A system and method for producing high purity MMA

Abstract

The present application relates to a system for preparing high-purity MMA, comprising a diethyl ketone separation unit for separating diethyl ketone from ethylene carbonylation products; a condensation reaction unit arranged downstream of the diethyl ketone separation unit, for performing condensation reaction on the product separated by the diethyl ketone separation unit to generate MMA; and a rectification separation unit arranged downstream of the condensation reaction unit, for separating the product of the condensation reaction unit to obtain high-purity MMA. After the synthesis of methyl propionate by ethylene carbonylation, the byproduct DEK is first separated and removed by the diethyl ketone separation unit, and the methyl propionate and methanol material containing the diethyl ketone after removal are subjected to condensation reaction with formaldehyde to generate MMA, effectively avoiding the problem of difficult separation of diethyl ketone DEK and MMA with very similar boiling points, and then high-purity MMA is easily obtained by separation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical separation technology, in particular to a system and method for preparing high-purity MMA. BACKGROUND

[0002] Methyl methacrylate (MMA) is an organic compound, which is an important chemical raw material, a monomer for producing transparent plastic polymethyl methacrylate (PMMA), and can be copolymerized with other vinyl monomers to obtain products with different properties for manufacturing organic glass, paint, lubricating oil additive, plastic, adhesive, resin, wood impregnant, motor coil impregnant, ion exchange resin, paper glazing agent, textile printing and dyeing aid, leather treatment agent, printing and dyeing aid, and insulation pouring material, etc.

[0003] The main methods for producing MMA include acetone cyanohydrin method, tertiary butanol / isobutene direct oxidation method, ethylene carbonylation method, methyl propionate aldol condensation method, etc. Among them, the ethylene carbonylation method is a research hotspot in recent years. In the process of preparing MMA, it is relatively difficult to completely remove diethyl ketone (DEK) and obtain optically pure MMA in the MMA refining unit because the boiling points of DEK and MMA are very similar. SUMMARY

[0004] The purpose of the present application is to provide a system and method for preparing high-purity MMA to solve the above problems.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] A system for preparing high-purity MMA for preparing high-purity MMA, comprising:

[0007] A diethyl ketone separation unit for separating diethyl ketone in the ethylene carbonylation product;

[0008] A condensation reaction unit arranged downstream of the diethyl ketone separation unit for condensation reaction of the product separated by the diethyl ketone separation unit to generate MMA;

[0009] A rectification separation unit arranged downstream of the condensation reaction unit for separating the product of the condensation reaction unit to obtain high-purity MMA.

[0010] After the synthesis of methyl propionate by ethylene carbonylation, the byproduct DEK is first separated and removed by the diethyl ketone separation unit. Since the boiling point difference between methyl propionate and DEK is large, this process is relatively easy. The material containing methyl propionate and methanol after removing DEK is condensed with formaldehyde to generate MMA, effectively avoiding the separation difficulty of DEK and MMA with very similar boiling points, and then high-purity MMA is easily obtained by separation.

[0011] Preferably, the diethyl ketone separation unit comprises a rectification tower, the absolute pressure of which is 0.5-1.5 bar, and the operating temperature of which is 50-100℃.

[0012] Preferably, the condensation reaction unit comprises a mixer and a condensation reactor; the absolute pressure of the condensation reactor is 0.1-10 bar, and the temperature of which is 100-600℃.

[0013] Preferably, the condensation reactor is provided with at least two, and at least comprises a condensation reactor loaded with a basic catalyst and a condensation reactor loaded with an acidic catalyst, wherein the basic catalyst can be a Na, K, Cs, Ca, Mg, Zn, Ba series catalyst supported by silicon dioxide; the acidic catalyst can be sulfuric acid, hydrochloric acid, ferric chloride, silicotungstic acid, phosphotungstic acid, acidic resin catalyst.

[0014] Preferably, the rectification separation unit comprises an impurity removal unit, an MMA recovery tower (B11) and an MMA refining tower (B12);

[0015] The impurity removal unit is used to remove at least one of the impurities DME, DMM, ethylene, propylene, methanol, methyl propionate, water, MIB;

[0016] The MMA recovery tower (B11) is used to recover a small amount of MMA remaining in the impurities;

[0017] The MMA refining tower (B12) is used to refine high-purity MMA.

[0018] Preferably, the impurity removal unit is composed of a plurality of rectification towers connected in series, and the operating pressure of each rectification tower is 0-5.0 bar, and the operating temperature of which is 20-200℃.

[0019] Preferably, the system is further provided with an esterification reactor (B13) after the rectification separation unit, and the tower bottom effluent of the MMA refining tower (B12) and the overhead effluent of the impurity removal unit are sent to the esterification reactor (B13), and the overhead effluent of the esterification reactor (B13) is refluxed to the impurity removal unit.

[0020] Preferably, the absolute pressure of the esterification reactor (B13) is 0.1-0.4 bar, and the operating temperature of which is 80-140℃.

[0021] A method for preparing high-purity MMA, which is operated by using the above-mentioned system for preparing high-purity MMA, and specifically comprises the following steps:

[0022] (1) ethylene carbonylation product (S1) is separated by diethyl ketone separation unit to separate diethyl ketone, and a stream (S2) containing methyl propionate and methanol is obtained;

[0023] (2) the stream (S2) obtained in step (1) is introduced into a condensation reaction unit to react with formaldehyde to generate a material (S7) containing MMA;

[0024] (3) the material (S7) obtained in step (2) is introduced into a subsequent rectification separation unit for further separation to obtain high-purity MMA.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] 1. After the synthesis of methyl propionate by ethylene carbonylation, the byproduct DEK is separated and removed by a diethyl ketone separation unit. Since the boiling point difference between methyl propionate and DEK is large, this process is relatively easy. The material containing methyl propionate and methanol after removal of diethyl ketone is subjected to condensation reaction with formaldehyde to generate MMA, effectively avoiding the problem of difficult separation of DEK and MMA with very similar boiling points. High-purity MMA is then easily obtained by separation.

[0027] 2. The conversion rate of formaldehyde raw material is low, and it is difficult to remove formaldehyde by conventional separation methods, which affects the purity of the product and causes waste of formaldehyde resources. By improving the condensation unit (at least including a condensation reactor loaded with a basic catalyst and a condensation reactor loaded with an acidic catalyst, respectively, for condensation reaction), the conversion rate of formaldehyde is improved, and the conversion rate of formaldehyde can reach 100%, avoiding the influence of formaldehyde on the quality of the product in the subsequent MMA separation section.

[0028] 3. The present application further provides an esterification reactor after the rectification unit for further reaction of the separated byproduct, and the reaction product is recycled, further improving the yield of MMA. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Figure 1 is a structural schematic diagram of the system of embodiment 1 of the present application;

[0030] Figure 2 Figure 2 is a structural schematic diagram of the system of embodiment 2 of the present application;

[0031] Figure 3 Figure 3 is a structural schematic diagram of the system of embodiment 3 of the present application;

[0032] Figure 4 Figure 4 is a structural schematic diagram of the system of embodiment 4 of the present application;

[0033] Figure 5 Figure 5 is a structural schematic diagram of the system of embodiment 5 of the present application. DETAILED DESCRIPTION

[0034] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] A system for preparing high-purity MMA, the system comprising a diethyl ketone separation unit for separating diethyl ketone from ethylene carbonylation products, a condensation reaction unit arranged downstream of the diethyl ketone separation unit, for carrying out condensation reaction on the products separated by the diethyl ketone separation unit to generate MMA, and a rectification separation unit arranged downstream of the condensation reaction unit, for separating the products of the condensation reaction unit to obtain high-purity MMA.

[0037] Referring to Figure 1 , specifically, the diethyl ketone separation unit specifically comprises a rectification column B2, the condensation reaction unit specifically comprises a mixer B3, a first condensation reactor B41 (loaded with a Cs-based catalyst supported by silica), a second condensation reactor B42 (loaded with a sulfuric acid catalyst), and the rectification separation unit specifically comprises a rectification column B7, a rectification column B10, an MMA recovery column B11, and an MMA refining column B12.

[0038] The specific connection relationship of each tower is as follows: along the flow direction, the rectification column B2, the mixer B3, the first condensation reactor B41, the second condensation reactor B42, the rectification column B7, and the rectification column B10 are connected in series through pipelines in sequence, the MMA recovery column B11 is connected to the top of the rectification column B10, and the MMA refining column B12 is connected to the tank of the rectification column B10.

[0039] When the system is used to specifically prepare high-purity MMA, the flow of each stream is as follows:

[0040] 1. The ethylene carbonylation product S1 (containing methyl propionate, methanol, and diethyl ketone) prepared by ethylene carbonylation is introduced into the rectification column B2 to remove diethyl ketone, and the diethyl ketone stream S3 is discharged from the tank of the rectification column B2;

[0041] 2. The S2 stream (containing methyl propionate and methanol) obtained from the top of the rectification column B2 and the external S4 stream (containing formaldehyde and methanol) are mixed in the mixer B3;

[0042] 3. The mixed material S5 is introduced into the first condensation reactor B41 loaded with an alkaline catalyst to carry out condensation reaction, to obtain the stream S6, which is then introduced into the second condensation reactor B42 loaded with an acidic catalyst to carry out condensation reaction again, to obtain the S7 material, which contains MMA, methyl propionate, methanol, H2O, methyl isobutyrate, methyl acetal, dimethyl ether, methyl methacrylate, propionic acid, and the like;

[0043] 4. S7 material enters rectification tower B7 to remove light components including dimethyl ether, methylal, ethylene, propylene, methyl propionate, methanol, etc. The tower bottom material stream S10 is sent to rectification tower B10 to remove methyl propionate, water, methyl isobutyrate;

[0044] 5. The rectification tower B10 tower bottom discharge S14 (containing most of the MMA) stream is sent to MMA refining tower 12. The rectification tower B10 overhead stream S15 enters MMA recovery tower B11 to recover MMA. The recovered MMA-containing stream S17 is taken from the tower bottom and sent to MMA refining tower B12. After refining in MMA refining tower B12, high-purity MMA product is obtained from the tower top, i.e. stream S18.

[0045] 6. The rectification tower B11 overhead stream S16 and the rectification tower B12 tower bottom stream S21 are sent to subsequent processing processes.

[0046] The process parameters of each tower are shown in Table 2, and the specific components of the raw material stream S1 and stream S18 are shown in Table 1.

[0047] Example 2

[0048] As Figure 2 , the difference between this embodiment and Example 1 is that the system for preparing high-purity MMA further comprises rectification tower B8 between rectification tower B7 and rectification tower B10, and the rest is the same as Example 1.

[0049] The rectification tower B7 tower bottom discharge enters rectification tower B8 for rectification to remove methyl propionate and water. The rectification tower B8 tower bottom material S12 enters rectification tower B10 to remove methyl isobutyrate. The rectification tower B8 overhead material S13 enters decanter B9 to separate the aqueous phase and the organic phase.

[0050] The process parameters of each tower are shown in Table 2, and the specific components of the raw material stream S1 and stream S18 are shown in Table 1.

[0051] Example 3

[0052] As Figure 3 , the system includes, in the direction of the stream flow, rectification tower B2, mixer B3, first condensation reactor B41 (loaded with silica-supported Cs-based catalyst), second condensation reactor B42 (loaded with acidic resin catalyst), rectification tower B6, rectification tower B8, rectification tower B10, MMA recovery tower B11 connected to the top of rectification tower B10, MMA refining tower 12 connected to the tower bottom of rectification tower B10, and esterification reactor B13 downstream of refining tower 12.

[0053] When preparing high-purity MMA through this system, the flow of each stream is as follows:

[0054] 1. The ethylene carbonylation product S1 (containing methyl propionate, methanol, diethyl ketone) obtained by ethylene carbonylation is introduced into a rectification tower B2, and diethyl ketone is removed. The S3 stream of diethyl ketone is obtained from the tower bottom;

[0055] 2. The S2 stream (containing methyl propionate and methanol) obtained from the top of the rectification tower B2 and the external S4 stream (containing formaldehyde and methanol) are introduced into a mixer B3 for mixing;

[0056] 3. The mixed material S5 is introduced into a first condensation reactor B41 filled with a basic catalyst for condensation reaction, to obtain a stream S6, which is then introduced into a second condensation reactor B42 filled with an acidic catalyst for further condensation reaction, to obtain a S7 material containing MMA, methyl propionate, methanol, H2O, methyl isobutyrate, methylal, dimethyl ether, methyl methacrylate, propionic acid and the like;

[0057] 4. The S7 material is introduced into a rectification tower B6, and light components including dimethyl ether, methylal, ethylene, propylene and the like are removed;

[0058] 5. The material S8 taken from the tower bottom is sent to a rectification tower B8 for removal of methyl propionate, water and methanol. The overhead material S13 of the rectification tower B8 is introduced into a decanter B9 for separation of an aqueous phase and an organic phase. The organic phase S11 is introduced into an esterification reactor B13. After reaction, the overhead material of the esterification reactor B13 is returned to the rectification tower B8;

[0059] 6. The tower bottom material of the rectification tower B8 is introduced into a rectification tower B10. The tower bottom material S14 (containing most of the MMA) of the rectification tower B10 is sent to an MMA refining tower 12. The overhead stream S15 of the rectification tower B10 is introduced into an MMA recovery tower B11 for recovery of MMA. The MMA-containing stream S17 recovered from the tower bottom is sent to the MMA refining tower B12 for refining. High-purity MMA product, i.e. the stream S18, is obtained from the overhead of the MMA refining tower B12;

[0060] 7. The overhead stream S16 of the rectification tower B11 and the tower bottom stream S21 of the rectification tower B12 are introduced into the esterification reactor B13. The tower bottom material S20 of the esterification reactor B13 is introduced into a post-treatment process.

[0061] The process parameters of each tower are shown in Table 2, and the specific components of the raw material stream S1 and the stream S18 are shown in Table 1.

[0062] Example 4

[0063] In this example, the rectification tower B8 in Example 3 is replaced by a rectification tower B7, and the rest is the same.

[0064] The process parameters of each tower are shown in Table 2, and the specific components of the raw material stream S1 and the stream S18 are shown in Table 1.

[0065] Example 5

[0066] This example is based on Example 4, and rectification tower B8 is added.

[0067] When preparing high-purity MMA through the system, the flow of each stream is as follows:

[0068] 1. The ethylene carbonylation product S1 (containing methyl propionate, methanol, and diethyl ketone) obtained by ethylene carbonylation is introduced into rectification tower B2 to remove diethyl ketone, and the diethyl ketone is discharged from the tower bottom;

[0069] 2. The S2 stream (containing methyl propionate and methanol) obtained from the top of rectification tower B2 and the external S4 stream (containing formaldehyde and methanol) are mixed in mixer B3;

[0070] 3. The mixed material S5 is introduced into the first condensation reactor B41 filled with basic catalyst to perform condensation reaction, to obtain stream S6, which is then introduced into the second condensation reactor B42 filled with acidic catalyst to perform condensation reaction again, to obtain S7 material, which contains MMA, methyl propionate, methanol, H2O, methyl isobutyrate, methyl acetal, dimethyl ether, methyl methacrylate, propionic acid, and the like;

[0071] 4. The S7 material is introduced into rectification tower B6 to remove light components including dimethyl ether, methyl acetal, ethylene, propylene, and the like;

[0072] 5. The material stream S8 taken from the tower bottom of rectification tower B6 is sent to rectification tower B7 to remove methyl propionate and methanol; the overhead stream S11 is sent to esterification reactor B13 to perform esterification reaction, and after the reaction, the overhead material of esterification reactor B13 is returned to rectification tower B7;

[0073] 6. The material stream S10 taken from the tower bottom of B7 is sent to rectification tower B8 to remove methyl propionate and water, and the overhead material S13 of rectification tower B8 is introduced into decanter B9 to separate the aqueous phase and the organic phase;

[0074] 7. The material at the tower bottom of rectification tower B8 is introduced into rectification tower B10, the tower bottom material S14 (containing most of the MMA) is sent to MMA refining tower 12, and the overhead stream S15 of rectification tower B10 is introduced into MMA recovery tower B11 to recover MMA, the stream S17 containing MMA recovered is taken from the tower bottom and sent to MMA refining tower B12, and high-purity MMA product, i.e., stream S18, is obtained from the overhead of MMA refining tower B12;

[0075] 8. The overhead stream S16 of rectification column B11 and the bottom stream S21 of rectification column B12 are fed into esterification reactor B13, and the material S20 from the bottom of esterification reactor B13 is fed into the post-treatment process.

[0076] The process parameters of each column are shown in Table 2, and the specific components of material stream S1 and stream S18 are shown in Table 1.

[0077] Table 1 Components of key streams in Examples 1-5

[0078]

[0079] Table 2 Key process parameters (pressure and temperature) of column bottoms in Examples 1-5

[0080]

[0081]

[0082] The above description of the examples is for the purpose of enabling one of ordinary skill in the art to understand and use the application. Various modifications to these examples can be readily made, and the generic principles described herein can be applied to other examples without departing from the scope of the application. Accordingly, the application is not limited to the examples described above, but is to be controlled by the limitations set forth in the following claims, and by equivalents of those claims.

Claims

1. A system for the production of high purity MMA, for the production of high purity MMA, characterized in that, The system comprises: a diethyl ketone separation unit for separating diethyl ketone from ethylene carbonylation products, comprising a rectification tower (B2); a condensation reaction unit arranged downstream of the diethyl ketone separation unit, for performing condensation reaction on the product separated by the diethyl ketone separation unit to generate MMA; a rectification separation unit arranged downstream of the condensation reaction unit, for separating the product of the condensation reaction unit to obtain high-purity MMA; the rectification separation unit comprises an impurity removal unit, an MMA recovery tower (B11) and an MMA refining tower (B12); the impurity removal unit is used for removing at least one of impurities, such as dimethyl ether, methylal, ethylene, propylene, methanol, methyl propionate, water and methyl isobutyrate; the MMA recovery tower (B11) is used for recovering a small amount of MMA remaining in the impurities; the MMA refining tower (B12) is used for refining to obtain high-purity MMA.

2. The system for producing high purity MMA according to claim 1, wherein, The distillation column (B2) is operated at a pressure of 0.5 to 1.5 bar abs and a temperature of 50 to 100 °C. o C.

3. The system for producing high purity MMA according to claim 1, wherein The condensation reaction unit comprises a mixer (B3) and condensation reactors (B41, B42); the absolute pressure of the condensation reactor is 0.1-10 bar, and the temperature is 100-600℃.

4. The system for producing high purity MMA according to claim 3, wherein The condensation reactor (B41, B42) is provided with at least two condensation reactors filled with basic catalysts and at least one condensation reactor filled with acidic catalysts.

5. The system for producing high purity MMA according to claim 1, wherein The impurity removal unit is composed of multiple rectification towers connected in series; the operating pressure of each rectification tower is 0-5.0 bar, and the operating temperature is 20-200℃.

6. The system for producing high purity MMA according to claim 5, wherein The system is further provided with an esterification reactor (B13) after the rectification separation unit; the tower bottom effluent of the MMA refining tower (B12) and the overhead effluent of the impurity removal unit are sent to the esterification reactor (B13); the overhead effluent of the esterification reactor (B13) is refluxed to the impurity removal unit.

7. The system for producing high purity MMA according to claim 6, wherein The absolute pressure of the esterification reactor (B13) is 0.1-0.4 bar, and the operating temperature is 80-140℃.

8. A process for the production of high purity MMA, characterized in that, The system is used for preparing high-purity MMA.

9. The method of claim 8, wherein the MMA has a purity of 99.9% or more. Specifically comprising the following steps: (1) ethylene carbonylation products (S1) are separated by a diethyl ketone separation unit to separate diethyl ketone, to obtain a stream (S2) containing methyl propionate and methanol; (2) the stream (S2) obtained in step (1) is introduced into a condensation reaction unit to perform condensation reaction with formaldehyde to generate a material (S7) containing MMA; (3) the material (S7) obtained in step (2) is introduced into a subsequent rectification separation unit to further separate to obtain high-purity MMA.

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