EP4308538A1 - Nouveau procédé de production en continu d'acide méthacrylique par hydrolyse catalytique de méthacrylate de méthyle - Google Patents

Nouveau procédé de production en continu d'acide méthacrylique par hydrolyse catalytique de méthacrylate de méthyle

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Publication number
EP4308538A1
EP4308538A1 EP22710598.8A EP22710598A EP4308538A1 EP 4308538 A1 EP4308538 A1 EP 4308538A1 EP 22710598 A EP22710598 A EP 22710598A EP 4308538 A1 EP4308538 A1 EP 4308538A1
Authority
EP
European Patent Office
Prior art keywords
column
meth
methacrylic acid
methyl methacrylate
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22710598.8A
Other languages
German (de)
English (en)
Inventor
Steffen Krill
Daniel Helmut König
Dirk BRÖLL
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Roehm GmbH Darmstadt
Original Assignee
Roehm GmbH Darmstadt
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Roehm GmbH Darmstadt filed Critical Roehm GmbH Darmstadt
Publication of EP4308538A1 publication Critical patent/EP4308538A1/fr
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
    • C07C51/377—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by splitting-off hydrogen or functional groups; by hydrogenolysis of functional groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/09—Preparation of carboxylic acids or their salts, halides or anhydrides from carboxylic acid esters or lactones
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation

Definitions

  • the present invention describes a continuous process for the production of methacrylic acid by catalytic hydrolysis of methyl methacrylate, which has been produced starting from C-2, C-3 or C-4 raw materials.
  • methyl methacrylate of high purity is used
  • a further aspect of the present invention is the separation of an MMA-water azeotrope from the desired product, methacrylic acid, and its recycling into the reaction.
  • azeotrope processing of the MMA-MeOH and MMA-water mixtures from methacrylic acid production with processing sections of the MMA production process, with optional starting materials such as MMA and / or water in can be recycled to the methacrylic acid production process and/or one or more of these azeotropes can optionally be used in the production of MMA.
  • the present invention makes it possible to save on apparatus and thus reduces the investment costs when constructing a new plant.
  • the present process allows an increase in the product yields and, associated therewith, a reduction in the by-products and the associated disposal costs, as well as a reduction in the specific energy consumption.
  • the present invention describes a new, continuous process for the production of methacrylic acid (MAS) based on the hydrolysis of methyl methacrylate (MMA) or other methacrylate esters.
  • MAS methacrylic acid
  • MMA methyl methacrylate
  • Methacrylic acid is used in large amounts for the production of polymers or together with other copolymerizable compounds in copolymers.
  • Methacrylic acid Component of solvent-resistant gloves can be used in the manufacture of dimensionally stable foams and carbon fibers, is the basis in formulations for concrete superplasticizers (PCEs) and a large number of other polymers in which MAS creates specific properties.
  • PCEs concrete superplasticizers
  • methacrylic acid is the starting material for special esters, which are produced by esterification with the corresponding alcohols.
  • Methacrylic acid is also used for the production of hydroxy esters, which are components of lacquer and paint formulations.
  • the production of MAS is based on three possible raw material groups, based on C3, C4 or C2 building blocks.
  • the first commercially important group is represented by C3 building blocks.
  • MAS is produced mainly from hydrocyanic acid and acetone via the resulting acetone cyanohydrin (ACH) as the central intermediate.
  • ACH acetone cyanohydrin
  • This process has the disadvantage that very large amounts of ammonium sulfate are obtained, the processing of which is associated with very high costs.
  • Other C3-based processes that use a raw material base other than ACH have been described in the relevant patent literature and have now been implemented on a production scale, but they have similar problems.
  • MAS methacrylic acid amide
  • the ACH is usually first reacted with sulfuric acid, with a sulfuric acid solution of MASA being formed after going through a multi-stage reaction sequence.
  • This mixture of substances is reacted with water, whereby MASA is hydrolyzed to MAS and the resulting ammonia is obtained as ammonium hydrogen sulphate.
  • MASA is reacted with water at moderate pressures and temperatures between 50° and 210° in the presence of superstoichiometric amounts of sulfuric acid to form methacrylic acid.
  • HIBS hydroxyisobutyric acid amide
  • HIBS hydroxyisobutyric acid amide
  • Such a process is described in US Pat. No. 3,487,101, methacrylic acid itself and methacrylic acid esters derived therefrom becoming accessible.
  • HIBS is mixed in the liquid phase in the presence of homogeneous basic catalysts with, for example, caustic soda, with HIBS forming intermediate salts from which water can be eliminated at temperatures of up to 320 °C and MAS is formed.
  • the MAS can then be removed overhead.
  • high-boiling esters for example dimethyl phthalate or phthalic anhydride, are used as dehydrating agents which also serve as solvents in the reaction matrix. Very good selectivities of about 98% are described at high conversions. In view of the complicated and multi-stage process to produce HIBS, it is understandable that this process is not considered in the industry as
  • HIBS can be obtained in two stages by multiple hydrolysis of acetone cyanohydrin, with hydroxyisobutyric amide being formed as an intermediate product, which in turn can react further to form the acid.
  • sulfuric acid as a reagent, ammonium sulphate-containing sulfuric acid solutions are formed, the regeneration of which is arbitrarily complex.
  • EP 04 87853 describes a complex, multi-stage process starting from acetone cyanohydrin, with hydroxyisobutyric acid also being used here as a starting material for the central step in the production of MA.
  • ACH is catalytically hydrolyzed in a first reaction step, for example in the presence of heterogeneous manganese dioxide catalysts.
  • Hydroxyisobutyric acid amide (HIBA) is formed in high yield.
  • HIBA is reacted with methyl formate or mixtures of methanol/carbon monoxide, with complex
  • MHIB methyl hydroxyisobutyrate
  • Formamide is dehydrated to hydrocyanic acid in a separate reaction stage, and HCN can then be reacted with acetone to form ACH.
  • MHIB is hydrolyzed with water in the presence of a heterogeneous acidic ion exchanger to form HIBS, which is then reacted catalytically with basic alkali metal salts to form methacrylic acid with elimination of water.
  • HIBS methyl hydroxyisobutyrate
  • isobutylene or tert-butanol are used as C-4-based raw materials as educts in MAS production. These are converted into MAS over several process steps. Methyl tert-butyl ether (MTBE), which is converted to isobutene by methanol elimination, can also be used as a third alternative starting material.
  • MTBE Methyl tert-butyl ether
  • isobutylene or tert-butanol is oxidized to form methacrolein in a first stage, which is then reacted with oxygen to form methacrylic acid.
  • the resulting MAS is either isolated and purified or converted to MMA and other esters.
  • the C4 route is started from the steamer field product IBEN or alternatively TBA, which is oxidized to methacrolein (MAL) in the first step by means of gas-phase oxidation.
  • MAL methacrolein
  • the MAL obtained as an intermediate is oxidized to MAS.
  • the gaseous reaction products are cooled in a subsequent quenching step and largely condensed. It is characteristic of the process that the second reaction stage does not show complete conversion in terms of MAL and unreacted MAL is recovered in an absorption and desorption unit (recycle MAL) in order to then feed it back to the second reaction stage.
  • recycle MAL absorption and desorption unit
  • Isobutylene or tert-butanol can be reacted with atmospheric oxygen in the gas phase at the heterogeneous catalyst to form MAL and then by means of an oxidative esterification reaction of MAL using methanol to form MMA.
  • This method is described inter alia in US 5,969,178 and US 7,012,039.
  • the disadvantages of this process relate in particular to a high energy requirement, which is due, among other things, to the pressureless mode of operation. In this process, the problem of evaporation of MAL is avoided, since the process takes place in the liquid phase, so MAL does not have to be converted into the gaseous state and the problem of mixing with critical oxygen-containing gases is avoided in this way.
  • a solution for optimizing the two-stage isobutene gas phase process with MAS as an intermediate stage cannot be derived from this.
  • the gas phase process runs at moderate pressures of between 1 and 2 bar absolute and generates a process gas in which the product component is only contained at around 4 to 6% by volume.
  • the isolation of the product of value from the inert gas ballast is correspondingly energy-intensive and consumes large amounts of cooling energy and steam for multi-stage distillative work-up steps.
  • What these processes also have in common is that they are usually carried out in the gas phase in the presence of heterogeneous catalysts.
  • the separation effort is also considerable, in particular due to the need to separate the MAS, also with regard to the gas ballast.
  • Ethylene as a C2 building block can also be used as a raw material for MAS production.
  • Propionaldehyde (PA) or, as a secondary product of PA, propionic acid can be produced and isolated by reacting ethylene with carbon monoxide or synthesis gas.
  • the unsaturated carbonyl compounds can be efficiently prepared from these primary intermediates with formalin or formaldehyde in the sense of an aldolization.
  • Methacrolein is obtained from PA and MAS is obtained directly from propionic acid. Methacrolein, in turn, can be further oxidized to MAS catalytically.
  • US Pat. No. 8,791,296 describes a process for preparing methacrylic acid based on the hydrolysis of methacrylic esters, which comprises the following process steps: preparation of acetone cyanohydrin, conversion of acetone cyanohydrin to methacrylamide, esterification of methacrylamide in the presence of alkanols to the corresponding methacrylic ester and hydrolysis of the methacrylic ester to methacrylic acid.
  • the first step in the process includes Hydrolysis of methyl methacrylate to methacrylic acid. Three distillation steps at different pressures are then necessary.
  • the process comprises a reactor, a rectification column for separating off methanol, the top condensate of which is returned to the reactor, and a further rectification column operated in vacuo for separating off low boilers.
  • Methacrylic acid is isolated in pure form and of high quality as the top product, more precisely as the condensate of the top stream, of a third column operated under vacuum.
  • a further task was the simplification of product processing in order to achieve a specification-compliant (meth)acrylic acid quality as well as the optimal separation and recycling or material recycling of the resulting MMA-containing azeotropes.
  • the method according to the invention has the following method steps (a) and (b):
  • This rectification column - hereinafter also simply referred to as column - is characterized by the following features: (i) In the upper region of the column, at the top of the column, a mixture consisting of the alcohol and (meth)acrylic ester is separated off.
  • the (meth)acrylic ester is preferably MMA, the alcohol is correspondingly methanol and the (meth)acrylic acid formed is methacrylic acid.
  • (meth)acrylic acids is known in the art, acrylic acid and methacrylic acid being understood here.
  • (meth)acrylic ester is known in the art, which is to be understood as meaning acrylic ester and methacrylic ester.
  • the process can also be applied to other alkyl (meth)acrylates, such as in particular butyl (meth)acrylate or ethylhexyl methacrylate, with slight modifications which can be easily and specifically deduced by a person skilled in the art. It is even possible to apply the process to functionalized (meth)acrylates such as hydroxyethyl methacrylate.
  • the process has a reactor I in which at least one catalyst is preferably provided.
  • This reactor I does not necessarily have to be a reactor operated in isolation. Rather, reactor I can also be in the form of a reaction area.
  • Reactor I can be inside and/or outside of the rectification column. However, this reactor is preferably implemented outside the rectification column in a separate area, which is shown in more detail in FIGS. 1, 2 and 3 for preferred embodiments. Flow tube reactors have proven to be particularly favorable for such a separate reactor I.
  • the reaction is generally preferably carried out at temperatures in the range from 20 to 200.degree. C., particularly preferably at 40 to 150.degree. C., in particular at 60 to 110.degree.
  • the reaction temperature depends on the set system pressure.
  • the reaction temperature is preferably from 60 to 130.degree. C., particularly preferably from 70 to 120.degree. C. and very particularly preferably from 80 to 110.degree.
  • the reaction is preferably carried out in the pressure range from 5 to 200 mbar, in particular at 10 to 100 mbar and particularly preferably at 20 to 50 mbar.
  • the reactor is located outside the column, different pressure and temperature conditions can be selected there than in the column. This has the advantage that the reaction parameters of the reactor can be set independently of the operating conditions in the column.
  • the reaction is preferably carried out at pressures in the range 0.5 to 20 bar, more preferably 1 to 10 bar, most preferably 3 to 5 bar.
  • the reaction time of the reaction depends on the reaction temperature; the residence time in the reactor for a single pass is preferably 0.5 to 15 minutes and more preferably 1 to 5 minutes.
  • the process according to the invention is preferably carried out in such a way that reactor I is fed continuously with a reactant mixture of (meth)acrylic ester and water in a molar ratio of between 1:20 and 20:1.
  • the molar feed ratio of water to methyl methacrylate is preferably 0.5 to 20:1, particularly preferably 0.5 to 10:1 and very particularly preferably 1.0 to 4:1.
  • reaction mixture may comprise other components such as, for example, solvents, catalysts and polymerization inhibitors.
  • the rectification column can be made from any material suitable for this purpose. These include, but are not limited to, stainless steel and other suitable inert materials. Preference is given to an embodiment of the present invention in which the starting materials (meth)acrylic ester and water present in the side draw S1 are recycled to the reaction region of the reactor I. There these starting materials are reacted together with fresh water and (meth)acrylic acid ester.
  • the side draw stream is optionally subjected to a phase separation before the at least partial recirculation in the reaction.
  • the column used according to the invention is designed in such a way that the (meth)acrylic acid is removed in a purity of more than 95% by weight via side draw S2.
  • the side draw S2 is generally located in the column below the side draw S1 and the feed stream
  • the pressure at the top of the reaction column used according to the present invention is preferably from 5 to 1200 mbar, particularly preferably from 20 to 1100 mbar and very particularly preferably from 50 to 500 mbar.
  • the top stream obtained is preferably subjected to a further material separation after removal from the column in order to obtain the remaining methyl (meth)acrylate and the corresponding alcohol, in particular methyl methacrylate and methanol, separately from one another. In this way, purified methyl (meth)acrylate that has not been completely converted can be returned to the process to increase the yield.
  • High boilers such as added inhibitors can be discharged from the bottom of the rectification column used according to the present invention by customary methods. This can be done, for example, using a thin-film evaporator or a corresponding alternative device.
  • the isolated, evaporating substances are particularly preferably returned to the rectification column and non-evaporating high boilers are discharged.
  • any rectification column which has 5 to 20 plates each in the upper, middle and lower region can be used for the reaction according to the present invention.
  • the number of plates in the upper area is particularly preferably 5 to 15 and in the middle and lower area each 5 to 15.
  • the number of plates in a plate column is multiplied by the plate efficiency or the number of theoretical T as the number of plates stages in the case of a packed column or a column with random packings.
  • Examples of a rectification column with trays include such as bubble-cap trays, sieve trays, tunnel trays, valve trays, slot trays, sieve-slot trays, perforated bubble-cap trays, nozzle trays, centrifugal trays, for a rectification column with packings, packings corresponding to the state of the art and industrially available are suitable. Examples are the Raschig Super Ring or the Sulzer NeXRing. Industrially available packings are suitable as structured packing metallic structured packings such as MellapakPlus (Sulzer) or the RMP structured packing from RVT. Structured packings with catalyst pockets, for example Katapak (Sulzer), can also be used.
  • a rectification column with combinations of sections of trays, sections of packing and/or sections of structured packing can also be used.
  • a rectification column with random packings and/or structured packings for the 3 regions is preferably used. Particular preference is given to using internals which lead to low pressure losses during operation according to the invention.
  • chimney tray collectors are particularly suitable for the complete removal of liquid side streams.
  • manifolds enable high distribution densities and can reduce uneven liquid distributions, thereby reducing the risk of polymerization.
  • Feed streams of the fresh reactants are fed into reactor I with the recycle stream, which consists predominantly of unreacted reactants and was obtained from the column.
  • An inert boiling oil can be present at the bottom of the column in order to avoid long residence times for the (meth)acrylic acid target product.
  • (Meth)acrylic acid is preferably drawn off in gaseous form between the middle and lower region, while at the top of the column the methanol formed is drawn off as an azeotrope with methyl (meth)acrylate and traces of water as the lowest-boiling reaction component. Unreacted starting materials are returned to the reaction area, for example by means of a pump.
  • heterogeneous catalysts including in one embodiment of a reaction region within the column.
  • Acidic fixed bed catalysts in particular acidic ion exchangers, are particularly suitable as heterogeneous catalysts.
  • the particularly suitable acidic ion exchangers include, in particular, cation exchange resins such as styrene-divinylbenzene polymers containing sulfonic acid groups.
  • cation exchange resins such as styrene-divinylbenzene polymers containing sulfonic acid groups.
  • Suitable cation exchange resins can be obtained commercially under the trade name Amberlyst®, under the trade name Dowex® and under the trade name Lewatit®.
  • a heterogeneous fixed bed catalyst can be used in any section of the rectification column. This is preferably used in the middle region of the column.
  • the amount of catalyst in liters is preferably 1/10 to 10 times, particularly preferably 1/5 to 5 times, the amount of newly formed (meth)acrylic acid to be produced in L/h.
  • the amount of catalyst in the feed to reactor I is in a ratio of 1:10 to 10:1, preferably between 1:5 and 5, to the amount of (meth)acrylic acid measured in liters and taken off via the side draw S2 of the column 1.
  • the catalyst can be provided in a separate area of the reactor I, this area being connected to the other areas of the apparatus. This separate arrangement of the catalyst area is preferred, it being possible for the educts to be continuously passed through the catalyst area. This continuously produces (meth)acrylic acid and newly formed methanol.
  • An alternative embodiment is the use of a homogeneous catalyst, such as sulfuric acid. Disadvantages of such an embodiment are the high material requirements with regard to corrosion resistance and the effort involved in separating for the recovery and recycling of the homogeneous catalyst.
  • the bottom of the column contains an inert boiling oil which does not take part in the reaction.
  • high-boiling, inert substances with long-term thermal stability are referred to as boiling oils. These substances have a boiling point that is higher than the boiling points of the components involved in the reaction.
  • a boiling oil is preferably used in order to ensure that the (meth)acrylic acid formed is removed by distillation without polymerization.
  • the boiling point of the boiling oil should not be too high either, in order to reduce the thermal stress on the (meth)acrylic acid formed.
  • the boiling point of the optionally used boiling oil is particularly preferably from 170 to 400.degree. C., in particular from 240 to 290.degree. C., at normal pressure (1013 mbar).
  • Suitable boiling oils include higher-chain, unbranched paraffins having 12 to 20 carbon atoms, aromatic compounds such as alkyl-substituted phenols or naphthalene compounds, sulfolane (tetrahydro-thiophene-1,1-dioxide) or mixtures of these. 2,6-di-tert-butyl-para-cresol, 2,6-di-tert-butyl phenol, sulfolane, diphyl or mixtures of these substances have proved to be particularly suitable boiling oils.
  • the optionally, but preferably, used boiling oil is very particularly preferably sulfolane.
  • Diphyl is a eutectic mixture of 75% by weight biphenyl oxide and 25% by weight biphenyl. It has also proved advantageous to use polymerization inhibitors.
  • the polymerization inhibitors that can be used with preference include octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, phenothiazine, hydroquinone, hydroquinone monomethyl ether, 4-hydroxy-2,2,6,6-tetramethylpiperidinooxyl ( TEMPOL), 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, para-substituted phenylenediamines such as e.g.
  • Phenothiazine and/or hydroquinone monomethyl ether are very particularly preferred.
  • the inhibitor can be metered into the feed before the reactor and/or after the reactor and/or into the rectification column, preferably at the top thereof.
  • the stream of substance separation containing a mixture of MMA and methanol can be processed in a further separate plant in such a way that methanol and MMA are separated from one another.
  • a pressure swing distillation for example, is suitable for this.
  • the separated MMA can be fed back into the process according to the invention.
  • the methanol can be used in a separate plant to produce MMA.
  • MMA and methanol can be separated by extraction in a separate plant. This is particularly preferably done by extracting the stream obtained via the side draw S1 with the top stream of the rectification column. At least one of the phases formed can be used again in a chemical reaction. This reaction can also involve the production of further alkyl (meth)acrylates, in particular MMA.
  • these separate plants are part of a production plant for the production of MMA or already exist in these production plants in another function.
  • This production plant can be chosen relatively freely on a C2, C3 or C4
  • FIG. 1 Three embodiments of the method according to the invention are conceivable for the method. These are shown in Figures 1 to 3.
  • the process according to FIG. 1 is the preferred embodiment, since the yield and the specific steam consumption can be particularly optimized according to this embodiment.
  • the feed streams methyl methacrylate (1) and water (2) are mixed with the recycle stream (15) and fed to the preheater (H) and heated to the reaction temperature.
  • the recycle stream consists mainly of the unreacted educts methyl methacrylate and water, as well as portions of methanol and methacrylic acid.
  • the reactants (3) heated to reaction temperature are fed to reactor I (A).
  • the hydrolysis reactor is operated in a temperature range between 80 °C and 110 °C and in a pressure range between 3 bar and 5 bar.
  • the molar feed ratio of water to methyl methacrylate is between 1.5 and 4.
  • the hydrolysis reactor is preferably designed as a flow tube reactor and is equipped with an acidic fixed bed catalyst.
  • the reactor product stream (4) is reduced to the column operating pressure by means of an expansion valve (B) and fed into the distillation column (C), preferably below the first side draw S1 below the upper separating region (C1) of the column.
  • the pressure at the top of the column is between 0.05 and 1 bar.
  • the reactor product stream also contains the reaction by-product methanol and the unreacted starting materials methyl methacrylate and water.
  • the distillation column (C) consists of three separation sections: the upper separation section (C1), the middle separation section (C2) and the lower separation section (C3).
  • an external phase separator (E) can optionally be installed between the upper and middle separation section according to the first exemplary embodiment described above. This variant is shown as embodiment II in FIG.
  • phase separator (E) can also be installed inside the column between the two separating sections (C1) and (C2). This variant is in turn shown as embodiment III in FIG. 3 by way of example.
  • the low-boiling reaction by-product methanol is separated from the intermediate boilers, the educts water and methacrylic acid, and drawn off at the top. Due to the azeotrope between methanol and methyl methacrylate, it is not possible to separate pure methanol.
  • the top product (8) therefore usually contains methyl methacrylate in addition to methanol. Condensation takes place via the condenser (D).
  • the top product (8) can be separated into the pure substances methanol and methyl methacrylate using a treatment method suitable for azeotropes. For example, methyl methacrylate can be returned to the process according to the invention.
  • the skilful introduction of the top product (8) in processes for the production of methyl methacrylate enables the almost complete recovery of the unreacted methyl methacrylate and the reuse of the by-product methanol.
  • the preferred infeed of the azeotrope mixture is in the extraction stage.
  • injection upstream of the esterification reactors is suitable.
  • the liquid effluent from the upper separation section (C1) is collected in a collector. Some or all of this liquid stream is passed out of the column as a side draw S1 (13). The second part is conducted as a liquid reflux stream via a distributor to the middle separation section (C2). The side offtake (13) is fed to the pump (G).
  • the liquid waste stream (13) is fed to the phase separator (E).
  • the organic phase (140) is completely separated off and fed to the pump (G) as a recycle stream (14).
  • the aqueous phase (14W) is fed partially or completely to the pump (G) as a recycle stream (14).
  • the second part, as a liquid reflux stream, after being mixed with the reactor product (5), is passed as a liquid stream via a distributor to the middle separation section (C2).
  • the phase separator (E) is outside of the column (C).
  • the phase separator (E) within the column as in an example
  • Embodiment III shown in Figure 3 are installed.
  • the liquid stream (13) collected in the collector is fed to the phase separator (E).
  • the organic phase (140) is separated off completely and fed to the pump (G) as recycle stream (14).
  • some or all of the aqueous phase (14W) is fed to the pump (G) as a recycle stream (14).
  • the second portion is sent as a liquid recycle stream to a header above the middle separation section (C2).
  • the methacrylic acid product is purified from the educts water and methyl methacrylate and any remaining traces of methanol in the middle separation section.
  • the product methacrylic acid is purified from methyl methacrylate and possibly remaining traces of methanol and water in the separation section (C2).
  • the liquid phase of the middle separation section is collected in a collector and sprayed onto the lower separation section (C3) by means of a distributor.
  • the gas stream rising from the lower separating section (C3) is partially passed out of the column as a side draw S2 (10) through suitable internals. This side stream S2 (10) contains the pure product (methacrylic acid).
  • Stream (11) is the boiling oil inflow. This is preferably injected via a suitable distribution device in the upper third of the separation section.
  • the high boilers are drawn off via the bottom outlet (12).
  • the high boilers are discharged by suitable design of the evaporator (F), such as a thin-film evaporator.
  • Substances with a boiling temperature at normal pressure (1013 mbar) of between 200 and 400° C., in particular between 240 and 290° C., are suitable as boiling oil. Suitable boiling oils are described above.
  • a polymerization inhibitor which can also simply be called a stabilizer, (6) is preferably introduced at the top of the column. A more detailed description of this can also be found above.
  • the side draw S1 (14) is brought to the reactor operating pressure by the pump (G) and then mixed with the fresh starting materials (1) and (2) as a recycle stream (15).
  • the usual process control of the prior art according to US Pat. No. 8,791,296 comprises 3 distillation columns in series.
  • the azeotrope of methanol and methyl methacrylate is separated off in the first column.
  • methyl methacrylate and water are separated from methacrylic acid, the variants with or without phase separation representing possible embodiments at the top.
  • methacrylic acid is obtained as a distillate. High-boiling by-products are drawn off as the bottom product.
  • the separation of the azeotrope methanol and methyl methacrylate (8) described in separation section (C1) takes place in a dedicated distillation column (I) first and then in a second distillation column (L) the separation of methyl methacrylate and water (17) from methacrylic acid.
  • Methacrylic acid is taken off as a side draw (10) and a boiling oil (11) can optionally be used in the bottom to remove high boilers and reduce the bottom temperature.
  • Two variants are possible at the top of this second distillation column (L). In a first variant, there is no phase separation and the condensate is divided accordingly into reflux and distillate. The second variant has a phase separation at the top.
  • the aqueous phase is used as reflux and partly discharged as distillate or from the process.
  • the organic phase is recycled into the reactor as distillate.
  • the azeotrope of methanol and methyl methacrylate is separated off as distillate (8) in the azeotrope column (I).
  • a mixture of water and methyl methacrylate is removed as a side draw (19) and methacrylic acid and high boilers are obtained at the bottom (16).
  • the MAS column (L) pure methacrylic acid is obtained as the top product (10) and high boilers are removed as the bottom product (18).
  • the second column can optionally be operated with boiling oil (11) in order to reduce the bottom temperature.
  • the methods according to the invention and its alternative embodiments share the feature that three separation steps have to be carried out, with two azeotropes having to be separated from the target product. To reduce the number of devices required, one or more separation steps are integrated in one device.
  • the target product is preferably drawn off as a side stream. What these processes also have in common is that a heterogeneous catalyst is used for the hydrolysis.
  • a plant for the production of methacrylic acid is also part of the present invention.
  • This novel system is characterized in that a heterogeneous catalyst for the hydrolysis of methyl methacrylate with water to form methacrylic acid and methanol is present in a reactor I, and that the system for processing azeotropes formed from methyl methacrylate and water as well as from
  • Methyl methacrylate and methanol has a rectification column with three separation zones, from which methacrylic acid is drawn off in high purity from a side stream draw.
  • FIG 2 shows an embodiment with an external phase separator
  • FIG. 3 shows an embodiment with an internal phase separator
  • FIG. 4 represents an alternative embodiment with two distillation columns connected in series
  • FIG. 5 represents a further alternative embodiment with two distillation columns connected in series streams
  • Example 1 In a setup according to the embodiment without phase separation according to FIG. 1, a methyl methacrylate feed stream (1) and a water feed stream (2) are mixed with the recycle stream (15) containing methanol, water, methyl methacrylate and methacrylic acid.
  • the individual streams have a pressure of 4 bar.
  • the temperature of the streams is 22 °C.
  • the methyl methacrylate feed (1) is 500 g/h and the recycle (15) is 1539 g/h.
  • the water inflow (2) is adjusted in such a way that a molar ratio of 2:1 water to MMA is established in the mixed total flow.
  • the stream is heated to the reaction temperature of 110 °C by means of a preheater (H).
  • reactor (A) there is a residence time of 60 min, a space-time yield based on methacrylic acid of 200 kg/(h*m 3 ) and an MMA conversion of 30%.
  • the reactor product stream (4) is expanded to 200 mbar using the expansion valve (B) and fed to the column feed (5) into the distillation column (C).
  • Distillation column is designed as a DN50 glass column.
  • the top packing section (C1) and the middle packing section (C2) each have 2 m Sulzer DX laboratory packing, the bottom packing section (C3) has 1 m Sulzer DX laboratory packing.
  • a collector is installed between the upper and middle packing section, via which the entire liquid phase of the upper section is drawn off as a side stream (13). Below this collector, the column feed (5) is fed via a distributor to the middle packing section (C2).
  • a collector is installed below the middle packing section, with the help of which the liquid phase is collected from the middle packing section and fed into a distributor. Between the collector and the distributor there is a nozzle for drawing off the gaseous product stream of methacrylic acid (10).
  • the liquid from the collector is fed to the lower packing section (C3) via the distributor.
  • a condenser (D) is installed at the top of the column, which achieves a condensate outlet temperature of 7°C.
  • Evaporator (F) is designed as a thin film evaporator.
  • the pressure at the top of the column is set at 100 mbar.
  • Stabilizer is sprayed onto the condenser via line (6) to prevent polymerization and is fed into the column via reflux (9).
  • the stabilizer flow is 10 g/h and consists of 2% MEHQ solution in methyl methacrylate.
  • the top temperature of the column is 15.1°C.
  • the upper packing section (C1) serves to separate the azeotrope methanol and methyl methacrylate from excess methyl methacrylate, water and methacrylic acid. 195 g/h of distillate (8) containing methanol and methyl methacrylate are drawn off. At the end of the upper packing section (C1) 1539 g/h recycle stream (13) are drawn off as a liquid side stream containing methanol, water, methyl methacrylate and methacrylic acid and fed to the pump (G) and compressed to 4 bar. In the middle packing section (C2), 386 g/h of methacrylic acid are separated from the lower-boiling components methyl methacrylate and water and drawn off as a gaseous side stream (10). In the middle of the lower packing section (C3), 10 g/h of sulfolane (11) is used
  • Boiling oil added to the column This ensures that methacrylic acid is not exposed to temperatures higher than 95 °C, which reduces the risk of polymerisation.
  • high boilers formed are discharged via the thin-film evaporator (F) as a bottom stream (12).
  • the sump temperature is 198 °C.
  • an almost methacrylic acid-free bottom is produced, which minimizes methacrylic acid losses.
  • Table 1 lists the mass flows observed and the material composition of the individual flows.
  • Table 2 shows the specific excipient consumption achieved with the process.
  • a methyl methacrylate feed stream (1) and a water feed stream (2) are mixed with the recycle stream (15) containing methanol, water, methyl methacrylate and methacrylic acid.
  • the individual streams have a pressure of 4 bar.
  • the temperature of the streams is 22 °C.
  • the methyl methacrylate feed (1) is 500 g/h and the recycle (15) is 1353 g/h.
  • the water feed (2) is adjusted in such a way that a molar ratio of 2:1 water to methyl methacrylate is established in the mixed total stream.
  • preheater (H) the current is on the
  • the reactor (A) there is a residence time of 60 min, a space-time yield based on methacrylic acid of 200 kg/(h*m 3 ) and an MMA conversion of 30%.
  • the reactor product stream (4) is expanded to 200 mbar using the expansion valve (B) and fed to the column feed (5) into the distillation column (C).
  • the distillation column is designed as a DN50 glass column.
  • the top packing section (C1) and the middle packing section (C2) each have 2 m Sulzer DX laboratory packing, the bottom packing section (C3) has 1 m Sulzer DX laboratory packing.
  • a collector is installed between the upper and middle packing section, via which the entire liquid phase of the upper packing section (C1) is drawn off as a side stream (13).
  • the column feed (5) is fed via a distributor to the middle packing section (C2).
  • a collector is installed below the middle packing section, with the help of which the liquid phase is collected from the middle packing section and fed into a distributor. Between the collector and the distributor there is a nozzle for drawing off the gaseous product stream of methacrylic acid (10).
  • the liquid from the collector is fed to the lower packing section (C3) via the distributor.
  • a condenser (D) is installed at the head of the column, which achieves a condensate outlet temperature of 7 °C.
  • Evaporator (F) is designed as a thin film evaporator.
  • the pressure at the top of the column is set at 100 mbar.
  • Stabilizer is sprayed onto the condenser via line (6) to prevent polymerization and is fed into the column via reflux (9).
  • the stabilizer flow is 10 g/h and consists of 2% MEHQ solution in methyl methacrylate.
  • the top temperature of the column is 15.9°C.
  • the upper packing section (C1) serves to separate the azeotrope methanol and methyl methacrylate from excess methyl methacrylate, water and methacrylic acid. 219 g/h of distillate (8) containing methanol and methyl methacrylate are drawn off.
  • Table 4 shows the specific excipient consumption achieved with the process.
  • the water inflow was adjusted in such a way that a molar ratio of 2:1 water to methyl methacrylate was established in the reactor inflow stream.
  • the individual streams have a pressure of 4 bar.
  • the reactor feed stream is heated to the reaction temperature of 110 °C with the aid of a preheater.
  • the reactor product stream contains methanol, water, methyl methacrylate and methacrylic acid and is sent to the bottom of the first distillation column.
  • a top pressure of 1000 mbar a top temperature of 64.3 °C and a bottom temperature of 83.3 °C are established.
  • the reflux ratio is set to 12.
  • the azeotrope (196 g/h) consisting of MEOH and MMA is drawn off at the top.
  • the bottom stream is 1840 g/h and mainly contains water, methyl methacrylate and methacrylic acid and a little methanol.
  • This stream is fed into the middle of a downstream second distillation column which is operated at a top pressure of 100 mbar. A top temperature of 38.9 °C and a bottom temperature of 93.2 °C are established. The reflux ratio is 0.7.
  • the overhead product (1471 g/h) consists of the azeotrope of water and MMA. The bottom product contains MA, traces of high boilers and stabilizers and is 385 g/h.
  • the bottom product from the second distillation column is fed into the middle of the third distillation column for fine purification of the methacrylic acid.
  • the third column is operated at a top pressure of 100 mbar and a top temperature of 93.2° C. and a bottom temperature of 98.6° C. are established.
  • the reflux ratio is set to 2. 380 g/h of methacrylic acid are obtained as a pure product at the top. In the bottom, 5 g/h of high boilers and stabilizers are removed via a thin film evaporator.
  • Each of the three distillation columns has a stabilizer addition at the condenser to prevent polymerization, and this stabilizer reaches the columns via the reflux.
  • the stabilizer stream is 10 g/h for each column and consists of 2% strength MEHQ solution in methyl methacrylate. Table 5 lists the observed mass flows and the material composition of the individual flows. Table 5: Mass flows and material composition
  • Table 6 shows the specific excipient consumption achieved with the process. A molar yield of 0.88 moles of MAS per mole of MMA used is achieved.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé en continu de production d'acide méthacrylique par hydrolyse catalytique de méthacrylate de méthyle, qui a été produit à base de matières premières C-2, C-3 ou C-4. Dans le procédé, du méthacrylate de méthyle ayant un degré de pureté élevé est mis à réagir avec de l'eau en présence d'un catalyseur de Brönstedt afin de former un mélange réactionnel contenant des réactifs et des produits et est traité dans une colonne de distillation, dont la tête génère un condensat contenant un azéotrope de MMA comprenant du méthanol, dont la partie centrale génère un condensat de vapeur qui contient de l'acide méthacrylique ayant un degré de pureté élevé, et dont le puisard accumule un mélange de matériaux qui contient des sous-produits ayant une température d'ébullition élevée et un faible acide méthacrylique.
EP22710598.8A 2021-03-15 2022-03-07 Nouveau procédé de production en continu d'acide méthacrylique par hydrolyse catalytique de méthacrylate de méthyle Pending EP4308538A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP21162491 2021-03-15
PCT/EP2022/055702 WO2022194590A1 (fr) 2021-03-15 2022-03-07 Nouveau procédé de production en continu d'acide méthacrylique par hydrolyse catalytique de méthacrylate de méthyle

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EP4308538A1 true EP4308538A1 (fr) 2024-01-24

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US (1) US20240034709A1 (fr)
EP (1) EP4308538A1 (fr)
CN (1) CN117043132A (fr)
TW (1) TW202302513A (fr)
WO (1) WO2022194590A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE191367C (fr) 1900-01-01
CH430691A (de) 1963-09-17 1967-02-28 Lonza Ag Verfahren zur Herstellung von Methacrylverbindungen
JP2959121B2 (ja) 1990-11-28 1999-10-06 三菱瓦斯化学株式会社 メタクリル酸の製造法
SG71815A1 (en) 1997-07-08 2000-04-18 Asahi Chemical Ind Method of producing methyl methacrylate
KR100579678B1 (ko) 2001-12-21 2006-05-15 아사히 가세이 케미칼즈 가부시키가이샤 산화물 촉매 조성물
ZA200303241B (en) 2002-05-01 2003-11-04 Rohm & Haas Improved process for methacrylic acid and methcrylic acid ester production.
DE102008043609A1 (de) * 2008-11-10 2010-05-12 Evonik Röhm Gmbh Verfahren zur Reduzierung des Wassergehalts in (Meth)acrylsäure
DE102011076642A1 (de) 2011-05-27 2012-11-29 Evonik Röhm Gmbh Verfahren zur Herstellung von Methacrylsäure

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TW202302513A (zh) 2023-01-16
US20240034709A1 (en) 2024-02-01
CN117043132A (zh) 2023-11-10

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