Method for controlling distillation reaction of ozone method for preparing glyoxylic acid monohydrate

Abstract

The application discloses an ozone method for preparing glyoxylic acid monohydrate distillation reaction control method, including the following steps: step S1, the glyoxylic acid-formic acid mixed solution obtained by oxidation reaction is introduced into the distillation kettle; step S2, the heat exchange jacket and heat exchange coil in the distillation kettle are passed through 80 DEG C hot water; step S3, the vacuum is opened, and the inside of the distillation kettle is subjected to vacuum distillation; step S4, the vacuum degree, temperature and material density in the reaction kettle are monitored; step S5, the distillation reaction endpoint is judged by the change trend of the material temperature, vacuum degree and density in the kettle; step S6, the finished product after distillation is discharged into the glyoxylic acid storage tank, and the formic acid solution evaporated and condensed is discharged into the receiving tank. The application controls the parameters of the distillation process accurately, stops the distillation of the material immediately when the reaction reaches the endpoint, guarantees that the glyoxylic acid monohydrate product reaches the accurate water content ratio, and prevents water from being over-steamed, so that the product cost is prevented from being increased.

Description

Technical Field

[0001] This invention relates to the field of glyoxylic acid monohydrate technology, specifically to a method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method. Background Technology

[0002] Glyoxylic acid is an important organic chemical intermediate with wide applications in fragrances, pharmaceuticals, paints, papermaking, and fine chemicals. There are three main methods for producing glyoxylic acid: glyoxal-nitric acid oxidation, oxalic acid electrolysis, and maleic anhydride ozone oxidation. Currently, most domestic glyoxylic acid producers use processes such as glyoxal-nitric acid oxidation, mainly producing 40-50% glyoxylic acid aqueous solutions. These products contain a high amount of impurities such as glyoxal, causing serious environmental pollution, low purity, and relatively poor quality. Glyoxylic acid monohydrate, as a high-purity glyoxylic acid product, can be used in high-end markets such as fine chemical products. Glyoxylic acid monohydrate is generally produced using maleic anhydride ozone oxidation or maleic anhydride ozone with catalyst oxidation, which is a more advanced process, producing high-purity, high-quality products with very little environmental pollution.

[0003] Relevant technical literature proposes techniques for further concentrating, purifying, and even crystallizing 40-50% glyoxylic acid aqueous solutions. Other literature proposes techniques for distilling the solvent from glyoxylic acid solutions obtained through maleic anhydride ozone oxidation. These documents only mention distillation, specifically vacuum distillation, to remove solvents like water, and provide parameters such as distillation temperature, time, and pressure. However, they do not specify how to determine when the distillation endpoint has been reached. In practice, sampling and testing are still necessary to determine the end of distillation. Furthermore, vacuum distillation sampling sometimes requires removing the vacuum; otherwise, sampling is not possible. If testing reveals that distillation is not complete, vacuuming and distillation must continue, posing significant challenges to practical operation, especially in industrial-scale continuous production.

[0004] Distillation is required in the ozone process for producing glyoxylic acid monohydrate. If the distillation reaction is insufficient, or if distillation is stopped too early, or if too much water remains in the mixture, the glyoxylic acid content will be below 80%, and the subsequent crystallization process cannot proceed normally. Alternatively, the product may partially crystallize, forming a mixture of crystals and solution, resulting in a substandard product. Conversely, if the distillation reaction is excessive, or if distillation is stopped too late, excessive water will be evaporated from the mixture, resulting in a glyoxylic acid content exceeding 80% and less than one unit of water of crystallization remaining. This will prolong the subsequent crystallization process or result in a viscous solution that does not crystallize for an extended period, affecting the rapid production of glyoxylic acid monohydrate or impacting the product's economic viability.

[0005] In the above distillation process, without a rapid, online method for determining the distillation endpoint, continuous sampling and analysis are necessary. During sampling and analysis, distillation must be temporarily stopped, and even vacuum sampling may be required while awaiting results. If the endpoint is not reached, distillation must be restarted. If excessive distillation is detected, it requires calculation, addition of pure water, mixing, and further sampling and analysis, wasting energy.

[0006] Currently, relevant physical parameters for the distillation of glyoxylic acid monohydrate are largely unavailable in available literature, requiring gradual exploration through practical experience. Therefore, this invention aims to find a method for controlling the distillation reaction endpoint when preparing glyoxylic acid monohydrate using the ozone method, achieving reliable control and rapid, accurate determination of the distillation endpoint to improve distillation quality. Summary of the Invention

[0007] The purpose of this invention is to provide a method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for controlling the distillation reaction in the ozone process for preparing glyoxylic acid monohydrate, characterized by comprising the following steps:

[0010] Step S1: Pour the glyoxylic acid-formic acid mixed solution obtained from the oxidation reaction into a distillation vessel;

[0011] Step S2: Pass 80°C hot water into the heat exchange jacket and heat exchange coil of the distillation kettle;

[0012] Step S3: Open the vacuum valve on the distillation vessel to perform reduced pressure distillation inside the distillation vessel;

[0013] Step S4: Monitor the vacuum level, temperature, and material density inside the reactor.

[0014] Step S5, determine the endpoint of the distillation reaction: based on the temperature of the material inside the vessel and the trend of the vacuum degree, when the temperature reaches 50-55℃ and the pressure reaches 5-4kPa, it is preliminarily determined that the endpoint of the distillation reaction has been reached; at the same time, monitor the density change, and when the density reaches 1500kg / m3, it is determined that the endpoint of the distillation reaction has been reached.

[0015] In step S6, the distilled product is discharged into the glyoxylic acid storage tank, and the evaporated and condensed dilute formic acid solution is discharged into the receiving tank.

[0016] Preferably, in step S1, the amount of glyoxylic acid-formic acid mixed solution poured into the distillation vessel is controlled by a flow meter on the feed pipeline and a level gauge on the distillation vessel.

[0017] Preferably, the distillation vessel in step S2 is equipped with a heat exchange jacket and a heat exchange coil. The jacket and coil are heated by 80°C hot water, and the hot water is controlled by a regulating valve.

[0018] Preferably, the online vacuum monitoring in step S3 uses a pressure sensor to display the real-time vacuum level of the distillation vessel; and a condenser, a dilute formic acid receiving tank, and a glyoxylic acid storage tank are provided.

[0019] Preferably, an online flow meter is installed on the vacuum line of the condenser in step S3. When the condenser malfunctions and cannot condense effectively, the flow meter will display a large flow rate, issue a condensation abnormality alarm, and stop distillation.

[0020] Preferably, the temperature, pressure, and density monitoring device in step S4 is an online sensor with a display screen for displaying the real-time parameters of the distillation vessel.

[0021] Preferably, in step S4, the boiling point of the azeotrope of water and formic acid is lower than that of glyoxylic acid. Water and formic acid in the solution are distilled out. As the distillation proceeds, the concentration of glyoxylic acid solution gradually increases, the distillation temperature gradually rises to 50-55°C, and the pressure gradually decreases to 5-4 kPa (A).

[0022] Preferably, in step S5, when the temperature of the material inside the vessel reaches 50-55°C and the pressure reaches 5-4 kPa(A), it is preliminarily determined that the distillation reaction has reached its endpoint; the density change is monitored, and when the density reaches 1500 kg / m3, it is determined that the distillation reaction has reached its endpoint.

[0023] Preferably, in step S6, before discharging the 80% glyoxylic acid solution after distillation, the density test value should be checked and confirmed, and corrections should be made if necessary to eliminate the influence of air bubbles in the 80% glyoxylic acid solution.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention precisely controls the reaction endpoint of distillation, thereby stopping the feeding of materials when the reaction reaches its endpoint. This avoids excessive or insufficient material produced after the distillation reaction, which would result in excessive water, formic acid, etc. remaining in the mixture. This ensures the rapid production of glyoxylic acid monohydrate in the subsequent crystallization process. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This embodiment provides a method for controlling the distillation reaction in the ozone method for producing glyoxylic acid monohydrate, including the following steps:

[0028] Step S1: Pour the glyoxylic acid-formic acid mixed solution obtained from the oxidation reaction into a distillation vessel;

[0029] Step S2: Pass 80°C hot water into the heat exchange jacket and heat exchange coil of the distillation kettle;

[0030] Step S3: Open the vacuum valve on the distillation vessel to perform reduced pressure distillation inside the distillation vessel;

[0031] Step S4: Monitor the vacuum level, temperature, and material density inside the reactor.

[0032] Step S5, Determine the endpoint of the distillation reaction: Based on the temperature of the material inside the vessel and the trend of vacuum changes, when the temperature reaches 50-55℃ and the pressure reaches 5-4 kPa(A), it is preliminarily determined that the distillation reaction endpoint has been reached; monitor the density change, and when the density simultaneously reaches 1500 kg / m³, the endpoint is reached. 3 Determine that the distillation reaction has reached its endpoint;

[0033] In step S6, the distilled product is discharged into the glyoxylic acid storage tank, and the evaporated and condensed dilute formic acid solution is discharged into the receiving tank.

[0034] In step S1, the amount of glyoxylic acid-formic acid mixed solution poured into the distillation vessel is controlled by the flow meter on the feed pipeline and the level gauge on the distillation vessel.

[0035] The distillation vessel in step S2 is equipped with a jacket and a heating coil, and is heated by 80°C hot water, which is controlled by a regulating valve.

[0036] In step S3, the online vacuum monitoring uses a pressure sensor to display the real-time vacuum level of the distillation vessel; and a condenser, a dilute formic acid receiving tank, and a glyoxylic acid storage tank are also installed.

[0037] An online flow meter is installed on the vacuum line of the condenser in step S3. When the condenser malfunctions and cannot condense effectively, the flow meter will display a large flow rate, issue a condensation abnormality alarm, and stop distillation.

[0038] The temperature, pressure, and density monitoring device in step S4 is an online sensor with a display screen to show the real-time parameters of the distillation vessel.

[0039] In step S4, the boiling point of the azeotrope of water and formic acid is lower than that of glyoxylic acid. Water and formic acid in the solution are distilled out. As the distillation proceeds, the concentration of glyoxylic acid solution gradually increases, the distillation temperature gradually rises to 50-55℃, and the pressure gradually decreases to 5-4 kPa (A).

[0040] Step S5: When the temperature of the material inside the vessel reaches 50–55°C and the pressure reaches 5–4 kPa(A), it is preliminarily determined that the distillation reaction has reached its endpoint; monitor the density change, and the density simultaneously reaches 1500 kg / m³. 3 The endpoint of the distillation reaction is determined by this process.

[0041] In step S6, before discharging the 80% glyoxylic acid solution after distillation, the density test value should be checked and confirmed, and corrections should be made if necessary to eliminate the influence of air bubbles in the 80% glyoxylic acid solution.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0043] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for controlling the distillation reaction in the ozone process for preparing glyoxylic acid monohydrate, characterized in that, Includes the following steps: Step S1: Pour the glyoxylic acid-formic acid mixed solution obtained from the oxidation reaction into a distillation vessel; Step S2: Pass 80°C hot water into the heat exchange jacket and heat exchange coil of the distillation kettle; Step S3: Open the vacuum valve on the distillation vessel to perform reduced pressure distillation inside the distillation vessel; Step S4: Monitor the vacuum level, temperature, and material density inside the reactor. Step S5, Determine the endpoint of the distillation reaction: Based on the temperature of the material inside the vessel and the trend of vacuum changes, when the temperature reaches 50-55℃ and the pressure reaches 5-4 kPa(A), it is preliminarily determined that the distillation reaction endpoint has been reached; simultaneously monitor the density change, and when the density reaches 1500 kg / m³, the reaction is considered to have reached the endpoint. 3 Determine that the distillation reaction has reached its endpoint; In step S6, the distilled product is discharged into the glyoxylic acid storage tank, and the evaporated and condensed dilute formic acid solution is discharged into the receiving tank.

2. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, In step S1, the amount of glyoxylic acid-formic acid mixed solution poured into the distillation vessel is controlled by the flow meter on the feed pipeline and the level gauge on the distillation vessel.

3. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, The distillation vessel in step S2 is equipped with a heat exchange jacket and a heat exchange coil. The jacket and coil are heated by 80°C hot water, which is controlled by a regulating valve.

4. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, The online vacuum monitoring in step S3 uses a pressure sensor to display the real-time vacuum level of the distillation vessel; and a condenser, a dilute formic acid receiving tank, and a glyoxylic acid storage tank are also provided.

5. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, An online flow meter is installed on the vacuum line of the condenser in step S3. When the condenser malfunctions and cannot condense effectively, the flow meter will display a large flow rate, issue a condensation abnormality alarm, and stop distillation.

6. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, The temperature, pressure, and density monitoring device in step S4 is an online sensor with a display screen to show the real-time parameters of the distillation vessel.

7. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, In step S4, the boiling point of the azeotrope of water and formic acid is lower than that of glyoxylic acid. Water and formic acid in the solution are distilled out. As the distillation proceeds, the concentration of glyoxylic acid solution gradually increases, the distillation temperature gradually rises to 50-55℃, and the pressure gradually decreases to 5-4 kPa (A).

8. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, In step S5, when the temperature of the material inside the vessel reaches 50–55°C and the pressure reaches 5–4 kPa(A), it is preliminarily determined that the distillation reaction has reached its endpoint; simultaneously, the density change is monitored, and the density simultaneously reaches 1500 kg / m³. 3 The endpoint of the distillation reaction is determined by this process.

9. The method for controlling the distillation reaction of glyoxylic acid monohydrate preparation by ozone method according to claim 1, characterized in that, In step S6, before discharging the 80% glyoxylic acid solution after distillation, the density test value should be checked and confirmed, and corrections should be made if necessary to eliminate the influence of air bubbles in the 80% glyoxylic acid solution.