Apparatus for producing isobutyric acid and method for producing isobutyric acid

Abstract

The present invention provides an apparatus for producing isobutyric acid and a method for producing isobutyric acid that can improve the conversion rate. [Solution] The apparatus for producing isobutyric acid includes a reaction tank, an air intake pipe, an exhaust pipe, and a stirrer. The air intake pipe communicates with the reaction tank so that working gas is introduced into the reaction tank. The exhaust pipe communicates with the reaction tank so that the reaction gas is led out of the reaction tank. The stirrer is installed inside the reaction tank and includes a hollow shaft and a number of blades. The hollow shaft has a first end and a second end arranged opposite each other, the first end having an intake port exposed above the liquid surface of the reaction tank, and the second end having an exhaust port immersed below the liquid surface. The exhaust pipe is connected to a condenser at the end opposite the reaction tank, where the reaction gas is condensed to obtain isobutyraldehyde and a terminal gas, and the isobutyraldehyde is returned to the reaction tank via a pump for re-reaction, thereby improving the conversion rate.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for producing isobutyric acid and a method for producing isobutyric acid, and more particularly to an apparatus for producing isobutyric acid and a method for producing isobutyric acid that achieve both high efficiency and high safety. [Background technology]

[0002] Isobutyric acid is a short-chain saturated fatty acid with four carbon atoms, commonly used in the synthesis of isobutyric acid esters, and has significant economic value due to its applications in spices, pharmaceuticals, and food preservatives. Existing isobutyric acid is mainly produced by isobutyraldehyde oxidation or isobutanol oxidation. However, the isobutanol oxidation method produces many byproducts, has high production costs and low yields, so the isobutyraldehyde oxidation method remains the primary method for producing isobutyric acid.

[0003] Conventional reaction tanks R, as shown in Figure 1, use the rotating shaft A of a stirrer M to rotate the blade L, thereby achieving the effect of stirring and mixing the reaction gas G and the reaction liquid. However, conventional reaction tanks R have low contact efficiency between the reaction gas G and the reaction liquid, resulting in a significant decrease in yield, which is disadvantageous for industrial production, and the yield decreases even further, especially at low oxygen concentrations. In addition, because a mechanical shaft seal is used, leakage and static electricity are easily generated, which is very dangerous for the reaction process. In the oxidation of isobutyraldehyde, low contact efficiency between gas and liquid leads to a decrease in mixing effectiveness, resulting in problems such as low reaction selectivity and a large amount of by-products.

[0004] Conventional reaction process technologies allow for the control of the organic solvent gas phase concentration to the lower limit of the explosion by adjusting operating parameters (lowering temperature, increasing pressure) to eliminate flammable material hazards, and also eliminate fire source hazards (static electricity) by improving the materials of the equipment. However, in order to maintain high yields, oxygen (combustion aid) concentrations exceeding the limiting oxygen concentration (LOC) are used, so a hazard factor in the form of a combustion aid still exists in the overall reaction process.

[0005] Therefore, overcoming the aforementioned drawbacks by improving the yield and safety of isobutyric acid production through process improvements is a crucial challenge for this project. [Overview of the project] [Problems that the invention aims to solve]

[0006] The technological problem that this invention aims to solve is to provide an apparatus for producing isobutyric acid and a method for producing isobutyric acid, in response to the shortcomings of the prior art. [Means for solving the problem]

[0007] To solve the above technical problems, another technical means employed by the present invention is to provide an apparatus for producing isobutyric acid. The aforementioned apparatus for producing isobutyric acid includes a reaction tank, an air intake pipe, an exhaust pipe, and a stirrer. The aforementioned air intake pipe communicates with the aforementioned reaction tank so that working gas is introduced into the aforementioned reaction tank, the aforementioned exhaust pipe communicates with the aforementioned reaction tank so that the post-reaction gas is led out of the aforementioned reaction tank, and the aforementioned stirrer is installed in the aforementioned reaction tank and includes a hollow shaft and a plurality of blades, the aforementioned hollow shaft having a first end and a second end arranged opposite to each other, the aforementioned first end having an intake hole exposed above the liquid surface of the aforementioned reaction tank, and the aforementioned second end having an exhaust hole immersed below the aforementioned liquid surface. The aforementioned exhaust pipe is connected to a condenser at the end opposite to the aforementioned reaction tank, and the aforementioned post-reaction gas is condensed to obtain isobutyraldehyde and terminal gas, and the conversion rate is improved by returning the isobutyraldehyde to the reaction tank via a pump.

[0008] In one embodiment, the aforementioned condenser includes a first tube and a second tube, the aforementioned terminal gas is discharged from the aforementioned first tube, and the aforementioned isobutyraldehyde is discharged from the aforementioned second tube.

[0009] In one embodiment, a concentration sensor is further installed in the aforementioned first tube.

[0010] In one embodiment, the aforementioned exhaust pipe further includes a pressure gauge and a control valve.

[0011] In one embodiment, the aforementioned working gas is air, nitrogen gas, or oxygen gas.

[0012] To solve the above technical problems, another technical means employed by the present invention is to provide a method for producing isobutyric acid. The aforementioned method for producing isobutyric acid is used in the aforementioned apparatus for producing isobutyric acid, and the aforementioned method for producing isobutyric acid includes a step of providing isobutyraldehyde by injecting isobutyraldehyde into the aforementioned reaction tank; a step of replacing the atmosphere by injecting nitrogen gas into the aforementioned reaction tank via the aforementioned air intake pipe; and an oxidation reaction step of obtaining isobutyric acid by injecting the aforementioned working gas into the aforementioned reaction tank via the aforementioned air intake pipe and allowing the aforementioned isobutyraldehyde and the aforementioned working gas to react to the end of the reaction.

[0013] In one embodiment, the process of replacing the aforementioned atmosphere involves setting the pressure to 1 kg / cm². 2 ~10kg / cm 2 This further includes using a control valve to control the situation.

[0014] In one embodiment, the process of replacing the atmosphere is considered complete when the oxygen content of the terminal gas becomes less than 0.005%.

[0015] In one embodiment, during the period of the oxidation reaction described above, the oxygen content of the terminal gas described above is 0.005% to 8%.

[0016] In one embodiment, the endpoint of the reaction described above is when the oxygen content of the terminal gas described above reaches 7% to 8%.

[0017] To further understand the features and technical details of the present invention, please refer to the following detailed description of the invention and the accompanying drawings. However, the accompanying drawings provided are for reference and illustrative purposes only and do not limit the scope of the claims of the present invention. [Effects of the Invention]

[0018] As one of the advantageous effects of the present invention, the isobutyric acid production apparatus and the isobutyric acid production method according to the present invention improve the yield and safety of isobutyric acid due to technical features such as "the aforementioned stirrer includes a hollow shaft and a plurality of blades, the aforementioned hollow shaft has a first end and a second end arranged opposite to each other, the aforementioned first end is provided with an air intake hole exposed above the liquid level of the aforementioned reaction tank, and the aforementioned second end is provided with an exhaust hole immersed below the aforementioned liquid level", and "the aforementioned exhaust pipe is connected to a condenser at an end opposite to the aforementioned reaction tank, and the gas after the aforementioned reaction is condensed to obtain isobutyraldehyde and tail gas".

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram of a conventional reaction tank in the prior art. [Figure 2] It is a schematic diagram of the isobutyric acid production apparatus in the present invention. [Figure 3] It is a side view of the stirrer of the isobutyric acid production apparatus in the present invention. [Figure 4] It is a top view of the stirrer of the isobutyric acid production apparatus in the present invention. [Figure 5] It is a flowchart of the isobutyric acid production method in the present invention. [Figure 6] It is a diagram showing the change in oxygen concentration during the reaction process of the isobutyric acid production method in the present invention.

Embodiments for Carrying Out the Invention

[0020] The following describes how the "apparatus for producing isobutyric acid and method for producing isobutyric acid" according to the present invention can be implemented by certain specific embodiments, and those skilled in the art will be able to understand the advantages and effects of the present invention based on the contents disclosed herein. The present invention can be implemented or applied by other different specific embodiments, and various modifications and changes can be made to each detail herein, based on different viewpoints and applications, as long as they do not deviate from the concept of the present invention. It should be noted in advance that the accompanying drawings of the present invention are for simple schematic explanation and are not drawn to actual size. The technical content of the present invention will be described in more detail below based on the embodiments, but the scope of protection of the present invention is not limited by the contents disclosed.

[0021] It should be understood that while this specification may use terms such as “first,” “second,” and “third” to describe various elements or signals, these elements or signals are not limited by these terms. These terms are primarily used to distinguish one element from another, or one signal from another. Furthermore, the term “or” as used herein may, depending on the context, include any one or more of the items listed in relation to the subject.

[0022] [First Embodiment] As shown in Figures 2 to 4, the isobutyric acid production apparatus 100 according to the first embodiment of the present invention includes a reaction tank 10, an air intake pipe 20, an exhaust pipe 30, and a stirrer 40. The reaction tank 10 is a sealed tank capable of containing a reaction liquid 11. In the present invention, the reaction liquid 11 is isobutyraldehyde. Furthermore, isobutyraldehyde is introduced into the reaction tank 10 via an isobutyraldehyde supply tube 50. In one embodiment, a third control valve 51 may be installed in the isobutyraldehyde supply tube 50 to control the amount of isobutyraldehyde used to introduce into the reaction tank 10. The air intake pipe 20 communicates with the reaction tank 10 so that a working gas 12 is introduced into the reaction tank 10. In the present invention, the working gas 12 may be air, nitrogen gas, or oxygen gas.

[0023] Specifically, the gas normally present in the reaction tank is the atmosphere (i.e., air). Before the oxidation reaction can proceed, nitrogen gas is first introduced into the reaction tank 10 via the air intake pipe 20 to pressurize it, so that the atmospheric pressure in the reaction tank 10 is 1 kg / cm². 2 ~10kg / cm 2 It is maintained in this state. Subsequently, oxygen gas is introduced as an oxidizing agent to carry out an oxidation reaction with isobutyraldehyde. In another embodiment of the present invention, air may be introduced as an oxidizing agent, as air is readily available and easily separated from isobutyric acid, simplifying the process, reducing manufacturing costs, and improving safety.

[0024] Furthermore, the agitator 40 of the isobutyric acid production apparatus 100 according to the present invention includes a hollow shaft 41 and a plurality of blades 42, and the plurality of blades 42 are fixed to an impeller 421. The hollow shaft 41 has a first end 43 and a second end 44 arranged opposite each other, the first end 43 has an intake port 431 exposed above the liquid surface of the reaction tank 10, and the second end 44 has an exhaust port 441 immersed below the liquid surface. Therefore, when introducing oxygen gas or air, by guiding the oxygen gas or air from the intake port 431 of the first end 43 to the exhaust port 441 of the second end 44, the oxygen gas or air can be guided to the bottom of the reaction liquid 11 in the reaction tank 10, thereby improving the mixing efficiency of the gas and liquid. In other words, the agitator 40 of the present invention combines intake, exhaust, and stirring functions.

[0025] In one embodiment of the present invention, the opening and closing of the air intake pipe 20 and the exhaust pipe 30 can be controlled by controlling a first control valve 21 and a second control valve 31, respectively, thereby controlling the progress of the oxidation reaction in the reaction tank 10. For example, first, the first control valve 21 and the second control valve 31 are opened simultaneously to introduce the working gas 12 into the reaction tank 10 and replace the gas in the reaction tank 10. Then, the second control valve 31 is closed, and the working gas 12 is introduced from the air intake pipe 20 to pressurize, and then oxygen gas or air is introduced to carry out the oxidation reaction. In the present invention, the first control valve 21 and the second control valve 31 may be back pressure valves. However, the above example is merely one embodiment, and the present invention is not limited thereto. In one embodiment of the present invention, excellent reaction efficiency can be obtained by starting the oxidation reaction when the gas in the reaction tank 10 has a nitrogen gas:oxygen gas ratio of 99.995:0.005.

[0026] Furthermore, the exhaust pipe 30 is connected to the reaction tank 10 to guide the reaction gas out of the reaction tank 10. The exhaust pipe 30 is connected to a condenser 32 at the end opposite to the reaction tank 10, where the reaction gas is condensed to obtain isobutyraldehyde and terminal gas. The condensed isobutyraldehyde is returned to the reaction tank 10 to improve the conversion rate. In addition, the condenser 32 includes a first tube 321 and a second tube 322. The first tube 321 is connected to the upper end of the condenser 32 to discharge the terminal gas, and the second tube 322 is connected to the lower end of the condenser 32 to discharge isobutyraldehyde. In one embodiment of the present invention, a pressure gauge 34 is installed in the exhaust pipe 30 so that the pressure in the reaction tank 10 can be observed.

[0027] In one embodiment of the present invention, a concentration sensor 33 may be further installed in the first tube 321 to observe the concentration of the terminal gas. Specifically, the terminal gas may be oxygen gas, air, or nitrogen gas. That is, by observing the oxygen concentration and isobutyraldehyde concentration at the observation outlet end with the concentration sensor 33, the reaction oxygen concentration will be kept below the limiting oxygen concentration (LOC), and the endpoint of the reaction can be controlled to balance reaction efficiency and the safety of the oxidation reaction.

[0028] [Second Embodiment] As shown in Figure 5, a second embodiment of the present invention provides a method for producing isobutyric acid. The method for producing isobutyric acid is carried out using the isobutyric acid production apparatus described above, and the method includes: a step S1 of providing isobutyraldehyde, injecting isobutyraldehyde into the reaction tank 10; a step S2 of replacing the atmosphere, injecting nitrogen gas into the reaction tank 10 via the air intake pipe 20; and an oxidation reaction step S3 of injecting the working gas 12 into the reaction tank 10 via the air intake pipe 20, and reacting the isobutyraldehyde and the working gas 12 to the end of the reaction to obtain isobutyric acid.

[0029] In step S1, isobutyraldehyde is placed in the reaction tank 10 and stirred by the stirrer 40. In this invention, the stirrer 40 is a hollow stirrer that includes an intake port 431 installed at the first end 43 and an exhaust port 441 installed at the second end 44. As a result, the gas flows within the hollow shaft 41, introducing oxygen gas or air to the bottom of the reaction liquid 11 in the reaction tank 10, thereby improving the mixing efficiency of the gas and liquid.

[0030] In the atmospheric replacement step S2, the second control valve 31 is used to set the pressure to 1 kg / cm². 2 ~10kg / cm 2It may be controlled to any integer between 1 and 10 (for example). In one embodiment of the present invention, the flow rate through which the working gas 12 is introduced via the air intake pipe 20 may be 1 L / min to 10 L / min (for example, any integer between 1 and 10). Subsequently, the oxygen content in the terminal gas is observed with the concentration sensor 33, and the process of replacing the atmosphere described above is considered complete when the oxygen content in the terminal gas falls below 0.005%.

[0031] In oxidation reaction step S3, the reaction temperature may be between 20°C and 100°C, and the reaction pressure may be 1 kg / cm². 2 ~10kg / cm 2 This may also be the case. After the reaction, since isobutyric acid has a high boiling point and is not easily volatile, it remains in the reaction tank 10, and isobutyraldehyde can be discharged from the reaction tank 10 via the exhaust pipe 30. In this invention, the conversion rate of isobutyraldehyde is 90% or more. Notably, to prevent the oxygen concentration from falling into the explosive range, the oxygen content in the terminal gas during the oxidation reaction can be set to 0.005% to 8% (for example, any integer between 0.005 and 8). Finally, when the oxygen content of the terminal gas becomes 7% to 8% (for example, 7.2%, 7.4%, 7.6%, 7.8%), it is the end of the reaction, and at this point, the liquid in the reaction tank 10 is isobutyric acid. In other words, as shown in Table 1 and Figure 6 below, Figure 6 is a diagram showing the change in oxygen concentration during the reaction process of the method for producing isobutyric acid in this invention. We demonstrated that when the oxygen content of the terminal gas reached 7% to 8%, the incoming oxygen was no longer being consumed, indicating that the reaction had reached its endpoint.

[0032] [Table 1]

[0033] Furthermore, by opening and closing the fourth control valve 52, the flow of isobutyraldehyde discharged in the second tube 322 back to the isobutyraldehyde supply tube 50 can be controlled, as well as the amount flowing into the reaction tank 10. By recovering and reusing the isobutyraldehyde after the reaction, the overall conversion rate of isobutyraldehyde can be further increased. In one embodiment of the present invention, the fourth control valve 52 may be a ball valve so that it can be opened or closed quickly.

[0034] Furthermore, as shown in Table 1 above, the oxygen concentration gradually increases over time. Also, as shown in Table 2 below, the critical oxygen concentration for isobutyraldehyde is 8.8%, and the critical oxygen concentration for isobutyric acid is 8%. Therefore, the method for producing isobutyric acid according to the present invention allows for setting an outlet oxygen concentration value, and when this value is reached, the reaction is immediately stopped to avoid the risk of explosion.

[0035] [Table 2]

[0036] Examples of the present invention are shown in Table 3 below. In Table 3, the product was removed from the reaction tank and analyzed by gas chromatography (GC). The conversion rate is the number of moles of isobutyraldehyde remaining / the number of moles of isobutyraldehyde supplied × 100%. The selectivity is the number of moles of isobutyric acid / the number of moles of isobutyraldehyde supplied × 100%.

[0037] [Table 3]

[0038] As shown in Table 3 above, the difference between Example 1 and Example 2 is the type of reaction tank. When the reaction temperature, time, and pressure are all the same, by using a hollow shaft stirring tank, the mixing efficiency of the reaction gas and liquid increases, the selectivity of isobutyric acid increases, and the conversion rate of isobutyraldehyde is significantly improved. The difference between Example 2 and Example 3 lies in the increase in temperature. Comparing the results of Example 2 and Example 3, it can be seen that if the temperature is heated from 30 °C to 60 °C, the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde can be further improved. The difference between Example 3 and Example 4 lies in the increase in pressure. Comparing the results of Example 3 and Example 4, it can be seen that if the pressure is increased from 1 kg / cm 2 to 5 kg / cm 2 , the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde can be further improved.

[0039] Furthermore, the difference between Example 4 and Example 5 lies in the increase in temperature. Comparing the results of Example 4 and Example 5, it can be seen that if the temperature is heated from 60 °C to 80 °C, the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde can be further improved. The difference between Example 5 and Example 6 lies in the increase in pressure (however, the reaction temperature decreases). Comparing the results of Example 5 and Example 6, it can be seen that if the pressure is increased from 5 kg / cm 2 to 10 kg / cm 2 , even if the temperature is lowered from 80 °C to 60 °C, the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde can be further improved. In the most excellent example of the present invention, by reacting at a reaction temperature of 80 °C and a reaction pressure of 10 kg / cm 2 for 60 minutes, the selectivity of isobutyric acid reached 93%, and the conversion rate of isobutyraldehyde reached 90%.

[0040] [Advantageous Effects According to Embodiment] One of the advantageous effects of the present invention is that the apparatus for producing isobutyric acid and the method for producing isobutyric acid according to the present invention improve the yield and safety of isobutyric acid through the following technical features: "The aforementioned agitator includes a hollow shaft and a plurality of blades, the aforementioned hollow shaft has a first end and a second end arranged opposite to each other, the aforementioned first end is provided with an intake port exposed above the liquid surface in the aforementioned reaction tank, and the aforementioned second end is provided with an exhaust port immersed below the aforementioned liquid surface," and "The aforementioned exhaust pipe is connected to a condenser at the end opposite to the aforementioned reaction tank, and the aforementioned post-reaction gas is condensed to obtain isobutyraldehyde and a terminal gas."

[0041] Furthermore, the isobutyric acid production apparatus of the present invention is a gas induction magnetic shaft seal stirrer that combines the functions of intake, exhaust, and stirring, and can efficiently improve the mass transfer rate between gas and liquid. In particular, it is possible to further improve the reaction yield when carrying out the oxidation reaction under low oxygen concentration. In addition, the isobutyric acid production apparatus of the present invention employs a magnetic shaft seal (dry seal), which prevents leakage and static electricity generation, thereby improving the safety of the reaction process. Furthermore, in the isobutyric acid production apparatus of the present invention, a concentration sensor can be installed in the first tube to improve safety, thereby monitoring the concentration of the terminal gas, detecting the oxygen concentration at the reactor outlet, controlling the isobutyraldehyde concentration at the tube outlet, and controlling the endpoint of the reaction to enhance safety.

[0042] Furthermore, since the isobutyric acid production apparatus according to the present invention is equipped with a hollow stirrer, the efficiency of the oxidation reaction can be improved without adding a catalyst, and the production cost of isobutyric acid can be reduced.

[0043] The information disclosed above represents only preferred and implementable embodiments of the present invention, and the claims of the present invention are not limited thereto. Therefore, any equivalent technical modifications made using the description and drawings of the present invention are all included within the scope of the claims of the present invention. [Explanation of Symbols]

[0044] 100 ···Isobutyric acid production equipment R,10 ··Reaction tank A... Rotating shaft 11 ···Reaction solution 12 ···Working gas 20 ···Air intake pipe 21 ···First control valve 30... Exhaust pipe 31 ···Second control valve 32 ···Capacitor 321 ···First tube 322 ···Second tube 33 ···Concentration sensor 34. Pressure gauge M,40 ···Agitator 41 ···Hollow shaft L,42 ···Blade 421 ···Impeller 43 ···First end 431 ···Intake port 44...Second end 441 ···Exhaust port 50 ···Isobutyraldehyde dispensing tube 51 ···Third control valve 52 ···Fourth control valve S1 ... Process for producing isobutyric acid S2 ... Process for producing isobutyric acid S3 ... Process for producing isobutyric acid

Claims

1. An apparatus for producing isobutyric acid, comprising a reaction tank, an air intake pipe, an exhaust pipe, and a stirrer, The air intake pipe is connected to the reaction tank so that the working gas is introduced into the reaction tank. The exhaust pipe is connected to the reaction tank so as to guide the gas after the reaction to the outside of the reaction tank. The agitator is installed in the reaction tank and includes a hollow shaft and a plurality of blades, the hollow shaft having a first end and a second end arranged opposite each other, the first end having an intake port exposed above the liquid surface of the reaction tank, and the second end having an exhaust port immersed below the liquid surface. An apparatus for producing isobutyric acid, characterized in that the exhaust pipe is connected to a condenser at the end opposite to the reaction tank, and the gas after the reaction is condensed to obtain isobutyraldehyde and terminal gas.

2. The apparatus for producing isobutyric acid according to claim 1, wherein the condenser includes a first tube and a second tube, the terminal gas is discharged from the first tube, and the isobutyraldehyde is returned to the reaction tank via the second tube to continue the reaction.

3. The apparatus for producing isobutyric acid according to claim 2, wherein a concentration sensor is further installed in the first tube, and the residual liquid in the reaction tank is isobutyric acid when the oxygen content of the terminal gas is 7% to 8%.

4. The apparatus for producing isobutyric acid according to claim 1, wherein the exhaust pipe further includes a pressure gauge and a control valve.

5. The apparatus for producing isobutyric acid according to claim 1, wherein the working gas is air, nitrogen gas, or oxygen gas.

6. A method for producing isobutyric acid, carried out using the isobutyric acid production apparatus described in claim 1, The method for producing isobutyric acid is as follows: The process of providing isobutyraldehyde involves injecting isobutyraldehyde into the reaction tank, A step of replacing the atmosphere by injecting nitrogen gas into the reaction tank through the air intake pipe, A method for producing isobutyric acid, comprising an oxidation reaction step of injecting the working gas into the reaction tank via the air intake pipe and reacting the isobutyraldehyde with the working gas until the end of the reaction to obtain isobutyric acid.

7. In the process of replacing the atmosphere, the pressure is set to 1 kg / cm². ２ ~10 kg / cm² ２ A method for producing isobutyric acid according to claim 6, further comprising using a control valve to control the process.

8. The method for producing isobutyric acid according to claim 6, wherein the process of replacing the atmosphere is deemed to be completed when the oxygen content of the terminal gas becomes less than 0.005%.

9. The method for producing isobutyric acid according to claim 6, wherein during the oxidation reaction period, the oxygen content of the terminal gas is 0.005% to 8%.

10. The method for producing isobutyric acid according to claim 6, wherein the endpoint of the reaction is when the oxygen content of the terminal gas becomes 7% to 8%.

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