A method of absorbing dimethyl ethylene ketone

Abstract

The application discloses a method for absorbing dimethyl ethylene ketone, which comprises the following steps: absorbing dimethyl ethylene ketone-rich gas through an absorbent; and the absorbent comprises an absorption solvent and dimethyl ethylene ketone oligomers dissolved in the absorption solvent. The method can overcome the defects of the prior art, such as a large amount of solvent used in the dimethyl ethylene ketone DMK absorption process and low absorption efficiency, and can significantly improve the concentration of DMK in the solution after absorption.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for absorbing dimethyl ethylene ketone. BACKGROUND

[0002] Dimethyl ethylene ketone (DMK) is an important member of the enone class of compounds. Due to its carbon-carbon double bond and carbon-oxygen double bond being directly connected, it is extremely active in nature, and thus it can only exist stably in solution for about 5 hours at low temperature. On the other hand, DMK is also a key intermediate for the preparation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB), and the obtained TMCB can be obtained by hydrogenation to obtain high value-added polyester monomer 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO).

[0003] The commonly used method for capturing DMK in industry is solution absorption method, however, this method has the following problems: (1) DMK has low solubility in ester absorption solvents, and the reported DMK concentration after absorption of the ester solvent is all below 20wt%, resulting in a huge amount of solvent used in the absorption process; (2) although the reported selectivity of the dimerization process can reach 99%, however, in the actual process, the absorbed DMK is prone to side reactions in the dimerization process, and the yield is generally 80% to 99%, and some trace impurities generated in the dimerization process will affect the catalyst activity in the subsequent TMCB hydrogenation process to prepare CBDO. SUMMARY

[0004] In order to solve the above two problems, the purpose of the present application is to overcome the defects of the prior art that the solvent used in the dimethyl ethylene ketone DMK absorption process is large and the absorption efficiency is low, and to provide a method for absorbing dimethyl ethylene ketone, which can significantly improve the concentration of DMK in the solution after absorption.

[0005] In order to achieve the above purpose, the present application provides a method for absorbing dimethyl ethylene ketone, which comprises: absorbing a gas rich in dimethyl ethylene ketone by an absorbent; the absorbent comprises an absorption solvent and a dimethyl ethylene ketone oligomer dissolved in the absorption solvent.

[0006] The method of the present application can overcome the defects of the prior art that the solvent used in the dimethyl ethylene ketone DMK absorption process is large and the absorption efficiency is low, and can significantly improve the concentration of DMK in the solution after absorption. DETAILED DESCRIPTION

[0007] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0008] The application provides a method for absorbing dimethyl ethylene ketone, which comprises: absorbing dimethyl ethylene ketone-rich gas through an absorbent; the absorbent comprises an absorption solvent and dimethyl ethylene ketone oligomers dissolved in the absorption solvent. The method of the application can overcome the defects of the prior art, such as large solvent consumption and low absorption efficiency in the dimethyl ethylene ketone DMK absorption process, and can significantly improve the concentration of DMK in the solution after absorption.

[0009] In the application, the purpose of the application can be achieved by using the absorbent, and there is no special requirement for the specific composition of the absorbent, which can be determined according to the concentration of dimethyl ethylene ketone in the raw material; according to a preferred embodiment of the application, the concentration of dimethyl ethylene ketone oligomers in the absorbent is 0.1-3wt%, preferably 0.1-1wt%, for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1wt%. Thus, the absorption efficiency and the concentration of DMK in the solution after absorption can be further improved.

[0010] In the application, there is no special requirement for the absorption conditions, and according to a preferred embodiment of the application, the absorption conditions comprise: the temperature is-30℃ to 30℃, preferably-20℃ to 10℃, for example, -20℃, -10℃, 0℃ or 10℃. Thus, the absorption efficiency and the concentration of DMK in the solution after absorption can be further improved.

[0011] In the application, dimethyl ethylene ketone oligomers can be used in the application, for example, one or more selected from the group consisting of dimethyl ethylene ketone carbon-carbon double bond addition homopolymers, dimethyl ethylene ketone carbon-oxygen double bond addition homopolymers and dimethyl ethylene ketone carbon-carbon double bond addition and carbon-oxygen double bond addition block copolymers.

[0012] In the application, preferably, the dimethyl ethylene ketone oligomers are selected from the group consisting of dimethyl ethylene ketone carbon-carbon double bond addition homopolymers and / or dimethyl ethylene ketone carbon-carbon double bond addition and carbon-oxygen double bond addition block copolymers.

[0013] According to a preferred embodiment of the application, preferably, the dimethyl ethylene ketone oligomers are dimethyl ethylene ketone carbon-carbon double bond addition and carbon-oxygen double bond addition block copolymers. Thus, the absorption efficiency and the concentration of DMK in the solution after absorption can be further improved.

[0014] In this invention, there are no special requirements for the molecular weight of the dimethyl ketene oligomer. For this invention, the number average molecular weight of the dimethyl ketene oligomer is preferably 300-1500, more preferably 400-1300, for example 400, 420, 450, 500, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, etc., but this invention is not limited to this, and its molecular weight is determined by GPC.

[0015] In this invention, the range of absorbent solvents that can be selected is relatively wide. Commonly used absorbent solvents in the art can all be used in this invention. For this invention, the absorbent solvent is preferably selected from any one or more of fatty acid alkyl esters, fatty acid anhydrides, and alkanes.

[0016] In this invention, there are no special requirements for the types of fatty acid alkyl esters, fatty acid anhydrides, and alkanes. Commonly used types in the art can be used in this invention. The following description of the types of substances is exemplary, but does not limit the scope of this invention.

[0017] According to one embodiment of the present invention, the structure of the fatty acid alkyl ester is as shown in formula (I):

[0018]

[0019] Wherein, R1 is H or an alkyl group having 1-6 carbon atoms, and R2 is an alkyl group having 1-6 carbon atoms;

[0020] Preferably, the fatty acid alkyl ester is one or more selected from n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, n-butyl propionate, n-butyl butyrate, ethyl isobutyrate, propyl isobutyrate, and isobutyl isobutyrate.

[0021] According to one embodiment of the present invention, the fatty acid anhydride has the structure of formula (II):

[0022]

[0023] Among them, R3 and R4 are H, alkyl groups having 1-6 carbon atoms;

[0024] Preferably, the fatty acid anhydride is one or more of isobutyric anhydride, isobutyric acid anhydride, acetic anhydride, propionic anhydride, and isobutyric acid propionate.

[0025] According to one embodiment of the present invention, the alkane is a C6-10 alkane; preferably, the alkane is one or more selected from n-hexane, n-heptane, 2-methylheptane, and n-octane.

[0026] The present invention does not have any special requirements on the composition of the gas rich in dimethyl ketene. Any gas containing dimethyl ketene can be absorbed by the absorption method of the present invention. The following is an illustrative description of the embodiments of the present invention, but the present invention is not limited to this scope.

[0027] According to one embodiment of the present invention, the volume content of dimethyl ketene in the gas rich in dimethyl ketene is 5-90%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%.

[0028] According to one embodiment of the present invention, preferably, the gas rich in dimethyl ketene contains 5-70% dimethyl ketene, with the remainder being an inert gas.

[0029] The present invention does not have any special requirements for the source of the gas rich in dimethyl ketene. For the present invention, it is preferred that the gas rich in dimethyl ketene is obtained by the thermal decomposition reaction of isobutyric acid and / or isobutyric anhydride, followed by multi-stage cooling to remove isobutyric acid and / or isobutyric anhydride from the system.

[0030] In this invention, there are no special requirements for the reaction conditions of the thermal pyrolysis process. The following is an illustrative description of the embodiments of this invention, but the invention is not limited to this scope.

[0031] According to one embodiment of the present invention, the reaction conditions of the thermal pyrolysis process include: a temperature of 350 to 650°C, preferably 350 to 550°C.

[0032] According to one embodiment of the present invention, the pressure is 1 kPa to 0.3 MPa, preferably 10 kPa to 0.1 MPa.

[0033] According to one embodiment of the present invention, the dwell time is 0.1 to 4 seconds, preferably 0.1 to 1 second.

[0034] According to one embodiment of the present invention, a dilution gas is introduced during pyrolysis.

[0035] In this invention, there are no special requirements for the amount and type of diluting gas used. The following is an illustrative description of the embodiments of this invention, but this invention is not limited to this scope.

[0036] According to one embodiment of the present invention, the volume ratio of isobutyric acid and / or isobutyric anhydride to dilution gas is (1:30) to (1:0.2), preferably (1:20) to (1:0.5).

[0037] According to one embodiment of the present invention, the diluting gas is selected from inert gases, preferably nitrogen.

[0038] In the following examples, the DMK-rich gas was generated as follows: Isobutyric anhydride was introduced into a vaporizer at 300°C at a rate of 1.2 mL / min. The vaporized isobutyric anhydride gas was mixed with hot nitrogen gas at a flow rate of 4.8 L / min (nitrogen preheated at 300°C). The mixed gas was then introduced into a pyrolysis reactor made of quartz tube with a diameter of 15 mm and a length of 800 mm. The reactor internal temperature was 410°C. The resulting pyrolysis product was rapidly cooled to 40°C to remove isobutyric anhydride and isobutyric acid from the system, yielding a DMK-rich gas. Online gas chromatography analysis showed that the DMK content in this gas phase was 9.53%.

[0039] The structural formula of DMK is:

[0040] The concentration of DMK in the solution is obtained by testing the substance content through chromatographic analysis and calculation. The equilibrium concentration of DMK after absorption is calculated as: mass of DMK in the solution / total mass of the absorption solution.

[0041] In this invention, the homopolymer prepared by the carbon-carbon double bond addition of dimethyl ketene has the following structural formula. n>4;

[0042] In this invention, the homopolymer prepared by the carbon-oxygen double bond addition of dimethyl ketene has the following structural formula. n>4;

[0043] In this invention, the block copolymer of dimethyl ketene with carbon-carbon double bond addition and carbon-oxygen double bond addition contains at least a portion of the following units in its molecular chain segments:

[0044] Example 1

[0045] The additive used in this embodiment is a homopolymer prepared by carbon-carbon double bond addition of dimethyl ketene, with a molecular weight of 1050. The main absorbent solvent is n-butyl acetate, and the mass content of DMK homopolymer in the absorbent is 0.5 wt%.

[0046] DMK was absorbed using 300 mL of the above absorption solution at a temperature of -10℃. The concentration change of DMK in the absorption solvent is shown in Table 1. It can be seen that the equilibrium concentration of DMK after absorption can reach 31.98 wt%.

[0047] Table 1

[0048]

[0049] Example 2

[0050] The additive used in this embodiment is a block copolymer prepared by the addition of carbon-carbon double bonds and carbon-oxygen double bonds of dimethyl ketene, with a molecular weight of 420. The main solvent for absorption is n-butyl acetate, and the mass content of DMK homopolymer in the absorbent is 0.5 wt%.

[0051] DMK was absorbed using 300 mL of the above absorption solution at a temperature of -10℃. The concentration change of DMK in the absorption solvent is shown in Table 2. It can be seen that the equilibrium concentration of DMK after absorption can reach 36.51 wt%.

[0052] Table 2

[0053]

[0054] Comparative Example 1

[0055] In this comparative example, only n-butyl acetate was used as the absorption solvent. DMK was absorbed using 300 mL of the above absorption solution at -10°C. The concentration change of DMK in the absorption solvent is shown in Table 3. It can be seen that the equilibrium concentration of DMK after absorption was only 16.93 wt%.

[0056] Table 3

[0057]

[0058] Comparative Example 2

[0059] In this comparative example, a butyl acetate solution containing 0.5 wt% tetramethylcyclobutanedione (TMCB) was used as the absorption solvent. DMK was absorbed using 300 mL of the above absorption solution at -10°C. The concentration change of DMK in the absorption solvent is shown in Table 4. It can be seen that the equilibrium concentration of DMK after absorption was only 22.31 wt%.

[0060] Table 4

[0061]

[0062] Example 3

[0063] The additive used in this embodiment is a homopolymer prepared by carbon-carbon double bond addition of dimethyl ketene, with a molecular weight of 600. The main absorption solvent is n-butyl acetate, and the mass content of DMK homopolymer in the absorbent is 0.9 wt%.

[0064] DMK was absorbed using 300 mL of the above absorption solution at a temperature of -10℃. The concentration change of DMK in the absorption solvent is shown in Table 1. It can be seen that the equilibrium concentration of DMK after absorption can reach 33.08 wt%.

[0065] Table 5

[0066]

[0067] Example 4

[0068] The additive used in this embodiment is a homopolymer prepared by carbon-carbon double bond addition of dimethyl ketene, with a molecular weight of 600. The main absorbent solvent is n-butyl acetate, and the mass content of DMK homopolymer in the absorbent is 1.2 wt%.

[0069] DMK was absorbed using 300 mL of the above absorption solution at a temperature of -10℃. The concentration change of DMK in the absorption solvent is shown in Table 1. It can be seen that the equilibrium concentration of DMK after absorption can reach 28.24 wt%.

[0070] Table 6

[0071]

[0072]

[0073] Example 5

[0074] The additive used in this embodiment is a homopolymer prepared by carbon-carbon double bond addition of dimethyl ketene, with a molecular weight of 600. The main absorbent solvent is n-butyl acetate, and the mass content of DMK homopolymer in the absorbent is 0.05 wt%.

[0075] DMK was absorbed using 300 mL of the above absorption solution at a temperature of -10℃. The concentration change of DMK in the absorption solvent is shown in Table 1. It can be seen that the equilibrium concentration of DMK after absorption can reach 19.48 wt%.

[0076] Table 7

[0077]

[0078] Example 6

[0079] The method of Example 1 was followed, except that the oligomer was a homopolymer formed by the addition of carbon and oxygen double bonds of dimethyl ketene, and all other conditions were the same. The DMK absorption results are shown in Table 8.

[0080] Table 8

[0081]

[0082] Example 7

[0083] The method of Example 1 was followed, except that the oligomer was a block copolymer of dimethyl ketene with carbon-carbon double bond addition and carbon-oxygen double bond addition, and all other conditions were the same. The DMK absorption results are shown in Table 9.

[0084] Table 9

[0085]

[0086] Example 8

[0087] The method of Example 1 was followed, except that the molecular weight of the oligomer was 350, while all other conditions were the same. The DMK absorption results are shown in Table 10.

[0088] Table 10

[0089]

[0090] Example 8

[0091] The method of Example 1 was followed, except that the main solvent for absorption was isobutyric anhydride, while all other conditions were the same. The DMK absorption results are shown in Table 10.

[0092] Table 10

[0093]

[0094] Example 9

[0095] The method of Example 1 was followed, except that the main solvent for absorption was n-octane, while all other conditions were the same. The DMK absorption results are shown in Table 11.

[0096] Table 11

[0097]

[0098] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for absorbing dimethyl ketene, the method comprising: The gas rich in dimethyl ketene is absorbed by an absorbent; characterized in that the absorbent comprises an absorbent solvent and a dimethyl ketene oligomer dissolved in the absorbent solvent; The concentration of dimethyl ketene oligomer in the absorbent is 0.1-3 wt%. The dimethyl ketene oligomers are block copolymers of dimethyl ketene with carbon-carbon double bond addition and carbon-oxygen double bond addition.

2. The method according to claim 1, wherein, The concentration of dimethyl ketene oligomer in the absorbent is 0.1-1 wt%.

3. The method according to claim 1 or 2, wherein, The absorption conditions include a temperature of -30°C to 30°C.

4. The method according to claim 3, wherein, The absorption conditions include a temperature of -20°C to 10°C.

5. The method according to claim 1 or 2, wherein, The number average molecular weight of the dimethyl ketone oligomer is 300-1500.

6. The method according to claim 5, wherein, The number average molecular weight of the dimethyl ketone oligomer is 400-1300.

7. The method according to claim 1 or 2, wherein, The absorbent solvent is selected from any one or more of fatty acid alkyl esters, fatty acid anhydrides, and alkanes; The structure of the fatty acid alkyl ester is as shown in formula (I): Wherein, R1 is H or an alkyl group having 1-6 carbon atoms, and R2 is an alkyl group having 1-6 carbon atoms; The structure of the fatty acid anhydride is as shown in formula (II): Among them, R3 and R4 are each H and alkyl groups having 1-6 carbon atoms; The alkane is a C6-10 alkane.

8. The method according to claim 7, wherein, The fatty acid alkyl ester is one or more selected from the following: n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, n-butyl propionate, n-butyl butyrate, ethyl isobutyrate, propyl isobutyrate, and isobutyl isobutyrate; and / or The fatty acid anhydride is one or more of isobutyric anhydride, isoacetic anhydride, acetic anhydride, propionic anhydride, and isobutyric propionate; and / or The alkane is one or more selected from n-hexane, n-heptane, 2-methylheptane, and n-octane.

9. The method according to claim 1 or 2, wherein, The gas rich in dimethyl ketene has a volume content of 5-90% for dimethyl ketene.

10. The method according to claim 9, wherein, The gas rich in dimethyl ketene contains 5-70 wt% dimethyl ketene, with the remainder being inert gas.

11. The method according to claim 1 or 2, wherein, The gas rich in dimethyl ketene is prepared by thermal decomposition of isobutyric acid and / or isobutyric anhydride, followed by cooling to remove isobutyric acid and / or isobutyric anhydride from the system.

12. The method according to claim 11, wherein, The conditions for the thermal decomposition reaction include a temperature of 350–650°C.

13. The method according to claim 12, wherein, The conditions for the thermal decomposition reaction include a temperature of 350–550°C.

14. The method according to claim 11, wherein, During thermal pyrolysis, a dilution gas is introduced, and the volume ratio of isobutyric acid and / or isobutyric anhydride to the dilution gas is (1:30) to (1:0.2).

15. The method according to claim 14, wherein, During thermal pyrolysis, a dilution gas is introduced, with the volume ratio of isobutyric acid and / or isobutyric anhydride to the dilution gas being (1:20) to (1:0.5); and / or The diluent gas is selected from inert gases.

16. The method according to claim 15, wherein, The diluting gas is nitrogen.

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