Copper-bismuth catalyst and preparation method thereof

Abstract

The invention discloses a copper-bismuth catalyst and a preparation method thereof. The outer surface of the copper-bismuth catalyst particle is divided into a blocky crystalline region and a particle crystalline region, the particle size of crystals in the blocky crystalline region is 200-700 nm, and the particle size of crystals in the particle crystalline region is 20-40 nm. The catalyst has the special morphology, is applied to a reaction for preparing 1, 4-butynediol from formaldehyde and acetylene, and has the advantages of high catalytic activity, high BYD selectivity and good wear resistance.

Description

Technical Field

[0001] This invention relates to a copper-bismuth catalyst and its preparation method, and particularly to a copper-bismuth catalyst for the preparation of 1,4-butynedialdehyde by the acetylacetyl-aldehyde method and its preparation method. Background Technology

[0002] 1,4-Butynediol (BYD), characterized by its unsaturated double bonds and hydroxyl structure, is primarily used in the manufacture of fine chemicals and as a chemical intermediate. With the rapid development of the fine chemicals field, the demand for BYD is increasing year by year. As an important intermediate for the catalytic hydrogenation to 1,4-butanediol (BDO), BYD has a broad downstream market, involving industries such as tetrahydrofuran (THF), γ-butyrolactone (GBL), polybutylene terephthalate (PBT), polyurethane (PU), polybutylene succinate (PBS), polybutylene adipate (PBAT), N-methylpyrrolidone (NMP), and polytetrahydrofuran (PTMEG).

[0003] Currently, the acetylene-aldehyde process (also known as the Reppe process) is widely used industrially to produce BYD. The acetylene-aldehyde process refers to the reaction of formaldehyde and acetylene in a slurry bed reactor under the action of a catalyst to produce BYD. The most commonly used catalyst for this route is a copper-bismuth catalyst. The copper-bismuth catalyst uses copper as the active component and bismuth oxide as a promoter. In the acetylene-aldehyde reaction, copper is first reduced to Cu by formaldehyde. + It then further reacts with acetylene to form a copper acetylide complex for catalytic reaction. Bismuth in the catalyst is used to prevent excessive reduction of copper to Cu. 0 This prevents acetylene polymerization.

[0004] Copper-bismuth catalysts are classified into supported and unsupported types. Unsupported copper-bismuth catalysts mainly include CuO-Bi₂O₃ type and malachite type catalysts. This type of catalyst is primarily used in the Invista process for producing BYD using the acetylacetyl alcohol reaction. For example, CN103170342A discloses a method for preparing a nano-CuO-Bi₂O₃ catalyst and its application in the acetylacetyl alcohol synthesis of 1,4-butynediol. CN106964385A discloses an unsupported copper-bismuth catalyst and its preparation method for preparing 1,4-butynediol; this catalyst is a composite oxide of Cu, Bi, and Si or a basic carbonate compound. However, the preparation of the above-mentioned unsupported copper-bismuth catalysts still suffers from problems such as complex preparation processes, high energy consumption, and demanding equipment requirements. Furthermore, they often suffer from poor sphericity and flowability, and wear resistance and effective utilization of active components are often not simultaneously achieved. Therefore, there is a need to develop unsupported copper-bismuth catalysts that are simpler to prepare and can balance various performance characteristics. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a copper-bismuth catalyst and its preparation method. This catalyst has a unique morphology and, when applied to the reaction of formaldehyde-acetylene to 1,4-butynediol, exhibits advantages such as high catalytic activity, high BYD selectivity, and good wear resistance.

[0006] The present invention provides a copper-bismuth catalyst, wherein the outer surface of the copper-bismuth catalyst particles is divided into a bulk crystallization region and a granular crystallization region, wherein the particle size of the crystals in the bulk crystallization region is 200-700 nm, and the particle size of the crystals in the granular crystallization region is 20-40 nm.

[0007] Furthermore, the grains in the bulk crystalline region are smooth and dense bulk crystals. The bulk crystals are cuboids or near-cuboids. The grain size of the bulk crystals is measured by the longest side length.

[0008] Furthermore, in the bulk crystallization region, the bulk crystals are distributed in a disordered stacking state.

[0009] Furthermore, the grains in the granular crystallization region are small-sized granular crystals with rough surfaces.

[0010] Furthermore, in the granular crystallization region, the granular crystals are distributed in a disordered stacking state, and even further, the granular crystals are distributed in a loose and porous stacking state.

[0011] Furthermore, based on the total external surface area of ​​the copper-bismuth catalyst, the bulk crystalline region accounts for 30% to 90%, preferably 50% to 80%, and the particulate crystalline region accounts for 10% to 70%, preferably 20% to 50%.

[0012] Furthermore, the copper-bismuth catalyst is microsphere-shaped with a particle size of 4–30 μm.

[0013] Furthermore, the copper-bismuth catalyst, based on the weight of the catalyst, contains, in terms of metal oxides, 90%–95% CuO and 5%–10% Bi₂O. 3。

[0014] The present invention also provides a method for preparing the above-mentioned copper-bismuth catalyst, comprising the following steps:

[0015] (1) Dissolve copper salts and bismuth salts in water;

[0016] (2) Add inorganic sodium salt and / or inorganic potassium salt to the solution in step (1) to obtain a mixed solution;

[0017] (3) The mixed solution obtained in step (2) is mixed with the precipitant solution for neutralization reaction. After the reaction is completed, the mixture is aged, filtered, washed and dried to obtain the copper bismuth catalyst.

[0018] Further, in step (1), it is preferable to first dissolve the copper salt and the acidic solution in water, then add the bismuth salt and stir until dissolved. The acidic solution is at least one of nitric acid solution, hydrochloric acid solution, sulfuric acid solution, acetic acid solution, etc., preferably nitric acid solution. The mass concentration of the acidic solution is not less than 65%, and the mass of the acidic solution is 0.5% to 10% of the mass of the copper salt, preferably 5% to 7%.

[0019] Further, in step (1), the copper salt is selected from one or more of copper nitrate, copper sulfate, or copper chloride, preferably at least one of copper nitrate and copper sulfate, and more preferably copper nitrate. The bismuth salt is selected from one or more of bismuth nitrate, bismuth sulfate, or bismuth chloride, preferably at least one of bismuth nitrate and bismuth sulfate, and more preferably bismuth nitrate.

[0020] Further, in step (1), the copper salt and bismuth salt are dissolved in water, and the concentration of the copper salt in the resulting solution is 0.1-5 mol / L, preferably 2-5 mol / L, and the concentration of the bismuth salt is 0.01-1 mol / L, preferably 0.05-0.2 mol / L.

[0021] Further, in step (2), the amount of inorganic sodium salt and / or inorganic potassium salt added is 3% to 15% of the mass of copper salt, preferably 5% to 10%.

[0022] Furthermore, in step (2), the inorganic sodium salt is NaCl and the inorganic potassium salt is KCl.

[0023] Further, in step (3), the precipitant solution is at least one of NaOH solution, Na2CO3 solution, and NaHCO3 solution, preferably NaOH solution and Na2CO3 solution. The concentration of the precipitant solution is 0.1-5 mol / L, preferably 2-5 mol / L.

[0024] Further, in step (3), the reaction temperature of the neutralization reaction is 30-70°C, preferably 45-55°C; the reaction time is 30-50 min; and the pH of the reaction system is 6.0-9.0, preferably 6.5-7.0.

[0025] Further, in step (3), the aging conditions are as follows: first, age at 30-70°C, preferably 35-40°C, for 2-4 hours, and then age at 15-25°C for 8-24 hours.

[0026] Furthermore, in step (3), the filtration and washing are performed using conventional methods in the art. The drying temperature is 40℃~80℃, and the drying time is 12h~36h.

[0027] The present invention also provides the application of the above-mentioned copper bismuth catalyst in the preparation of 1,4-butynediol by the acetylation of formaldehyde.

[0028] Furthermore, in the application, the reaction raw materials are a mixture of formaldehyde aqueous solution and acetylene gas, wherein the mass concentration of the formaldehyde aqueous solution is 30% to 45%, and the acetylene mixture is a mixture of acetylene and nitrogen gas, wherein the volume content of acetylene is 20% to 80% based on the volume of the mixture.

[0029] Furthermore, in the aforementioned application, the mass of the catalyst used is 5% to 20% of the mass of the formaldehyde aqueous solution.

[0030] Furthermore, the application is carried out in a slurry bed reactor.

[0031] Furthermore, the reaction temperature is 85–95℃, and the reaction time is 5–15 h.

[0032] Furthermore, the catalyst is activated before the reaction at a temperature of 60–75°C for 1–12 hours. The activation atmosphere is a mixture of acetylene and nitrogen, wherein the volume content of acetylene is 20%–80% based on the volume of the mixture.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) The outer surface of the copper bismuth catalyst particles of the present invention has two different structural morphologies, namely, a blocky crystallization region and a granular crystallization region. The blocky crystals are smooth and dense, while the granular crystals are small and rough. This not only enhances the wear resistance of the catalyst, but also ensures that the reactants are in contact with a suitable specific surface area. This structural feature plays a positive role in the complementary addition of the catalytic reaction.

[0035] (2) The copper bismuth catalyst of the present invention is applied to the reaction of formaldehyde acetylene to 1,4-butynediol, and has the characteristics of high catalytic activity, high BYD selectivity and long service life.

[0036] (3) The catalyst preparation process of this invention is simple and does not require complex equipment and processing methods. The reaction temperature is not high, saving production energy consumption. Attached Figure Description

[0037] Figure 1 This is a low-magnification SEM image of the catalyst obtained in Example 1;

[0038] Figure 2 Here is a SEM image of a single catalyst microsphere from Example 1;

[0039] Figure 3 Here is a SEM image of a single catalyst microsphere from Example 2;

[0040] Figure 4 SEM image of the bulk crystalline region of the catalyst obtained in Example 3;

[0041] Figure 5 Here is a SEM image of the particle crystallization region of the catalyst obtained in Example 3;

[0042] Figure 6 This is a SEM image of a single catalyst microsphere from Comparative Example 1. Detailed Implementation

[0043] The present invention will be further illustrated by the following embodiments, but these embodiments do not limit the scope of the invention.

[0044] In this invention, the SEM images were obtained using a German ZEISS GeminiSEM 300 scanning electron microscope.

[0045] In this invention, the particle size of the copper bismuth catalyst particles was measured using a BT-9300ST laser particle size analyzer.

[0046] Example 1

[0047] (1) Dissolve 2899g Cu(NO3)2·3H2O and 248g concentrated HNO3 (mass concentration of 68%) in deionized water, then dissolve 173.8g Bi(NO3)3·5H2O in the solution and make up to 4L. The concentration of copper salt is 3mol / L and the concentration of bismuth salt is 0.09mol / L.

[0048] (2) In step (1), 233.7 g of NaCl was added to the solution at room temperature with stirring. The stirring speed was 220 r / min. The mixture was stirred until it was completely dissolved to obtain a mixed solution.

[0049] (3) Dissolve 337.5g of anhydrous Na2CO3 and 255g of NaOH solid in 3.3L of water to prepare a precipitant solution with an alkaline concentration of 3mol / L. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the reaction temperature at 47℃ and the pH value at 6.8. After 30min, the neutralization reaction ends. Let it stand at 37℃ for 3h for aging, and then continue to stand at room temperature (25℃) for 15h for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 60℃ for 16h to obtain the copper-bismuth catalyst. Based on the weight of the catalyst, the metal contained is calculated as metal oxide, containing 93.4% CuO and 6.2% Bi2O3. The particle size of the catalyst microspheres is 5-12μm. See the electron micrograph of the catalyst. Figure 1 and Figure 2 .

[0050] Ten catalyst particles were randomly selected, each with an outer surface divided into a bulk crystalline region and a particulate crystalline region. The bulk crystalline region consisted of smooth, dense bulk crystals with a side length of 500–600 nm, while the particulate crystalline region consisted of rough, small-sized particulate crystals with a particle size of 30–40 nm. Based on the total outer surface area of ​​each catalyst particle, the bulk crystalline region accounted for 50%–75%, and the particulate crystalline region accounted for 25%–50%.

[0051] Example 2

[0052] (1) Dissolve 2899g Cu(NO3)2·3H2O and 248g concentrated HNO3 (68% by mass) in deionized water, then dissolve 173.8g Bi(NO3)3·5H2O in the solution and bring the volume to 4L. This yields an acidic solution with a copper salt concentration of 3mol / L and a bismuth salt concentration of 0.09mol / L.

[0053] (2) In step (1), 298.2 g KCl was added to the solution at room temperature with stirring. The stirring speed was 240 r / min. The mixture was stirred until it was completely dissolved to obtain a mixed solution.

[0054] (3) Dissolve 337.5g of anhydrous Na2CO3 and 255g of NaOH solid in 3.3L of water to prepare a precipitant solution with an alkaline concentration of 3mol / L. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the reaction temperature at 51℃ and the pH at 6.6. After 30min, the neutralization reaction ends. Let it stand at 39℃ for 4h for aging, and then continue to stand at room temperature (25℃) for 18h for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 50℃ for 24h to obtain the copper-bismuth catalyst. Based on the weight of the catalyst, the metal contained is calculated as metal oxide, containing 93.2% CuO and 6.4% Bi2O3. The particle size of the catalyst microspheres is 4-8μm. See the electron micrograph of the catalyst. Figure 3 .

[0055] Ten catalyst particles were randomly selected, each with an outer surface divided into a bulk crystalline region and a particulate crystalline region. The bulk crystalline region consisted of smooth, dense bulk crystals with a side length of 400–570 nm, while the particulate crystalline region consisted of rough, small-sized particulate crystals with a particle size of 30–40 nm. Based on the total outer surface area of ​​each catalyst particle, the bulk crystalline region accounted for 40%–70%, and the particulate crystalline region accounted for 30%–60%.

[0056] Example 3

[0057] (1) Dissolve 2899g Cu(NO3)2·3H2O and 248g concentrated HNO3 (mass concentration of 68%) in deionized water, then dissolve 173.8g Bi(NO3)3·5H2O in the solution and make up to 4L. The concentration of copper salt is 3mol / L and the concentration of bismuth salt is 0.09mol / L.

[0058] (2) In step (1), 233.7 g of NaCl was added to the solution at room temperature with stirring. The stirring speed was 220 r / min. The mixture was stirred until it was completely dissolved to obtain a mixed solution.

[0059] (3) Dissolve 1049g of anhydrous Na2CO3 solid in 3.3L of water to prepare a precipitant solution with an alkaline concentration of 3mol / L. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the reaction temperature at 47℃ and the pH at 6.8. After 40min, the neutralization reaction ends. Let it stand at 37℃ for 3h for aging, and then continue to stand at room temperature (25℃) for 15h for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 60℃ for 16h to obtain the copper-bismuth catalyst. Based on the weight of the catalyst, the metal content is calculated as metal oxides, containing 93.5% CuO and 6.0% Bi2O3. The catalyst microspheres have a particle size of 6-14μm. See the electron micrograph of the catalyst. Figure 4 and Figure 5 .

[0060] Ten catalyst particles were randomly selected, each with an outer surface divided into a bulk crystalline region and a particulate crystalline region. The bulk crystalline region consisted of smooth, dense bulk crystals with a side length of 400–600 nm, while the particulate crystalline region consisted of small, rough-surfaced particulate crystals with a particle size of 20–35 nm. Based on the total outer surface area of ​​each catalyst particle, the bulk crystalline region accounted for 50%–85%, and the particulate crystalline region accounted for 15%–50%.

[0061] Example 4

[0062] (1) Dissolve 1932g Cu(NO3)2·3H2O and 165g concentrated HNO3 (mass concentration of 68%) in deionized water, then dissolve 97g Bi(NO3)3·5H2O in the solution and make up to 4L. The concentration of copper salt is 2mol / L and the concentration of bismuth salt is 0.05mol / L.

[0063] (2) In step (1), 115.9 g of NaCl was added to the solution at room temperature with stirring. The stirring speed was 220 r / min. The mixture was stirred until it was completely dissolved to obtain a mixed solution.

[0064] (3) Dissolve 225g of anhydrous Na2CO3 and 150g of NaOH solid in 3L of water to prepare a precipitant solution with an alkaline concentration of 2mol / L. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the reaction temperature at 47℃ and the pH at 6.8. After 40min, the neutralization reaction ends. Let it stand at 37℃ for 3h for aging, and then continue to stand at room temperature (25℃) for 15h for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 60℃ for 16h to obtain the copper-bismuth catalyst. Based on the weight of the catalyst, the metal contained is calculated as metal oxide, including 92.8% CuO and 6.5% Bi2O3. The particle size of the catalyst microspheres is 4-18μm.

[0065] Ten catalyst particles were randomly selected, each with an outer surface divided into a bulk crystalline region and a particulate crystalline region. The bulk crystalline region consisted of smooth, dense bulk crystals with a side length of 400–550 nm, while the particulate crystalline region consisted of rough, small-sized particulate crystals with a particle size of 30–40 nm. Based on the total outer surface area of ​​each catalyst particle, the bulk crystalline region accounted for 30%–60%, and the particulate crystalline region accounted for 40%–70%.

[0066] Example 5

[0067] (1) Dissolve 1932g Cu(NO3)2·3H2O and 165g concentrated HNO3 (mass concentration of 68%) in deionized water, then dissolve 97g Bi(NO3)3·5H2O in the solution and make up to 4L. The concentration of copper salt is 2mol / L and the concentration of bismuth salt is 0.05mol / L.

[0068] (2) In step (1), 115.9 g of NaCl was added to the solution at room temperature with stirring. The stirring speed was 220 r / min. The mixture was stirred until it was completely dissolved to obtain a mixed solution.

[0069] (3) Dissolve 450g of anhydrous Na2CO3 and 305g of NaOH solid in 3L of water to prepare a precipitant solution with an alkaline concentration of 4mol / L. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the reaction temperature at 47℃ and the pH at 7.0. After 30min, the neutralization reaction ends. Let it stand at 37℃ for 3h for aging, and then continue to stand at room temperature (25℃) for 15h for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 60℃ for 16h to obtain the copper-bismuth catalyst. Based on the weight of the catalyst, the metal contained is calculated as metal oxide, including 94.2% CuO and 5.3% Bi2O3. The particle size of the catalyst microspheres is 4-12μm.

[0070] Ten catalyst particles were randomly selected, each with an outer surface divided into a bulk crystalline region and a particulate crystalline region. The bulk crystalline region consisted of smooth, dense bulk crystals with a side length of 400–500 nm, while the particulate crystalline region consisted of rough, small-sized particulate crystals with a particle size of 25–40 nm. Based on the total outer surface area of ​​each catalyst particle, the bulk crystalline region accounted for 35%–70%, and the particulate crystalline region accounted for 30%–65%.

[0071] Comparative Example 1

[0072] (1) Dissolve 2899g Cu(NO3)2·3H2O and 248g concentrated HNO3 (68% by mass) in deionized water, then dissolve 173.8g Bi(NO3)3·5H2O in the solution and bring the volume to 4L. The concentration of copper salt is 3mol / L and the concentration of bismuth salt is 0.09mol / L. Dissolve 337.5g anhydrous Na2CO3 and 255g NaOH solid in 3.3L of water to prepare a precipitant solution with an alkaline concentration of 3mol / L.

[0073] (2) The copper- and bismuth-containing solution from step (1) was mixed with the precipitant solution and then subjected to a neutralization reaction. The temperature was controlled at 47°C and the pH at 6.8. The neutralization reaction ended after 30 minutes. The mixture was then aged at 37°C for 3 hours, and then aged at room temperature (25°C) for another 15 hours. Finally, the mixture was filtered and washed to obtain the precipitate. The precipitate was dried at 60°C for 16 hours to obtain the copper-bismuth catalyst. The electron micrograph of the catalyst is shown below. Figure 6 Its catalyst particles have only a single morphology on their outer surface.

[0074] Comparative Example 2

[0075] (1) Dissolve 2899g Cu(NO3)2·3H2O and 248g concentrated HNO3 (mass fraction of 68%) in deionized water, then dissolve 173.8g Bi(NO3)3·5H2O in the solution and bring the volume to 4L. The concentration of copper salt is 3mol / L and the concentration of bismuth salt is 0.09mol / L.

[0076] (2) In step (1), 724.7 g of NaCl was added to the solution at room temperature with stirring. The stirring speed was 220 r / min. The mixture was stirred until it was completely dissolved to obtain a mixed solution.

[0077] (3) Dissolve 337.5g of anhydrous Na2CO3 and 255g of NaOH solid in 3.3L of water to prepare a precipitant solution with a molar concentration of 3M. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the temperature at 47℃ and the pH at 6.8. After the neutralization reaction is completed in 30 minutes, let it stand at 37℃ for 3 hours for aging, and then continue to stand at room temperature (25℃) for 15 hours for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 60℃ to obtain the copper-bismuth catalyst. The outer surface of its catalyst particles contains only a single morphology.

[0078] Comparative Example 3

[0079] (1) Dissolve 2899g Cu(NO3)2·3H2O and 248g concentrated HNO3 (mass fraction of 68%) in deionized water, then dissolve 173.8g Bi(NO3)3·5H2O in the solution and bring the volume to 4L. The concentration of copper salt is 3mol / L and the concentration of bismuth salt is 0.09mol / L.

[0080] (2) In step (1), 29g NaCl was added to the solution at room temperature and stirred at 220r / min until it was completely dissolved to obtain a mixed solution.

[0081] (3) Dissolve 337.5g of anhydrous Na2CO3 and 255g of NaOH solid in 3.3L of water to prepare a precipitant solution with an alkaline concentration of 3mol / L. Mix the mixed solution obtained in step (2) with the precipitant solution and carry out a neutralization reaction. Control the reaction temperature at 47℃ and the pH at 6.8. After 30min, the neutralization reaction ends. Let it stand at 37℃ for 3h for aging, and then continue to stand at room temperature (25℃) for 15h for aging. Finally, filter and wash to obtain the precipitate. Dry the precipitate at 60℃ for 16h to obtain the copper-bismuth catalyst. The outer surface of its catalyst particles contains only a single morphology.

[0082] Application examples

[0083] The catalysts of Examples 1-5 and Comparative Examples 1-3 were tested under the same conditions.

[0084] (1) The wear test conditions were as follows: 100g (denoted as m1) of copper-bismuth catalyst was accurately weighed and placed in the grinding chamber of the wear rate tester, and rotated at a constant speed of 60r / min for 10h. The catalyst was then removed, and small particles and dust with a particle size not exceeding 2μm were separated using a cyclone separator. The weight of the remaining catalyst was accurately weighed and denoted as m2. The wear rate of the catalyst was W%.

[0085]

[0086] (2) The catalytic evaluation test conditions are as follows:

[0087] The reaction was carried out in a batch stirred reactor. 15 g of copper-bismuth catalyst and 150 mL of 35 wt% formaldehyde aqueous solution were added to the reactor. The temperature was 70 °C, and a mixture of 70% acetylene and nitrogen gas was introduced at a flow rate of 5 L / h to activate the catalyst for 10 h. After activation, the temperature was raised to 90 °C to carry out the formaldehyde acetylation reaction. Samples were taken periodically for analysis throughout the process. After catalyst separation, the solution composition was analyzed by gas chromatography (GC). The results after 8 h and 15 h of reaction are shown in Table 1.

[0088] Table 1

[0089]

[0090] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, the technical features of the present invention can be combined in any other suitable manner, and these simple modifications and combinations should also be considered within the scope of the present invention and are all within the protection scope of the present invention.

Claims

1. A copper-bismuth catalyst, characterized in that, The outer surface of the copper-bismuth catalyst particles is divided into a bulk crystallization region and a granular crystallization region. The particle size of the crystals in the bulk crystallization region is 200-700 nm, and the particle size of the crystals in the granular crystallization region is 20-40 nm.

2. The copper-bismuth catalyst according to claim 1, characterized in that, The grains in the blocky crystallization region are blocky crystals with smooth and dense surfaces. The blocky crystals are cuboids or cuboid-like, and the grain size of the blocky crystals is measured by the longest side length.

3. The copper-bismuth catalyst according to claim 1 or 2, characterized in that, In the blocky crystallization region, the blocky crystals are distributed in a disordered stacking state.

4. The copper-bismuth catalyst according to claim 1, characterized in that, The grains in the granular crystallization region are small-sized granular crystals with rough surfaces.

5. The copper-bismuth catalyst according to claim 1 or 4, characterized in that, In the granular crystallization region, the granular crystals are distributed in a disordered stacking state, and further, the granular crystals are distributed in a loose and porous stacking state.

6. The copper-bismuth catalyst according to claim 1, characterized in that, Based on the total external surface area of ​​the copper-bismuth catalyst, the bulk crystalline region accounts for 30% to 90%, preferably 50% to 80%, and the particulate crystalline region accounts for 10% to 70%, preferably 20% to 50%.

7. The copper-bismuth catalyst according to claim 1, characterized in that, The copper-bismuth catalyst is in the form of microspheres with a particle size of 4–30 μm.

8. The copper-bismuth catalyst according to claim 1, characterized in that, The copper-bismuth catalyst, based on the weight of the catalyst, contains, as metal oxides, 90%–95% CuO and 5%–10% Bi₂O. 3。 9. A method for preparing a copper-bismuth catalyst according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Dissolve copper salts and bismuth salts in water; (2) Add inorganic sodium salt and / or inorganic potassium salt to the solution in step (1) to obtain a mixed solution; (3) The mixed solution obtained in step (2) is mixed with the precipitant solution for neutralization reaction. After the reaction is completed, the mixture is aged, filtered, washed and dried to obtain the copper bismuth catalyst.

10. The method according to claim 9, characterized in that, In step (1), copper salt and acidic solution are first dissolved in water, then bismuth salt is added and stirred until dissolved; the acidic solution is at least one of nitric acid solution, hydrochloric acid solution, sulfuric acid solution, and acetic acid solution, preferably nitric acid solution; The acidic solution has a mass concentration of not less than 65%, and the mass of the acidic solution is 0.5% to 10% of the mass of the copper salt, preferably 5% to 7%.

11. The method according to claim 9, characterized in that, In step (1), the copper salt is selected from one or more of copper nitrate, copper sulfate or copper chloride, preferably at least one of copper nitrate and copper sulfate, and more preferably copper nitrate; the bismuth salt is selected from one or more of bismuth nitrate, bismuth sulfate or bismuth chloride, preferably at least one of bismuth nitrate and bismuth sulfate, and more preferably bismuth nitrate.

12. The method according to claim 9, characterized in that, In step (1), copper salt and bismuth salt are dissolved in water. The concentration of copper salt in the resulting solution is 0.1-5 mol / L, preferably 2-5 mol / L, and the concentration of bismuth salt is 0.01-1 mol / L, preferably 0.05-0.2 mol / L.

13. The method according to claim 9, characterized in that, In step (2), the amount of inorganic sodium salt and / or inorganic potassium salt added is 3% to 15% of the mass of copper salt, preferably 5% to 10%.

14. The method according to claim 9 or 13, characterized in that, In step (2), the inorganic sodium salt is NaCl and the inorganic potassium salt is KCl.

15. The method according to claim 9, characterized in that, In step (3), the precipitant solution is at least one of NaOH solution, Na2CO3 solution, and NaHCO3 solution, preferably NaOH solution and Na2CO3 solution; and / or, The concentration of the precipitant solution is 0.1–5 mol / L, preferably 2–5 mol / L.

16. The method according to claim 9, characterized in that, In step (3), the reaction temperature of the neutralization reaction is 30-70°C, preferably 45-55°C; the reaction time is 30-50 min; and the pH of the reaction system is 6.0-9.0, preferably 6.5-7.

0.

17. The method according to claim 9, characterized in that, In step (3), the aging conditions are as follows: first, age at 30-70°C, preferably 35-40°C, for 2-4 hours, and then age at 15-25°C for 8-24 hours.

18. The use of a copper-bismuth catalyst according to any one of claims 1-8 or a catalyst prepared by the method according to any one of claims 9-17 in the preparation of 1,4-butynediol by the acetylenelation of formaldehyde.

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