Apparatus for producing isobutanoic acid and method for producing isobutanoic acid

Abstract

This invention discloses an apparatus and a method for manufacturing isobutyric acid. The apparatus for manufacturing isobutyric acid includes a reaction tank, an inlet pipe, an outlet pipe, and a stirrer. The inlet pipe is connected to the reaction tank to introduce working gas into the reaction tank. The outlet pipe is connected to the reaction tank to guide the reacted gas out of the reaction tank. The stirrer is disposed 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 a suction port and protrudes above the liquid surface of the reaction tank, while the second end has an exhaust port and is submerged in the liquid surface. The other end of the outlet pipe relative to the reaction tank is connected to a condenser to condense the reacted gas to obtain isobutyraldehyde and tail gas. The isobutyraldehyde can be pumped back to the reaction tank for further reaction to increase the conversion rate.

Description

Technical Field

[0001] This invention relates to an apparatus and a method for manufacturing isobutyric acid, and particularly to an apparatus and method for manufacturing isobutyric acid that are both highly efficient and safe. Prior Technology

[0002] Isobutyric acid is a short-chain saturated fatty acid with four carbon atoms, frequently used in the synthesis of isobutyrate esters, which have significant economic value in the fields of fragrances, pharmaceuticals, and food preservatives. Currently, isobutyric acid is primarily manufactured using isobutyraldehyde oxidation and isobutanol oxidation methods. However, the isobutanol oxidation method produces numerous byproducts, resulting in higher manufacturing costs and lower yields; therefore, isobutyraldehyde oxidation remains the main method for producing isobutyric acid.

[0003] As shown in Figure 1, the traditional reaction tank R utilizes the rotating shaft A of the stirrer M to drive the blades L to rotate, thereby achieving the effect of mixing the reactant gas G with the reaction liquid. However, the traditional reaction tank R suffers from low contact efficiency between the reactant gas G and the reaction liquid, resulting in a significant reduction in yield and making it unsuitable for industrial production, especially at low oxygen concentrations. Furthermore, the use of mechanical shaft seals easily leads to leaks and static electricity, posing a significant risk to the reaction process. In the oxidation of isobutyraldehyde, the low contact efficiency between the gas and liquid results in poor mixing, low reaction selectivity, and numerous byproducts.

[0004] In previous reaction process techniques, although the concentration of organic solvents in the gaseous phase could be controlled within the lower explosive limit by adjusting operating parameters (lowering temperature, increasing pressure) to eliminate the hazard of flammable materials, and the hazard of ignition sources (static electricity) could be eliminated by improving equipment materials, the concentration of oxygen (combustion oxidizer) was used higher than the limiting oxygen concentration (LOC) to maintain a high yield. Therefore, the hazard of combustion oxidizers still existed in the entire reaction process.

[0005] Therefore, improving the production yield and safety of isobutyric acid through process improvement to overcome the aforementioned defects has become one of the important issues that this business aims to address. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an apparatus and a method for manufacturing isobutyric acid, which address the shortcomings of the prior art.

[0007] To solve the aforementioned technical problems, another technical solution adopted by the present invention is to provide an apparatus for manufacturing isobutyric acid, comprising: a reaction tank; an inlet pipe connected to the reaction tank for introducing a working gas into the reaction tank; an outlet pipe connected to the reaction tank for guiding a reacted gas out of the reaction tank; and a stirrer disposed in the reaction tank, the stirrer comprising a hollow shaft; and a plurality of blades, the hollow shaft having a first end and a second end disposed opposite to each other, the first end having an exhaust port exposed above the liquid surface of the reaction tank, and the second end having an exhaust port submerged in the liquid surface; wherein, the other end of the outlet pipe relative to the reaction tank is connected to a condenser to condense the reacted gas to obtain isobutyraldehyde and a tail gas, the tail gas isobutyraldehyde being pumped back to the reaction tank to increase the conversion rate.

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

[0009] In one embodiment, a concentration sensor is also provided on the first tube.

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

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

[0012] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide a method for manufacturing isobutyric acid, which utilizes the aforementioned equipment for manufacturing isobutyric acid. The method includes: providing isobutyraldehyde by injecting isobutyraldehyde into the reaction tank; atmosphere replacement by injecting nitrogen gas into the reaction tank through the inlet pipe; and oxidation reaction by injecting the working gas into the reaction tank through the inlet pipe, so that the isobutyraldehyde reacts with the working gas until the reaction endpoint is reached to obtain isobutyric acid.

[0013] In one embodiment, the atmosphere replacement step further includes using a control valve to control the pressure at 1 to 10 kg / cm².

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

[0015] In one embodiment, during the oxidation reaction, the oxygen content of the exhaust gas ranges from 0.005% to 8%.

[0016] In one embodiment, the reaction endpoint is when the oxygen content of the exhaust gas is 7-8%.

[0017] One of the beneficial effects of this invention is that the equipment and method for manufacturing isobutyric acid provided by this invention can improve the yield and safety of isobutyric acid production through the following technical solutions: "The stirrer 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 a suction hole and protrudes above the liquid surface of the reaction tank, the second end has a vent hole and is submerged in the liquid surface," and "The vent pipe is connected to a condenser at the other end relative to the reaction tank to condense the reaction gas to obtain isobutyraldehyde and a tail gas," the tail gas isobutyraldehyde is pumped back to the reaction tank to increase the conversion rate.

[0018] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Simple Explanation of the Diagram

[0019] Figure 1 is a schematic diagram of a conventional reaction vessel in the prior art.

[0020] Figure 2 is a schematic diagram of the apparatus for manufacturing isobutyric acid according to the present invention.

[0021] Figure 3 is a side view of the stirrer of the apparatus for manufacturing isobutyric acid according to the present invention.

[0022] Figure 4 is a top view of the stirrer of the apparatus for manufacturing isobutyric acid according to the present invention.

[0023] Figure 5 is a flowchart of the method for manufacturing isobutyric acid according to the present invention.

[0024] Figure 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. Implementation

[0025] The following specific embodiments illustrate the implementation of the "apparatus and method for manufacturing isobutyric acid" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention. Furthermore, the accompanying drawings of this invention are for simple illustrative purposes only and are not depictions of actual dimensions; this is stated in advance. The following embodiments will further describe the relevant technical content of this invention in detail, but the disclosed content is not intended to limit the scope of protection of this invention.

[0026] It should be understood that while terms such as "first," "second," and "third" may be used in this document to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. Furthermore, the term "or" as used herein should, as appropriate, include any combination of one or more of the associated listed items.

[0027] [First Embodiment]

[0028] Referring to Figures 2 to 4, a first embodiment of the present invention provides an apparatus 100 for manufacturing isobutyric acid, comprising: a reaction tank 10, an inlet pipe 20, an outlet pipe 30, and a stirrer 40. The reaction tank 10 is a closed tank capable of containing a reaction liquid 11; in this invention, the reaction liquid 11 is isobutyraldehyde. Further, isobutyraldehyde flows into the reaction tank 10 through an isobutyraldehyde feed pipe 50. In one embodiment, a third control valve 51 may be provided on the isobutyraldehyde feed pipe 50 to control the amount of isobutyraldehyde entering the reaction tank 10. The inlet pipe 20 is connected to the reaction tank 10 to introduce a working gas 12 into the reaction tank 10. In this invention, the working gas 12 may be air, nitrogen, or oxygen.

[0029] Specifically, under normal circumstances, the gas present in reaction tank 10 is ordinary atmosphere (i.e., air). Before the oxidation reaction, nitrogen gas can be introduced into reaction tank 10 through air inlet pipe 20 to pressurize it, so that the atmospheric pressure in the reaction tank is maintained at 1 kg / cm2 to 10 kg / cm2. Subsequently, oxygen is introduced as an oxidant to react with isobutyraldehyde. In another embodiment of the present invention, air can also be introduced as an oxidant, which is readily available and easily separated from isobutyric acid, simplifying the process, reducing production costs, and improving safety.

[0030] Furthermore, the stirrer 40 of the apparatus 100 for manufacturing isobutyric acid of the present invention includes a hollow shaft 41 and a plurality of blades 42, with the plurality of blades 42 fixed on an impeller 421. The hollow shaft 41 has a first end 43 and a second end 44 disposed opposite to each other. The first end 43 is provided with a suction port 431 and protrudes above the liquid surface of the reaction tank 10, while the second end 44 is provided with a venting port 441 and is submerged in the liquid surface. Therefore, when oxygen or air is introduced, oxygen or air can be guided from the suction port 431 of the first end 43 to the venting port 441 of the second end 44, thereby guiding the oxygen or air to the bottom of the reaction liquid 11 in the reaction tank 10 and increasing the mixing efficiency of the gas and liquid. In other words, the stirrer 40 of the present invention has the functions of suction, venting, and stirring.

[0031] In one embodiment of the present invention, a first control valve 21 and a second control valve 31 may be respectively provided on the inlet pipe 20 and the outlet pipe 30 to control the opening and closing of the inlet pipe 20 and the outlet pipe 30, thereby controlling the oxidation reaction in the reaction tank 10. For example, 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 to replace the gas in the reaction tank 10. Then, the second control valve 31 is closed, and the working gas 12 is continuously introduced from the inlet pipe 20 for pressurization, and then oxygen 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 examples are only one feasible embodiment and are not intended to limit the present invention. In one embodiment of the present invention, the gas in the reaction tank 10 may start the oxidation reaction when the nitrogen:oxygen ratio is 99.995:0.005 to achieve better reaction efficiency.

[0032] Additionally, the outlet pipe 30 is connected to the reaction tank 10 to guide the reacted gas out of the reaction tank 10. Furthermore, the other end of the outlet pipe 30 relative to the reaction tank 10 can be connected to a condenser 32 to condense the reaction gas to obtain isobutyraldehyde and tail gas. The condensed isobutyraldehyde can be returned to the reaction tank to improve the conversion rate. Further, the condenser 32 may include a first pipe 321 and a second pipe 322. The first pipe 321 can be connected to the upper end of the condenser 32 to discharge tail gas, and the second pipe 322 can be connected to the lower end of the condenser 32 to discharge isobutyraldehyde. In one embodiment of the present invention, a pressure gauge 34 can be further installed on the outlet pipe 30 to monitor the pressure in the reaction tank 10.

[0033] In one embodiment of the present invention, a concentration sensor 33 may be further provided on the first tube 321 to monitor the concentration of the exhaust gas. Specifically, the exhaust gas may be oxygen, air, or nitrogen. That is, the concentration sensor 33 monitors the oxygen concentration and isobutyraldehyde concentration at the outlet to ensure that the reaction oxygen concentration is lower than the limit oxygen concentration (LOC) and to control the reaction endpoint, taking into account both reaction efficiency and the safety of the oxidation reaction.

[0034] [Second Embodiment]

[0035] Referring to Figure 5, the second embodiment of the present invention provides a method for manufacturing isobutyric acid, which utilizes the aforementioned equipment for manufacturing isobutyric acid. The method includes at least the following steps: S1: providing isobutyraldehyde by injecting isobutyraldehyde into the reaction tank 10; S2: atmosphere replacement by injecting nitrogen gas into the reaction tank 10 through the inlet pipe 20; and S3: oxidation reaction by injecting the working gas 12 into the reaction tank 10 through the inlet pipe 20, so that the isobutyraldehyde reacts with the working gas 12 until the reaction endpoint is reached to obtain isobutyric acid.

[0036] In step S1, isobutyraldehyde is placed into the reaction tank 10 and stirred by a stirrer 40. In this invention, the stirrer 40 is a hollow stirrer, which includes an extraction port 431 at the first end 43 and an exhaust port 441 at the second end 44, so that gas can flow in the hollow shaft 41 to guide oxygen or air to the bottom of the reaction liquid 11 in the reaction tank 10, thereby increasing the mixing efficiency of gas and liquid.

[0037] In the atmosphere replacement step S2, the pressure can be controlled at 1 kg / cm² to 10 kg / cm² (e.g., any positive number between 1 and 10) using the second control valve 31. In one embodiment of the invention, the flow rate at which the working gas 12 is introduced through the intake pipe 20 can be 1 L / min to 10 L / min (e.g., any positive number between 1 and 10). Subsequently, the oxygen content of the exhaust gas is monitored using the concentration sensor 33, and the atmosphere replacement step is considered complete when the oxygen content of the exhaust gas is less than 0.005%.

[0038] In the oxidation reaction of step S3, the reaction temperature can be from 20°C to 100°C, and the reaction pressure can be from 1 kg / cm² to 10 kg / cm². After the reaction, isobutyric acid, due to its high boiling point, is not easily volatilized and will remain in the reaction tank 10, while isobutyraldehyde can be discharged from the reaction tank 10 through the exhaust pipe 30. In this invention, the conversion rate of isobutyraldehyde is at least 90%. It is worth noting that the oxygen content of the tail gas during the oxidation reaction can be from 0.005% to 8% (e.g., any positive number between 0.005 and 8) to ensure that the oxygen concentration does not fall within the explosive range. Finally, when the oxygen content of the tail gas is 7% to 8% (e.g., 7.2%, 7.4%, 7.6%, 7.8%), the reaction endpoint is reached, and the liquid in the reaction tank 10 at this point is isobutyric acid. In other words, as shown in Table 1 and Figure 6 below, the figure shows the oxygen concentration change during the reaction process of the isobutyric acid manufacturing method of this invention. When the oxygen content in the exhaust gas reaches 7% to 8%, it indicates that the incoming oxygen is no longer being consumed, and it also indicates that the reaction has reached its endpoint.

[0039] Table 1 Reaction time (minutes) Oxygen concentration at outlet (%) 0 0 2 2 5 3 10 3.2 15 3.3 20 3.5 25 3.6 30 3.8 35 4.5 40 4.8 45 5.8 50 6.7 55 7.8 60 8

[0040] Furthermore, the amount of isobutyraldehyde discharged from the second pipe 322 can be controlled by opening or closing the fourth control valve 52 to allow it to flow back into the isobutyraldehyde feed pipe 50 and into the reaction tank 10. By recovering and reusing the reacted isobutyraldehyde, the overall isobutyraldehyde conversion rate can be further increased. In one embodiment of the present invention, the fourth control valve 52 can be a ball valve for rapid opening or closing.

[0041] Furthermore, as shown in Table 1 above, the oxygen concentration increases with time. According to 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 manufacturing isobutyric acid of the present invention can set an outlet oxygen concentration value, and stop the reaction when this value is reached to avoid the risk of explosion. chemicals Lower explosive limit % Explosion limit % Limiting oxygen concentration (LOC) Isobutyraldehyde 1.6% 10.6% 8.8% Isobutyric acid 1.6% 7.3% 8%

[0042] Examples of the present invention are shown in Table 3 below. In Table 3, the products in the reaction tank were subjected to gas chromatography (GC) analysis, wherein the conversion rate was 100% (residual moles of isobutyraldehyde / feed moles of isobutyraldehyde); and the selectivity was 100% (moles of isobutyric acid / feed moles of isobutyraldehyde).

[0043] Table 3 Example Reactor type Reaction temperature (°C) Reaction time (minutes) Pressure (kg / cm²) Isobutyraldehyde conversion rate (%) Isobutyric acid selectivity (%) 1 General mixing tank 30 60 1 40 81 2 Hollow shaft mixing tank 30 60 1 70 85 3 Hollow shaft mixing tank 60 60 1 73 86 4 Hollow shaft mixing tank 60 60 5 85 91 5 Hollow shaft mixing tank 80 60 5 86 90 6 Hollow shaft mixing tank 60 60 10 87.5 90 7 Hollow shaft mixing tank 80 60 10 90 93

[0044] As shown in Table 3 above, the difference between Example 1 and Example 2 lies in the form of the reaction vessel. Under the same reaction temperature, time, and pressure, using a hollow shaft stirred tank increases the mixing efficiency of the reaction gas and liquid, thereby improving the selectivity of isobutyric acid and significantly increasing the conversion rate of isobutyraldehyde. 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 increasing the temperature from 30℃ to 60℃ can further improve the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde. 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 increasing the pressure from 1 kg / cm² to 5 kg / cm² can further improve the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde.

[0045] 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 increasing the temperature from 60°C to 80°C can further improve the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde. The difference between Example 5 and Example 6 lies in the increase in pressure. Comparing the results of Example 5 and Example 6, it can be seen that increasing the pressure from 5 kg / cm² to 10 kg / cm² can further improve the selectivity of isobutyric acid and the conversion rate of isobutyraldehyde. In a preferred embodiment of the present invention, using a reaction temperature of 80°C and a reaction pressure of 10 kg / cm² for 60 minutes can achieve an isobutyric acid selectivity of 93% and an isobutyraldehyde conversion rate of 90%.

[0046] [Beneficial Effects of the Examples]

[0047] One of the beneficial effects of the present invention is that the equipment and method for manufacturing isobutyric acid provided by the present invention can improve the yield and safety of isobutyric acid manufacturing through the technical solutions of "the stirrer 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 is provided with a suction hole and exposed above the liquid surface of the reaction tank, and the second end is provided with a vent hole and submerged in the liquid surface" and "the other end of the vent pipe is connected to a condenser relative to the reaction tank to condense the reaction gas to obtain isobutyraldehyde and a tail gas".

[0048] Furthermore, the apparatus for manufacturing isobutyric acid of the present invention is a magnetically sealed stirrer that combines gas extraction, exhaust, and stirring functions, effectively improving the gas-liquid mass transfer rate, especially during oxidation reactions at low oxygen concentrations, thereby increasing the reaction yield. Moreover, the apparatus for manufacturing isobutyric acid of the present invention uses a magnetically sealed (dry seal) shaft, preventing leakage and static electricity, thus improving the safety of the reaction process. Furthermore, the apparatus for manufacturing isobutyric acid of the present invention can be equipped with a concentration sensor on the first tube to monitor the concentration of the exhaust gas, detect the oxygen concentration at the reactor outlet, control the isobutyraldehyde concentration at the outlet, regulate the reaction endpoint, and enhance safety.

[0049] Furthermore, since the apparatus for manufacturing isobutyric acid of the present invention has a hollow stirrer, the efficiency of the oxidation reaction can be improved without adding a catalyst, thus saving the manufacturing cost of isobutyric acid.

[0050] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention specification and drawings are included in the scope of the patent application of the present invention.

[0051] 100: Equipment used for the manufacture of isobutyric acid R, 10: Reaction tank A: Shaft 11: Reaction solution 12: Working gas 20: Intake pipe 21: First control valve 30: Exhaust pipe 31: Second control valve 32: Condenser 321: First tube 322: Second tube 33: Concentration sensor 34: Pressure gauge M, 40: Stirrer 41: Hollow Shaft L, 42: Blade 421: Impeller 43: First end 431: Air extraction port 44: Second end 441: Exhaust port 50: Isobutyraldehyde feed pipe 51: Third control valve 52: Fourth control valve S1~S3: Steps

Claims

1. An apparatus for manufacturing isobutyric acid, comprising: One reaction tank; An air inlet pipe is connected to the reaction tank to introduce a working gas into the reaction tank; A gas outlet pipe is connected to the reaction tank to guide a reacted gas out of the reaction tank; A stirrer is disposed in the reaction tank. The stirrer includes a hollow shaft and a plurality of blades. The hollow shaft has a first end and a second end disposed opposite to each other. The first end is provided with a suction hole and protrudes above the liquid surface of the reaction tank. The second end is provided with a vent hole and is submerged in the liquid surface. The vent pipe is connected to a condenser at the other end of the reaction tank to condense the gas after reaction to obtain isobutyraldehyde and a tail gas.

2. The apparatus for manufacturing isobutyric acid as described in claim 1, wherein, The condenser includes a first tube and a second tube. The exhaust gas is discharged from the first tube, and the isobutyraldehyde is transported back to the reaction tank through the second tube to continue the reaction.

3. The apparatus for manufacturing isobutyric acid as described in claim 2, wherein, The first tube is also equipped with a concentration sensor. When the oxygen content of the exhaust gas is 7% to 8%, the residual liquid in the reaction tank is isobutyric acid.

4. The apparatus for manufacturing isobutyric acid as described in claim 1, wherein, The vent pipe further includes a pressure gauge and a control valve.

5. The apparatus for manufacturing isobutyric acid as claimed in claim 1, wherein, The working gas is air, nitrogen, or oxygen.

6. A method for producing isobutyric acid, utilizing the apparatus for producing isobutyric acid as described in claim 1, the method comprising: Isobutyraldehyde is provided and injected into the reaction vessel; Atmosphere replacement, wherein nitrogen is injected into the reaction tank through the air inlet pipe; And oxidation reaction, the working gas is injected into the reaction tank through the air inlet pipe, so that the isobutyraldehyde reacts with the working gas until the reaction endpoint to obtain isobutyric acid.

7. The method for manufacturing isobutyric acid as described in claim 6, wherein, The atmosphere replacement step further includes using a control valve to control the pressure at 1 to 10 kg / cm2.

8. The method for producing isobutyric acid as described in claim 6, wherein, In the atmosphere replacement step, the atmosphere replacement step is considered complete when the oxygen content of the exhaust gas is less than 0.005%.

9. The method for producing isobutyric acid as described in claim 6, wherein, During the oxidation reaction, the oxygen content of the exhaust gas ranges from 0.005% to 8%.

10. A method for producing isobutyric acid as described in claim 6, wherein, The reaction endpoint is when the oxygen content of the exhaust gas is 7% to 8%.

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