Post-treatment method of sucrose esterification reaction liquid

Abstract

A post-treatment method of a sucrose esterification reaction liquid belongs to the technical field of chemical engineering, and comprises the following steps: adding an ester substance into the sucrose esterification reaction liquid obtained in a sucralose production process, and then carrying out reduced-pressure supergravity rectification to remove water and acetic acid so as to obtain a sucrose ester-DMF (Dimethyl Formamide) solution; the ester substance is selected from organic acid esters with the boiling point lower than 180 DEG C. The method is simple in process flow, environment-friendly, low in sucrose ester loss rate and suitable for wide industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and particularly relates to a post-treatment method of sucrose esterification reaction liquid. Background Art

[0002] Sucralose is the only high-calorie sweetener on the market that is synthesized from sucrose. It has good stability, high safety, and pure sweetness, making it one of the most ideal sweeteners.

[0003] The existing sucralose synthesis process mainly adopts the single group protection method, including the three-step reaction process of esterification, chlorination and alcoholysis. The reaction liquid obtained by sucrose esterification cannot be directly used for the subsequent chlorination reaction because it contains impurities such as water and acetic acid. At the same time, due to the existence of azeotropic phenomenon, water and acetic acid are difficult to separate from the solvent DMF. In industry, a direct distillation process is often adopted to evaporate DMF and impurities such as water and acetic acid together to obtain a crude esterified product with high viscosity, and then fresh DMF is added for chlorination reaction. The obtained acidic DMF containing water and acetic acid needs to be processed through a series of processes before it can be reused. The process is cumbersome and energy consumption is large. At the same time, the distillation process will also cause the loss of sucrose esterification.

[0004] Patents CN108358807 and CN 111574394 mention the use of sodium hydroxide to neutralize acidic DMF, which is cumbersome and costly to operate. In addition, strong alkali will cause decomposition loss of DMF, generating a large amount of solid waste and waste gas that are difficult to handle.

[0005] In view of the shortcomings of the above-mentioned process, it is urgent to develop a new post-treatment method for sucrose esterification reaction liquid to overcome the problems of lengthy and cumbersome process, high energy consumption, and large product loss in the existing process. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the post-treatment process of sucrose esterification reaction liquid in the prior art, such as tedious process, high energy consumption and large product loss, thereby providing a post-treatment method for sucrose esterification reaction liquid. The present invention has a simple process flow, is environmentally friendly, has a low loss rate of product sucrose ester, and is suitable for a wide range of industrial applications.

[0007] To this end, the present invention provides the following technical solutions.

[0008] The present invention provides a post-treatment method for sucrose esterification reaction liquid, comprising:

[0009] Adding ester substances to the sucrose esterification reaction liquid obtained in the production process of sucralose, and then performing vacuum ultra-gravity distillation to remove water and acetic acid to obtain a sucrose ester-DMF solution;

[0010] The ester substance is selected from organic acid esters with a boiling point lower than 180°C.

[0011] In a possible implementation, the ester substance is selected from organic acid esters having a boiling point of 70-160°C.

[0012] In a possible embodiment, the ester substance is selected from one or more of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, phenyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isopentyl acetate, methyl cyclopropanecarboxylate, ethyl cyclopropanecarboxylate, tert-butyl cyclopropanecarboxylate, ethyl cyclobutanecarboxylate, and ethyl benzoylformate.

[0013] In a possible implementation, the sucrose esterification reaction liquid is obtained by reacting sucrose and acetic anhydride in a DMF solvent under the action of a Sn-containing catalyst, followed by quenching with water and removing the Sn-containing catalyst.

[0014] In one possible embodiment, cyclohexane extraction is used to remove the Sn-containing catalyst.

[0015] In a possible implementation, the sucrose esterification reaction solution comprises, by weight percentage, 80-93% DMF, 4-13% sucrose ester, 1.5-4% water, 1.1-1.5% acetic acid, 0.1-1% cyclohexane, and 0.1-1% DMAC (dimethylacetamide).

[0016] In a possible implementation, the amount of ester substances added is 0.5% to 5% by mass of the sucrose esterification reaction liquid, preferably 1% to 3% by mass.

[0017] In a possible implementation, the vacuum and high gravity distillation satisfies at least one of the following conditions:

[0018] (1) Absolute pressure 0.5KPa~60KPa;

[0019] (2) The speed is 500 to 2000 rpm;

[0020] (3) The heating temperature of the tower kettle is 35-90°C;

[0021] (4) The reflux ratio is 10:1 to 0.5:1.

[0022] In a possible implementation, the vacuum high gravity distillation is performed by a high gravity distillation machine, and the high gravity distillation machine is a multi-stage high gravity distillation machine with 1 to 3 stages.

[0023] In a possible implementation, the internal rotor packing of the ultra-gravity fractionator is a monolithic structured packing;

[0024] Optionally, the integral structured packing is selected from any one of foamed silicon carbide corrugated structured packing, foamed nickel structured packing, titanium alloy structured packing, fin guide plate structured packing, and modified plastic structured packing, or a combination of at least two of them.

[0025] In a possible implementation, the integral structured packing has an inner diameter of 50 to 300 mm, an outer diameter of 200 to 800 mm, and a height of 200 to 1000 mm.

[0026] In the method of the present invention, after the vacuum and ultra-gravity distillation is completed, a sucrose ester-DMF solution is extracted from the heavy component, and a mixed solution containing acetic acid, water, cyclohexane, ester substances and a small amount of DMF is extracted from the light component;

[0027] The sucrose ester-DMF solution, wherein the water content is less than 0.1% and the acetic acid content is less than 0.05%, can be directly used for subsequent chlorination reactions.

[0028] The technical solution of the present invention has the following advantages:

[0029] 1. The post-treatment method of the sucrose esterification reaction liquid of the present invention comprises: adding an ester substance to the sucrose esterification reaction liquid obtained in the production process of sucralose, and then performing vacuum ultra-gravity distillation to remove water and acetic acid to obtain a sucrose ester-DMF solution; the ester substance is selected from organic acid esters with a boiling point lower than 180°C.

[0030] The present invention adopts ultra-gravity distillation technology to purify the sucrose esterification reaction liquid containing water and acetic acid impurities, and utilizes the advantages of large gas-liquid two-phase contact area and fast phase interface renewal speed in ultra-gravity environment to promote the separation of light components and solvent DMF; at the same time, by adding ester substances to change the relative volatility of light components, the volatilization of acetic acid is promoted, the separation effect of the azeotropic system is significantly improved, and the loss of solvent DMF is reduced; the improvement of separation efficiency reduces the residence time of sucrose ester products in the high temperature environment of the tower bottom, and the product loss rate is reduced. The present invention directly processes the sucrose esterification reaction liquid obtained in the production process of sucralose, and the obtained sucrose ester-DMF solution can be directly used for subsequent chlorination reactions. The method of the present invention solves the problems of lengthy and cumbersome process, large energy consumption, and large product loss in traditional processes, and is suitable for a wide range of industrial applications. DETAILED DESCRIPTION

[0031] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0032] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0033] Main raw material sources of the examples:

[0034] Sucrose esterification reaction liquid: obtained by reacting sucrose and acetic anhydride in a DMF solvent under the action of a Sn-containing catalyst, quenching with water, and removing the Sn-containing catalyst by cyclohexane extraction;

[0035] Isobutyl formate: 97%, MacLean Biochemical Technology Co., Ltd.;

[0036] Isoamyl formate: 97%, Aladdin Technology Co., Ltd.;

[0037] Ethyl acetate: 99%, Aladdin Technology Co., Ltd.;

[0038] Ethyl cyclopropanecarboxylate: 98%, Aladdin Technology Co., Ltd.;

[0039] Phenyl formate: 98%, MacLean Biochemical Technology Co., Ltd.;

[0040] Ethyl formate: 99%, Aladdin Technology Co., Ltd.

[0041] Unless otherwise specified, the raw materials and reagents in the present invention can be purchased from commercial sources.

[0042] Ultra-gravity distillation machine: 3 stages, rotor diameter 850 mm, distillation chamber height 1500 mm, Zhejiang Xinchuangxing Technology Co., Ltd., 8503P;

[0043] Foamed silicon carbide corrugated structured packing: inner diameter 150mm, outer diameter 850mm, height 200mm, Zhejiang Xinchuangxing Technology Co., Ltd., SUS316L;

[0044] Modified plastic structured packing: inner diameter 150mm, outer diameter 850mm, height 200mm, Zhejiang Xinchuangxing Technology Co., Ltd., SUS316L;

[0045] Fin guide plate structured packing: inner diameter 150mm, outer diameter 850mm, height 200mm, Zhejiang Xinchuangxing Technology Co., Ltd., SUS316L.

[0046] Product composition analysis method:

[0047] Liquid chromatography analysis conditions: Waters liquid chromatograph, Waters XBridge Amide column, ELSD detector, mobile phase acetonitrile / ammonia water 65 / 35, column temperature 45°C.

[0048] Gas chromatography analysis conditions: Shimadzu gas chromatograph, HP-5 chromatographic column, inlet temperature: 140°C; detector temperature: 300°C; heating program: 50°C for 2 min, 10°C / min to 100°C; 5°C / min to 200°C; 20°C / min to 300°C, hold for 5 min.

[0049] Example 1

[0050] The structured packing used in the ultra-gravity distillation machine of this embodiment is foamed silicon carbide corrugated structured packing; the mass percentage composition of the sucrose esterification reaction liquid to be post-treated is DMF 91.29%, sucrose ester 5.14%, water 1.98%, acetic acid 1.12%, cyclohexane 0.25%, and DMAC 0.22%.

[0051] This embodiment provides a post-treatment method for a sucrose esterification reaction liquid, comprising:

[0052] Isobutyl formate was added to the sucrose esterification reaction liquid to be post-treated at a ratio of 1wt%, and the liquid was fed into an ultra-gravity distillation machine at a flow rate of 200kg / h for continuous vacuum ultra-gravity distillation. The absolute pressure of the distillation process was 53kPa, the rotation speed was 2000rpm, the temperature of the tower was 75°C, and the reflux ratio was 10:1. The heavy component extracted during the distillation process was a sucrose ester-DMF solution after dehydration and deacidification, with an extraction flow rate of 182.2kg / h; the light component was a mixture containing DMF and other impurities, with an extraction flow rate of 17.8kg / h.

[0053] The sucrose ester-DMF solution obtained after treatment in this example contains 94.34% DMF, 5.45% sucrose ester, 0.05% water, 0.02% acetic acid, and 0.14% heavy component impurities generated during the process; the recovery rate of sucrose ester is 97.5%.

[0054] Sucrose ester recovery rate = mass of sucrose ester in sucrose ester-DMF solution / mass of sucrose ester in the sucrose esterification reaction solution to be post-treated * 100%.

[0055] Heavy impurities refer to heavy components with larger molecular weight generated when sucrose esters are destroyed in the high temperature environment of the tower bottom.

[0056] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 50.06%, and the remaining components are water, acetic acid, cyclohexane, DMAC, and isobutyl formate.

[0057] Example 2

[0058] The structured packing used in the ultra-gravity distillation machine of this embodiment is a modified plastic structured packing; the mass percentage composition of the sucrose esterification reaction liquid to be post-treated is DMF 85.74%, sucrose ester 7.66%, water 3.88%, acetic acid 1.46%, cyclohexane 0.72%, and DMAC 0.54%.

[0059] This embodiment provides a post-treatment method for a sucrose esterification reaction liquid, comprising:

[0060] Isoamyl formate was added to the sucrose esterification reaction liquid to be treated at a ratio of 2wt%, and the liquid was fed into an ultra-gravity distillation machine at a flow rate of 200kg / h for continuous vacuum ultra-gravity distillation. The absolute pressure of the distillation process was 17kPa, the rotation speed was 500rpm, the bottom temperature was 40°C, and the reflux ratio was 7:1. The heavy component extracted during the distillation process was a sucrose ester-DMF solution after dehydration and deacidification, with an extraction flow rate of 171.8kg / h; the light component was a mixture containing DMF and other impurities, with an extraction flow rate of 28.2kg / h.

[0061] The sucrose ester-DMF solution obtained after treatment in this example contains 91.14% DMF, 8.51% sucrose ester, 0.08% water, 0.03% acetic acid, and 0.24% heavy component impurities generated during the process; the recovery rate of sucrose ester is 97.2%.

[0062] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 40.93%, and the remaining components are water, acetic acid, cyclohexane, DMAC, and isoamyl formate.

[0063] Example 3

[0064] The structured packing used in the ultra-gravity distillation machine of this embodiment is a fin guide plate structured packing; the mass percentage composition of the sucrose esterification reaction liquid to be post-treated is DMF 83.24%, sucrose ester 11.83%, water 2.75%, acetic acid 1.39%, cyclohexane 0.46%, and DMAC 0.33%.

[0065] This embodiment provides a post-treatment method for a sucrose esterification reaction liquid, comprising:

[0066] Ethyl acetate was added to the sucrose esterification reaction liquid to be treated at a ratio of 2wt%, and the liquid was fed into an ultra-gravity distillation machine at a flow rate of 200kg / h for continuous vacuum ultra-gravity distillation. The absolute pressure of the distillation process was 32kPa, the rotation speed was 1000rpm, the bottom temperature was 55°C, and the reflux ratio was 5:1. The heavy component extracted during the distillation process was a sucrose ester-DMF solution after dehydration and deacidification, with an extraction flow rate of 175.1kg / h; the light component was a mixture containing DMF and other impurities, with an extraction flow rate of 24.9kg / h.

[0067] The sucrose ester-DMF solution obtained after treatment in this example contains 86.82% DMF, 12.85% sucrose ester, 0.04% water, 0.02% acetic acid, and 0.27% heavy component impurities generated during the process; the recovery rate of sucrose ester is 98.0%.

[0068] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 38.66%, and the remaining components are water, acetic acid, cyclohexane, DMAC, and ethyl acetate.

[0069] Example 4

[0070] The structured packing used in the ultra-gravity distillation machine of this embodiment is foamed silicon carbide corrugated structured packing; the mass percentage composition of the sucrose esterification reaction liquid to be post-treated is DMF 85.74%, sucrose ester 7.66%, water 3.88%, acetic acid 1.46%, cyclohexane 0.72%, and DMAC 0.54%.

[0071] This embodiment provides a post-treatment method for a sucrose esterification reaction liquid, comprising:

[0072] Ethyl cyclopropanecarboxylate was added to the sucrose esterification reaction liquid to be treated at a ratio of 1.5wt%, and the liquid was fed into an ultra-gravity distillation machine at a flow rate of 200kg / h for continuous vacuum ultra-gravity distillation. The absolute pressure of the distillation process was 28kPa, the rotation speed was 1500rpm, the temperature of the tower was 50°C, and the reflux ratio was 3:1. The heavy component extracted during the distillation process was a sucrose ester-DMF solution after dehydration and deacidification, with an extraction flow rate of 170.7kg / h; the light component was a mixture containing DMF and other impurities, with an extraction flow rate of 29.3kg / h.

[0073] The sucrose ester-DMF solution obtained after treatment in this example contains 91.13% DMF, 8.69% sucrose ester, 0.02% water, 0.01% acetic acid, and 0.15% heavy component impurities generated during the process; the recovery rate of sucrose ester is 98.3%.

[0074] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 45.77%, and the remaining components are water, acetic acid, cyclohexane, DMAC, and ethyl cyclopropanecarboxylate.

[0075] Example 5

[0076] The structured packing used in the ultra-gravity fractionator of this embodiment is a modified plastic structured packing; the mass percentage composition of the sucrose esterification reaction liquid to be post-treated is DMF 83.24%, sucrose ester 11.83%, water 2.75%, acetic acid 1.39%, cyclohexane 0.46%, and DMAC 0.33%.

[0077] This embodiment provides a post-treatment method for a sucrose esterification reaction liquid, comprising:

[0078] Phenyl formate was added to the sucrose esterification reaction liquid to be treated at a ratio of 2.5wt%, and the liquid was fed into an ultra-gravity distillation machine at a flow rate of 200kg / h for continuous vacuum ultra-gravity distillation. The absolute pressure of the distillation process was 60kPa, the rotation speed was 1000rpm, the temperature of the tower was 90°C, and the reflux ratio was 5:1. The heavy component extracted during the distillation process was a sucrose ester-DMF solution after dehydration and deacidification, with an extraction flow rate of 173.6kg / h; the light component was a mixture containing DMF and other impurities, with an extraction flow rate of 26.4kg / h.

[0079] The sucrose ester-DMF solution obtained after treatment in this example contains 86.57% DMF, 12.88% sucrose ester, 0.09% water, 0.04% acetic acid, and 0.42% heavy component impurities generated during the process; the recovery rate of sucrose ester is 96.9%.

[0080] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 45.97%, and the remaining components are water, acetic acid, cyclohexane, DMAC, and phenyl formate.

[0081] Example 6

[0082] The structured packing used in the ultra-gravity distillation machine of this embodiment is a fin guide plate structured packing; the mass percentage composition of the sucrose esterification reaction liquid to be post-treated is DMF 91.29%, sucrose ester 5.14%, water 1.98%, acetic acid 1.12%, cyclohexane 0.25%, and DMAC 0.22%.

[0083] This embodiment provides a post-treatment method for a sucrose esterification reaction liquid, comprising:

[0084] Ethyl formate was added to the sucrose esterification reaction liquid to be treated at a ratio of 4.5wt%, and the liquid was fed into an ultra-gravity distillation machine at a flow rate of 200kg / h for continuous vacuum ultra-gravity distillation. The absolute pressure of the distillation process was 30kPa, the rotation speed was 1500rpm, the temperature of the tower was 50°C, and the reflux ratio was 2:1. The heavy component extracted during the distillation process was a sucrose ester-DMF solution after dehydration and deacidification, with an extraction flow rate of 170.89kg / h; the light component was a mixture containing DMF and other impurities, with an extraction flow rate of 29.11kg / h.

[0085] The sucrose ester-DMF solution obtained after treatment in this example contains 94.12% DMF, 5.61% sucrose ester, 0.09% water, 0.03% acetic acid, and 0.15% heavy component impurities generated during the process; the recovery rate of sucrose ester is 97.4%.

[0086] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 47.67% and the remaining components are water, acetic acid, cyclohexane, DMAC and ethyl formate.

[0087] Comparative Example 1

[0088] This comparative example is substantially the same as Example 1, except that isobutyl formate is not added in this comparative example.

[0089] The sucrose ester-DMF solution obtained after treatment in this comparative example contains 92.38% DMF, 5.44% sucrose ester, 1.01% water, 0.59% acetic acid, 0.05% DMAC, and 0.53% heavy component impurities generated in the process; the recovery rate of sucrose ester is 91.1%.

[0090] The light component comprises a mixture of DMF and other impurities, wherein DMF accounts for 84.51%, and the remaining components are water, acetic acid, cyclohexane, and DMAC.

[0091] It can be seen from Examples 1 to 6 that the sucrose ester-DMF solution prepared by the method of the present invention has a water content of <0.1% and an acetic acid content of <0.05%, and can be directly used in subsequent chlorination reactions.

[0092] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A post-treatment method for sucrose esterification reaction liquid, characterized in that: include: Adding ester substances to the sucrose esterification reaction liquid obtained in the production process of sucralose, and then performing vacuum ultra-gravity distillation to remove water and acetic acid to obtain a sucrose ester-DMF solution; The ester substance is selected from organic acid esters with a boiling point lower than 180°C.

2. The post-treatment method of sucrose esterification reaction liquid according to claim 1, characterized in that: The ester substance is selected from organic acid esters with a boiling point of 70-160°C.

3. The post-treatment method of sucrose esterification reaction liquid according to claim 1, characterized in that: The ester substance is selected from one or more of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, phenyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isopentyl acetate, methyl cyclopropanecarboxylate, ethyl cyclopropanecarboxylate, tert-butyl cyclopropanecarboxylate, ethyl cyclobutanecarboxylate, and ethyl benzoylformate.

4. The post-treatment method of the sucrose esterification reaction liquid according to any one of claims 1 to 3, characterized in that: The sucrose esterification reaction liquid is obtained by reacting sucrose and acetic anhydride in a DMF solvent under the action of a Sn-containing catalyst, then adding water for quenching, and removing the Sn-containing catalyst.

5. The post-treatment method of the sucrose esterification reaction liquid according to any one of claims 1 to 3, characterized in that: The sucrose esterification reaction liquid comprises, by mass percentage, 80-93% of DMF, 4-13% of sucrose ester, 1.5-4% of water, 1.1-1.5% of acetic acid, 0.1-1% of cyclohexane and 0.1-1% of dimethylacetamide.

6. The post-treatment method of the sucrose esterification reaction liquid according to any one of claims 1 to 3, characterized in that: The amount of ester substances added is 0.5% to 5% of the mass of the sucrose esterification reaction liquid, preferably 1% to 3%.

7. The post-processing method according to any one of claims 1 to 3, characterized in that: The vacuum high gravity distillation satisfies at least one of the following conditions: (1) Absolute pressure 0.5KPa~60KPa; (2) The speed is 500 to 2000 rpm; (3) The heating temperature of the tower kettle is 35-90°C; (4) The reflux ratio is 10:1 to 0.5:

1.

8. The post-treatment method of sucrose esterification reaction liquid according to any one of claims 1 to 3, characterized in that: The vacuum supergravity distillation is performed by a supergravity distillation machine, and the supergravity distillation machine is a multi-stage supergravity distillation machine with 1 to 3 stages.

9. The post-treatment method of sucrose esterification reaction liquid according to claim 8, characterized in that: The internal rotor packing of the ultra-gravity fractionator is an integral structured packing; Optionally, the integral structured packing is selected from any one of foamed silicon carbide corrugated structured packing, foamed nickel structured packing, titanium alloy structured packing, fin guide plate structured packing, and modified plastic structured packing, or a combination of at least two of them.

10. The post-treatment method of sucrose esterification reaction liquid according to claim 9, characterized in that: The inner diameter of the integral structured packing is 50-300 mm, the outer diameter is 200-800 mm, and the height is 200-1000 mm.