Method for improving the quality of chlorinated products in maltol production

Abstract

The invention provides a method for improving the quality of chlorinated products in maltol production, and relates to the technical field of maltol preparation. Soft water is added to a methanol solution recovered by acidic chlorination hydrolysis to carry out a hydrolysis reaction; after the hydrolysis reaction is completed, the solution is allowed to stand for stratification, and heavy phase impurities are discharged to obtain a recovered methanol solution. Since the methanol solution recovered by the chlorination hydrolysis is acidic, after the soft water is added, non-polar ketone and ester impurities in the methanol solution recovered by the chlorination hydrolysis undergo a hydrolysis reaction under acidic conditions to generate corresponding acids and alcohols; after standing for a period of time, heavy phase turbid impurities naturally sink, and methanol liquid is in the upper layer; then the methanol liquid and the heavy phase turbid impurities are separated to obtain a methanol solution in which the methanol content is increased from 54% to more than 65%; when the high-purity methanol solution is fed into a chlorination system for repeated use, the impurity content in the methanol solution is low, so that there are few side reactions in the chlorination reaction, and the chlorination product is stable, has a high yield, and has good quality.

Description

Technical Field

[0001] The invention belongs to the technical field of maltol preparation, and particularly relates to a method for improving the quality of chlorinated products in maltol production. Background Art

[0002] The maltol production process is mainly divided into Grignard process, chlorination process, sublimation process, crystallization process and drying and packaging process. The chlorination process includes chlorination reaction, chlorination hydrolysis reaction and neutralization reaction. In the chlorination process, methanol aqueous solution is used as the solvent of the chlorination reaction, as reported in the chlorination hydrolysis production method in the production of maltol of publication number CN106366062A, so the use of methanol is extensive and large in amount in the production of maltol.

[0003] In the prior art, methanol recovered from chlorination is usually purified, the methanol is recovered, and then distilled to remove impurities. However, the purity of the purification in this purification method is low. During the continuous circulation of methanol aqueous solution, the methanol aqueous solution contains a large amount of impurities. The impurities are mainly aldehydes (formaldehyde, acetaldehyde), ketones (acetone), alcohols (ethanol, propanol), esters and organic acids, etc. The presence of the above impurities causes a large number of side reactions in the chlorination reaction, resulting in a low content and instability of the reaction product. Summary of the invention

[0004] In view of this, the present invention provides a method for improving the quality of chlorinated products in maltol production.

[0005] A method for improving the quality of chlorinated products in maltol production comprises the following steps: S1: adding soft water to the methanol solution recovered from the acidic chlorination hydrolysis to carry out a hydrolysis reaction, so that impurities are separated from the methanol aqueous solution; S2: After the hydrolysis reaction is completed, the reaction is allowed to stand for stratification, and the heavy phase impurities are discharged to obtain a recovered methanol solution.

[0006] Preferably, in the step S1, the volume ratio of the methanol solution recovered by the chlorination hydrolysis to soft water is 2.5-3.5:1.

[0007] Preferably, in the step S1, the pH of the methanol solution recovered by the chlorination hydrolysis is 1-2.

[0008] Preferably, in the step S1, the hydrolysis reaction time is at least 20 minutes.

[0009] Preferably, a methanol purification system is used to improve the quality of the chlorinated product, the methanol improvement system comprises a reaction unit and a step-by-step separation unit, the reaction unit comprises a soft water inlet pipe, a chlorination hydrolysis methanol recovery pipe, and a reactor, the soft water inlet pipe is connected to the first inlet of the reactor, the chlorination hydrolysis methanol recovery pipe is connected to the second inlet of the reactor, and the outlet of the reactor is connected to the step-by-step separation unit, so that the soft water in the soft water inlet pipe and the impurities in the chlorination hydrolysis methanol recovery pipe are hydrolyzed and stratified to recover methanol, and the step-by-step unit performs separation to recover the methanol solution.

[0010] Preferably, the step-by-step separation unit includes a first stratification tank, a second stratification tank, and a methanol recovery tank. The outlet of the reactor is connected to the inlet of the first stratification tank, the outlet of the first stratification tank is connected to the inlet of the second stratification tank, and the outlet of the second stratification tank is connected to the inlet of the methanol recovery tank. The methanol solution after hydrolysis and separation is transported to the first stratification tank, the first stratification tank is subjected to static separation, and the supernatant is continuously transported to the second stratification tank for static separation again to recover methanol.

[0011] Preferably, the reaction unit further comprises a delivery pump, the inlet of the delivery pump is connected to the lower outlet of the reactor, and the outlet of the delivery pump is connected to the lower inlet of the first stratification tank.

[0012] Preferably, the flow rate of the delivery pump is 0.05m / s-0.2m / s.

[0013] Preferably, a first overflow port is provided at the top of the first stratification tank, a second overflow port is provided at the top of the second stratification tank, the first overflow port is connected to the lower inlet of the second stratification tank, and the second overflow port is connected to the inlet of the methanol recovery tank.

[0014] Preferably, the step-by-step separation unit includes three separation components, which are respectively connected to the bottom outlets of the reactor, the first stratification tank, and the second stratification tank. The separation components include a deposition tube, a sight glass, and a drain valve. The inlet of the deposition tube is connected to the bottom outlet of the reactor or the bottom outlet of the first stratification tank or the bottom outlet of the second stratification tank, the outlet of the deposition tube is connected to the sight glass, and the lower part of the sight glass is connected to the drain valve for precise separation.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The method for improving the quality of chlorinated products in maltol production comprises the following steps: adding soft water to a methanol solution recovered by acidic chlorination hydrolysis to carry out a hydrolysis reaction; standing the solution after the hydrolysis reaction is completed, discharging heavy phase impurities after stratification to obtain a recovered methanol solution; since the methanol solution recovered by the chlorination hydrolysis is acidic, after adding soft water, non-polar ketone and ester impurities in the methanol solution recovered by the chlorination hydrolysis undergo a hydrolysis reaction under acidic conditions to generate corresponding acids and alcohols; after standing the solution for a period of time, heavy phase turbid impurities naturally sink, and methanol liquid is in the upper layer; then, the methanol liquid and the heavy phase turbid impurities are separated to obtain a methanol solution in which the methanol content is increased from 54% to more than 65%; when the high-purity methanol solution is fed into a chlorination system for repeated use, the impurity content in the methanol solution is low, so that there are few side reactions in the chlorination reaction, and the chlorination product is stable, has a high yield and is of good quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the process flow chart of the methanol purification system.

[0017] Figure 2 It is a schematic diagram of the structure of the separation component.

[0018] In the figure: methanol purification system 10, reaction unit 100, soft water inlet pipe 110, first valve 111, chlorination hydrolysis methanol recovery pipe 120, second valve 121, reactor 130, stirring element 131, delivery pump 140, step-by-step separation unit 200, first stratification tank 210, first overflow port 211, second stratification tank 220, second overflow port 221, methanol recovery storage tank 230, separation component 240, deposition tube 241, sight glass 242, drain valve 243, inlet valve 244. DETAILED DESCRIPTION

[0019] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0020] A method for improving the quality of chlorinated products in maltol production comprises the following steps: S1: adding soft water to the methanol solution recovered from the acidic chlorination hydrolysis to carry out a hydrolysis reaction, so that impurities are separated from the methanol aqueous solution; S2: After the hydrolysis reaction is completed, the reaction is allowed to stand for stratification, and the heavy phase impurities are discharged to obtain a recovered methanol solution.

[0021] Specifically, after the chlorination reaction is completed, the feed liquid is transferred to the chlorination hydrolysis kettle, and first heated to recover methanol. After the methanol recovery is completed, it is heated again for high-temperature rearrangement; the methanol first heated to recover is the methanol solution recovered by the acidic chlorination hydrolysis.

[0022] The method for improving the quality of chlorinated products in maltol production comprises the following steps: adding soft water to a methanol solution recovered by acidic chlorination hydrolysis to carry out a hydrolysis reaction; standing the solution after the hydrolysis reaction is completed, discharging heavy phase impurities after stratification to obtain a recovered methanol solution; since the methanol solution recovered by the chlorination hydrolysis is acidic, after adding soft water, non-polar ketone and ester impurities in the methanol solution recovered by the chlorination hydrolysis undergo a hydrolysis reaction under acidic conditions to generate corresponding acids and alcohols; after standing the solution for a period of time, heavy phase turbid impurities naturally sink, and methanol liquid is in the upper layer; then, the methanol liquid and the heavy phase turbid impurities are separated to obtain a methanol solution in which the methanol content is increased from 54% to more than 65%; when the high-purity methanol solution is fed into a chlorination system for repeated use, the impurity content in the methanol solution is low, so that there are few side reactions in the chlorination reaction, and the chlorination product is stable, has a high yield and is of good quality.

[0023] Furthermore, in the step S1, the volume ratio of the methanol solution recovered by the chlorination hydrolysis to soft water is 2.5-3.5:1. When the volume ratio of the methanol solution recovered by the chlorination hydrolysis to soft water is less than 2.5-3.5:1, the hydrolysis is incomplete; when the volume ratio of the methanol solution recovered by the chlorination hydrolysis to soft water is greater than 2.5-3.5:1, the whole system is turbid and cannot be separated into layers.

[0024] Furthermore, the volume ratio of the methanol solution recovered by the chlorination hydrolysis to soft water is 3:1.

[0025] Furthermore, in the step S1, the pH of the methanol solution recovered by the chlorination hydrolysis is 1-2.

[0026] Furthermore, in the step S1, the hydrolysis reaction time is at least 20 minutes to ensure complete hydrolysis.

[0027] Please see Figure 1 to Figure 2The method for improving the quality of chlorinated products in maltol production as described above uses a methanol purification system 10 to improve the quality of chlorinated products. The methanol improvement system includes a reaction unit 100 and a step-by-step separation unit 200. The reaction unit 100 includes a soft water inlet pipe 110, a chlorination hydrolysis methanol recovery pipe 120, and a reactor 130. The soft water inlet pipe 110 is connected to a first inlet of the reactor 130, the chlorination hydrolysis methanol recovery pipe 120 is connected to a second inlet of the reactor 130, and the outlet of the reactor 130 is connected to the step-by-step separation unit 200; In the production process of ethyl maltol, the acidic methanol solution recovered by chlorination hydrolysis in the methanol recovery pipe 120 and the soft water in the soft water inlet pipe 110 are added into the reactor 130 for hydrolysis reaction. After the hydrolysis reaction, after standing for a period of time, the heavy phase turbid impurities naturally sink, and the methanol liquid is on the upper layer. The methanol liquid is then transported to the step-by-step separation unit 200 for separation. Through the above system, the impurities in the material in the methanol recovery pipe 120 are removed, and then during the recycling process of methanol, there are fewer impurities, the impact on the chlorination reaction is reduced, and the quality of the chlorinated product is good.

[0028] Furthermore, the step-by-step separation unit 200 includes a first stratification tank 210, a second stratification tank 220, and a methanol recovery tank 230. The outlet of the reactor 130 is connected to the inlet of the first stratification tank 210, the outlet of the first stratification tank 210 is connected to the inlet of the second stratification tank 220, and the outlet of the second stratification tank 220 is connected to the inlet of the methanol recovery tank 230. The upper clear liquid containing methanol in the reactor 130 is transported to the first stratification tank 210, and after standing and stratification, the clear liquid containing methanol is transported to the second stratification tank 220 for further standing and stratification, so as to perform continuous three-stage separation through the reactor 130, the first stratification tank 210, and the second stratification tank 220, so that the impurities are separated thoroughly, and the separation equipment is simple, and the solution entering the methanol recovery tank 230 has a high methanol content and a low impurity content.

[0029] Furthermore, the soft water inlet pipe 110 is provided with a first valve 111, and the chlorination hydrolysis methanol recovery pipe 120 is provided with a second valve 121, so as to control the volume ratio of soft water to the material in the chlorination hydrolysis methanol recovery pipe 120 to 1:3 by controlling the opening of the first valve 111 and the second valve 121, so that the hydrolysis reaction proceeds normally.

[0030] Furthermore, the reaction unit 100 further includes a delivery pump 140 , an inlet of the delivery pump 140 is connected to a lower outlet of the reactor 130 , and an outlet of the delivery pump 140 is connected to a lower inlet of the first stratification tank 210 .

[0031] Furthermore, the flow rate of the delivery pump 140 is 0.05 m / s-0.2 m / s, and the flow rate of the liquid entering the first stratification tank 210 is controlled by the delivery pump 140 so as not to affect the separation condition in the first stratification tank 210 .

[0032] Furthermore, a first overflow port 211 is provided at the upper portion of the first stratification tank 210, and a second overflow port 221 is provided at the upper portion of the second stratification tank 220. The first overflow port 211 is connected to the lower inlet of the second stratification tank 220, and the second overflow port 221 is connected to the inlet of the methanol recovery tank 230. In the first stratification tank 210, after standing for a long time, the upper layer of the clear liquid containing methanol automatically overflows through the first overflow port 211 into the second stratification tank 220 for further separation, thereby improving the separation efficiency of the clear liquid and impurities.

[0033] Furthermore, the height of the second overflow port 221 is higher than that of the first overflow port 211 , so that the standing time is increased and the liquid entering the second stratification tank 220 through the first overflow port 211 does not affect the stratification of the second stratification tank 220 itself.

[0034] Furthermore, a stirring element 131 is provided in the reactor 130 to ensure sufficient hydrolysis reaction.

[0035] Furthermore, the step-by-step separation unit 200 includes a separation component 240, and there are three separation components 240. The three separation components 240 are respectively connected to the bottom outlets of the reactor 130, the first stratification tank 210, and the second stratification tank 220. The separation component 240 includes a deposition tube 241, a sight glass 242, and a drain valve 243. The inlet of the deposition tube 241 is connected to the bottom outlet of the reactor 130 or the bottom outlet of the first stratification tank 210 or the bottom outlet of the second stratification tank 220, the outlet of the deposition tube 241 is connected to the sight glass 242, and the lower part of the sight glass 242 is connected to the drain valve 243. When a large amount of impurities are deposited at the bottom of the reactor 130 or the first stratification tank 210 or the second stratification tank 220, the drain valve 243 is opened by observing the sight glass 242 to discharge the heavy phase turbid impurities.

[0036] Furthermore, the deposition tube 241 is a cone, and the inlet of the deposition tube 241 is the end with a larger opening. When the amount of impurities is small, the impurities are allowed to stand still and separate in the deposition tube 241, so that the separation is thorough.

[0037] Furthermore, the separation component 240 also includes a liquid inlet valve 244, one end of the liquid inlet valve 244 is connected to the outlet of the deposition tube 241, and the other end of the liquid inlet valve 244 is connected to the sight glass 242; when it is necessary to discharge impurities, first open the liquid inlet valve 244 to allow the impurities to enter the sight glass 242, then observe the sight glass 242, open the liquid drain valve 243 to discharge the impurities, if the amount of impurities is small, then observe that no impurities flow into the sight glass 242, then close the liquid inlet valve 244 to prevent the required methanol from being discharged; the liquid in the sight glass 242 can be left to stand again, then observe the sight glass 242, open the liquid drain valve 243 to discharge the impurities to prevent the required methanol liquid from being lost. Embodiment 1:

[0038] In the production process of ethyl maltol, the methanol solution recovered by chlorination hydrolysis in the methanol recovery pipe 120 and the soft water in the soft water inlet pipe 110 are added into the reactor 130, and the volume ratio of the soft water to the methanol solution recovered by chlorination hydrolysis is controlled to be 1:3 by the first valve 111 and the second valve 121, and the pH value of the methanol solution recovered by chlorination hydrolysis is 1-2. The stirring is carried out by the stirring member 131 for 30 minutes to make the hydrolysis reaction complete and generate the corresponding acid and alcohol, and then the mixture is allowed to stand for 30 minutes, and the heavy phase turbid impurities naturally sink, and the methanol liquid is in the upper layer, and the heavy phase turbid impurities in the lower layer are discharged, and then the methanol liquid is transported to the first layering tank 210 by the delivery pump 140. In the first layering tank 210, after a long After standing for a period of time, as the liquid is replenished, the upper layer of the clear liquid containing methanol automatically overflows into the second stratification tank 220 through the first overflow port 211 for further separation. After standing in the second stratification tank 220 for a period of time, as the liquid is replenished, the upper layer of the clear liquid containing methanol automatically overflows into the methanol recovery tank 230 through the second overflow port 221. The reactor 130, the first stratification tank 210 and the second stratification tank 220 are used for continuous three-stage separation, so that the impurities are completely separated. The methanol content in the solution entering the methanol recovery tank 230 is 68%. When the high-purity methanol solution is sent to the chlorination system for repeated use, the impurity content in the methanol solution is low, so that the side reactions in the chlorination reaction are reduced and the yield of the chlorination reaction product is improved.

[0039] Comparative Example 1: In the production process of ethyl maltol, the methanol solution recovered from chlorination and hydrolysis is distilled to remove impurities. The distillation temperature is 90°C, and the recovered methanol has a content of 54%.

[0040] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for improving the quality of chlorinated products in maltol production, characterized in that: The following steps are involved: S1: adding soft water to the methanol solution recovered from the acidic chlorination hydrolysis to carry out a hydrolysis reaction, so that impurities are separated from the methanol aqueous solution; S2: After the hydrolysis reaction is completed, the reaction is allowed to stand for stratification, and the heavy phase impurities are discharged to obtain a recovered methanol solution.

2. The method for improving the quality of chlorinated products in maltol production as claimed in claim 1, characterized in that: In the step S1, the volume ratio of the methanol solution recovered by the chlorination hydrolysis to soft water is 2.5-3.5:

1.

3. The method for improving the quality of chlorinated products in maltol production as claimed in claim 1, characterized in that: In the step S1, the pH of the methanol solution recovered by the chlorination hydrolysis is 1-2.

4. The method for improving the quality of chlorinated products in maltol production as claimed in claim 1, characterized in that: In the step S1, the hydrolysis reaction time is at least 20 minutes.

5. The method for improving the quality of chlorinated products in maltol production according to any one of claims 1 to 4, characterized in that: A methanol purification system is used to improve the quality of chlorinated products. The methanol improvement system includes a reaction unit and a step-by-step separation unit. The reaction unit includes a soft water inlet pipe, a chlorination hydrolysis methanol recovery pipe, and a reactor. The soft water inlet pipe is connected to a first inlet of the reactor, the chlorination hydrolysis methanol recovery pipe is connected to a second inlet of the reactor, and the outlet of the reactor is connected to the step-by-step separation unit to hydrolyze and stratify the soft water in the soft water inlet pipe and the impurities in the chlorination hydrolysis methanol recovery pipe to recover methanol. The step-by-step unit performs separation to recover the methanol solution.

6. The method for improving the quality of chlorinated products in maltol production according to claim 5, characterized in that: The step-by-step separation unit includes a first stratification tank, a second stratification tank, and a methanol recovery tank. The outlet of the reactor is connected to the inlet of the first stratification tank, the outlet of the first stratification tank is connected to the inlet of the second stratification tank, and the outlet of the second stratification tank is connected to the inlet of the methanol recovery tank. The methanol solution after hydrolysis and separation is transported to the first stratification tank, the first stratification tank is subjected to static separation, and the supernatant is continuously transported to the second stratification tank for static separation again to recover methanol.

7. The method for improving the quality of chlorinated products in maltol production according to claim 6, characterized in that: The reaction unit further comprises a delivery pump, the inlet of the delivery pump is connected to the lower outlet of the reactor, and the outlet of the delivery pump is connected to the lower inlet of the first stratification tank.

8. The method for improving the quality of chlorinated products in maltol production according to claim 7, characterized in that: The flow rate of the delivery pump is 0.05m / s-0.2m / s.

9. The method for improving the quality of chlorinated products in maltol production according to claim 7, characterized in that: A first overflow port is arranged at the upper part of the first stratification tank, a second overflow port is arranged at the upper part of the second stratification tank, the first overflow port is connected to the lower inlet of the second stratification tank, and the second overflow port is connected to the inlet of the methanol recovery storage tank.

10. The method for improving the quality of chlorinated products in maltol production according to claim 7, characterized in that: The step-by-step separation unit includes three separation components, which are respectively connected to the bottom outlets of the reactor, the first stratification tank, and the second stratification tank. The separation components include a deposition tube, a sight glass, and a drain valve. The inlet of the deposition tube is connected to the bottom outlet of the reactor or the bottom outlet of the first stratification tank or the bottom outlet of the second stratification tank, the outlet of the deposition tube is connected to the sight glass, and the lower part of the sight glass is connected to the drain valve for precise separation.

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