MXPA99009949A - Apparatus and process for the high yield production of methyl methacrylate or methacrylic acid - Google Patents

Abstract

Se revelan un proceso de alto rendimiento para la producción de metacrilato de metilo oácido metacrílico, y un aparato para incrementar el rendimiento en un proceso para la producción de metacrilato de metilo oácido metacrílico.

Description

Apparatus and Process for the Production, with High Performance, of Methacrylate of Methyl or Methacrylic Acid The present invention relates to a high performance process for the production of methyl methacrylate ("MAM") or methacrylic acid ("AMA"), and an apparatus for increasing the yield in a process for the production of MAM and AMA. To prepare MAM, a number of business processes are used. In one such process, MAM is prepared from acetone cyanohydrin ("CHA"). The process is described in U.S. Patent No. 4,529,816 ("816").

In this process, CHA is: (1) hydrolyzed by means of sulfuric acid to produce a-hydroxyisobutyramide ("HIBAM") and its sulfate ester a-sulfatoisobutyramide ("SIBAM"); (2) HIBAM and SIBAM are thermally converted to 2-methacrylamide ("MTAM") and a small amount of methacrylic acid AMA; which (3) are then esterified with methanol to produce MAM. The residual HIBAM is esterified in methyl a-hydroxyisobutyrate ("MOB"). In step (2) of the reaction, the conversion of SIBAM to MTAM occurs more easily than the conversion of HIBAM to MTAM. To facilitate the thermal conversion of HIBAM to MTAM, both heat and longer residence time must be provided. A decrease in the thermal conversion of the desired products results in a decreased overall yield for the process. The process for preparing AMA may be the same as that used to prepare MAM, except that instead of esterifying the MTAM and AMA with methanol, water is added to the mixture of MTAM and AMA to convert the MTAM to AMA. The MAM and AMA market is extremely expensive and unstable. A slight improvement in the performance of the process can result in a significant market advantage. There is a need for a commercial process of improved performance to prepare MAM or AMA. In the U.S. patent no. 5,393,918 reveals a proposal to improve the performance of an MAM process. In addition to the conversion of MTAM to MAM, the patent discloses a process by means of which the HIBAM and SIBAM of stage (1) above are esterified into methyl-a-methoxyisobutyrate ("a-MEMOB"), methyl-β-methoxyisobutyrate. ("ß-MEMOB") and methyl a-hydroxyisobutyrate ("MOB"). The α-MEMOB, β-MEMOB and MOB are then isolated and converted to MAM in a separate step. This eliminates the need for thermal conversion of HIBAM and SIBAM in MTAM, but requires fractional distillation to separate the a-MEMOB, ß-MEMOB and MOB from MAM, and a subsequent stage of dehydration to convert the a-MEMOB, ß- MEMOB and MOB in MAM. The thermal conversion of HIBAM and SIBAM to MTAM is typically carried out in a fractionation reactor. The fractionation reactor contains a heat exchange device to provide the heat necessary for the fractionation reaction, and a thermal conversion apparatus that provides the necessary retention time under the heated conditions for the fractionation reaction to place. A typical thermal conversion apparatus (1) of a fractionation reactor known in the art is a multi-pass metal tube (Figure 1). In one embodiment, the metal tube may contain a baffle (2) separating the tube to provide a passage (3) having a curve (4) of 180 ° to minimize the space required to house the fractionation reactor, an extension (5) through which the reagents enter the conversion apparatus thermal, and a constriction (6) through which the mixture of the fractionation reactor leaves the thermal conversion apparatus. These characteristics of a typical thermal conversion apparatus result in the remixing of HIBAM, SIBAM, MTAM and AMA. The remixing of these components results in less than a plug flow and reduced total yields, since the retention time of the components in the fractionation reactor will vary. Some part of each component will not have, sufficient retention time in the fractionation reactor, while another part of each component may have a prolonged retention time in the fractionation reactor. As a result of the insufficient retention time in the fractionation reactor, there may be a down-conversion of HIBAM. As a result of a "prolonged retention time in the fractionation reactor, there may be an overconversion or degradation of SIBAM, MTAM and AMA." U.S. Patent No. 4,748,268 discloses a process for preparing methacrylic acid esters with the use of a reactor. In the process, a feed stream containing methacrylic acid, a saturated C C-C aliphatic alcohol, a catalyst and a liquid organic substance is fed continuously into a plug flow reactor. Stopper flow is used for the esterification reaction The process is not directed to the conversion of HIBAM and SIBAM into MTAM in a thermal conversion apparatus Despite the disclosures in the prior art, there is a continuing need for a commercial process of improved performance to prepare MAM.

It has been found that the use of a plug flow in the thermal conversion apparatus of an MAM process significantly improves the thermal conversion of HIBAM and SIBAM in MTAM, and thus provides improved performance of the total process. By plug flow it is meant that the fluid velocity in the tube is almost the same through the cross section of the tube. In a first aspect, the present invention provides a process for preparing a monomer selected from methacrylic acid and methyl methacrylate, which includes: (A) hydrolyzing acetone cyanohydrin to produce a hydrolysis mixture including a-hydroxyisobutyramide, isobutyramide of sulfate, 2-methacrylamide and methacrylic-Lco acid; (B) thermally converting the hydrolysis mixture into a fractionation reactor that includes a thermal conversion apparatus with plug flow, with the retention time necessary to produce a fractionation reactor mixture including 2-methacrylamide and methacrylic acid; (C) reacting the fractionation reactor mixture and a material selected from methanol and water in at least one reactor to produce a monomer selected from methacrylic acid and methyl methacrylate.

In a second aspect, the present invention provides a thermal conversion apparatus, which includes: a tube with means for maintaining plug flow. In the process of the invention, CHA is hydrolyzed to produce a hydrolysis mixture that includes, but is not limited to, MTAM, AMA, HIBAM and SIBAM. As is known in the art, the amount of each component in the hydrolysis mixture will vary depending on the reaction conditions. The hydrolysis reaction is carried out in an excess of sulfuric acid. The concentration of the sulfuric acid feed used is not critical, however a concentration of 95% to 100% is preferred. For the hydrolysis reaction, any reactor known in the art which is suitable for conducting the hydrolysis reactions can be used. The hydrolysis can be conducted in a hydrolysis reactor. Alternatively, hydrolysis can be conducted in more than one hydrolysis reactor. If more than one hydrolysis reactor is used, hydrolysis reactors are usually connected in series. It is contemplated that a parallel adaptation of the hydrolysis reactors could be useful in certain cases. In one embodiment, one to five reactors connected in series may be useful to drive the hydrolysis reaction. It is preferable to use a series of two or three reactors for the hydrolysis reaction. The hydrolysis is typically conducted at a temperature ranging from 70 ° C to 135 ° C, preferably from 75 ° C to 105 ° C. The temperature can be maintained at a value or changed during the course of the hydrolysis reaction in each hydrolysis reactor used. If more than one reactor is used, preferably the temperature of the first reactor varies from 75 ° C to 90 ° C, and the temperature of the subsequent reactors from 90 ° C to 105 ° C. The hydrolysis is conducted for a sufficient time to maximize the previous esterification yield of HIBAM, SIBAM, MTAM and AMA. The time required for hydrolysis can vary from 1 minute to 60 minutes, although longer times may be required. The hydrolysis mixture is transferred to the fractionation reactor which includes a thermal conversion apparatus with plug flow, and thermally converted into a fractionation reactor mixture. The fractionation reactor mixture includes, but is not limited to, predominantly MTAM and smaller amounts of AMA, HIBAM and SIBAM. The first part of the fractionation reactor is a heating unit. The heating unit of the fractionation reactor can be a preheater or a heater. The preheater or heater of the fractionation reactor typically are heat exchange devices. The preheater or heater of the fractionation reactor is used to bring the reaction mixture to the temperature necessary for the fractionation reaction to occur. The outlet temperature in the preheater of the fractionation reactor typically varies from 110 ° C to 135 ° C. The outlet temperature in the fractionation reactor heater typically ranges from 135 ° L to 165 ° C. Alternatively, the preheater and heater of the fractionation reactor can be folded into a heating unit. If a heating unit is used in the fractionation reactor, the outlet temperature in the heating unit typically varies from 135 ° C to 165 ° C. Any type of heat exchange device known in the art will suffice as the preheater or heater of the fractionation reactor, as long as it is resistant to the high temperatures and very acidic conditions present in this process. Suitable heat exchange devices include plate and frame, plate and fin, spiral and tubular. Suitable building materials include, but are not limited to, Hastelloy B, Hastelloy B-2, Hastelloy B-3, Inconel and tantalum alloys. The second part of the fractionation reactor is the thermal conversion apparatus of the invention (Figure 2). As discussed above, the thermal conversion apparatus is where the thermal conversion of the hydrolysis mixture occurs, ie, HIBAM and SIBAM to MTAM. The critical aspect of the invention is to control the residence time of the reagents in the thermal conversion apparatus. The thermal conversion apparatus must provide the required retention time under suitable temperatures to complete the fractionation reaction, without causing degradation of the desired products. It is understood that the desired retention time will vary depending on the hydrolysis mixture, and the temperature in the thermal conversion apparatus. In general, the desired retention typically ranges from 1 to 15 minutes, preferably from 2 to 12 minutes, and better from 3 to 10 minutes, however, as discussed above, based on the hydrolysis mixture and the temperature in the Thermal conversion apparatus, longer retention times may be required. Control of the retention time in the thermal conversion apparatus is provided by maintaining the plug flow in the apparatus. Many embodiments are contemplated for the design of the thermal conversion apparatus of the present invention, which are suitable for maintaining the plug flow and, thereby, providing the desired retention time. In one embodiment, the thermal conversion apparatus is at least one straight tube. In an alternative embodiment, where space limitations require curves in the tube, the plug flow is maintained in the thermal conversion apparatus with the use of Cheng rotating blades (CRV ™, Cheng Fluid Systems trademark) or Similar equipment in the curves of at least one tube. In another embodiment, the plug flow is maintained by selecting the geometry of the apparatus, such as the diameters and lengths of the tube, the curves of the at least one tube within the apparatus, and the provision of a gradual enlargement in the inlet and constriction and ? the output of the device. The gradual enlargement and constriction may be concentric or eccentric, and may be provided by the use of LAD ™ (wide angle diffusers, Cheng Fluid Systems trademark) or similar equipment, or at least one specially designed tube. In this embodiment, the diameter of the at least one tube, of the thermal conversion apparatus, is typically 2 to 3Scm. , preferably 10 to 30cm. , better from 15 to 28cm. The length of the at least one tube of the thermal conversion apparatus is sufficient to provide sufficient residence time for the hydrolysis mixture to be thermally converted to MTAM. The curves of the at least one tube are designed not pronounced, to minimize remixing. The design of the thermal conversion apparatus, described above, is not intended to be limited, as long as the design of the geometry of the thermal conversion apparatus to maintain the plug flow is within the competence of one skilled in the art. Factors that will be considered in the design of the thermal conversion apparatus include maintaining the plug flow, the desired retention time, the flow rate, the reaction mixture, and the temperature in the thermal conversion apparatus. The thermal conversion apparatus of one embodiment of this invention includes a tube (7) having plug flow. The tube can be made of any material that is resistant to strong acid and at high temperatures. Suitable materials include, but are not limited to, Hastelloy B, Hastelloy B-2, Hastelloy B-3 and tantalum alloys. The length of the tube of the thermal conversion apparatus is sufficient to provide the desired retention time. The plug flow in the tube of the thermal conversion apparatus can generally be maintained by means of at least one of the characteristics of the design. Some of these features are illustrated in Figure 2. The tube of the thermal conversion apparatus may have curves (8) that are not pronounced (see Figure 2). The tube of the thermal conversion apparatus may contain an extension (9) at the beginning of the thermal conversion apparatus, where the expansion is gradual so as to minimize the remixing of the reagents entering the tube (see Figure 2). The tube of the thermal conversion apparatus may contain a constriction (10) at the end of the thermal conversion apparatus, where the constriction is gradual so as to minimize the remixing of the material exiting the tube (see Figure 2). The diameter of the tube can be selected in order to favor the plug flow. The tube can also be straight, in which case, the plug flow is maintained. An alternative, so that the curves in the tube are not pronounced, while maintaining the plug flow, is to have a CRV ™ in each curve. The design, which has any of the characteristics described above, reduces the remixing and maintains the plug flow at this point in the process. As a result of reduced remixing, thermal conversion performance losses are reduced, thereby increasing the performance of the entire process. The thermal conversion is typically carried out at temperatures ranging from 135 ° C to 165 ° C. The temperature can vary or be constant in this index. The third part of the fractionation reactor is the cooler of the fractionation reactor. The fractionation reactor cooler can be at least one heat exchange device that is used to lower the temperature of the fractionation reactor mixture before the esterification reaction, to prevent degradation of the fractionation reactor mixture. The cooler of the fractionation reactor can be any type of heat exchange device, as long as it is resistant to the high temperatures and very strong acid conditions present in the process. Suitable heat exchange devices include plate and frame, plate and fin, spiral and tubular. Suitable building materials include, but are not limited to, Hastelloy B, Hastelloy B-2, Hastelloy B-3 and tantalum alloys. The outlet temperature in the cooler of the fractionation reactor typically varies from 90 ° C to 110 ° C. The retention time in the fractionation reactor, which includes the thermal reactor heater and preheater, the thermal conversion apparatus and the fractionation reactor cooler, may vary, based on temperatures and reaction mixtures, but is typically 1 minute to 30 minutes, preferably 3 minutes to 20 minutes, and better from 5 minutes to 15 minutes. The fractionation reactor mixture can be transferred to at least one reactor, wherein the fractionation reactor mixture is contacted with methanol and reacted by means of methods known in the art to produce an esterification mixture. which includes, but is not limited to, predominantly MAM, with smaller amounts of AMA, MTAM, MEMOB, MOB, methanol, mineral acids and MAM / AMA copolymer, or else it is contacted with water and reacted by means known in the art to produce a mixture that predominantly includes AMA. The reaction conditions are not critical, and can be varied on a wide scale. The only requirement is that the conditions be sufficiently accessible, so that the secondary reactions that lead to the degradation of the products do not occur to an unacceptable degree. The reaction is typically carried out at a temperature ranging from 85 ° C to 180 ° C. The temperature can be maintained at a value or changed during the course of the reaction. The esterification reaction can be carried out in a continuous flow stirred tank reactor or in a plug flow reactor, as described above. Alternatively, the esterification reaction can be carried out in one or more reactors. If more than one reactor is used, they can be connected in parallel or in series. The MAM and AMA in the esterification reactor mixture are isolated from the esterification reactor mixture. Such isolation can be done by means of a method known in the art. For example, the MAM and AMA of the esterification reaction are isolated by separation of the esterification mixture in organic and inorganic phases. In general, the organic phase will contain a higher amount of MAM and a smaller amount of AMA, and the inorganic phase will contain predominantly sulfuric acid. The organic acid AMA can be isolated using an aqueous basic bath, such as a solution of aqueous ammonia, sodium, calcium or potassium hydroxide, sodium or calcium carbonate or organic amines, such as trimethyl amine. The basic compound of the aqueous basic bath forms a salt with the AMA which is soluble in the aqueous phase, formed by the addition of the basic aqueous bath, and less soluble in the inorganic phase. Accordingly, the MAM divisions move into the organic phase, and the salt divisions of AMA into the aqueous phase. The aqueous basic bath can be added during the separation of the esterification mixture into organic and inorganic phases. In such a case, an adequate amount of basic bath is added so that the inorganic acid phase is neutralized and the AMA salt is formed. Alternatively, the organic phase can be removed, and the basic bath added at some later time. Occasionally, a stable emulsion forms after the basic bath. To facilitate the breaking of the emulsion and separation of the aqueous and organic phases formed during the basic aqueous bath, a low level of a strong acid or a strong acid salt can be added to the area where the separation will occur. This strong acid or strong acid salt acts as a demulsifier. Strong acids or salts of suitable strong acids include, but are not limited to, sulfuric acid, methane sulphonic acid, ammonium hydrogen sulfate or p-toluene sulfonic acid. Sulfuric acid is preferable. The level of strong acid or strong acid salt added can vary from 100 ppm to 5,000 ppm, preferably 200 ppm to 1,000,000 ppm. Then the organic phase can be removed, and the MAM purified by methods known in the art, for example, by means of various distillation techniques to provide adequate degrees of purity of the MAM monomer, as required by the end use. The AMA salt in the aqueous phase is generally acidified again, and the AMA is recovered by known methods. Then the AMA can be recycled for another use. Polymerization inhibitors are useful for preventing "polymerization during the MAM preparation process and during the storage and transportation of MAM." The polymerization inhibitor may include a polymerization inhibitor soluble in water or alcohol. enunciative, but not ~ 1imitative, hydroquinone; 4-methoxyphenol; 4-ethoxyphenol; 4 -propoxyphenol; 4-butoxifenol; 4-heptoxyphenol; monobenzyl ether of hydroquinone; 1,2-dihydroxybenzene; 2-methoxyphenol; 2,5-dichlorhydroquinone; 2,5-di-tert-butylhydroquinone; 2-acetylhydroquinone; hydroquinone monobenzoate; 1,4-dimercaptobenzene; 1,2-dimercaptobenzene; 2, 3, 5-trimethylhydroquinone; 4-aminophenol; 2 -aminophenol; 2-N, N-dimethylaminophenol; 2-mercaptophenol; 4-mercaptophenol; catechol; monobutyl ether; 4-ethylaminophenol; 2,3-dihydroxyacetophenone; pyrogallol; 1,2-dimethyl ether; 2-methylthiophenol; t-butyl catechol; di-tert-butylnitroxide; di-tert-amylnitroxide; 2, 2, 6, 6-tetramethylpiperidinyloxy; 4-hydroxy-2, 2,6,6-tetramethyl-piperidinyloxy; 4 -oxo-2, 2,6,6-tetramethyl-piperidinyloxy; 4-dimethylamino 2, 2, 6, 6-tetramethyl-piperidinyloxy; 4-amino-2, 2,6,6,6-tetramethyl-piperidinyloxy; 4-ethanoyloxy-2, 2,6,6-tetramethylpiperidinyloxy; 2,2,5,5-tetramethyl-pyrrolidinyloxy; 3-amino-2, 2,5,5-tetramethyl-pyrrolidinyloxy; 2,2,5,5-tetramethyl-l-oxa-3-azacyclopentyl-3-oxy; 2, 2, 5, 5-tetramethyl-3-pyrrolinyl-l-oxy-3-carboxylic acid; 2,2,3,3,5,5,6,6-octamethyl-l, 4-diazacyclohexyl-1,4-dioxy; sodium nitro phenolate; copper compounds such as copper dimethyldithiocarbamate; copper diethyldithiocarbamate; copper dibutyldithiocarbamate; copper salicylate; Methylene blue; iron; phenothiazine; 1,4-benzenediamine, N- (1,4-dimethylpentyl) -N'-phenyl; 1,4-benzenediamine, N- (1, 3-dimethylbutyl) -N'-phenyl; isomers thereof; mixtures of two or more thereof; or mixtures of one or more of the foregoing with molecular oxygen. The polymerization inhibitor is typically used at levels ranging from 100 ppm to 4,000 ppm by weight. The process of this invention finally refers to the esterification of MTAM and MAM. Therefore, the thermal conversion of HIBAM and SIBAM to MTAM is critical to the process that provides high yields. Therefore, it is possible to measure the efficiency of the process of the invention by measuring the yield after the hydrolysis reaction and the yield after the thermal conversion in the process of the invention, and then subtracting the yield after the thermal conversion of the yield after of the hydrolysis reaction. The yield after the hydrolysis reaction is the measured amounts of HIBAM, SIBAM, AMA and MTAM. The performance after thermal conversion, is the measured amounts of AMA and MTAM. The following examples are intended to illustrate the process and thermal conversion apparatus of the invention. For examples 1 to 10 (comparative), the process of the invention was carried out using the thermal conversion apparatus of figure 1. CHA was hydrolyzed in HIBAM, SIBAM, MTAM and AMA using sulfuric acid, and HIBAM, SIBAM, MTAM and AMA were supplied to the thermal conversion apparatus. The samples were removed after the hydrolysis reaction and after the fractionation reactor. The yield analysis, after the hydrolysis reaction and the fractionation reactor, was performed by means of nuclear magnetic resonance (NMR). The results of the NMR and the loss of total yield are shown in Table 1.

Table 1 Performance Example Hydrolysis Thermal conversion Total loss 1 95.71 91.91 3.80 2 96.32 92.62 3.70 3 96.82 92.73 4.09 4 97.40 91. 31 6.09 5 97.88 91. 27 6.61 6 97.23 92. 46 4.77 7 97.43 91. 54 5.89 8 97.22 93. 35 3.87 9 98.00 92. 46 5.54 10 97.00 91. 73 5.27 Fifteen additional comparative examples were carried out. The average total yield loss for a total of twenty-five comparative examples was 5.22% +/- 0.26% with 95% safety. Then the MTAM was esterified with methanol and the phase was separated into organic and aqueous phases, and then the organic layer was distilled to produce pure MAM. For examples 11 to 20, the process of the invention was carried out using the thermal plug flow conversion apparatus of Figure 2. CHA was hydrolysed in HIBAM SIBAM, MTAM and AMA using sulfuric acid, and HIBAM, SIBAM, MTAM AND AMA were supplied to the thermal conversion device. The samples were removed after the hydrolysis reaction, and after the fractionation reactor. The yield analysis, after the hydrolysis reaction and the fractionation reactor, was carried out by means of nuclear magnetic resonance (NMR).

The results of the NMR and the loss of total yield are shown in Table 2.

Table 2 Performance Example Hydrolysis Thermal conversion Total loss 11 - 95".73 92.06 3.67 12 96.21 92.82 3.46 13 96.10 92.10 4.00 14 96.97 93.60 3.37 15 97.86 92.54 5.32 16 96.70 93.98 2.72 17 99.00 92.45 6.55 18 98.55 94.49 4.06 19 97.88 93.84 4.04 20 98.16 93.67 4.49 The above results show that using the thermal plug flow conversion apparatus of the invention, in the process of the invention, the total yield increased by 0.65% +/- 0.38% safety. A typical plant can produce an excess of 100 million pounds of MAM or AMA annually. Based on this production index, the increased yield from the joroceso of this invention could result in the plant having an increase in product of 650,000 pounds per year. -

Claims (15)

Claims

1. A process for preparing a monomer selected from methacrylic acid and methyl methacrylate, comprising: (A) hydrolyzing acetone cyanohydrin to produce a hydrolysis mixture comprising α-hydroxyisobutyramide, α-sulfatoisobutyramide, 2-methacrylamide and methacrylic acid; (B) thermally converting the hydrolysis mixture into a fractionation reactor comprising a thermal plug flow conversion apparatus, with the retention time necessary to produce a reactor reactor mixture comprising 2-methacrylamide and methacrylic acid; (C) reacting the fractionation reactor mixture in at least one reactor with a material selected from methanol and water, to produce a monomer selected from methacrylic acid and methyl methacrylate.

2. The process according to claim 1, further comprising a step in a step (D) wherein an organic stream comprising methyl methacrylate and methacrylic acid, and an inorganic stream comprising sulfuric acid are separated from the reaction mixture.

3. The process according to claim 2, further comprising separating and purifying the methyl methacrylate from the organic stream.

4. The process according to claim 2, wherein an aqueous basic bath is added to the reaction mixture during the separation step (D).

5. The process according to claim 4, wherein the demulsifier is also added to the reaction mixture during the separation step (D). =

6. The process according to claim 5, wherein the demulsifier is an acidic material.

7. A process according to claim 1, wherein the hydrolysis reaction is conducted in at least one hydrolysis reactor.

8. A process according to claim 1, wherein the hydrolysis reaction is conducted in three hydrolysis reactors.

9. A thermal conversion apparatus, comprising: at least one tube with means for maintaining plug flow.

10. The thermal conversion apparatus, according to claim 9, wherein the at least one tube has a straight length.

11. The thermal conversion apparatus according to claim 9, wherein the at least one tube has at least one curve, and the at least one curve has a Cheng Rotation Blade.

12. The thermal conversion apparatus according to claim 9, wherein the plug flow is maintained, at least partially, by the curves in the at least one tube, said curves are not pronounced.

13. The thermal conversion apparatus according to claim 9, wherein the plug flow is maintained, at least partially, by means of an extension that is at the beginning of the thermal conversion apparatus, wherein said expansion is gradual to mode to minimize the remixing of reagents that enter the at least one tube.

14. The thermal conversion apparatus according to claim 9, wherein the plug flow is maintained, at least partially, by means of a constriction at the end of the thermal conversion apparatus, wherein said constriction is gradual so as to minimize the remixing of the reagents and products that come out of the at least one tube.

15. The thermal conversion apparatus according to claim 9, wherein the plug flow is maintained, at least partially, by selecting the diameter of the tube. Ream A high performance process for the production of methyl methacrylate or methacrylic acid, and an apparatus for increasing the yield in a process for the production of methyl methacrylate or methacrylic acid are disclosed.