Synthesis method of 1, 4-butynediol
The synthesis process of 1,4-butynediol was optimized by electrochemical methods. The electrode autocatalytic strategy of copper electrode and Cu-Bi electrode was adopted to solve the problems of mass transfer resistance and catalyst deactivation, and achieve rapid and efficient synthesis of 1,4-butynediol.
Patent Information
- Application Number
- CN202510716458.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2025-09-12
AI Technical Summary
The existing 1,4-butynediol synthesis method has liquid-solid mass transfer resistance, which leads to excessively long reaction times and easy deactivation of the catalyst, requiring regular replacement.
An electrochemical method was adopted, using a copper electrode with a mixed layer on the surface as the anode. Through the electrode autocatalytic strategy, the reaction system was optimized to a gas-liquid two-phase reaction. Combined with a Cu-Bi electrode as the cathode, the reaction conditions such as pH value, temperature and stirring speed were controlled to reduce the mass transfer resistance.
The reaction time is significantly shortened from the traditional 40 hours to 1-2 hours, the reaction efficiency is improved, the catalyst deactivation problem is solved, and the product purity and yield are high.
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Figure CN120625072A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of synthesis of 1,4-butynediol, and in particular relates to a synthesis method of 1,4-butynediol. Background Art
[0002] 1,4-Butynediol is an important precursor for the synthesis of 1,4-butanediol and is widely used as an upstream raw material for polyurethanes. The currently reported mainstream synthesis method for 1,4-butynediol is the acetylene-aldehyde coupling method, which uses a slurry bed reactor. The specific process involves adding formaldehyde solution and basic copper carbonate (catalyst) to the slurry bed reactor, then introducing acetylene under stirring for 10-30 hours to activate the catalyst. Following activation, the reaction is continued at 60-90°C for 20-60 hours to yield the product, 1,4-butynediol.
[0003] In this method, the catalyst is typically in solid form. Reactants in the liquid phase must diffuse onto the catalyst surface before a reaction can occur, and the reaction products must diffuse from the catalyst surface into the liquid phase. This process involves liquid-solid mass transfer resistance, limiting mass transfer efficiency. This results in prolonged reaction times and the catalyst is prone to deactivation, requiring regular equipment cleaning and catalyst replacement. Summary of the Invention
[0004] The purpose of the present invention is to provide a method for synthesizing 1,4-butynediol, thereby reducing the mass transfer resistance during the reaction process and shortening the reaction time.
[0005] The present invention adopts the following technical solution: a method for synthesizing 1,4-butynediol, comprising the following steps:
[0006] Add formaldehyde solution and buffer solution into the electrochemical reactor; the pH value of the buffer solution is 8.0±0.1;
[0007] Acetylene gas is introduced into the mixed solution in the electrochemical reactor, stirred, and a 2.8-3.2V direct current is introduced to cause the acetylene gas and formaldehyde solution to react at a reaction temperature of 40-60°C. A copper electrode having a mixed layer on its surface composed of CuO and Cu2O is used as the anode.
[0008] After the reaction is completed, the solvent is removed from the solution to obtain 1,4-butynediol.
[0009] Furthermore, the copper electrode is prepared by an anodic oxidation method.
[0010] Furthermore, the preparation method of the copper electrode is:
[0011] Polish and clean the surface of the copper foil;
[0012] The cleaned copper foil was placed in a 0.1 M NaOH solution as a working electrode and oxidized at a constant potential of +0.8 V vs. Ag / AgCl until a mixed layer was formed on the surface of the working electrode. The copper foil was taken out and blown dry to obtain a copper electrode.
[0013] Furthermore, the preparation method of the buffer solution is:
[0014] Na2SO4 and NaHCO3 were dissolved in deionized water, and benzotriazole and PEG-400 were added to obtain a mixed solution; wherein the mass ratio of deionized water, Na2SO4, NaHCO3, benzotriazole and PEG-400 was 1000:2.84:0.84:0.12:5.
[0015] The pH value of the mixed solution was adjusted to 8.0±0.1 to obtain a buffer solution.
[0016] Furthermore, before adding the formaldehyde solution and the buffer solution into the electrochemical reactor, the process includes:
[0017] The formaldehyde solution and the buffer solution were mixed together, with the mass ratio of the formaldehyde solution to the buffer solution being 10:(1.8-2.0).
[0018] Furthermore, a Cu-Bi electrode is used as the cathode, wherein the Bi content is 1-5 wt%.
[0019] Furthermore, the electrochemical reaction time is 1-2 hours.
[0020] Furthermore, the stirring speed is 300-400 rpm.
[0021] Furthermore, the reaction temperature is controlled by water circulation.
[0022] The beneficial effects of the present invention are as follows: the present invention prepares 1,4-butynediol by an electrochemical method, thereby changing the preparation system of 1,4-butynediol; compared with the traditional gas-liquid-solid three-phase reaction, the strategy of electrode autocatalysis is adopted to optimize the reaction system to a gas-liquid two-phase reaction, thereby reducing the mass transfer resistance during the reaction process and thus shortening the reaction time. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 The gas chromatogram of the product obtained in Example 1 of the present invention is shown in FIG. DETAILED DESCRIPTION
[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0025] The invention discloses a method for synthesizing 1,4-butynediol, comprising the following steps: adding a formaldehyde solution and a buffer solution into an electrochemical reactor; the pH value of the buffer solution is 8.0±0.1; introducing acetylene gas into the mixed solution in the electrochemical reactor, stirring, and introducing a 2.8-3.2V direct current to react the acetylene gas and the formaldehyde solution at a reaction temperature of 40-60°C; wherein a copper electrode having a mixed layer on the surface is used as an anode, the mixed layer being composed of CuO and Cu2O; and removing the solvent from the solution after the reaction is completed to obtain 1,4-butynediol.
[0026] The present invention prepares 1,4-butynediol by an electrochemical method, thereby changing the preparation system of 1,4-butynediol; compared with the traditional gas-liquid-solid three-phase reaction, the electrode autocatalysis strategy is adopted to optimize the reaction system to a gas-liquid two-phase reaction, thereby reducing the mass transfer resistance during the reaction process and thus shortening the reaction time.
[0027] In the present invention, the copper electrode is produced by an anodic oxidation method. Specifically, the copper electrode is prepared by polishing and cleaning the surface of the copper foil. For example, the surface of the copper foil is polished with 2000-grit sandpaper and then ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes.
[0028] Next, the cleaned copper foil is placed as a working electrode in a 0.1M NaOH solution (other alkaline solutions commonly used in the art can also be used) and oxidized at a constant potential of +0.8V vs. Ag / AgCl until a mixed layer forms on the surface of the working electrode. The copper foil is then removed and air-dried to obtain the desired electrode. This method allows for rapid preparation of the desired electrode.
[0029] The present invention provides a buffer solution prepared by dissolving Na2SO4 and NaHCO3 in deionized water, adding benzotriazole and PEG-400 to obtain a mixed solution; wherein the mass ratio of deionized water, Na2SO4, NaHCO3, benzotriazole, and PEG-400 is 1000:2.84:0.84:0.12:5. The pH of the mixed solution is adjusted to 8.0±0.1 to obtain a buffer solution. The pH of the buffer solution can affect the yield of the product because the reaction equation involves a cascade reaction, generating propargyl alcohol and then butynediol. Excessively high or low pH values both reduce the proportion of butynediol in the product.
[0030] In one embodiment, before adding the formaldehyde solution and the buffer solution into the electrochemical reactor, the process includes: mixing the formaldehyde solution and the buffer solution together, wherein the mass ratio of the formaldehyde solution to the buffer solution is 10:(1.8-2.0).
[0031] More specifically, the electrochemical reaction uses a Cu-Bi electrode as the cathode, with a Bi content of 1-5 wt%. The addition of Bi improves the electrode's corrosion resistance and stability, as well as its mechanical properties, maintaining good structural integrity during long-term operation and extending its service life. Furthermore, the presence of Bi stabilizes monovalent copper ions in solution.
[0032] Compared to the reaction time of preparing 1,4-butynediol using a traditional slurry bed reactor (usually about 40 hours under laboratory conditions), in the present invention, 1,4-butynediol is prepared using an electrochemical reaction, and an anode with a mixed layer is used as a catalyst, which increases the catalytic activity. This is because the electrochemical reaction reduces the activation energy and does not require an additional activation process. Moreover, when using a slurry bed reactor, the catalyst will increase the viscosity of the three-phase reaction system with the stirring motion. In the reaction system of the present invention, there is no solid particle catalyst, the system viscosity is low, and the mass transfer resistance is reduced. That is, the solid-liquid mass transfer resistance of the traditional method is eliminated, which greatly shortens the reaction time to only 1-2 hours and significantly improves the process efficiency. At the same time, the problem of catalyst deactivation is also solved.
[0033] Preferably, the stirring speed in the present invention is 300-400 rpm, and the reaction temperature is controlled by water circulation. By designing the stirring speed, the transfer rate of reactants and products between the electrode surface and the solution can be increased, thereby affecting the rate and efficiency of the electrochemical reaction.
[0034] It should be noted that the electrochemical reactor device in the present invention includes: a copper anode chamber and a cathode chamber separated by an anion exchange membrane, a gas diffusion electrode structure cathode; and an online copper ion concentration monitoring system.
[0035] Example 1.
[0036] Polish the copper foil surface with 2000-grit sandpaper and ultrasonically clean it for 10 minutes in acetone, ethanol, and deionized water, sequentially. Use the copper foil as the working electrode (anode) and place it in a 0.1 M NaOH solution. Potentiostatically oxidize it at +0.8 V vs. Ag / AgCl for 30 minutes (until the copper foil surface is completely covered with a CuO / Cu2O mixed layer). Remove the copper foil and blow dry it with nitrogen gas until ready for use.
[0037] Take 500 mL of deionized water, dissolve 1.42 g of Na2SO4 and 0.42 g of NaHCO3, add 0.06 g of benzotriazole and 2.5 mL of PEG-400, and adjust the pH to 8.0 with dilute H2SO4 / NaOH to prepare a buffer solution.
[0038] In the electrochemical reactor, the anode with a mixed layer and the Cu-Bi cathode are fixed. According to the mass ratio of formaldehyde solution to buffer solution of 5:1, the buffer solution is added to 100g of 38% formaldehyde solution, and then added to the electrochemical reaction vessel.
[0039] Add 100g of 38% formaldehyde solution by mass, pass 3.2V direct current, and simultaneously pass acetylene gas at a flow rate of 20ml / min. Control the reaction temperature at 60°C by water bath circulation; maintain the stirring speed at 400rpm, stop the reaction after 1h, cool and evaporate to remove the solvent to obtain 52.8g of white crystalline 1,4-butynediol. The yield based on formaldehyde is 96.7%. The purity detected by gas chromatography internal standard method is 99.5%. Among them, Figure 1 The gas chromatogram of the product of this example is shown in FIG. 1 , where the abscissa represents retention time and the ordinate represents voltage. It can be seen from the figure that, in addition to the solvent peak, there is only one chromatographic peak of 1,4-butynediol, so the purity of the product is very high, reaching 99.5%.
[0040] Example 2.
[0041] In this example, the pH value of the buffer solution was 8.1, and 52.97 g of white crystalline 1,4-butynediol was obtained with a yield of 97% based on formaldehyde. The remaining steps were the same as those in Example 1.
[0042] Example 3.
[0043] In this example, 2.8 V direct current was applied to obtain 52.5 g of white crystalline 1,4-butynediol, with a yield of 96.1% based on formaldehyde. The remaining steps were the same as those in Example 1.
[0044] Example 4.
[0045] In this example, 3.0 V direct current was applied to obtain 52.7 g of white crystalline 1,4-butynediol, with a yield of 96.5% based on formaldehyde. The remaining steps were the same as those in Example 1.
[0046] Example 5.
[0047] In this example, 100 g of a 28% formaldehyde solution was added, and the solvent was removed by rotary evaporation at reduced temperature to obtain 38.9 g of white crystalline 1,4-butynediol, with a yield of 96.96% based on formaldehyde. The remaining steps and results were the same as in Example 1.
[0048] Example 6.
[0049] In this example, the stirring speed was maintained at 300 rpm, and the remaining steps and results were the same as those in Example 5, yielding 38.8 g of white crystalline 1,4-butynediol, with a yield of 96.96% based on formaldehyde.
[0050] Example 7.
[0051] In this example, the stirring speed was maintained at 350 rpm, and the remaining steps and results were the same as those in Example 5, yielding 38.9 g of white crystalline 1,4-butynediol, with a yield of 96.96% based on formaldehyde.
[0052] Example 8.
[0053] In this example, 100 g of a 20% formaldehyde solution was added, and the solvent was removed by rotary evaporation at a reduced temperature to obtain 27.8 g of white crystalline 1,4-butynediol. The yield based on formaldehyde was 96.93%. The remaining steps and results were the same as in Example 1.
[0054] Example 9.
[0055] In this example, the reaction temperature was controlled at 40° C. by water bath circulation, and the solvent was removed by warm rotary evaporation to obtain 51.9 g of white crystalline 1,4-butynediol, with a yield of 95.03% based on formaldehyde. The remaining steps and results were the same as in Example 1.
[0056] Example 10.
[0057] In this example, the reaction temperature was controlled at 45° C. by water bath circulation, and the solvent was removed by warm rotary evaporation to obtain 52.3 g of white crystalline 1,4-butynediol, with a yield of 95.77% based on formaldehyde. The remaining steps and results were the same as in Example 1.
[0058] Example 11.
[0059] In this example, the reaction temperature was controlled at 50° C. by water bath circulation, and the solvent was removed by warm rotary evaporation to obtain 52.4 g of white crystalline 1,4-butynediol, with a yield of 96.0% based on formaldehyde. The remaining steps and results were the same as in Example 1.
[0060] Example 12.
[0061] In this example, the reaction temperature was controlled at 55° C. by water bath circulation, and the solvent was removed by warm rotary evaporation to obtain 52.7 g of white crystalline 1,4-butynediol, with a yield of 96.5% based on formaldehyde. The remaining steps and results were the same as in Example 1.
[0062] Example 13.
[0063] In this example, the reaction was stopped after 2 h, and the solvent was removed by warm rotary evaporation to obtain 53.1 g of white crystalline 1,4-butynediol. The yield based on formaldehyde was 97.2%. The remaining steps and results were the same as those in Example 1.
[0064] Example 14.
[0065] In this example, the reaction was stopped after 1.2 h, and the solvent was removed by warm rotary evaporation to obtain 52.7 g of white crystalline 1,4-butynediol. The yield based on formaldehyde was 96.5%. The remaining steps and results were the same as in Example 1.
[0066] Example 15.
[0067] In this example, the reaction was stopped after 1.5 h, and the solvent was removed by warm rotary evaporation to obtain 52.9 g of white crystalline 1,4-butynediol. The yield based on formaldehyde was 96.87%. The remaining steps and results were the same as in Example 1.
[0068] Example 16.
[0069] In this example, the reaction was stopped after 1.8 h, and the solvent was removed by warm rotary evaporation to obtain 53.0 g of white crystalline 1,4-butynediol. The yield based on formaldehyde was 97.1%. The remaining steps and results were the same as those in Example 1.
Claims
1. A method for synthesizing 1,4-butynediol, characterized in that: The following steps are involved: Adding formaldehyde solution and buffer solution into the electrochemical reactor; the pH value of the buffer solution is 8.0±0.1; Acetylene gas is introduced into the mixed solution in the electrochemical reactor, and a 2.8-3.2V direct current is introduced while stirring to allow the acetylene gas and formaldehyde solution to react at a temperature of 40-60°C. A copper electrode having a mixed layer on its surface composed of CuO and Cu2O is used as the anode. After the reaction is completed, the solvent is removed from the solution to obtain 1,4-butynediol.
2. The method for synthesizing 1,4-butynediol according to claim 1, wherein: The copper electrode is prepared by an anodic oxidation method.
3. The method for synthesizing 1,4-butynediol according to claim 2, wherein: The preparation method of the copper electrode is as follows: Polish and clean the surface of the copper foil; The cleaned copper foil was placed in a 0.1 M NaOH solution as a working electrode and subjected to constant potential oxidation at +0.8 V vs. Ag / AgCl until the mixed layer was formed on the surface of the working electrode. The copper foil was taken out and blown dry to obtain the copper electrode.
4. A method for synthesizing 1,4-butynediol according to claim 2 or 3, characterized in that: The preparation method of the buffer solution is: Na2SO4 and NaHCO3 were dissolved in deionized water, and benzotriazole and PEG-400 were added to obtain a mixed solution; wherein the mass ratio of deionized water, Na2SO4, NaHCO3, benzotriazole and PEG-400 was 1000:2.84:0.84:0.12:
5. The pH value of the mixed solution is adjusted to 8.0±0.1 to obtain the buffer solution.
5. A method for synthesizing 1,4-butynediol according to claim 2 or 3, characterized in that: Before adding formaldehyde solution and buffer solution into the electrochemical reactor, the following steps are included: Mix the formaldehyde solution and the buffer solution together, with the mass ratio of the formaldehyde solution to the buffer solution being 10:(1.8-2.0).
6. The method for synthesizing 1,4-butynediol according to claim 5, wherein: A Cu-Bi electrode was used as the cathode, wherein the Bi content was 1-5 wt%.
7. The method for synthesizing 1,4-butynediol according to claim 6, wherein: The electrochemical reaction time is 1-2h.
8. The method for synthesizing 1,4-butynediol according to claim 7, wherein: The stirring speed is 300-400 rpm.
9. The method for synthesizing 1,4-butynediol according to claim 8, wherein: The reaction temperature is controlled by water circulation.