A method for preparing a composite catalyst for synthesizing 1,4-butynediol

Abstract

The invention discloses a preparation method of a composite catalyst for synthesizing 1,4-butynediol, and relates to the technical field of BDO synthesis. The preparation method includes: preparing solution A with active metal salts of copper and zirconium, preparing solution B with active metal salts of copper, bismuth and magnesium, and dissolving a precipitant in deionized water to prepare solution C; dropping solution A and solution C synchronously and uniformly into a buffer solution to form slurry D; then dropping solution B and solution C synchronously and uniformly into slurry D to form slurry E, which continues to react or undergoes a hydrothermal reaction; after the reaction is completed, the catalyst is obtained by aging, filtering, washing and drying. The composite catalyst prepared by the method has a large and uniform particle size, is conducive to solid-liquid separation, and exhibits high activity and selectivity, and is mainly used in the field of catalytic reactions for preparing 1,4-butynediol.

Description

Technical Field

[0001] The invention relates to the technical field of 1,4-butanediol (BDO) synthesis, and in particular to a method for preparing a composite catalyst for synthesizing 1,4-butynediol. Background Art

[0002] At present, the main production processes of BDO include the Reppe method, butadiene method, propylene alcohol method, and maleic anhydride method. Among them, coal-based acetylene aldehyde BDO has the lowest cost and is the mainstream production process in the market. The Reppe method first synthesizes 1,4-butynediol (BYD) from acetylene and formaldehyde under the action of a copper-based catalyst, and then BYD is hydrogenated to generate BDO under the action of a nickel catalyst.

[0003] For the catalyst for synthesizing 1,4-butynediol from acetylene and formaldehyde, the main catalyst on the market is copper-bismuth catalyst. For example, patent CN202310292666.8 discloses a supported copper-bismuth catalyst for 1,4-butynediol synthesis and a preparation method thereof. The catalyst includes an Al2O3 and SiO2 composite oxide carrier, and CuO and Bi2O3 loaded on the Al2O3 and SiO2 composite oxide carrier. The method includes in-situ synthesis of the composite oxide carrier, controlling the strength, particle size and filtration speed of the oxide carrier by modification of the auxiliary agent, synthesis temperature and speed modulation, and the oxide carrier and the active metal are simultaneously generated in situ. Most of the active metals can be embedded in the carrier in a semi-coated state. In the catalytic synthesis reaction of 1,4-butynediol, it has the characteristics of high catalytic activity and less loss of copper and silicon. However, although the catalyst prepared by this patent has high activity, the particles are small, which is not conducive to the separation of the reaction solution and the catalyst after the reaction is completed. The size of the catalyst is related to many aspects, including the catalytic effect of the alkyne hydroformylation reaction, its own thermal stability, and the difficulty of solid-liquid separation after the reaction. Generally speaking, catalysts with smaller particle sizes have higher catalytic activity, but they will bring problems such as poor filterability and poor stability, making it difficult to achieve solid-liquid separation after the alkyne hydroformylation reaction is completed.

[0004] Patent CN202311765258.6 discloses a silicon-magnesium-doped copper-bismuth catalyst for the production of 1,4-butynediol and a preparation method thereof. The catalyst is a carrier-free catalyst, and its composition includes silicon dioxide, magnesium oxide, copper basic carbonate compounds and bismuth basic carbonate compounds. The catalyst particle size D10 ranges from 5 to 10 μm, D50 ranges from 15 to 24 μm, and D90 ranges from 31 to 40 μm. It is prepared by coprecipitation. The silicon-magnesium-doped copper-bismuth catalyst of this patent has high activity, high selectivity for catalytic synthesis of 1,4-butynediol, low catalyst dosage, high catalyst wear resistance, not easy to dust during the reaction, and less catalyst loss. It can be used in both reactors and fixed beds, which is convenient for industrial production. However, the catalyst particles prepared by the deposition precipitation method of this patent are prone to agglomeration, which affects the activity of the catalyst. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a composite catalyst for synthesizing 1,4-butynediol, so as to solve the problem that the catalyst existing in the existing catalyst for preparing 1,4-butynediol has good activity, but the catalyst particles are uneven, and the generally small particles are not conducive to solid-liquid separation after the reaction is completed, and the prepared catalyst particles are easy to agglomerate, resulting in low catalyst activity, and further provide a method for preparing a catalyst that can have a larger particle size and high activity.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a composite catalyst for synthesizing 1,4-butynediol, the preparation method comprising the following steps:

[0008] S1: preparing copper and zirconium metal salts into solution A, preparing active metal salts of copper, bismuth and magnesium into solution B, and adding acid to solution A and solution B to adjust the pH of the solution;

[0009] Dissolve the precipitant in deionized water to prepare solution C;

[0010] S2: Add buffer solution into the reactor, stir and heat, then drop solution A and solution C into the buffer solution simultaneously and at a uniform speed. After the dropwise addition, react for a period of time to form slurry D.

[0011] S3: Solution B and solution C are added dropwise to slurry D at a constant speed simultaneously. After the addition, slurry E can be treated by any of the following methods a) or b):

[0012] a) the slurry E continues to react in the reactor for a period of time;

[0013] b) transferring the slurry E to a high-pressure reactor for hydrothermal reaction;

[0014] S4: taking out the slurry after the reaction in S3 and aging it;

[0015] S5: filtering the aged material, washing the filter cake multiple times, and then drying to obtain a catalyst.

[0016] Furthermore, the active metal salts of copper, zirconium, bismuth and magnesium are selected from nitrates, sulfates or acetates, and the pH of solution A and solution B is adjusted to 4.0-6.0 with an acidic solution.

[0017] Furthermore, the precipitant is a carbon dioxide storage material, and the solution C is adjusted to a pH of 8.5 to 10.5 using an alkaline solution.

[0018] Furthermore, the buffer solution is at least one of deionized water, polyethylene glycol, N-methyldiethanolamine, 1,2-propylene glycol, 1,3-propylene glycol, and propylene glycol; the buffer solution is heated to a temperature of 50-100° C. and the stirring speed is 200-700 rpm.

[0019] Furthermore, the temperature of the hydrothermal reaction of the slurry E in the high-pressure reactor is 50-110° C., and the reaction time is 1-12 hours.

[0020] Furthermore, the aging time is 2-48 hours, and the aging temperature is 20-40°C.

[0021] Furthermore, the molar ratio of copper, zirconium, bismuth and magnesium in the active metal salt of copper, zirconium, bismuth and magnesium is 8-32:0.1:1:1.

[0022] A catalyst prepared by the method.

[0023] Furthermore, at least 80% of the catalyst particle size is between 20-40 μm.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention provides a method for preparing a composite catalyst for synthesizing 1,4-butynediol, wherein active metal salts of copper, zirconium, bismuth and magnesium are prepared into a composite catalyst, and precipitation reactions are performed twice using different metal salts during the preparation process, so that the finally prepared catalyst has relatively high activity and selectivity.

[0026] 2. The present invention provides a method for preparing a composite catalyst for synthesizing 1,4-butynediol. The catalyst particles prepared by the method are large and relatively uniform in size and are easy to separate from the reaction liquid, thereby solving the problem of difficulty in separating the catalyst and the reaction liquid caused by the small particle size of conventional catalysts. The entire catalyst can maintain structural integrity under high-temperature reaction, thereby enhancing the stability of the catalyst. At the same time, the composite structure catalyst prepared by the method of the present invention forms an inner-and-outer wrapped structure through two precipitation reactions, and a special interface effect is formed at the inner and outer interfaces, thereby improving the overall catalytic activity and selectivity.

[0027] 3. The present invention provides a method for preparing a composite catalyst for synthesizing 1,4-butynediol. In the preparation process, a carbon dioxide storage material is used as a precipitant, so that the prepared catalyst particles are dispersed and not easy to agglomerate, thereby improving the activity of the catalyst to a certain extent, and showing a higher conversion rate of 1,4-butynediol in a shorter reaction time. At the same time, since the carbon dioxide storage material can decompose alcohol organic matter in the reaction process after being used as a precipitant, the operation of adding other organic matter to the buffer solution is reduced. Deionized water is preferably used as the buffer solution, which reduces the preparation cost for the entire preparation process.

[0028] 4. The present invention provides a method for preparing a composite catalyst for synthesizing 1,4-butynediol, which has a simple preparation process and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a SEM image of the catalyst prepared in Example 3 of the present invention;

[0030] Figure 2 This is a diagram of the catalyst evaluation device;

[0031] Figure 3 It is a schematic diagram of the standard curve for formaldehyde determination in the product analysis method of the present invention.

[0032] Markings in the accompanying drawings:

[0033] 1. Nitrogen cylinder; 2. Acetylene cylinder; 31. First mass flow meter; 32. Second mass flow meter; 33. Third mass flow meter; 4. Condenser; 5. Peristaltic pump; 6. Beaker; 7. Oil bath; 8. Online pH detector; 9. Four-necked flask. DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0036] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0037] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0038] The reagents and equipment used in the present invention are all known products or obtained by purchasing commercially available products. The carbon dioxide storage material (CO2SM) used in the preparation of the catalyst is obtained according to the preparation method of patent application number CN201410578343.6 (the patent name is a method for rapid synthesis of carbon dioxide storage materials). The specific preparation method is: at 35°C, 20g of ethylenediamine is dissolved in 80g of polyethylene glycol, and 3g of water is added to eliminate the foaming phenomenon in the process. A gas containing 12% (vol.) CO2 is introduced into the solution at a gas flow rate of 400ml / min, and continuously introduced for 3h, washed with anhydrous ethanol, filtered, and vacuum dried at 60°C for 2h to obtain CO2SM powder.

[0039] The specific preparation method of the catalyst of the present invention is illustrated by the following examples.

[0040] Embodiment 1:

[0041] S1: Prepare solution A: Weigh 376 g Cu(NO3)2﹒3H2O and 4.29 g Zr(NO3)4﹒5H2O into water containing nitric acid, and dilute to 2000 mL after they are dissolved. The final pH of solution A is 4.5. Prepare solution B: Weigh 376 g Cu(NO3)2﹒3H2O, 50 g Bi(NO3)3﹒5H2O and 26 g Mg(NO3)2﹒6H2O into water containing nitric acid, and dilute to 2000 mL after they are dissolved. The final pH of solution B is 4.5.

[0042] Preparation of solution C: Weigh 160 g of carbon dioxide storage material and dissolve it in deionized water to prepare 2000 mL of solution, and adjust the pH to 9.5 with 2 M sodium hydroxide aqueous solution.

[0043] S2: Add 30 mL of deionized water into the reactor and heat to 90 °C at 300 rpm.

[0044] 20 mL of solution A, 50 mL of solution B and 210 mL of solution C were transferred and added to the reactor at a uniform rate. After solution A was dripped, the feed of solution C was stopped at the same time and reacted for 10 minutes to form slurry D. The dripping speed of solution A was 1 mL / min, and the dripping speed of solution C was 3 mL / min.

[0045] S3: Solution B and solution C are added dropwise to slurry D at a uniform rate in parallel. After the addition is completed, the reaction is continued for 1 hour to form slurry E. The dropping speed of solution B is 1 mL / min, and the dropping speed of solution C is 3 mL / min.

[0046] S4: The slurry E was aged in a forced air drying oven for 24 h at an aging temperature of 35°C.

[0047] S5: After aging, filter and then wash the filter cake with deionized water for multiple times. Dry the washed filter cake at 110° C. for 24 h. The obtained catalyst sample is numbered as Catalyst 1.

[0048] Embodiment 2:

[0049] S1: Prepare solution A: weigh 376 g Cu(NO3)2﹒3H2O and 4.29 g Zr(NO3)4﹒5H2O and put them into water containing nitric acid. After they are dissolved, the volume is adjusted to 2000 mL. The pH of solution A is 4.5. Prepare solution B: weigh 376 g Cu(NO3)2﹒3H2O, 50 g Bi(NO3)3﹒5H2O and 26 g Mg(NO3)2﹒6H2O and put them into water containing nitric acid. After they are dissolved, the volume is adjusted to 2000 mL. The pH of solution B is 4.5.

[0050] Preparation of solution C: Weigh 160 g of carbon dioxide storage material and dissolve it in deionized water to prepare 2000 mL of solution, and adjust the pH to 9.5 with 2 M sodium hydroxide aqueous solution.

[0051] S2: Add 30 mL of deionized water into the reactor and heat to 90°C at 300 rpm.

[0052] 20 mL of solution A, 50 mL of solution B and 210 mL of solution C were transferred and added to the reactor at a uniform rate. After the dripping of solution A was completed, the feeding of solution C was stopped at the same time. The reaction lasted for 10 minutes to form slurry D. The dripping speed of solution A was 1 mL / min, and the dripping speed of solution C was 3 mL / min.

[0053] S3: Solution B and solution C are added dropwise to slurry D at a uniform rate in parallel, and after the addition is completed, slurry E is obtained. The dropping speed of solution B is 1 mL / min, and the dropping speed of solution C is 3 mL / min.

[0054] The slurry E was transferred to a high-pressure reactor for hydrothermal reaction at 90°C for 2 h. After the hydrothermal reaction was completed, the heating was turned off and the mixture was naturally cooled to room temperature.

[0055] S4: The naturally cooled slurry E was aged in a forced air drying oven for 24 h at an aging temperature of 35°C.

[0056] S5: Filter, then wash the filter cake with deionized water for multiple times, dry the washed filter cake at 110° C. for 24 h, and obtain a catalyst sample numbered as catalyst 2.

[0057] Example 3

[0058] S1: Prepare solution A: Weigh 376 g Cu(NO3)2﹒3H2O and 4.29 g Zr(NO3)4﹒5H2O into water containing nitric acid, and dilute to 2000 mL after they are dissolved. The final pH of solution A is 4.5. Prepare solution B: Weigh 376 g Cu(NO3)2﹒3H2O, 50 g Bi(NO3)3﹒5H2O and 26 g Mg(NO3)2﹒6H2O into water containing nitric acid, and dilute to 2000 mL after they are dissolved. The final pH of solution B is 4.5.

[0059] Preparation of solution C: 160 g of carbon dioxide storage material was weighed and dissolved in deionized water to prepare 2000 mL of solution, and the pH was adjusted to 9.5 with 2 M sodium hydroxide aqueous solution.

[0060] S2: Add 30 mL of deionized water into the reactor and heat to 90 °C at 300 rpm.

[0061] Weigh 20 mL of solution A, 50 mL of solution B and 235 mL of solution C, add solution A and solution C to the reactor at a uniform rate, stop feeding solution C at the same time after solution A is dripped, and react for 10 minutes to form slurry D. The dripping speed of solution A is 1 mL / min, and the dripping speed of solution C is 3 mL / min.

[0062] S3: Solution B and solution C are added dropwise to slurry D at a uniform rate in parallel. After the addition of solution B and solution C is completed, the reaction is continued for 1 hour to form slurry E. The dropping speed of solution B is 1 mL / min, and the dropping speed of solution C is 3.5 mL / min.

[0063] S4: The slurry E was aged in a forced air drying oven for 24 h at an aging temperature of 35°C.

[0064] S5: After aging, filter and then wash the filter cake with deionized water for multiple times. Dry the washed filter cake at 110°C for 24 h. The obtained catalyst sample is numbered as Catalyst 3.

[0065] Comparative Example 1

[0066] The difference from Example 1 is that the order of step S2 and step S3 is swapped, that is, solution B and solution C are first added synchronously and uniformly to the buffer solution to form a slurry, and then solution A and solution B are added synchronously and uniformly to the slurry. The other steps are the same as Example 1, and the obtained catalyst sample is numbered as catalyst 4.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that in step S1, solution A is prepared: 376 g Cu(NO3)2﹒3H2O is weighed and placed in water containing 5 g nitric acid, and the volume is adjusted to 2000 mL after it is dissolved. Solution B is prepared: 376 g Cu(NO3)2﹒3H2O, 50 g Bi(NO3)3﹒5H2O and 26 g Mg(NO3)2﹒6H2O are weighed and placed in water containing 5 g nitric acid, and the volume is adjusted to 2000 mL after it is dissolved. The catalyst sample finally prepared is numbered as catalyst 5.

[0069] Comparative Example 3

[0070] The difference from Example 1 is that in step S1, solution C is prepared by weighing 160 g of ammonium bicarbonate and dissolving it in deionized water to prepare a 2000 mL solution, and adjusting the pH to 9.5 with a 2M sodium hydroxide aqueous solution. The catalyst sample finally prepared is numbered as catalyst 6.

[0071] Catalyst activity evaluation

[0072] Catalyst activity evaluation device such as Figure 2 As shown, the reaction body of the alkyne hydroformylation catalytic reaction evaluation device is a four-necked flask 9, one of the openings of the four-necked flask 9 is connected to the acetylene bottle 2 and the nitrogen bottle 1, and in addition, the first mass flowmeter 31 and the second mass flowmeter 32 are respectively provided on the pipelines connecting the four-necked flask 9 with the nitrogen bottle 1 and the acetylene bottle 2. A condenser 4 is installed at one of the openings of the four-necked flask 9, and a third mass flowmeter 33 is provided on the pipeline connecting the condenser 4 with the outside. The third opening of the four-necked flask 9 is connected to a beaker 6 containing a mixed solution of sodium hydroxide and sodium carbonate, which is used to adjust the pH of the reaction solution, and a peristaltic pump 5 is provided on the connected pipeline. An online pH detector 8 is provided at one of the openings of the four-necked flask 9, which can detect the pH of the reaction system in real time.

[0073] Before acetylene (flow rate 33ml / min) is introduced into the four-necked flask 9, it needs to be purified by dilute alkali, dilute acid and distilled water. During the reaction, a constant temperature oil bath and magnetic stirring are used. The tail gas during the reaction is discharged from the condenser through the sodium sulfite tail gas absorption liquid. 1 g of catalyst and 20 mL of formaldehyde (mass fraction 37%) aqueous solution are added to the four-necked flask 9. N2 (flow rate 30ml / min) is first introduced to replace the air in the four-necked flask 9 for 30 minutes, the temperature of the reaction system is raised to 90°C, stirring is turned on (500rpm / min), acetylene is introduced, nitrogen is turned off to start the reaction, and the reaction time is 5h. After the reaction, the temperature of the reaction system is lowered to room temperature, and acetylene gas is introduced during the cooling process. After that, the catalyst is separated from the reaction liquid. The catalyst is washed alternately with deionized water and ethanol, and stored and recovered in a vacuum drying oven.

[0074] Product analysis method

[0075] (1) Formaldehyde analysis: The formaldehyde analysis method complies with the National Environmental Protection Standard of the People's Republic of China HJ601-2011, and the unconverted residual formaldehyde in the product solution is determined by acetylacetone spectrophotometry. The formaldehyde solution is calibrated and then prepared into a 10 mg / L HCHO standard solution, and a standard curve is drawn. The standard curve is as follows: Figure 3 As shown, the standard curve equation is Y=0.2022X +0.0136, R 2 The standard curve has a good linear relationship and can be used as an evaluation method.

[0076] (2) Analysis of 1,4-butynediol: The content of 1,4-butynediol in the reaction solution was determined by gas chromatography. The gas chromatograph model was 7890A, the chromatographic column model was DB-5, and the detector was FID detector (i.e. hydrogen flame ionization detector). 300°C, vaporization chamber 250°C

[0077] Physical property analysis methods of catalysts

[0078] SEM image detection of catalyst: The morphology of the catalyst sample was observed using a Hitachi S-4800 scanning electron microscope. Determination method: The catalyst sample was pre-sprayed with gold, the conductive glue was evenly covered on the sample holder, and then different areas were selected for observation and imaging. The SEM image of the catalyst prepared in Example 3 is shown in FIG. Figure 1 As shown, the catalyst particles prepared in Comparative Example 3 agglomerate with each other, which is not the case. Figure 1 The catalyst particles shown are well dispersed.

[0079] The particle size of the catalyst was measured by a wet laser particle size analyzer.

[0080] After the catalyst was degassed at high temperature for 2 h, the low-temperature N2 adsorption-desorption isotherm was measured. The specific surface area of ​​the catalyst was calculated according to the BET multi-point method. The particle size distribution and specific surface area calculation results are shown in Table 1.

[0081] Table 1 Particle size distribution of catalyst

[0082]

[0083] From the results of the catalyst particle size in Table 1 above, it can be seen that changing the order of precipitation or the different precipitants during the catalyst preparation process will affect the specific surface area of ​​the catalyst. Changing the precipitant will also affect the particle size of the prepared catalyst. For example, when using ammonium bicarbonate precipitant, the particle size distribution of the final prepared catalyst is uneven.

[0084] The activity and selectivity of the prepared catalyst were evaluated. The specific evaluation results are shown in Table 2 below.

[0085] Table 2 Evaluation results of catalysts

[0086]

[0087] According to the catalyst activity and selectivity results in Table 2 above, after step S1 and step S2 are swapped, the prepared catalyst has a relatively obvious effect on both activity and selectivity; while changing the components of the metal salt in the catalyst preparation process ultimately has a relatively large impact on the selectivity and a relatively small impact on the catalyst activity.

[0088] Changing the precipitant in the catalyst preparation process, such as replacing it with the conventional precipitant ammonium bicarbonate, does not significantly affect the selectivity of the catalyst, but the activity is reduced.

[0089] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A method for preparing a composite catalyst for synthesizing 1,4-butynediol, characterized in that: The preparation method comprises the following steps: S1: preparing copper and zirconium metal salts into solution A, preparing active metal salts of copper, bismuth and magnesium into solution B, and adding acid to solution A and solution B to adjust the pH of the solution; Dissolve the precipitant in deionized water to prepare solution C; S2: Add buffer solution into the reactor, stir and heat, then drop solution A and solution C into the buffer solution at a constant speed. After the dropwise addition, react for a period of time to form slurry D; S3: Solution B and solution C are added dropwise to slurry D at a constant speed simultaneously. After the addition, slurry E can be treated by any of the following methods a) or b): a) the slurry E continues to react in the reactor for a period of time; b) transferring the slurry E to a high-pressure reactor for hydrothermal reaction; S4: taking out the slurry after the reaction in S3 and aging it; S5: filtering the aged material, washing the filter cake multiple times, and then drying to obtain a catalyst; The precipitant is a carbon dioxide storage material, the solution C is adjusted to a pH of 8.5 to 10.5 with an alkaline solution; the solution A and the solution B are adjusted to a pH of 4.0 to 6.0 with an acidic solution; The buffer is at least one of deionized water, polyethylene glycol, N-methyldiethanolamine, 1,2-propylene glycol, 1,3-propylene glycol, and propylene glycol; The temperature of the hydrothermal reaction of the slurry E in the high-pressure reactor is 50-110° C., and the reaction time is 1-12 hours; the aging time is 2-48 hours, and the aging temperature is 20-40° C.

2. The method for preparing a composite catalyst for synthesizing 1,4-butynediol according to claim 1, characterized in that: The active metal salts of copper, zirconium, bismuth and magnesium are selected from nitrates, sulfates or acetates.

3. The method for preparing a composite catalyst for synthesizing 1,4-butynediol according to claim 1, characterized in that: The buffer solution is heated to a temperature of 50-100° C. and stirred at a speed of 200-700 rpm.

4. The method for preparing a composite catalyst for synthesizing 1,4-butynediol according to claim 2, characterized in that: The molar ratio of copper, zirconium, bismuth and magnesium in the active metal salt of copper, zirconium, bismuth and magnesium is 8 to 32: 0.1:1:1, where the molar concentration of copper in solution A is the same as the molar concentration of copper in solution B.

5. A catalyst prepared by the method for preparing a composite catalyst for synthesizing 1,4-butynediol according to any one of claims 1 to 4.

6. The catalyst according to claim 5, characterized in that The particle size of the catalyst is at least 80% between 20 and 40 μm.

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