A supported copper bismuth catalyst, a preparation method and application thereof

Abstract

The application discloses a supported copper bismuth catalyst for 1,4-butynediol synthesis and a preparation method thereof. The catalyst uses a g-C3N4 carrier, CuO and Bi2O3 supported on the g-C3N4 carrier, the mass percentage of CuO in the catalyst is 15-60%, the mass percentage of Bi2O3 is 2-10%, and the rest is the carrier. The method uses a one-step pyrolysis method to prepare the supported copper bismuth catalyst, a method of spray drying is used to synthesize a catalyst with a multilayer planar structure, and most of the active metals can be clamped in the carrier. The supported copper bismuth catalyst is used in the catalytic synthesis of 1,4-butynediol, the conversion rate of formaldehyde can be as high as 95.61%, the yield of generated 1,4-butynediol can be as high as 94.09%, and the selectivity of 1,4-butynediol can be as high as 98.41%. The catalyst has good stability during use and can maintain high activity for a long time.

Description

TECHNICAL FIELD

[0001] The present application relates to a supported copper bismuth catalyst and its preparation method and application, belonging to the field of organic catalysis. BACKGROUND

[0002] 1,4-butynediol is an important intermediate for preparing 1,4-butanediol (BDO), which is an important organic and fine chemical raw material and is widely used in medicine, chemical industry, textile, papermaking, automobile and daily chemical industry. Its downstream derivatives include polytetramethylene ether glycol (PTMEG), polybutylene terephthalate (PBT), tetrahydrofuran (THF) and the like. PTMEG is mainly used for producing spandex; PBT can be used as an engineering plastic for automobile, electronic appliances, light industry and industrial parts, and can also be used as a new type of fabric fiber, film and optical fiber; THF is widely used as a solvent in the pharmaceutical and perfume industries. In recent years, BDO has been widely used as a synthetic raw material for degradable plastics, which is an important organic chemical product for realizing plastic environmental protection substitution, so the market demand for BDO has increased significantly.

[0003] At present, the main process for industrial production of 1,4-butynediol is the modified Reppe method (acetylene aldehyde method), which is prepared by reacting formaldehyde and acetylene under the action of a catalyst. The core of the Reppe method is a copper bismuth catalyst. In recent years, people have developed acetylene reaction catalysts using diatomaceous earth, zeolite, silicon dioxide and the like as carriers. For example, patent US9006129B2 discloses a catalyst using magnesium silicate as a carrier, patent US4288641 discloses an acetylene reaction catalyst using molecular sieve as a carrier, and patents CN107952443A and CN102950002A respectively report an acetylene reaction catalyst using silicon oxide as a carrier. However, such catalysts have the following disadvantages: the catalytic active sites are easy to aggregate, affecting the catalytic activity; the catalyst components are easy to lose during use, resulting in poor catalyst stability and short service life; and the catalyst preparation process is complex and relatively expensive. SUMMARY

[0004] The present application aims to provide a supported copper bismuth catalyst and its preparation method. By using g-C3N4 containing abundant N atoms as a carrier, the strong interaction between CuO and Bi2O3 and N atoms in g-C3N4 is utilized to effectively improve the exposure rate and loading rate of the catalytic active sites and improve the stability of the catalyst. At the same time, the synergistic catalytic effect between CuO / Bi2O3 and g-C3N4 is utilized to further improve the catalytic efficiency of the catalyst. The supported copper bismuth catalyst prepared by the present application is applied to the reaction of formaldehyde and acetylene to synthesize 1,4-butynediol, which has the advantages of good catalytic activity, high stability, less copper loss, long service life and easy separation.

[0005] In order to achieve the above object, the application provides a supported copper-bismuth catalyst, which comprises a g-C3N4 carrier and CuO and Bi2O3 supported on the g-C3N4 carrier, wherein the mass percentage of CuO is 15-60%, the mass percentage of Bi2O3 is 2-10%, and the rest is the carrier.

[0006] In an embodiment of the application, the specific surface area of the catalyst is 50-100 m 2 / g.

[0007] The application further provides a preparation method of the supported copper-bismuth catalyst, which comprises the following steps.

[0008] (1) mixing and grinding a copper salt, a bismuth salt and a g-C3N4 precursor;

[0009] (2) pyrolyzing the mixture obtained in step (1) in a muffle furnace in an air atmosphere;

[0010] (3) adding the pyrolysis product obtained in step (2) into deionized water, stirring thoroughly, washing and filtering, and then slushing the obtained solid with deionized water for standby;

[0011] (4) spray drying the slurry obtained in step (3) to obtain the supported copper-bismuth catalyst.

[0012] In an embodiment of the application, the copper salt comprises at least one of copper nitrate, copper sulfate, copper chloride and copper acetate, and preferably copper nitrate; and the bismuth salt comprises at least one of bismuth nitrate, bismuth chloride and bismuth sulfate, and preferably bismuth nitrate.

[0013] In an embodiment of the application, the g-C3N4 precursor comprises at least one of melamine, urea and hydroxylamine.

[0014] In an embodiment of the application, in step (2), the temperature rising rate of the muffle furnace is 1-10℃ / min, the temperature falling rate is 1-10℃ / min, the temperature for pyrolysis is 350-600℃, and the pyrolysis time is 2-8h.

[0015] In an embodiment of the application, in step (3), the temperature for washing is 30-60℃, and the washing is stopped when the conductivity of the washing liquid is less than 300μs / cm.

[0016] In an embodiment of the application, in step (4), the water content of the slurry is 40-80%, and the drying temperature is 90-130℃.

[0017] The application further provides application of the supported copper-bismuth catalyst in the field of catalytic reactions.

[0018] In an embodiment of the application, the application comprises using the catalyst to catalyze the reaction of formaldehyde and acetylene to synthesize 1,4-butynediol.

[0019] In an embodiment of the application, the catalytic synthesis step of the 1,4-butynediol comprises: placing the catalyst and the formaldehyde solution into a reactor, pre-activating the catalyst, the activation temperature is 70 DEG C, the reaction time is 2h, after activation, acetylene gas is introduced at a speed of 200mL / min, and the temperature is raised to 90 DEG C, the acetylenation reaction of formaldehyde is carried out, and the reaction time is 10-18h, wherein the concentration of the formaldehyde solution is 15-45%, and the mass ratio of the catalyst to the formaldehyde solution is 1:4-1:20.

[0020] Advantages of the application

[0021] (1) The method of the application uses g-C3N4 as a carrier, CuO as an active component, and Bi2O3 as an auxiliary component, the reactants are mixed, and then a supported copper-bismuth catalyst is prepared by one-step high-temperature pyrolysis, the prepared catalyst has the characteristics of high catalytic activity, good stability, less copper loss, and long service life.

[0022] (2) The preparation method of the supported copper-bismuth catalyst for synthesizing 1,4-butynediol of the application utilizes in-situ synthesis, the carrier and the active metal are simultaneously generated in-situ, the catalyst with a planar multi-layer stacking structure is synthesized by a spray drying method, and most of the active metal is embedded in the layered carrier, which can effectively reduce the loss of copper during the reaction.

[0023] (3) The application uses g-C3N4 rich in N atoms as a carrier, utilizes the strong interaction between N atoms and CuO and Bi2O3, and enables CuO and Bi2O3 to be better dispersed on the carrier, and at the same time, the catalyst is more stable during the CuO / Bi2O3 reaction process.

[0024] (4) The supported copper-bismuth catalyst of the application has high catalytic activity, when it is used in the reaction of formaldehyde and acetylene to synthesize 1,4-butynediol, the conversion rate of formaldehyde can be as high as 95.61%, the yield of the generated 1,4-butynediol can be as high as 94.09%, and the selectivity of the 1,4-butynediol can be as high as 98.41%. The catalyst has good stability and can maintain high activity for a long time during use. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a scanning electron microscope image of the catalyst in Example 1;

[0026] Figure 2Scanning electron microscope element distribution of the catalyst in Example 1;

[0027] Figure 3 Cyclic performance curve of the catalyst in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0028] Unless otherwise defined, technical or scientific terms used in the claims and specification shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The present application is further illustrated by the following specific examples, but the present application is not limited to the following specific examples.

[0029] Example 1

[0030] A supported copper bismuth catalyst, comprising a g-C3N4 carrier and CuO and Bi2O3 supported on the g-C3N4 carrier, in terms of mass percentage, the mass percentage of CuO in the catalyst is 27.9%, the mass percentage of Bi2O3 is 8.5%, and the rest is the carrier g-C3N4.

[0031] A preparation method of a supported copper bismuth catalyst, comprising the following steps:

[0032] (1) First, 50 g of urea, 10 g of copper nitrate trihydrate and 2 g of bismuth nitrate pentahydrate are weighed and mixed thoroughly, and then ground;

[0033] (2) The mixture obtained in step (1) is pyrolyzed in a muffle furnace at a temperature increasing rate of 2℃ / min, a pyrolysis temperature of 400℃, a pyrolysis time of 4h, and a temperature decreasing rate of 2℃ / min.

[0034] (3) After cooling to room temperature, 200 mL of deionized water is added to the pyrolysis product obtained, and washing is performed by beating, at a washing temperature of 30℃, until the conductivity of the washing liquid is less than 300μs / cm.

[0035] (4) The sample washed in step (3) is configured into a slurry with a water content of 45% using distilled water, and is spray dried at 100℃ to form a supported copper bismuth catalyst for 1.4-butyne diol production.

[0036] Figure 1 and Figure 2 Scanning electron microscope and scanning electron microscope element distribution photos of the catalyst sample in Example 1, from which it can be seen that the catalyst has a sheet structure, and CuO and Bi2O3 are uniformly distributed on the surface of the g-C3N4 carrier.

[0037] Example 2

[0038] The difference between Example 2 and Example 1 is that in the catalyst, the mass percentage of CuO is 51.2%, the mass percentage of Bi2O3 is 7.7%, and the remainder is the support g-C3N4.

[0039] A method for preparing a supported copper-bismuth catalyst includes the following steps:

[0040] (1) First, weigh out 50g of urea, 20g of copper chloride dihydrate and 2g of bismuth chloride, mix them thoroughly and grind them;

[0041] (2) The mixture obtained in step (1) is pyrolyzed at high temperature in a muffle furnace. The heating rate of the muffle furnace is 5℃ / min, the pyrolysis temperature is 500℃, the pyrolysis time is 3h, and the cooling rate of the muffle furnace is 2℃ / min.

[0042] (3) After cooling to room temperature, add 200 mL of deionized water to the obtained pyrolysis product and wash it by slurrying at a temperature of 35°C until the conductivity of the washing solution is less than 300 μs / cm.

[0043] (4) The washed sample from step (3) is prepared into a slurry with a water content of 50% by distilled water and spray-dried at 90°C to obtain a supported copper-bismuth catalyst for the production of 1,4-butynediol.

[0044] Example 3

[0045] The difference between Example 3 and Example 1 is that in the catalyst, the mass percentage of CuO is 53.3%, the mass percentage of Bi2O3 is 3.2%, and the remainder is the support g-C3N4.

[0046] A method for preparing a supported copper-bismuth catalyst includes the following steps:

[0047] (1) First, weigh out 50g of melamine, 20g of copper acetate monohydrate and 1g of bismuth nitrate pentahydrate, mix them thoroughly and grind them.

[0048] (2) The mixture obtained in step (1) is pyrolyzed at high temperature in a muffle furnace. The heating rate of the muffle furnace is 8℃ / min, the pyrolysis temperature is 550℃, the pyrolysis time is 2h, and the cooling rate of the muffle furnace is 5℃ / min.

[0049] (3) After cooling to room temperature, add 200 mL of deionized water to the obtained pyrolysis product and wash it by slurrying at a temperature of 50°C until the conductivity of the washing solution is less than 300 μs / cm.

[0050] (4) The washed sample in step (3) is prepared into a slurry with a water content of 60% by distilled water and spray-dried at 110°C to obtain the supported copper bismuth catalyst for the production of 1,4-butynediol.

[0051] Example 4

[0052] The difference between Example 4 and Example 1 is that in the catalyst, the mass percentage of CuO is 58.0%, the mass percentage of Bi2O3 is 3.9%, and the remainder is the support g-C3N4.

[0053] A method for preparing a supported copper-bismuth catalyst includes the following steps:

[0054] (1) First, weigh out 50g of melamine, 30g of copper nitrate trihydrate and 1g of bismuth sulfate, mix them thoroughly and grind them;

[0055] (2) The mixture obtained in step (1) is pyrolyzed at high temperature in a muffle furnace. The heating rate of the muffle furnace is 5℃ / min, the pyrolysis temperature is 500℃, the pyrolysis time is 6h, and the cooling rate of the muffle furnace is 8℃ / min.

[0056] (3) After cooling to room temperature, add 200 mL of deionized water to the obtained pyrolysis product and wash it by slurrying at a temperature of 50°C until the conductivity of the washing solution is less than 300 μs / cm.

[0057] (4) The washed sample in step (3) is prepared into a slurry with a water content of 75% by distilled water and spray-dried at 95°C to obtain the supported copper bismuth catalyst for the production of 1,4-butynediol.

[0058] Example 5

[0059] The difference between Example 5 and Example 1 is that in the catalyst, the mass percentage of CuO is 18.6%, the mass percentage of Bi2O3 is 6.2%, and the remainder is the support g-C3N4.

[0060] A method for preparing a supported copper-bismuth catalyst includes the following steps:

[0061] (1) First, weigh out 50g of hydroxylamine, 14g of copper sulfate pentahydrate and 2g of bismuth chloride, mix them thoroughly and grind them;

[0062] (2) The mixture obtained in step (1) is pyrolyzed at high temperature in a muffle furnace. The heating rate of the muffle furnace is 2℃ / min, the pyrolysis temperature is 500℃, the pyrolysis time is 4h, and the cooling rate of the muffle furnace is 5℃ / min.

[0063] (3) After cooling to room temperature, add 200 mL of deionized water to the obtained pyrolysis product and wash it by slurrying at a temperature of 55°C until the conductivity of the washing solution is less than 300 μs / cm.

[0064] (4) The washed sample in step (3) is prepared into a slurry with a water content of 60% by distilled water and spray-dried at 125°C to obtain the supported copper bismuth catalyst for the production of 1,4-butynediol.

[0065] Compare with Example 1

[0066] The difference between Comparative Example 1 and Example 1 is that the catalyst in Comparative Example 1 is an unsupported catalyst, that is, without g-C3N4 support. In the catalyst, the mass percentage of CuO is 93.2% and the mass percentage of Bi2O3 is 6.8%.

[0067] A method for preparing a supported copper-bismuth catalyst includes the following steps:

[0068] (1) First, weigh out 20g of copper nitrate trihydrate and 1g of bismuth nitrate pentahydrate, mix them thoroughly, and grind them;

[0069] (2) The obtained mixture was pyrolyzed at high temperature in a muffle furnace. The heating rate of the muffle furnace was 2℃ / min, the pyrolysis temperature was 400℃, the pyrolysis time was 4h, and the cooling rate of the muffle furnace was 2℃ / min.

[0070] (3) After cooling to room temperature, add 200 mL of deionized water to the obtained pyrolysis product and wash it by slurrying at a temperature of 30°C until the conductivity of the washing solution is less than 300 μs / cm.

[0071] (4) The washed sample in step (3) is prepared into a slurry with a water content of 45% by distilled water and spray-dried at 100°C to obtain the unsupported copper bismuth catalyst for the production of 1,4-butynediol.

[0072] Compare with Example 2

[0073] The difference between Comparative Example 2 and Example 1 is that the catalyst in Comparative Example 1 is an unsupported catalyst, that is, without g-C3N4 support. In the catalyst, the mass percentage of CuO is 94.3% and the mass percentage of Bi2O3 is 5.7%.

[0074] A method for preparing a supported copper-bismuth catalyst includes the following steps:

[0075] (1) First, weigh out 20g of copper acetate monohydrate and 1g of bismuth nitrate pentahydrate, mix them thoroughly, and grind them;

[0076] (2) The mixture obtained in step (1) is pyrolyzed at high temperature in a muffle furnace. The heating rate of the muffle furnace is 8℃ / min, the pyrolysis temperature is 550℃, the pyrolysis time is 2h, and the cooling rate of the muffle furnace is 5℃ / min.

[0077] (3) After cooling to room temperature, add 200 mL of deionized water to the obtained pyrolysis product and wash it by slurrying at a temperature of 40°C until the conductivity of the washing solution is less than 300 μs / cm.

[0078] (4) The washed sample in step (3) is prepared into a slurry with a water content of 60% by distilled water and spray-dried at 110°C to obtain the unsupported copper bismuth catalyst for the production of 1,4-butynediol.

[0079] Performance evaluation:

[0080] Stability test: The catalysts of Examples 1-5 and Control Examples 1-2 were tested under the following conditions: 10g of catalyst was used to make a slurry with 200mL of deionized water, the pH was adjusted to 5.5-6.0 with acetic acid, and the mixture was stirred at 900r / min for 10 days. The mixture was then separated by centrifugation using 10mL centrifuge tubes. After centrifugation, the supernatant was taken to test for copper residue. The specific results are shown in Table 1.

[0081] Table 1. Stability test results of catalysts in Examples 1-5 and Comparative Examples 1-2

[0082]

[0083] As can be seen from the results in Table 1, the supported copper-bismuth catalyst prepared by the method of the present invention has a stable structure, less copper loss during the experiment, and a longer service life.

[0084] Chemical activity test: The catalysts from Examples 1-5 and Comparative Examples 1-2 were used to synthesize 1,4-butynediol. In the experiment, 3.5 g of the catalyst and 100 mL of 35% formaldehyde solution were added to a reactor equipped with a stirrer for pre-activation at 70°C for 2 h. After activation, acetylene gas was introduced at a rate of 200 mL / min, and the temperature was raised to 90°C. The formaldehyde acetylation reaction was carried out under normal pressure. After 18 h, the temperature was lowered, and the acetylene introduction was stopped. The reaction solution was analyzed by gas chromatography, and the formaldehyde conversion rate was analyzed by sodium sulfite titration. Specific results are shown in Table 2.

[0085] Table 2. Results of catalyst chemical activity tests in Examples 1-5 and Comparative Examples 1-2

[0086] Catalyst Formaldehyde conversion / % 1,4-Butynediol yield / % 1,4-Butynediol selectivity / % Example 1 90.61 89.17 98.41 Example 2 95.61 94.09 98.41 Example 3 92.68 91.61 98.85 Example 4 91.72 90.40 98.56 Example 5 90.35 89.02 98.53 Control 1 78.74 73.84 93.78 Control 2 76.61 71.76 93.67

[0087] As can be seen from Table 2, when the catalysts of Examples 1-5 are used to catalyze the synthesis of 1,4-butynediol from formaldehyde and acetylene, the formaldehyde conversion rate is high, reaching up to 95% or more, and the selectivity and yield of 1,4-butynediol are high, reaching 94% or more and 98% or more, respectively, which are much higher than those of Control Examples 1 and 2, indicating that the supported copper-bismuth catalyst of the present invention has good catalytic activity.

[0088] Catalyst recycling test: The catalysts from Example 2 and Control Example 1 were tested for the number of recycling cycles. After each reaction, the wet catalyst was washed with water, washed with ethanol, and vacuum dried before being stored as the catalyst for the next reaction. Other conditions were the same as in the chemical activity test. The effects of catalyst stability and the number of recycling cycles on the yield of 1,4-butynediol were investigated. Specific results are as follows: Figure 3 As shown.

[0089] from Figure 3 It can be seen that the catalyst of the present invention does not show a significant decrease in catalytic effect after multiple cycles, and has good stability and service life.

[0090] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A supported copper-bismuth catalyst for the synthesis of 1,4-butynediol from formaldehyde and acetylene, characterized in that, The catalyst consists of a g-C3N4 support and CuO and Bi2O3 supported on the g-C3N4 support. By mass percentage, CuO accounts for 15-60% of the catalyst, Bi2O3 accounts for 2-10% of the catalyst, and the remainder is the support. The preparation method of the supported copper-bismuth catalyst includes the following steps: (1) Thoroughly mix and grind the copper salt, bismuth salt and g-C3N4 precursor; (2) The mixture obtained in step (1) is pyrolyzed in a muffle furnace; (3) Add the pyrolysis product obtained in step (2) to deionized water, stir thoroughly, wash and filter, and then slurry the resulting solid with deionized water for later use. The slurry obtained in step (3) was spray-dried to obtain a supported copper-bismuth catalyst.

2. A method for preparing the catalyst according to claim 1, characterized in that, Includes the following steps: (1) Thoroughly mix and grind the copper salt, bismuth salt and g-C3N4 precursor; (2) The mixture obtained in step (1) is pyrolyzed in a muffle furnace; (3) Add the pyrolysis product obtained in step (2) to deionized water, stir thoroughly, wash and filter, and then slurry the resulting solid with deionized water for later use. (4) Spray dry the slurry obtained in step (3) to obtain a supported copper bismuth catalyst for catalyzing the synthesis of 1,4-butynediol from formaldehyde and acetylene.

3. The preparation method according to claim 2, characterized in that, The copper salt includes at least one of copper nitrate, copper sulfate, copper chloride, and copper acetate; the bismuth salt includes at least one of bismuth nitrate, bismuth chloride, and bismuth sulfate.

4. The preparation method according to claim 2, characterized in that, The g-C3N4 precursor includes at least one of melamine, urea, and hydroxylamine.

5. The preparation method according to claim 2, characterized in that, In step (2), during pyrolysis, the heating rate of the muffle furnace is 1-10. o C / min, cooling rate 1-10 o The pyrolysis temperature is 350-600℃, and the pyrolysis time is 2-8h.

6. The preparation method according to claim 2, characterized in that, In step (3), the washing temperature is 30-60°C. o C. Stop washing when the conductivity in the washing solution is less than 300 μs / cm.

7. The preparation method according to claim 2, characterized in that, In step (4), the slurry has a water content of 40-80% and a drying temperature of 90-130°C. o C.

8. The application of the catalyst according to claim 1 in the catalytic synthesis of 1,4-butynediol from formaldehyde and acetylene.

9. The application according to claim 8, characterized in that, The catalytic synthesis steps of the 1,4-butynediol include: placing the catalyst and formaldehyde solution into a reactor for pre-activation of the catalyst at an activation temperature of 70°C. o C, the activation time is 2h, after activation, acetylene gas is introduced at a rate of 200mL / min, and the temperature is raised to 90°C. o C, the acetylation reaction of formaldehyde is carried out for 10-18 hours, wherein the concentration of formaldehyde solution is 15-45%, and the mass ratio of catalyst to formaldehyde solution is 1:4-1:20.

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