gib control canal) is a two-way dish; wavy oscilloscope; Dish blocks or something like that. The best use is the dish that has a channel or a double hole and the size of the hole is from 01 to 00 mm (and 0 is more preferable from 17 to 17 mm). In order to prevent condensation and precipitation of acrylic acid and the accumulation of the polymer associated with acrylic acid in the column, therefore, the dish is filled with materials to be used in mixing. It is preferable that the filling of materials be equipped with dishes that have the ability to withstand high pressure and temperature, and which are difficult to interact with the compounds in the remaining source solution. Therefore, it is recommended to pack materials from . stainless and alumina Jie metals

Yeo

No, therefore, the forms of filling materials are important, and those that increase the pressure drop for the reaction of the accelerator are preferred. Filling materials include well-known rings (Fie rings: Raschig, Lessing, poll, flexy and a series of small rings (made by Dotwell); a jumbo ring; an interlocking ring of metal fence© (made by Norton) and Interlocking saddle (made by Norton); packing materials as described by kagu (Chemichal Engineering handbook) kaugkau dinran “Check by Chemical Engineering Academy 6th ed.; page 04; Figures 11 and Mellabak ( 11 ) manufactured by UMO hivy Industrial SAMIT, Inc. ); Jimpak ( manufactured by CHYODA Corporation ); Techno-TACK ( manufactured by SANREI Techno Montz-PAK Corporation | 0 & Manufactured by Interlocks High “(Montz JmbH) Performance Structed Packing (Manufactured by Norton Inc.) and other fillers for base metal sheets described in Chemical Engineering kaugkau dinran (handbook "Check by Chemical Engineering Academy 6th ed.; p. 571). Among the materials are packing Raschig rings, Lessing rings, and elastomer rings; Vo series of small rings;" and large rings Raschig ¢; Because the surface area per 1 m³ and the void ratios for packing materials are higher; The exchanged substance is effective in transporting out; And the pressure drop reduces. Small chain rings are more preferable. When using the plate rack in the distillation column in the reaction device, the trend is from 70 to 2100 from the sum of the numbers of the theoretical phase. where the base point, Yo, is heated to 1715 °C or less; Preferably from 0 to 1710 AD, and the most preferred from 15 to Yéov

- Y-

M. This means that when the top of the column is calculated as in the first stage, the direction of all directions from 0 to 7009 of the sum of the numbers of the theoretical stage is identical to the lower direction with the upper direction of the condensing column plate shelf. So the direction corresponding to the direction with the reaction solution (compounds with a high boiling point) is heated by the heat exchanger with the corresponding side © in the direction of raising the temperature easily in the distillation apparatus, which is the side for one point when precipitating water containing maleic acid by condensation maleic acid and the preparation of polymer conjugates from water containing maleic acid with acrylic acid, and it occurs easily, so at a vector temperature that is low IS, it is difficult for the destruction reaction to occur for Michael compounds, according to this, the preparation of the polymer is possible To suppress and react the resulting degradation of Michael compounds by adjusting the temperature and 0 in a direction between 0 and 71010 of the sum of the number (lil) of the phase, where the direction of the top of the column is a point

The rule is as mentioned in the previous term. The retention time (depending on the separation of the solution to be disposed of from the bottom of the distillation reaction column) of the reaction solution (high-boiling compounds) in the reaction apparatus can be set to suit the temperature at the bottom of the column, but for example from 1.7 to Te hour, preferably from Vo #.. to Yo hour (Jad, and the most preferable from 1 to 10 hours. When the temperature is very high or when the retention time is long, ha The disintegration reactions continue, but this may affect the consistency of the reaction solution, the viscosity may increase, and speckling may occur inside the reaction apparatus.On the other hand, if the temperature is low, or the retention time is short Ol, it is difficult for the Michael compounds to be degraded appropriately. Therefore, in the step of zeotropic drying or the application of the 0 | crystal purification process as a purification step, maleic acid compounds sometimes come out in the form of maleic 4_ that contains water and precipitation can occur easily, so the Michael compounds are destroyed

ra _ with better efficiency and without Cali for the reaction solution when the heating temperatures are suitable for the destruction reaction of Michael compounds to occur quickly at equilibrium and it is dominant at the previous conditions; And the retention time is less. at the heat source” YE of the condensation reaction apparatus”; the heat exchange in a multi-tube; plate type heat exchanger © screw type heat exchanger; reciprocal of rotational ba; Thin evaporation film » reboiler or similar may be used. one, two, or more can be used in conjunction; Therefore, when using a thin evaporation membrane, it is preferable to use the mixture with a Jal partial heat source ¢ If the viscosity of the shattered material is high and the bottom of the column of the reaction device produces high heat, then the type of heat exchanger preferred to be used is heat exchanger Ye. Rotary, because the suppression in the forced heat exchanger type is partially equalized by the presence of a circulation pump, and when choosing a system in the solution at the bottom of the column of the reaction device, it continues and exits outside the reaction device. And the production of polymers and precipitates in the reaction device is reduced compared to the case of heating through the surface wall in the reaction device, so the retention time in the thickening device is appropriate. 13 If the viscosity of the remainder of the source liquid was high, the degradation reaction of Michael's compounds "may 0 come out of equilibrium for a long cycle as described in the Japanese patent 11-9778 Tz 14 For the diffusive Jalal, the heat exchange can be in the form of The diaphragm in some tubes is that this heat exchanger has a composition of JL daisy in Ala with high heat and efficiency required for boiling and evaporation in the reaction apparatus, therefore it inhibits the occurrence of damage to the properties of the solution

- ote

To make the reaction process better at 100 degrees or to 770 degrees and the most preferred

It occurs at 101 to Yeo degrees m

At this time, the preferred type of heat exchanger is limited to smashing to a degree

The temperature (the temperature of the bottom of the column) and the temperature of the source, which are from 15 to Av m; It is preferable for © that the difference between them be from Ye to Te, and when knowing the characteristics of the liquid, Jie is stability and exchange.

The heat exchanger, the change in characteristics, Jie, the increase in spotting and the increase in the viscosity of the oil is

It is governed by the difference between the smashing temperature (column bottom temperature) and the heating temperature as mentioned

In the previous field) and the most preferred is that the difference between the temperature of smashing and the degree of the bottom of the column

and temperature in the field.

0 And it is recommended that the amount of the circulating solution from the bottom of the column be in the compulsory heat exchange type, and it is preferable that the quantity be between 001 and 7000 cubic liters per hour, and better than that, 040 to Vou cubic meters per hour ; To ensure the effectiveness of the available heat and to discourage spotting from plankton, determine the amount of heat dispersed and adjust the amount in the cycle, as in the example, which is better for organizing the process for a longer time. Therefore, the collision plate in the solution and the like can be introduced into the system to reduce the

VO problems such as spotting and deterioration of solution consistency; When the points are cut from the surface of the liquid, when the liquid returns to the condensation column (condensation reaction system), the effect of impurities leading to the formation of polymers and sediments on the upper side of the collision plate is reduced. The preferred pressure in which the acrylic acid is produced by the smashing reaction and the bulk of the useful ingredients in the acrylic acid Jie feed solution that can evaporate and the acrylic is generated

acid + by hydrolyzing the Michael envelopes in the Ally dissociation step followed by equilibrium reactions.

Yeov

41 - — eg + the pressure of the column at the top (pressure gauge) of the pressure device is preferably 1.7 to 14 kPa (04 to torr $A and preferably more than 17.73 to 0 001 kPa (to 0:70060) from 01 to 7.7 kPa (torr You (vou) most preferred (operational pressure) column led temperatures preferably between 00 to LC * 1560 0 and more preferably 80 to 111 "©. Ninety to 0171 degrees Aggie It is also recommended to discourage distillation of by-products together by setting column top temperature and column top pressure as indicated above due to The boiling point of furfural “protoanemonin” is close to that of benzaldehyde “acrylic acid.The quality of the product is maintained even if the distillate of decomposition step 0 (c) is fed to the absorption column (absorption step (1)) which contains acrylic acid and the high-boiling components in the separation column (the high-boiling components in the separation column step (b.)) 1 as well; because the high temperature is not required for the dissociation reaction of Michael' compounds "compared to the temperature case very high at the top of the column and very high pressure Je at the top of the column; It is difficult to damage the properties of the reaction solution and not to reduce the decomposition rate. 0 in decomposition step (c); one or more selected Lewis acid catalysts; Lewis base ¢ and inorganic acids such as sulfuric acid and phosphoric + and alkali metals alkali earth metal ¢ and organic acids Jie organic acids: methane sulfonic acid and p-toluene sulfonic acid, N-oxyl compounds, amines and the like Ys Say used as a catalyst in the decomposition in order to promote the dissolution of compounds Michael ""

_ogy — Among the above co-factors of decomposition; n-oxyl compounds; Preferably used. The reason is that when the n-oxyl complex acts as an inhibitor of the polymerization of acrylic acid when it diffuses into the solution within the dissociation step; It is a distillation reaction column (distillation reaction device) for other steps; For example ; The absorption step of acrylic acid which contains gas and high boiling point © separator (high boiling point separator column 1) ; Furthermore the amount added as a catalyst is preferably 0.05 to 7 7 based on the liquid at the bottom of the column of the reaction apparatus; Preferably more than 100 to 1 7th of its mass. like that ; The catalyst will be sufficient to conduct the dissociation and in addition the timing of the catalyst is not limited to just the dissociation step. For example ; The catalyst may be added when 0 high-boiling components are fed into the reaction Bead used in the disintegration step; In addition to the absorption column in the absorption of acrylic acid and the different distillation columns used in each step. [Collection step (d)] Acrylic acid is generated by the decomposition of Michael compounds in the dissociation step (c) distilled to 0 out of the upper column of the reaction distillation apparatus 1 (dissociation step) and delivered to Acrylic acid absorption step (not explained) and high-boiling components separation column (11 distillation column, high-boiling component separation step (B1)) through line 1.4. They are collected in successive steps. At this time the concentration of maleic acid in the distillate extracted from the upper side of the Yo column of the Distillation Reaction Apparatus -7 is best as low as possible; But he'd rather be Yoo

Yio

7 of its mass or less and preferably more than 0.8 7 or less ; It should also be preferably 01#7 of mass or less, and preferably more than 0.6 7 or less. And so. The condensation troubles of acrylic acid derived from the distillate coming out of the Y-distillation reaction device has reduced ¢ and the amount of water entering the composition of the maleic acid contained in

© High Boiling Point Element Feed Solution 1) distillation column of the step in order to reduce the concentration of maleic acid in the distillate; For example ; It is preferable that a number of theoretical phase of the reactor uses a reflux device and the practical conditions are set as the reflux rate as mentioned above.

Ve as well; the content of Michael compounds in the distillate is 0.7 7 or less; More preferably LY / or less. like that ; Oxygen or a gas containing oxygen may be added to the distillate distilled from distillation apparatus 7 in order to prevent polymerization of the acrylic acid in the distillate. It contains All oxygen gas introduced into the liquid gas phase or liquid phase in the distillation lea - 7.

Yo includes pure oxygen-containing gas; Mixed gas, which is then obtained by diluting oxygen with unreacted gas (nitrogen and its analogues) air and its analogues. The amount of addition is prepared preferentially so that the concentration of oxygen is 0.00 to 75 of the weight depending on the volume of the distilled gas from the upper side of the column for the reaction distillation apparatus 1 and the most preferred. 0 to 7 of the weight and the most preferable 1005 to 71 by weight when the concentration of oxygen

[ - 44 In the distillate within a.d.) mentioned above, the effect of inhibiting polymerization is obtained consistently. In addition, the additional amount of active substance of acrylic acid that has been disposed outside the acrylic acid production system combined with oxygen or oxygen-containing gas is suppressed at a low level and the low level and pressure control of the dissociation step becomes ler © As previously described, the acrylic acid production process of the present invention provides a high-boiling component separation step (B1) which separates the high-boiling components in the feed into the dissociation step (C); as the step prior to dissociation step (c); The high-boiling components in the high-boiling component separation (Vo) step are fed to the dissociation step (c); The acrylic acid generated by the decomposition of Michael compounds is fed on the dissociation step (c) to the absorption step 0 of) the high-boiling components separation step (b1) and their analogues to be collected (collection step (d) ). (lay) All distillates can be fed from the dissociation step (c) to the absorption step (a) through the high-boiling component separation step (b1) (Fig. 1 reaction distiller 7 to line, A-11 to line . 1 11 to the absorption column©); or to the distillate from dissociation step (c) which Sea) (1b) is fed to step (a) during the VO high-boiling component separation step

WL to line 1 distillation column To distillation column 4 L Reaction 7 is distilled to line The remaining compounds can be fed to absorption step (a) through line 0 (¥) to absorption column passing through component separation step With a high boiling point (B1) (distillation device 11-a to the absorption column ©) and all 111. are fed to line 11- / to line 7 Jel) Ye distillates obtained on it from the dissociation step (c) to the desorption step (a) through the Yio step

Separation of components with a high boiling point (Ve) and is the most preferred (shape patterns ? and oF, but the absorption column is not explained). The efficiency of the acrylic acid production step can be further improved by adopting the previously mentioned model. Also, when the high-boiling component separation step (Eb1) is provided as a step prior to the decomposition step (c); It is possible to collect acrylic acid with components with a high boiling point in the component separation step (B1) and the successful dissociation step (C) and the like without preparing severe and severe separation conditions in the purification process (B), such as purification by crystallization and distillation purification . In addition, the decomposition of Michael compounds is carried out easily. In addition, when the distillate is fed to the dissociation step (c) to the absorption step (a) through the step of separating the component with a high boiling point (Ve) (b1). Undesirable components are reduced, especially maleic acid, which leads to problems such as Precipitation of the impurities furfural Jie and benzaldehyde that are hardly separated by crystallization in the high-boiling component step (b1); therefore the load of the purification step (b) can be reduced. In addition, even when the purification step (B) is performed under reaction conditions SY, it is characteristic of the purification process; A group of acrylic acid that was not separated in the 0 purification step (B) (crystalline purification step (Yer) and similar) is collected at successful temperatures in the component separation step (B1); By adopting the previous model. In addition, since the acrylic acid generated by the decomposition of Michael compounds contained in the low-boiling components in the dissociation step (c) was collected through the low-boiling component separation step (b of), the improvement of Product of Lay acrylic acid i - 41 —

So the sequential steps are optimized; While the successive paragraphs of the co-linked successive laws lead to the complementary interaction. The preferred mode of the present invention previously described is described later in detail; Representative process shown in Figure 4.

© First, the acrylic acid content in the solution that was absorbed in the © column is fed to the feeding device © through line VL, and the acrylic acid is output from the purification device © through line L. On the other hand, the components that are separated from the acrylic acid are disposed of on the separation device © from the purification device © and are fed to the purification column 1 (the column for separating components with a high boiling point) through line 4-1 the solution containing grade components

0 High boiling on purification column 1; then the distillate (containing acrylic acid and the component acrylic acid with a low boiling point) is purified and distilled off the top of the distillation column 1 column and recycled to absorption column? Through the IIL line, on the other hand, the other bottom solution containing Michael compounds and components with a high boiling point are fed to the distillation reaction device - ¥ through the line, A-? (dissociation step (c)). acrylic acid is recycled

-[, through line 1 distillation column to distillation column 1 generated in distillation reaction apparatus 0 fed with other low-boiling components distilled out of the distillation column and collected as MIL solution to absorption column? In addition, through line 1 distillation column of the Addl distillation reaction device, the solution is discarded. acrylic acid? Through line 1a-1. reaction-

A_47 [Examples] The present invention is specifically described later on based on examples. However, the mentioned examples do not limit the invention and all modifications within the scope of dividing the previously mentioned and later mentioned objectives included in the technical scope of the present invention. The evaluation methods performed in 0 examples are as follows. [ maleic acid quantitative ratio [ The ratio of the amount of maleic acid in the current example to the sum of maleic acid and anhydrous maleic anhydride in the components with a high boiling point for the separation step to the disintegration step is calculated by measuring the masses of maleic acid and the anhydrous maleic acid anhydride contained in 0 solution of the lower column of the high-boiling column by substituting the values obtained under the mentioned equation (1) to obtain the ratio of the amount of maleic acid. (maleic acid AS) by reacting the maleic acid content in the bottom column solution with methanol and by measuring the mass of monomethyl maleic acid generated through isolation and purification and converting the obtained value into the mass of maleic acid. In addition to that On the other hand, the anhydride (ALOU) maleic acid © is not reacted with methanol. On the other hand, the mass of the anhydrous maleic acid anhydride was obtained by measuring the total mass of the maleic acid and the anhydrous maleic acid anhydride. contained in the bottom column solution by liquid separation and purification methods and subtracting the mass of maleic acid from the total mass of maleic acid J and 0 of the anhydrous maleic acid anhydride to calculate the mass of the anhydrous maleic acid anhydride

Yeov

$A — — [ Equation 1 ] maleic acid [ (mass) / [ maleic acid (mass) + anhydrous maleic acid (mass) [ 6# << .no) 1) [Conversion rate] © The mass of the high-boiling component containing the feed solution to the disintegration step and the mass of the Michael compounds contained in the distillate after the disintegration step were measured by means of gaseous isolation and purification methods, and the rate of Michael compounds was calculated. Equation (¥) mentioned later. [Equation ?] Transformation (7) = Mass of dissolved Michael compounds / AS Michael compounds before dissociation 001 * (Y ) Ye [Optional] Then measure the mass of the dissolved Michael compounds Michael; and the mass of acrylic acid in the component with a high GLB degree fed to the dissociation step and the mass of acrylic acid contained in the distillate after the dissociation step from the Gob. (mentioned later. Vo [Equation (©)] Optional (7) = Mass of acrylic acid generated/Mass of Miches! compounds before dissociation * 001 (¥) [Formation of acrylic acid] Gas made Containing acrylic acid obtained by oxidation of propylene Yo with the catalyst in the gaseous state in contact with the absorption solvent Yéov

A - $4 -

To absorb it as a solution containing raw acrylic acid (absorption step) and then the components were removed

with a lower boiling point than the solution containing the obtained crude acrylic acid

It is applied to the azeotropic separation step to obtain a solution containing crude acrylic acid

It contains the component with a high boiling point. The composition of the solution containing the crude ©acrylic acid is acrylic acid : 793.05 by mass maleic acid 70.49 by mass maleic acid

anhydride : 70.77 by mass; Acrylic acid bipolymer (Michael compounds

ZY:) by mass furfural : 750.07 by mass" benzaldehyde : 70.07 by mass;

70.017: protoanemonin by mass and water: 70.6.5 by mass.

[Experimental example] 10-1

0 shal acrylic acid was collected by referring to the step diagram shown in the figure ?. In addition to that, in experiment Example No. 1-1, a boiling point separation column (number of stages: 50 stages of perforation plate distillation column) was used as a distillation column 1 for the step of separating components with a high boiling point. A reaction plate distillation column (Step number: 01 steps; 7 holes plate distillation column) was used as the reaction distillation apparatus ¥ for the dissociation step. In addition to that ads when using

0 disintegration step heat exchanger; Forced circulation type heat exchanger (UE) (Fig. 1) and when feed-through solutions are fed to the high-boiling separation column and the reaction distillation column; It was fed after removing impurities in solutions through stains (7-1 to 2-6). The degree of dissociation (column bottom temperature of the reaction distillation column) of the dissociation step at this time was Co We and the site temperature 7860 (the sixteenth step among the Vo theoretical step) of the total number of

0 The theoretical steps of the reaction distillation column were 171 °C, and the reflux rate was LE. In addition, the temperature of the heat source for the forced circulation type of heat exchanger was 771 °C, and it was

The difference in temperature (A) 1) between the decomposition temperature and the heat source of the forced circulating hall exchanger is 90 m. First, the solution containing the crude acrylic acid that was obtained from the Gob of previous manufacture, acrylic acid, is introduced into the distillation column (high-temperature separation column) with the distillate from the dissociation step described later. Distillation column 1 is controlled on working pressure: 47.7 (mmHg YO ) hPa and column bottom temperature: 94 5p Aad alee on reflux rate: 0.9 and residence time of distiller: 0 hours; The acrylic acid and other low-boiling components that were distilled from the top of the column were distilled to obtain the solution containing the high-boiling GUS (components with a high boiling point of 0) containing Michael compounds from the bottom of the column For distillation column 1. In addition, it contained the ratio of maleic acid (the ratio of the amount of maleic acid that was calculated from equation (1) mentioned earlier is also similar to the later experimental examples) to the amount of maleic acid contained in The solution containing components with a high boiling point was 738. In addition, Michael's compounds were contained by 747 by mass. Then the solution containing 0 high-boiling components obtained is introduced into reaction distillation apparatus 7 (reaction distillation column with plate) at 10 kg/h and Michael compounds are analyzed to be collected. The reaction conditions of the JY reaction distillation apparatus (dissociation step) and the result were shown in Table 1. Then the decomposition process of Michael compounds was completed for two weeks; But Jie problems did not occur, generating spots in the device and high pressure in the device. The viscosity of the disposed oil was also low (Ye solution, the bottom column of the reaction distillation device (Y), and the analysis of Michael compounds was carried out consistently. Measurement of Yeov

A _ 1e - the viscosity of the disposed cul die at a constant temperature (100 ° C) using a variable type viscometer. The transformation in the Michael compounds at this time was 7785 and the resultant was the acrylic acid of the Michael compounds fed © JAY.Y [Experimental example] 7-1 shal The acrylic acid was collected by the binding method As an experimental example 1-1 with the exception of using the partial source liquid of the crystallization step, which was obtained lle by means of successful crystallization purification of the absorption step in the previous formation of acrylic acid SA as a solution containing components with a boiling point High fed to the distillation column 1 0150118000 column (high separation column). Boiling 0 7717.1: acrylic acid. The inn at this point was acrylic acid. The components of the solution containing 7000 were: anhydrous maleic acid anhydride By weight: 76.77% of the weight: maleic acid / 0.10 of the weight by weight: 7.0 Michael (acrylic acid compounds by weight; a dipolymer by weight. 70.07: benzaldehyde by weight weight.” The aforementioned raw solution containing acrylic acid (the source liquid) was fed to the distillation column 1, and the distillation column was operated under the conditions shown in Table 1 to obtain the solution containing the component With a high boiling point containing Michael compounds from the bottom of distillation column 1, the solution containing the component with a high boiling point at this point contained maleic acid 777, depending on

Yiov i _ ey - It was the quantity of compounds. Anhydride anhydride maleic acid and maleic acid on the total amount of L by weight. 7 47 Michael Was the solution containing the components with a high boiling point fed to the reaction distillation apparatus? Z To conduct the dissolution of the 1-1 compounds, the reaction was carried out under the same conditions as the experimental example lea and 1 was run and the decomposed product was collected. The result was shown in the table, Michael ©, but some problems such as spotting did not appear in the Michael device. The dissolution process of the reaction compounds and some other facilities such as heat exchangers and high pressure continued; The viscosity of the discarded oil was also low, and the reaction was carried out stably. It was higher, 0-1, in the example, maleic acid, in the proportion of the ol amount, and it is considered according to the above-mentioned reason.

CT to 1-1 and according to the result of experimental examples 1-7 and 1-1 with a little compared to examples 0 in a high boiling point component containing maleic acid solution. It is understood that when there is an amount of A feeder to the shedding step is initially low and the high viscosity of the solution and the concentration of the polymers suppresses and disintegrates to be effective. Obtaining a solution containing a high-boiling point component in the conditions of the experimental example VO was changed to the case shown 1 distillation column except that the operating conditions of the distillation column and the solution containing the high-boiling point component obtained contained 1. In the table, maleic acid and maleic acid in a ratio of 7767 depending on the total amount of maleic acid on ZY + in proportion (Michael) compound dimer acrylic acid, as well as anhydrous anhydride was contained by mass of the solution containing the high-boiling point component

oY _— — getting it into a distillation reaction device (distillation column) and the dissolution process of Michael's compounds continued for two weeks, but no adhesion of spots was noticed in the reaction device and other facilities. Occurs as well as the viscosity of the waste oil was little and the process was stable © The conversion of Michael compounds was in the proportion of “ZY” and the acrylic acid yield of the fed Michael compounds was 7 and the result is shown in Table 1. [Experimental Example 7-7 ] A solution containing a high boiling point component was obtained in the same way as Example 10-1 except that the operating conditions of the distillation column were changed to those shown in Table 1 and the solution containing Ne of the high boiling point component obtained contained contains acrylic acid by 7017 by mass and contains maleic acid by 777 by weight depending on the total amount of maleic acid and anhydrous maleic acid The solution containing the component was fed to the reaction distillation device 7 and a dissociation process was performed Michael compounds Also, the solution that was obtained contained a small amount of Michael compounds compared to the experimental example 1-7 when the separation 0 column was fixed after two weeks, starting from the disintegration process, a small amount of stains stuck to the exchanger thermal. High viscosity of waste oil has also been demonstrated. As well as the level of adhesion spots and the rise in viscosity were at the level of the process of disintegration and can be conducted temporarily. The conversion of Michael's compounds at this time was TAY, and the acrylic acid yield of Michael's fed compounds was 777, and the results are shown in Table 1.

0e _

It is understood, according to the results of the experimental examples 7-1 and 7-7, that the rise in viscosity of the solution and the generation of

The polymers were then inhibited and the dissociation step was carried out in the presence of a concentration of Michael compounds as a preferred field (-71).

0 by mass based on 770000 by mass of the solution containing the component Je (boiling point)

of the present invention and adding an amount of maleic acid to the solution containing the high-boiling © nutrient component in the dissociation step.

[Experimental example [Y=

A high boiling point component separation step was performed. The dissociation step is the same as in the experimental example -1

1 Except that the degree of the position is 780 from the total number of the theoretical stage in which the upper side was used

From the column it was at 1410 degrees, Ashe, in which the process of collecting acrylic acid was carried out, and the solution 0 containing the high-boiling component contained Michael compounds with a percentage of 47 7 by mass and maleic

Ml maleic acid and maleic acid in a ratio of 8/a0/ depending on the total amount of acid

anhydride. The operating conditions are shown in Table 1. When the distillate was analyzed from the top and column of an apparatus

Distillation - reaction 7 and the combined solution in the lower stage of the reaction apparatus during the operation of the apparatus

Distillation and reaction 7 Maleic acid and anhydrous maleic acid anhydride were contained in a percentage of 78 Ye by weight in the distillate and contained maleic acid and anhydrous maleic acid anhydride in a percentage of 79760

By mass in the collected solution in the lower stage of the distillation column -

interaction.

Despite the continuation of the reaction distillation process 7, the pressure in the device was raised and the process continued for a while

A week then stopped and the conversion of Michael's compounds was ZA and the product of acrylic acid and Michael's 0 nutrient compounds were 7978 and the results are shown in Table 1. In the experimental field 1-7 the degree of

Yéov

eo _ -

The adjacent heat near the bottom stage of the distillation column is the reaction at

0 Agta score which is slightly higher compared to the experimental example YY (1-1 degree).

As a result (AN) maleic acid condenses near the lower stage in the reaction distillation column and it was considered that

Maleic acid, which contains water, is easily conjugated with Bas acrylic acid. And more; oo Since the amount of maleic acid present in the solution containing the high-boiling component was

Consider that the amount of maleic acid distilled from the upper side of the distillation-reaction column has been ay

By heating if it is considered in experimental example 7-1 that although the solution containing acrylic acid

In the same way as in experimental example 1-1, the amount of maleic acid in the solution was raised

Containing the high-boiling nutrient component in the dissociation step because the maleic acid present in the acrylicacid 0 compound was too much.

[Example Experimental 7-7]

Acrylic acid was collected according to the process and steps in a similar way. For the NY experimental example, although

Operate the reaction-distillation apparatus by setting the temperature of the lower stage at 110 degrees

And adjusting the reflux ratio in the atomizer-reaction at LF at this time, maleic acid VO and anhydrous maleic acid anhydride were obtained with a ratio of JY by mass in the total distillate of the distillation apparatus

The reaction of maleic acids and anhydrous maleic acid anhydride in a ratio of 7730 by mass in solution

of the compound at the bottom stage of the distillation column - reaction. Operation conditions and the like device

The reaction is shown in Table 1. The distillation column-reaction was continued for two weeks but was not observed

Adhesion of stains in the distillation apparatus - LY reaction, and no problems such as high pressure occurred in the apparatus, as well as the viscosity of damaged oils was low, and the operation was stable. Transforming Michael's vehicles

wrr

— 1e - was (LAT) and the yield of the fed acrylic acid was 7/4 and the results are shown in Table 1. The temperature was set in the experimental example apparatus 7-? adjacent to the lower stage of the distillation column - the reaction at 0011 Q which is slightly less compared to the experimental example 1-? to be operated and the reflux ratio therefore the problems Jie considered water-containing maleic acid precipitation, polymer preparation © and maleic acid distillation to be subdued [Example [YY] The acrylic acid was collected according to the operation and the steps in the experimental example (Jey N=) Each reaction device was operated by adjusting the temperature in the lower stage (VT stage within Yo theoretical stage) at 0 degrees and the reflux rate In lea distillation the reaction at 01.7 and more the solution containing Ve on the high boiling point component feeding the reactor contained Michael compounds by 47 7 by mass and 2610 maleic by 777 depending on the total amount of L maleic acid and anhydrous maleic acid anhydride. Likewise, maleic acid and anhydrous maleic acid anhydride were in a percentage by mass in the total distillate of the distillation-reaction column, and the percentage of maleic acid and anhydrous maleic acid anhydride was 775 by mass in the combined solution at the bottom stage of the column Distillation Vo reaction The operating conditions and reaction apparatus are shown in Table 1. The distillation apparatus - reaction 1 continued to operate for two weeks, but ly the pressure was raised in the distillation apparatus Operation ¥ The operation was shut down after a week of starting and switching Michael compounds were AL: and the acrylic acid product of Michael compounds fed JY and the results Ane in Table 1. According to the results of the experimental examples from 1-1 and 1-0” to FoF It is understood that the amounts of maleic acid and maleic acid | 0 anhydrous anhydride continued in the distillation of the distillation column - the reaction was reduced by control

It depends on the temperature of the lower stage of the distillation column, the reaction of the dissociation step and the adjustment of the reflux ratio. It is also understood that this contributes to reducing the amount of maleic acid in the solution containing the high-boiling component that was used in feeding the dissociation step to an amount or less and the acrylic acid was collected more effectively using the conditions described as el © in the dissociation step. [Example Experimental 4-1] The acrylic acid was collected in the same way as Experimental Example 1-1 except at process pressure in the distillation column—the reaction was at 47 YO (torr). The degree of disintegration was set at 000 and the reflux rate was set at

Sy LY and distillation apparatus - reaction? Shown in Table 1 and operating conditions of the distillation column 01 maleic The solution containing the high-boiling component feeding the distillation reaction device ¥ contained 0) anhydride ALOU maleic acid and maleic acid in a ratio of 294, depending on the amount of 0 percent of the compounds Michael was 747 by mass) and more than that when the components of the distillate were analyzed during the operation of the distillation apparatus - Reaction 1 The distillate contained maleic acid and anhydrous maleic acid anhydride in a proportion of 701 by mass. Device 7 continued to operate, but le showed that the VO ratio of maleic acid was high in the solution containing the high-boiling component, a problem of maleic acid precipitation occurred in the column, and a pressure rise occurred. The process stopped one week after starting the distillation apparatus - reaction 7 was confirmed for spots inside the column as the heat exchanger. The conversion of Michael compounds was 77648, and the acrylic acid yield for the Michael compounds fed was 774. The results are shown in the table?

OA — — [Example Exp 4-7] The acrylic acid was collected in the same way as Experiment 1- except that the operating pressure of the distillation reaction column was set at 350 hPa (479 torr) and the decomposition temperature was set at 10 m, reflux rate set at 0.7, operating conditions of the distillation column (¢) and distillation apparatus -© reaction? shown in Table 7. Also, the solution containing the high-boiling component feeding the distillation-reaction apparatus contained .75 maleic acid depending on the total amount of maleic acid and anhydrous maleic anhydride (the proportion of Michael compounds ' was 747 by mass) ly of that. Laie The components of the distillate were analyzed during the operation of the distillation apparatus - reaction? The distilled substance 0 contained maleic acid and anhydrous maleic acid anhydride in proportion 78 by mass of the whole The disintegration process of Michael compounds continued for two weeks but no spots were confirmed in the still-reactor and other auxiliary facilities and more; It was at a ratio of ZA 0 and the yield of acrylic acid for Michael compounds fed was 701. The results are shown in Table 7. According to the results of the experimental examples from 1-1 and ;-1 to ;-?, it is understood that The amount of maleic acid in the solution containing the high-boiling component that was used to feed the dissociation step is reduced to a specified amount or less; and the amounts of maleic acid and anhydrous maleic acid present in the distillation column - Jeli I said effectively by varying the operating pressure and reaction temperature of the Yéov distillation column

4e -

distillation column - reaction to Ale Als and collection of acrylic acid effectively while precipitation was prevented

maleic acid in the column.

[Example 0]

Although the component separation step, Je, boiling point, and dissociation step, Jie, was performed using the example method 1-1, except for © that he used a simple distillation apparatus (a device that performs both filtration and condensation, apparatus combining a

(still and a condenser instead of a distillation apparatus - reaction? in the dissociation step. solution composition

The feeding related steps and operating conditions are shown in Table SY

When the composition of the distilled substance was analyzed from the simple distillation apparatus, the distilled substance contained:

maleic acid and anhydrous maleic acid anhydride in a ratio of 718 by mass of the whole and while it continued

0 The process of dissociating Michael compounds for one week. Spots were confirmed on the Jie heat exchanger auxiliary distillation apparatus. In addition, the viscosity of the solution in the reaction apparatus was very high. As well as the conversion of Michael compounds was ZAY and the acrylic acid yield of Michael compounds fed was LV and the results are shown in Table 7. [Experimental Example 1]

9 Was acrylic acid collected according to the steps shown in the figure? As well as the example + and use a distillation column with a tray with a sieve with a number of stages consisting of 500 stages as a distillation column 1 (a column for separating components that have a high boiling point) and use a distillation column - reaction 1 with the tray Distillation device - reaction (number of stages Yo) separation column (column) with dissociation step and use thin film evaporator as heat exchanger B4 equipped with dissociation vessel

Yo 7-1 as a heat source and then obtain the solution containing acrylic acid in a manner similar to the example

Yéov

a.1-

1.1 At operating pressure of capacity 1 distillation column and the solution was placed in the distillation column 1-1

mmhg (hpa 35) and bottom column temperature TA °C and operated at 0.4 reflux ratio and time

Reaction © hours to obtain a solution containing a high-boiling component containing

Michael compounds from the bottom of the distillation column 1. pall acrylic acid was obtained from the Ad© distillation column. Then the solution containing component Je was introduced to the obtained boiling point

It in the distillation apparatus - reaction? (Tray distillation reaction column » dissociation step) at ES 01

/ h and the acrylic acid and low boiling point components were evaporated by E-4 thin film evaporator

To circulate in the distillation apparatus - the reaction, and on the other hand, the solution of the lower part of the column was introduced from

Evaporator 2-4 to disintegration vessel 7-1. Dissociation vessel 7-1 was operated at 050 seconds and 0 normal pressure and the reaction time was 10 hours. The dissociation solution heat dissociated in the dissociation vessel was cycled to an evaporator

The thin film 18-4 was removed from a pump, then the dissociation reaction of the Michael compounds and the assembly of acrylic acid took place.

generated. When the dissolution of mechanical compounds continued for 9 weeks, the viscosity of the solution was raised in an apparatus

Dripping - reaction ¥ and minor stains were found on the device. Auxiliary facilities Jie heat exchanger

Although the operation was at the possible level. The conversion of Michael compounds was 770 and the product of acrylic acid Ve to Michael compounds was LZ. Dissociation conditions and yield are shown in the table?

[Experimental example [V

The collection of acrylic acid was carried out in the same way as Example 1-1 except that the aqueous solution contained tempo

1. (4-hydroxy-2,2,6,6-tetramethylpyperizinoxyl) was placed at 7 kg/h of

The side of the top of the distillation column 1. The process of dissolution of the Michael compounds continued for two weeks, and Lady To did not have spots in the distillation apparatus - reaction ¥ and other facilities, and no pressure rise occurred in the

m

11 = column. SUAS, the viscosity of the waste oils was low and the distillation column-reaction was working stably. The adhesion of the polymers in the Michael Dissociation System was negligible compared to other experimental examples and the viscosity of the waste oil was also low. The conversion of the Michael compounds was in the ratio of ZAA and the acrylic acid product that was used in feeding the dissociation step 7787 and the dissociation conditions and results are shown in © Table 1. [Experimental example [A] collected acrylic acid and carried out on Similar to experimental example 1-1 except that the decomposition temperature (the temperatures below the column) was set at 1700 ° 0. ; The temperature of the heat source rotary type heat exchanger is set at 7710 *©. Distillation Reaction Apparatus 1 - It was operated at the 0 degree temperature (AT) difference between the decomposition temperature and the decomposition of 100°C. When the decomposition process of Michael’s compounds continued for two weeks; Pigmentation is observed on the surface heat carrier of the heat exchanger. The conversion ratio of “Michael compounds” was AY and the yield of acrylic acid to feeder of “Michael compounds” “LL YA.” The result is as shown in Table 7. Table 1 [JEN | Jed [JR | JR [JAI | JED] Example | [os Yeov

117 — - Experimental 1 Experimental 1 Experimental 1! Experimental | Demo 1 Demo 1 Demo | Experimental Y-v r-v + l 10-1 7-1 m-1 1-1 Separation step of the high-boiling point compound bottom temperature d b "residence time h) Ve b A solution containing a high-boiling point component (feed solution For the dissociation step) the proportion of the amount of maleic acid vA +7 As 17 17 YA A 7 containing water the total amount of the mass of maleic acid aA .A .A .A 4.8 Yo 4.6 4.6 .Michael compounds AA A As phase degree VY.10 VY VY.10 Yeu 10" 70 lower maleic concentration 0 at stage Yo lo nor $0 fo £0 $0 $0 lower 7 in mass. The concentration of maleic hid) acid by mass. Y Y Y Y Y A 7 1 bee Y } * > 1 i.e. 1 il yiv 7 a 5 5 reflux ratio of the

A 10 - Change | Change | Change 1 Change | Change 1 Change | Change | Change N-oxyl cis used | user | user | user | user user | user | user | TO Dissociation efficiency of Michael ole compounds cm table? JE JE Example Example Example Experimental Example A | demo 7 | demo + | Demo © 1 Demo ;- | Experimental 4- 1 Y Separation step of high boiling point compound aA 4A aA aA aA AA “a” a “a”|” Jind temperature residence time (hours) VY VY VY VY VY VY Feed rate F/B A solution containing a component with a high boiling point (the feed solution for the dissociation step) ve vy vA TA YA The proportion of the amount of maleic acid containing water is 7 acid. L L L £Y £Y 7 Components Michael Ce | Ytov i — 14 — 10 70 Nor You 0 Ve Degree of Dissociation Residence Time (h)

Yoo 10. Nobody YY. 10 10 Degree of lower stage maleic acid Concentration 7 at lower stage 01 A 8 1 Y Y X A 7 $Y 11 1 Concentration of maleic acid distilled by mass 1 bb none 1" B J bri 1 oo. reflux ratio aaa - not not not not not} » Not used Not used N-oxyl compounds Efficacy of dissociating compounds

Michael

TA As AY Ya AA AY 7 Transformation 3 vi Ao Ao aA qo Selectivity / Mala Dahm 04.0 TA Val 17.4 7 Output vy 11 A Yo. YA 10 exhaust oil viscosity

lo _— — and ') \ *( 'F/B' in Tables 1 and y stands for feed rate (kg/h) and solution extraction rate of the feed solution to the high boiling point component separation step and 'ratio The amount of maleic 1 containing ell means the percentage of maleic acid calculated from the above equation (1) and the total maleic acid laid (FY) means the total amount of maleic acid and maleic acid Anhydrous anhydride© and 'residence time (; *)' means the value calculated by the formula and 'mass of the remaining solution' in the reaction apparatus/feed rate of the extracted solution discharged from the reaction apparatus. and 'minimum phase (© *)' means column phase distillation column — reaction with field 01 ad theoretical phase respectively oe 1 ¥ 0 6” Ve catalyst 1 then prepare catalyst molybdenum bismuth according to description of example 1 of 4 7.0156 - AA - JP and this is referred to as catalyst 1. The metal element component of catalyst 1 was Si 0.08 4103 M 11.5 311.7 0.2 Mo 12 11 catalyst II 8 Then prepare the catalyst vanadium 1 molybdenum according to To describe example 1 of AA = 0065 * 504 JP - This is referred to as the (second) catalyst The metal component of the IT catalyst (excluding the atomic oxygen ratio) of the (second) catalyst was . 1.2 85 1002.3 1177 6.1 17 12 140 Yeov

[Experimental Example 4] Acrylic acid was prepared according to the steps shown in Figure © [Manufacture of [acrylic acid] Using a reactor for preparing acrylic acid equipped with Ble to circulate the heating medium at an outer end and a stored reaction tube with an inner diameter of Yo mm and a length of 0001 mm and is equipped with a perforated tube plate © with a thickness of VO mm dividing the casing into 7 top and bottom in a position from Your casing lower part . The heating medium was circulated to the lower part and the upper part of the reactor to control the temperature and (1) ceramic balls (length Y mm) with an average diameter of mm and (Y) a mixture in which the catalyst was mixed ( I) with ceramic balls with a diameter of 0 mm by Verve 0 | (©) catalyst (1) and (;) Joh rings) layer ©0800 mm) made of stainless With an outer diameter of © mm and an inner diameter of 4.9 mm and a shag of 1 mm. (*) A mixture in which the catalyst (ID) is mixed with ceramic balls with a diameter of © mm with a ratio of Yo:Vo (layer length Teo mm) and (1) catalyst (1) (length The layer is 1400 mm) filled in this order from the lower al to the upper part of the reaction tubes. VO then circulated propylene and air (moisture ratio 1 4) and part of the air discharged from the absorption column?* (circulating gas) were recirculated The relevant feed rates and gas cooling temperature were adjusted for feeding so that the vacuum velocity of the first reaction zone was 1750/hr (517).A compound was also circulated from a gas mixture containing feedstock and the circulating gas that was circulated in the first reaction zone was ZA : propylene by volume; oxygen 715.4 by volume; water 77 by volume and nitrogen gas and propane 00 and acetic acid 5 acrylic acid y Cox and the like as products.

E — 17+ The temperature of the heating medium was modified in the first and second reaction region respectively so that the conversion of propylene from the exit orifice at a pressure of 0.15 Mpa in the second reaction region was Feo +97 in mol and the conversion of acrolein was 7.5.5 + 1 in moles and gas containing acrylic acid 717 by mass of acrylic acid was obtained in the ratio of 1807/7 kg 1 s. Then the gas © containing acrylic acid was cooled to 10001 C with a foot cooler to an acrylic acid absorption column? as a solution. Sia is an acrylic acid adsorption column with materials. It is equipped with theoretical stages consisting of a YY stage and is equipped with a gas feeding hole containing acrylic acid, an exit hole for the absorption solution extractor at the Jind cia column, and an aqueous solution entry hole for absorbing the evacuated gas at the column. Bottom part of the column and a feeding tube for the distillate from the distillation apparatus - reaction for the dissociation step at the 0 side part of the column and is also equipped with a cooler to cool part of the gas to be evacuated from and when the solvent absorbs acrylic acid, hydroquinone containing water equivalent to eda Yoo from million by mass of the amount of acrylic acid in the acrylic acid-containing gas in the absorbent column TF and fed this to the absorbent column at 1001 kg/h. And then the absorption column operation was performed? At the solution at the top of the column with a degree of 11.9 Asie VO and a pressure of 0101 Mpa and the degree of refrigeration of the refrigeration gas 4007 times and the recirculation rate of 779 at this time all the condensed materials have been recycled by refrigeration of the refrigerated recirculation gas that has been recycled in the absorption column?. Then the distillate from reaction distiller 1 was fed into the dissociation step at 7.77 AS/h from the column side fraction of the absorption column column ¥. And the absorption efficiency in the absorption column? It was 0 177 (crystallization step [ Yéov

1A — — Then the obtained solution containing acrylic acid was fed into the absorption column ? to a dynamic crystallizer© and purification was carried out by crystallization 4 times. Then perform dynamic crystallization with the lah crystallization device described in JP-B- 5537. The device is a metal tube with a length of 6 m and an inner diameter of 700 mm equipped with a storage device © at the lower part to which the liquid is transported to the upper part of the tube by means of a circulating pump. Also, the liquid is designed to be able to flow out if the membrane falls off. The outer part of the tube consists of a double jacket and is designed to be at a constant temperature by means of a thermostat and dynamic crystallization is carried out by the method below. 1.crystallization: 0 the solution containing acrylic acid is fed to the storage vessel and run into a tube in the case of a Jie film drop by a circulating pump and the temperature is reduced to the agglomeration point or less at 01 to 780 by mass of The solution containing acrylic acid fed to the storage vessel and then crystallized on the surface of the wall. Sweating: The circulating pump was stopped and the agglomeration point temperature was raised to the adjacent degree and about Zo NY Veo by mass of crystallized acrylic acid was left to filter. After filtration, the solution containing acid 80711 was pumped out into a vessel. Storage and solution leaching.

In the above processes the temperatures and agglomeration depended on the following steps; So it was obtained

acrylic acid at a speed of YY kg / h.

and more than that; The composition of the resulting aqueous liquid taken outside by the dynamic crystallizer was:

4 by mass 717 : acetic acid by mass; 0.4 maleic acid 7 by mass 5 21.00 : furfural by mass acrylic acid dimers /+.Y : benzaldehyde 5© (compounds of AI Ty ( Michael)

[dissociation step]

The resulting mother liquor containing Michael compounds was fed from the dynamic crystallizer © at

The purification step to the distillation apparatus - reaction 1 and Michael's compounds were dissociated to collect 0 acrylic acid

And since the distillation apparatus - reaction? The distillation column with external heat exchanger is Ve approved and the dissociation of the Michael compounds was carried out under conditions of dissociation temperature: 1710 °C; time: ; hours;

The pressure of the top of the column: 71.7 Kpa, and the temperature of the top of the column: AA Celsius. A vapor temperature of 0 V was used

6 As a heat source for the external rotary type heat exchanger and shell press

Mpa was 017 and the amount of solution circulating down the column was equivalent to Yoo m3/h (and the value of

Rotation amount denotes the converted value to state value performed in the factory based on Ve (Example 1 value performed in a microfactory). The temperature difference between the heat of dissociation

And the heat exchanger heat source was YO Celsius. Michael's convertibles were 7970 and selective

acrylic acid was ° Ly and the viscosity of the waste oil (viscometer and solution temperature 2 Yoo m)

.mpas Yo. was

Yéov

; 1 - acrylic acid was collected at 7.77 AS [h from Ad column site of the distillation apparatus - reaction? Rotary to the position of the column side of the column } to absorb Y through the line LA Composition of the distillate from lea distillation - reaction? Shown in the © table described below. When the crystals taken from the dynamic crystallizer were analyzed, the purity was 799.849 by mass, and they contained maleic acid s ppm 8001 acetic acid 5 ppm 08 © for Soom and sppm 1 M furfural ppm: +.° benzaldehyde and Ze formaldehyde by mass and ppm + dimer acrylic acid by mass. After operating for a period of VE for a day, the sticky materials in the device were checked. And the mass of the adhering materials in the reaction device was 0.0 grams transformed every day 0 and the measurements of the results of the above-mentioned transformations of Michael compounds, selectivity of acrylic acid, and viscosity of exhaust cull are shown in Table 4. [Experimental Example 01] In this example acrylic acid was produced by the Alles process of Experiment 9 except using a distillation column with tray as distillation apparatus - reaction 1 in the decomposition step. The apparatus used was equipped with a V0 with 01-stage sifter trays (five-stage equivalent) and a rotary-type heat exchanger (not shown). The dissociation step of Michael compounds is shown below. [dissociation step]

[ vy — — the resulting source liquid in the crystallizer — 0 was fed to a lower stage of the distillation apparatus - reaction ¥ with tray. The thermal dissociation of the Michael compounds was carried out under thermal dissociation conditions of: 171 °C and residence time: ; Hours, the pressure of the top of the column is 7707 Kpa, the percentage of V.0 reflux, and the temperature of the column value is 8 seconds. The rotary © type external heat exchanger process was modified to circulate a similar amount from Example 9. The heat difference between the decomposition temperature and the heat exchanger heat source was Augie Yo, the transformation of the Michael compounds was 797/7, and the selectivity of the acrylic acid was LAA And the viscosity of the waste oil was 118 mpas, and the problems, Jie, stains in the device, were uncertain in the operation of VE day (the amount of sticky substance in the reaction device after operation for a period of VE day YY. grams per day). 0, acrylic acid was collected at 7.77 kg [h] from the top of the column for the distillation apparatus - reaction? and trochanter to the column-side location of the |column to suck. And the composition of the distilled substance shown in the table? Measuring results of conversion of Michael compounds, acrylic acid selectivity and exhaust oil viscosity are shown in Table 4 and more; The crystals from the crystallizer had a purity of 744.44 by mass; 0 and contained: Water: ppm VY: maleic acid “ALS ppm 80: acetic acid” ppm ©0718 by mass ppm >. : furfural and ppm 0.4 : benzaldehyde by mass sppm / + : formaldehyde s ppm 56 : dimer acrylic acid by mass. [Experimental Example] 11 Yeo

[ ' ~ vy -

Acrylic acid was obtained according to the steps shown in Fig. 1. Similar operations to the method of Experimental Example 4 were performed in this example except that a high temperature component separation step was available prior to the decomposition step. Operation after the crystallization step is shown below [high boiling point component separation step]. The resulting source liquid was purified by the crystallization device © © to an intermediate stage (the tenth stage out of 10 stages and this is called “stage”) from the distillation column equipped with sieve trays with a number of stages of 79 Solely Boiling The distillation column 1 was controlled under operating conditions of pressure 9.7 Kpa and a reflux ratio of 2.7 Acrylic acid aes at 7.7 AS / h and the absorption column?

The composition of the distillate from distillation column 1 is shown in Figure 7.

[Decomposition glad] | 0 to the distillation apparatus - reaction 7 in 1 The solution was fed to the bottom of the distillation column and the rotary type heat exchanger process was modified 8011:6 acid. The column solution was disassembled to collect so that the circulation is the same way Experimental Example 4. More than that was the composition of the dissociation solution in

Bottom of the distillation column: 1,777.1 acrylic acid 0 by mass 715.7: maleic acid by mass furfural: dimer acrylic acids 79. benzaldehyde 744.4 by mass and other impurities 79.6 AX and more than The reaction distillation apparatus used was equipped with a heat exchanger and the pyrolysis of Michael compounds was performed at a pyrolysis of 1700 °C and residence time; Hours, top pressure 77.7 Kpa, top temperature Asie TA, and the temperature difference between the heat of decomposition 0 and the heat exchanger heat Yo was C. And the viscosity of the exhaust oil was 100 mpas. And the problems are like i _ vr - gdayum). And measurements of 001 day VE day (in VE spots in the device? They were not confirmed in the running period of 4. The viscosity of the exhaust oil is indicated in the table, acrylic acid, and the selectivity of the Michael compound compounds in the device? It was fed to the lower stage of the acrylic acids crystallization column, and when the crystals taken from the crystallizer were analyzed 1. distillation column? by mass ppm + Y benzaldehyde y by mass ppm “.Y furfural s ppm 01 maleic acid 5 ppm ppm ¢+ dimer acrylic acid s ppm 70 formaldehyde and [VY [experimental example] distillation except using Distillation column 11 In this example the procedure was done as in the experimental example A tray as a distillation device for and operation after the tellurization step shown below [separation step column 01 of the high-boiling component] into an intermediate stage (stage © crystallization The resulting source liquid was fed from the crystallizer equipped with sieve trays with 20 stages and a repeater (1 stage) to distillation column 01 of 0 and reflux rate hpa TAY for boiling. Then control the distillation column under pressure operating conditions

IY Yo and this was recycled to GATP 1 at 7.77 kg/h from the top of the acrylic acid distillation column and then collected by the absorption column? The composition of the distilled substance is shown in the table. [Decomposition]

Ysov

[ — not on the other hand; The Jind solution was fed to the distillation column 1 to the device oY. Michael's compounds present in the solution at the bottom of the column disintegrated to collect acrylic acid, and the solution at the bottom of the column was 77.1 acrylic acid with a mass of maleic acids. 719.7, Feofurals: 74.7, Winsaldehyde: 77.4, Dimer acrylic acid: 44.4 7, and other impurities: 79.76© by mass and more. Temperature envelope: 1071°C and residence time; hours; and column top pressure 71.7 kPa, 0.8 : reflux ratio, and column top temperature 4. The heat exchanger was modified to rotate by an amount similar to Example 9. The temperature difference between the heat of decomposition and the heat source of the heat exchanger was Yoo °C. The conversion of Michael's compounds was TAY 00, the selectivity of acrylic acid was 7948, the viscosity of the exhaust oil was Ae millipascal, and problems such as stains in the distillation apparatus were not proven in the operation of a VE day (the amount of adhering fluid in a VE day) It was 00 gm 1 day). The measurements resulting from the conversion of Michael compounds, the selectivity of acrylic acid, and the viscosity of waste oil are shown in Table 4. acrylic acid for a compound _ from the device? It was fed to the lower stage of distillation column 0 \. And when the crystals taken from the distillation apparatus were analyzed, the degree of purity of the crystals was 7989.97 by weight, the water was 5068 ppm by weight, “ppm acetic acid, maleic acid ppm ¢, and ppm benzaldehyde (+.) + and ppm ¢. + dimer acrylic acid y formaldehyde ppm 7Z”.+ by mass. Jud] 00 demo DY

[ vo — _ acrylic acid was produced according to the steps shown in Figure 1. In this example the process was carried out as in the method of Example 4 except for the as distillation column tray 1 (equipped with sieves from 01 stage) lly assembled a thin film clipper b to heat the resulting source liquid and dissociation vessel 1c and performed the dissociation of the Michael compounds in the dissociation step. © (Dissociation step] The source liquid obtained from the Michael compounds taken from the crystallizer © in the crystallization step was fed to the lower stage of the distillation column and the dissociation of the Michael compounds was performed. The process of dissociation of Michael compounds was carried out in dissociation vessel FV at disintegration vessel temperature of 170 degrees, gale pressure, and residence time; hours, and Ye part of the dissociation solution was fed again to evaporator B by means of a pump and the product was extracted. At this time, the thin-film evaporator "B" and the distillation column 1 were controlled so that the temperature at the bottom of the column was 40 °C. The process was carried out at a pressure of £0.0 kPa, a temperature of the top of the column 0, and a reflux rate of 0.5 to collect acid 8©0116. At this time the conversion of Michael IVY compounds and selectivity of acrylic acid 790 and the viscosity of the exhaust oil was 17 and the stains were fixed to the VO inner part of the distillation column 1 in the VE A day of operation (the amount of adherent material in 14 days is 5000 gm 1), as well as the results of measuring the conversion of Michael compounds, the selectivity of acrylic acid, and the viscosity of waste oil are shown in Table 4. Then acrylic acid 7.77 kg/h was collected from the top in distillation column 1 and this was circulated to the side of the absorption column ©?. The composition of the distilled substance is shown in Table 7. Finally, the crystals, Ye., taken from the crystallization apparatus, were analyzed. The purity of the acrylic acid crystals was 794.848 by mass. It contained water: T + vppm by mass 3 + ppm acetic acid at 5 “V+” ppm: maleic acid and Yeov

[ - 71 formaldehyde “ppm 1: benzaldehyde s 0” Y.AMfurfural ppm: small ppm and acrylic ppm 01: dimer acid by mass and the amount of furfural of acrylic acid produced was We and it was There is a quality problem. [Example Experimental 4] 1© Acrylic acid was produced according to the steps shown in Figure 7. In this example it was carried out in a manner identical to Example 4 except using a distillation column 1, thin-film residual source fluid, and compounds Michael was used instead of the distillation-reaction apparatus in the dissociation step of Michael compounds. Moreover, the thin-film evaporator "B" and distillation column 1 were controlled so that the degree of the solution of the column "Jind" was 10 ° C, and the operation was performed at a pressure at the top of the column Ve, YT, kPa, and a temperature at the top of the column, 98 ° C, and a percentage of reflux 1.0 to collect acrylic acid and at this time the viscosity of the waste oil was 160mpas and the spots were confirmed in 1 distillation column part in a running period of VE day (the amount of adhering material in VE day to g day). Die acrylic acid 7.77 kg/h was collected from the top of 1 distillation column and this was circulated to the side part of the absorption column ©. The composition of the distilled VO is shown in the table? Michael, the selectivity of acrylic acid and the viscosity of waste oil are shown in Table 4. When the crystals taken from the dynamic crystallizer were analyzed, the purity of acrylic acid was 799.434 by mass and water content: + 86 ppm and acetic acid: ppm YV and satisfied benzaldehyde 5 1 furfural ppm +.A 5 ppm 01 : maleic : zero ppm ppm © + : formaldehyde by mass; ppm 0.7 : dimer acrylic acid by mass. Yes table? : demo | experimental wail | demo | demo | demo? Yeov

VY - _— TT nw [ow [wv [oe]] Composition of the distillate in the dissociation step [vy | + | Except | maleicacid | Vee | eo | on - ka | for | benzaldehyde | +o | ot | 6 [eww formaldehyde dimer | ev | ov [ex [ov ee [oat] table; Example Example Jill Example Example 1 opel Demo 1 Demo 1 Demo 1 Demo | experimental Yo. 11 1" VY V¢ 5 Composition of the solution containing the high boiling point component (the feed solution of the dissociation step) vv vo vy 7 0 Percentage of the amount of maleic acid containing water 7 Total amount of maleic Sai Efficacy Dissociation of Michael compounds selectivity shift / en fo oe oe [ee | d | ah and more; table; represented by percentages of maleic acid content to water and total amount of maleic acid The amounts present in the solution are based on a compound with a high boiling point, and are specifically indicated

[ — YA -

'The ratio of the amount of maleic acid containing 'ell' to the weight ratio of maleic acid calculated by equation 1. The 'total amount of maleic acid' indicates the total amount of maleic acid containing water. and anhydrous maleic acid anhydride 'and product [7]' indicates the efficacy of the dissociation of compounds

Michael which denotes the value computed from equation 4 given below:

° Yield [%)] = Conversion x Selectivity 0 100

It is understood from Table 4 that the aggregation of the compound of the distilled materials, the percentage of the experimental ABS ob the amounts of maleic 1 in the distilled materials is reduced to a low level, and that the dissolution of the Michael ' ' compounds and the collection of acryli acrylic acid is taking place effectively in Experimental examples 11 and 11 in which the decomposition of Michael compounds was carried out by the distillation-reaction process during the high-boiling component separation step. And more; 0. It is understood that the dissolution efficiency of Michael compounds is high and the amount of adhering materials in the distillation column - the reaction in which the dissolution of Michael compounds takes place is also low compared to Alla. (table;).More; Since experimental examples 9 and 01 use the distillation-reaction process for the decomposition step of Michael compounds, these compounds are effectively decomposed to a certain degree and acrylic acid is collected, but Lay that the step of separating VO high-boiling components is not provided The amount of adhering material in the distillation-reaction column, the amount of adhering material in the distillation-reaction column, the amount of adhering material, and the viscosity become lle compared to the reaction of experimental examples 11 and AY, and more than that in Ala using the crystallization purification step When the amount of maleic acid in the resulting source liquid is not SE, this liquid can be fed directly to the dissociation step without passing through the 0 high boiling point component separation step. And each of the preferred to provide this step from the point of view of industrial efficiency.

ova ~ and which of the above experimental examples 1 and 41 are examples in which the decomposition does not take place by the distillation-decomposition process. pall) is less and the dissociation efficiency of Michael compounds is lower compared to other examples. Experimental Example 11 A dissociation vessel is used at the dissociation step and it is considered that no preparation of acrylic acid prepared by dissociation residue occurred in the dissociation vessel and the dissociation reaction by distillation ©-reaction. On the other hand; Experimental example VE is an example that does not use a distillation-reaction device and more than that. Although a thin film evaporator is used as a heat source, the heating of the remaining source liquid is insufficient and it is considered that only distillation occurred in the distillation column shill. And more than that, since it is not possible to secure enough time to conduct the dissociation reaction by the distillation-reaction process, it is difficult to perform the dissociation reaction of Michael compounds, so it is difficult to perform the dissociation reaction of Michael compounds. That is, the distillation-dissociation process depends on the dissociation step, and the precipitation of maleic acid is inhibited in the disintegration step, and the liquid in the source is treated at a high temperature and a low residence time. We conclude that the dissolution of Michael compounds and the collection of acrylic acid are more efficient when the high boiling point component separation step is provided. [Industrial abundance] According to the process of providing acrylic acid production of the present invention, and since the problems, Jie maleic sedimentation 0 and the resulting high pressure in the disintegration device, occur with difficulty in the dissolution step of Michael compounds. The dissolution of these compounds is effective, and thus acrylic acid is produced effectively and stably. Yiov

Ae = — This application is based on Japanese Patent No.—¥OYVYA 7005 filed in the Patent Office on December 1, 2009 and No. 617 Youll -1 filed in Japan on July 01, 7. Which then mentioned here for reference. Although the present invention has been described entirely by means of examples, it must be understood that it will be an obvious change and modification for those familiar with this field; Therefore, unless those changes and modifications are far from the perspective of the present invention after being defined here, they must be understood as being within this invention. Yio

Claims (1)

AY - - Claims 1 1 - A method for producing acrylic acid that includes 0) the step of adsorption of a gas containing A acrylic acid obtained by oxidizing le oxidizing ¥ a raw material in a gaseous state as a solution containing .acrylic acid ; (B1) Separation step of high boiling point components in a distillation column during step (B) of purification of © crude solution containing .acrylic acid 1 (C) Step of decomposition of Michael compounds present in boiling point components High 1 “acrylic acid ZY” and “A” (d) the step of collecting an amount of acrylic acid resulting from the dissociation step (z) decomposition 4 so that the ratio of the amount of maleic acid and anhydrous maleic acid A anhydride high boiling point 0 components obtained from high boiling point 11 component separation step (B1) to decomposition step (C) corresponds to the equation below: [Maleic acid TV (mass) (] x100 < 707 0) " 1 ¥ - A method for preparing acrylic acid according to claim 1 consisting also of (Yo) Y a crystallization step of separating compounds obtained from the crystallization of acrylic 1 10 in a solution of acrylic acid 2&1 from residual mother liquid as a product step to purify a solution containing acrylic acid (b) Cus that eda at least one © .of the liquid obtained in the purification step (Yo) and used in the feed 7 in the high boiling point component separation step (B1). Yéov 1?- A method for producing acrylic acid according to Claim 1, where the solution at the bottom of the "column obtained from the high-boiling point component separation step (Eb1) is fed into the decomposition step (C A part of the distillate is fed into the decomposition step (C) of the high boiling point components (Eb1) and a portion of the distillate obtained from the high boiling point components (Vo) ffs is fed © 0 The distillate obtained in the decomposition step 1 (c) is fed into the absorption step (). Where the temperature of the “temperature at the bottom of the distillation column, separation step (B1) for the components of the boiling point ranges between = 1718 C. The residence time of the solution at the bottom of the column ranges from Yo IY; - hour and the percentage of the solution that was used In feeding in the distillation column © to a mass of the extraction solution from the Jind distillation column 1 ranging * to .01 1 © - A method for producing acrylic acid According to any of the claims Cus 5-1, the concentration of Y Michael compounds in the high boiling point components that were used to feed the ¥ decomposition step (c) ranges from 01 to Ze by mass. 1 1 - A method for producing acrylic acid according to any of the claims 1 to © where the shal ¥ (z) decomposition step is carried out using the reaction and distillation process. Yiov 1 7 - The acrylic acid WY method according to claim 7, where the decomposition step (c) is chal according to the reaction and distillation process at a reflux temperature ratio of 0.5 Y to 3 using a distillation column shelf surface. —A 1 method for producing acrylic acid according to Claim 1 wherein the “shelf” surface distillation column is characterized by the presence of 7 or more theoretical steps and 70 to 7001 of “Jabal” theory works to adjust the upper side of the column distillation column with rack surface; as a base point at a temperature of 111 degrees Celsius or less. 1 4 - The acrylic acid cay method According to Claim 17 or Cun, the distillation column Y on the shelf surface is equipped with a tray with a hole with a hole of 01 to 5 mm in diameter. 01 1 - A method for producing acrylic acid according to any of the Claims Cus 95-1 The decomposition step (c) uses a rotary type heat exchanger that heats the high-boiling F components that are used In the feed in the decomposition step ¢ (c) to reach a temperature ranging from 1558 to 771 °C© and to control the temperature difference between the heat exchanger heat source and the 1 high boiling point components heated by the exchanger Thermal circuit of the short-circuit type at 1 temperature ranging from Ar No ° C. -11-1 A method for producing acrylic acid according to any of the protection elements 01-1 where a procedure is carried out Yiov AS — - ¥ decomposition step (c) in the presence of an N-oxyl compound. 11 1 - A method for producing acrylic acid in accordance with any of the claims Cus 11-1 The ¥ distillate obtained from the decomposition step (C) is used in the ¥ feed grade component separation step high boiling (EB1) and absorption step (a); Passing through the step of separating the high-boiling point component (B1). The absorption step feed is 77 ov by mass or less. Yeo