Isobutyric acid production apparatus and method for producing isobutyric acid

Abstract

The present invention provides an apparatus for producing isobutyric acid and a method for producing isobutyric acid, which can improve the conversion rate. [Solution] The isobutyric acid production apparatus includes a reaction tank, an air intake pipe, an exhaust pipe, and an agitator. The air intake pipe is connected to the reaction tank so that a working gas can be introduced into the reaction tank. The exhaust pipe is connected to the reaction tank so that the reacted gas can be guided out of the reaction tank. The agitator is installed in the reaction tank and includes a hollow shaft and multiple blades. The hollow shaft has a first end and a second end arranged opposite to each other, the first end having an air intake port exposed above the liquid surface in the reaction tank, and the second end having an exhaust port submerged below the liquid surface. The exhaust pipe is connected to a condenser at the end opposite the reaction tank, which condenses the reacted gas to obtain isobutyraldehyde and end gas. 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 are both highly efficient and highly safe. [Background technology]

[0002] Isobutyric acid is a short-chain saturated fatty acid with four carbon atoms. It is often used to synthesize isobutyric acid esters, and is highly economically valuable for its applications in spices, pharmaceuticals, food preservatives, and other fields. Conventional isobutyric acid is primarily produced by the isobutyraldehyde oxidation method or the isobutanol oxidation method. However, the isobutanol oxidation method produces many by-products, has high production costs, and has low yields, so the isobutyraldehyde oxidation method remains the primary method for producing isobutyric acid.

[0003] As shown in Figure 1, conventional reactors (R) use a rotating shaft (A) of an agitator (M) to rotate blades (L) to mix and stir the reactant gas (G) and the reactant liquid. However, conventional reactors (R) have low contact efficiency between the reactant gas (G) and the reactant liquid, resulting in a significant drop in yield, making them unsuitable for industrial production. This is especially true at low oxygen concentrations. Furthermore, the use of a mechanical shaft seal makes them prone to leaks and static electricity, which are extremely dangerous for the reaction process. In the oxidation of isobutyraldehyde, low gas-liquid contact efficiency leads to poor mixing, low reaction selectivity, and the production of large amounts of by-products.

[0004] In conventional reaction process technology, the concentration of the organic solvent in the vapor phase can be controlled to the lower explosion limit by adjusting the operating parameters (lowering the temperature, increasing the pressure) to eliminate the risk of flammable substances, and the risk of fire (static electricity) can be eliminated by improving the materials of the equipment. However, to maintain high yields, oxygen (combustion improver) concentrations exceeding the limiting oxygen concentration (LOC) are used, so the combustion improver still remains a risk factor throughout the entire reaction process.

[0005] Therefore, overcoming the above-mentioned drawbacks by improving the process to improve the yield and safety of isobutyric acid production is an important issue for this project. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem that the present 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] Another technical solution adopted by the present invention to solve the above technical problems provides an apparatus for producing isobutyric acid. The apparatus for producing isobutyric acid includes a reaction tank, an air intake pipe, an exhaust pipe, and an agitator. The air intake pipe is connected to the reaction tank to introduce working gas into the reaction tank, and the exhaust pipe is connected to the reaction tank to guide reacted gas out of the reaction tank. The agitator is installed in the reaction tank and includes a hollow shaft and multiple blades. The hollow shaft has opposite first and second ends, the first end having an air intake port exposed above the liquid level in the reaction tank, and the second end having an exhaust port submerged below the liquid level. The exhaust pipe is connected to a condenser at the end opposite the reaction tank to condense the reacted gas into isobutyric aldehyde and end gas, and the isobutyric aldehyde is returned to the reaction tank via a pump, thereby improving the conversion rate.

[0008] In some embodiments, the condenser includes a first tube and a second tube, and the end gas exits the first tube and the isobutyraldehyde exits the second tube.

[0009] In one embodiment, the first tube is further equipped with a concentration sensor.

[0010] In some embodiments, the exhaust pipe further includes a pressure gauge and a control valve.

[0011] In some embodiments, the working gas is air, nitrogen gas, or oxygen gas.

[0012] To solve the above technical problems, another technical solution adopted by the present invention provides a method for producing isobutyric acid, which is used in the isobutyric acid production apparatus, and includes: a step of injecting isobutyric aldehyde into the reaction tank to provide isobutyric aldehyde; a step of injecting nitrogen gas into the reaction tank through the air intake pipe to replace the atmosphere; and an oxidation reaction step of injecting the working gas into the reaction tank through the air intake pipe and reacting the isobutyric aldehyde with the working gas until the end of the reaction to obtain isobutyric acid.

[0013] In one embodiment, in the step of replacing the atmosphere, the pressure is 1 kg / cm 2 ~10kg / cm 2 and using a control valve to control the flow rate.

[0014] In one embodiment, the atmosphere substitution step is considered complete when the oxygen content of the end gas is less than 0.005%.

[0015] In one embodiment, during the oxidation reaction, the oxygen content of the end gas is between 0.005% and 8%.

[0016] In one embodiment, the end point of the reaction is when the oxygen content of the end gas is 7% to 8%.

[0017] To better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which are provided for reference and explanation only and do not limit the scope of the present invention. [Effects of the Invention]

[0018] One of the advantageous effects of the present invention is that the isobutyric acid production apparatus and isobutyric acid production method according to the present invention have the following technical features: "The agitator includes a hollow shaft and a plurality of blades, the hollow shaft has a first end and a second end arranged opposite each other, the first end having an intake hole exposed above the liquid surface of the reaction tank, and the second end having an exhaust hole immersed below the liquid surface"; and "The exhaust pipe is connected to a condenser at the end opposite the reaction tank, and the gas after the reaction is condensed to obtain isobutyric aldehyde and end gas." These technical features improve the yield and safety of isobutyric acid. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a conventional reaction tank in the prior art. [Figure 2] 1 is a schematic diagram of an apparatus for producing isobutyric acid according to the present invention. [Figure 3] FIG. 2 is a side view of an agitator of an apparatus for producing isobutyric acid according to the present invention. [Figure 4] FIG. 2 is a top view of an agitator of an apparatus for producing isobutyric acid according to the present invention. [Figure 5] 1 is a flowchart of a method for producing isobutyric acid according to the present invention. [Figure 6] FIG. 2 is a graph showing changes in oxygen concentration during the reaction process of the method for producing isobutyric acid according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes the implementation of the "apparatus for producing isobutyric acid and method for producing isobutyric acid" according to the present invention through 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 content disclosed herein. The present invention can be implemented or applied through other different specific embodiments, and various modifications and changes can be made to the details herein based on different perspectives and applications without departing 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 illustrations and are not drawn to actual size. The technical content of the present invention will be described in more detail based on the following embodiments, but the scope of protection of the present invention is not limited by the disclosed content.

[0021] It should be understood that although the present 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 element or one signal from another signal. Furthermore, the term "or" used in this specification may include any one or more combinations of the associated listed items, depending on the actual situation.

[0022] [First embodiment] As shown in FIGS. 2 to 4, an apparatus 100 for producing isobutyric acid according to a first embodiment of the present invention includes a reaction tank 10, an air intake pipe 20, an exhaust pipe 30, and an agitator 40. The reaction tank 10 is a sealed tank capable of accommodating a reaction liquid 11. In the present invention, the reaction liquid 11 is isobutyraldehyde. The 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 so as to control the amount of isobutyraldehyde introduced into the reaction tank 10. The air intake pipe 20 is connected to 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 present in the reaction tank is usually atmospheric air (i.e., air). Before carrying out the oxidation reaction, nitrogen gas is first introduced into the reaction tank 10 via the air intake pipe 20 to pressurize the reaction tank 10, so that the atmospheric pressure in the reaction tank 10 is 1 kg / cm. 2 ~10kg / cm 2 The temperature is maintained at 100°C. Then, 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. Air is easily available and can be easily separated from isobutyric acid, which simplifies the process, reduces production costs, and improves 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, with the first end 43 having an air inlet 431 exposed above the liquid surface in the reaction tank 10, and the second end 44 having an exhaust port 441 immersed below the liquid surface. Therefore, when oxygen gas or air is introduced, the oxygen gas or air is guided from the air inlet 431 of the first end 43 to the exhaust port 441 of the second end 44, thereby directing the 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 the liquid. In other words, the agitator 40 according to the present invention has intake, exhaust, and stirring functions.

[0025] In one embodiment of the present invention, the first control valve 21 and the second control valve 31 are respectively connected to the air intake pipe 20 and the exhaust pipe 30, and these valves are controlled to open and close, thereby controlling the progress of the oxidation reaction in the reaction tank 10. For example, the first control valve 21 and the second control valve 31 are first opened simultaneously to introduce the working gas 12 into the reaction tank 10 and replace the gas in the reaction tank 10. The second control valve 31 is then closed, and the working gas 12 is introduced through the air intake pipe 20 to pressurize the reaction tank 10, and oxygen gas or air is then introduced to carry out the oxidation reaction. In the present invention, the first control valve 21 and the second control valve 31 may be backpressure valves. However, the above example is merely one embodiment, and the present invention is not limited thereto. In one embodiment of the present invention, the oxidation reaction begins when the gas in the reaction tank 10 has a nitrogen gas:oxygen gas ratio of 99.995:0.005, thereby achieving excellent reaction efficiency.

[0026] An exhaust pipe 30 is connected to the reaction tank 10 to guide the reacted gas out of the reaction tank 10. The exhaust pipe 30 is connected to a condenser 32 at the end opposite the reaction tank 10, which condenses the reacted gas to obtain isobutyraldehyde and end gas. The condensed isobutyraldehyde is returned to the reaction tank 10, thereby improving the conversion rate. 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 end 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 to monitor the pressure in the reaction tank 10.

[0027] In some embodiments of the present invention, a concentration sensor 33 may be further installed in the first tube 321 to monitor the concentration of the end gas. Specifically, the end gas may be oxygen gas, air, or nitrogen gas. That is, by monitoring the oxygen concentration and isobutyraldehyde concentration at the observation outlet end with the concentration sensor 33, the reaction oxygen concentration can be kept below the limit oxygen concentration (LOC), and the end point of the reaction can be controlled to balance reaction efficiency and oxidation reaction safety.

[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, and includes a step S1 of providing isobutyric acid by injecting isobutyric aldehyde into the reaction tank 10, a step S2 of replacing the atmosphere by injecting nitrogen gas into the reaction tank 10 through the air intake pipe 20, and an oxidation reaction step S3 of injecting the working gas 12 into the reaction tank 10 through the air intake pipe 20 and reacting the isobutyric aldehyde with the working gas 12 until the end of the reaction to obtain isobutyric acid.

[0029] In step S1, isobutyraldehyde can be charged into the reaction tank 10 and stirred by the agitator 40. In the present invention, the agitator 40 is a hollow agitator including an intake hole 431 provided at a first end 43 and an exhaust hole 441 provided at a second end 44, whereby gas is caused to flow within the hollow shaft 41, thereby introducing oxygen gas or air to the bottom of the reaction liquid 11 in the reaction tank 10 and improving the mixing efficiency of the gas and the liquid.

[0030] In the atmosphere replacement step S2, the pressure is set to 1 kg / cm using the second control valve 31. 2 ~10kg / cm 2(e.g., any integer between 1 and 10). In one embodiment of the present invention, the flow rate of the working gas 12 introduced through the air intake pipe 20 may be 1 L / min to 10 L / min (e.g., any integer between 1 and 10). Thereafter, the oxygen content in the end gas is monitored by the concentration sensor 33, and when the oxygen content in the end gas becomes less than 0.005%, the atmosphere substitution step is deemed to be complete.

[0031] In the oxidation reaction step S3, the reaction temperature may be 20°C to 100°C, and the reaction pressure may be 1 kg / cm 2 ~10kg / cm 2 After the reaction, isobutyric acid remains in the reaction tank 10 due to its high boiling point and low volatility, while isobutyric aldehyde can be discharged from the reaction tank 10 via the exhaust pipe 30. In the present invention, the conversion rate of isobutyric aldehyde is 90% or higher. It is noteworthy that the oxygen content in the terminal gas during the oxidation reaction can be set to 0.005% to 8% (e.g., any integer between 0.005 and 8) so that the oxygen concentration does not fall within the explosive range. Finally, the reaction ends when the oxygen content in the terminal gas reaches 7% to 8% (e.g., 7.2%, 7.4%, 7.6%, or 7.8%), and the liquid in the reaction tank 10 at this time is isobutyric acid. In other words, as shown in Table 1 below and FIG. 6, FIG. 6 is a graph showing the change in oxygen concentration during the reaction process of the method for producing isobutyric acid according to the present invention. When the oxygen content of the end gas reached 7%-8%, it indicated that the incoming oxygen was no longer consumed and the end point of the reaction was reached.

[0032] [Table 1]

[0033] Furthermore, by opening and closing the fourth control valve 52, the amount of isobutyraldehyde discharged through the second tube 322 can be controlled to return to the isobutyraldehyde supply tube 50 and to control 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. Furthermore, as shown in Table 2 below, the limiting oxygen concentration for isobutyraldehyde is 8.8%, and the limiting oxygen concentration for isobutyric acid is 8%. Therefore, the method for producing isobutyric acid according to the present invention can set 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 in the reaction tank was taken out and analyzed by gas chromatography (GC). The conversion rate is the number of remaining moles of isobutyraldehyde / the number of moles of isobutyraldehyde supplied x 100%. The selectivity is the number of moles of isobutyric acid / the number of moles of isobutyraldehyde supplied x 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, the use of a hollow shaft stirred tank increases the mixing efficiency of the reaction gas and liquid, increases the selectivity for isobutyric acid, and significantly improves the conversion rate of isobutyric aldehyde. The difference between Example 2 and Example 3 is the increase in temperature. Comparing the results of Example 2 and Example 3, it can be seen that heating the temperature from 30°C to 60°C can further improve the selectivity for isobutyric acid and the conversion rate of isobutyric aldehyde. The difference between Example 3 and Example 4 is the increase in pressure. Comparing the results of Example 3 and Example 4, it can be seen that raising the pressure to 1 kg / cm 2 to 5kg / cm 2 It can be seen that if the pressure is increased to 1000 kJ / min, the selectivity for isobutyric acid and the conversion rate of isobutyraldehyde can be further improved.

[0039] Furthermore, the difference between Example 4 and Example 5 is the increase in temperature. Comparing the results of Example 4 and Example 5, it can be seen that the selectivity of isobutyric acid and the conversion rate of isobutyric aldehyde can be further improved by increasing the temperature from 60°C to 80°C. The difference between Example 5 and Example 6 is the increase in pressure (however, the reaction temperature is decreased). Comparing the results of Example 5 and Example 6, it can be seen that the selectivity of isobutyric acid and the conversion rate of isobutyric aldehyde can be further improved by increasing the pressure from 5 kg / cm 2 from 10 kg / cm 2 It can be seen that if the pressure is increased to 10 kg / cm, the selectivity for isobutyric acid and the conversion rate of isobutyraldehyde can be further improved even if the temperature is lowered from 80°C to 60°C. In the best example of the present invention, the reaction temperature is 80°C, and the pressure is 10 kg / cm. 2 By reacting for 60 minutes at a reaction pressure of 1000 kJ / min, the selectivity for isobutyric acid reached 93% and the conversion of isobutyraldehyde reached 90%.

[0040] [Advantageous Effects of the Embodiments] One of the advantageous effects of the present invention is that the isobutyric acid production apparatus and isobutyric acid production method according to the present invention have the following technical features: "The agitator includes a hollow shaft and a plurality of blades, the hollow shaft has a first end and a second end arranged opposite each other, the first end having an intake hole exposed above the liquid surface in the reaction tank, and the second end having an exhaust hole immersed below the liquid surface"; and "The exhaust pipe is connected to a condenser at the end opposite the reaction tank, and the gas after the reaction is condensed to obtain isobutyric aldehyde and end gas." These technical features improve the yield and safety of isobutyric acid.

[0041] Furthermore, the isobutyric acid production apparatus of the present invention is a magnetic shaft seal agitator for gas induction that combines the functions of intake, exhaust, and stirring, and can efficiently improve the mass transfer rate between gas and liquid. In particular, when an oxidation reaction is carried out under low oxygen concentrations, it is possible to further improve the reaction yield. Furthermore, the isobutyric acid production apparatus of the present invention employs a magnetic shaft seal (dry seal), which prevents leakage and static electricity and improves the safety of the reaction process. Furthermore, to improve safety, the isobutyric acid production apparatus of the present invention can be equipped with a concentration sensor in the first tube. This allows the concentration of the end gas to be monitored, the oxygen concentration at the reactor outlet end to be detected, and the isobutyric aldehyde concentration at the tube outlet to be controlled, thereby controlling the end point of the reaction and improving safety.

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

[0043] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, any equivalent technical modifications made using the specification and drawings of the present invention are included in the scope of the claims of the present invention. [Explanation of symbols]

[0044] 100 Isobutyric acid manufacturing 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... Mixer 41 Hollow shaft L,42 Blade 421 Impeller 43 First end 431 Air intake 44 Second end 441 Exhaust vent 50 Isobutyraldehyde Feeding Tube 51 Third control valve 52 Fourth control valve S1: Isobutyric acid manufacturing process S2: Isobutyric acid manufacturing process S3: Isobutyric acid manufacturing process

Claims

1. An apparatus for producing isobutyric acid, comprising a reaction tank, an air intake pipe, an exhaust pipe, and an agitator, wherein the air intake pipe is connected to the reaction tank so that a working gas containing air or oxygen gas is introduced into the reaction tank; the exhaust pipe is in communication with the reaction tank so as to guide the gas after the reaction out 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 has a first end and a second end arranged opposite to each other, the first end has an intake hole exposed above the liquid surface of the reaction tank, and the second end has an exhaust hole submerged below the liquid surface; 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 end gas.

2. 2. The apparatus for producing isobutyric acid according to claim 1, wherein the condenser comprises a first tube and a second tube, the end 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. 3. The apparatus for producing isobutyric acid according to claim 2, wherein a concentration sensor is further installed in the first tube, and when the oxygen content of the end gas is 7% to 8%, the residual liquid in the reaction tank is isobutyric acid.

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

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

6. A method for producing isobutyric acid carried out by the isobutyric acid production apparatus according to claim 1, The method for producing isobutyric acid includes the steps of: providing isobutyraldehyde by injecting isobutyraldehyde into the reaction tank; a step of injecting nitrogen gas into the reaction tank through the air intake pipe to replace the atmosphere; an oxidation reaction step of injecting the working gas into the reaction tank through 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 step of replacing the atmosphere, the pressure is set to 1 kg / cm ２ ~10 kg / cm ２ 7. The method for producing isobutyric acid according to claim 6, further comprising using a control valve to control the

8. 7. The method for producing isobutyric acid according to claim 6, wherein the atmosphere substitution step is completed when the oxygen content of the end gas becomes less than 0.005%.

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

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

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