Copper-bismuth catalyst as well as preparation method and application thereof

Abstract

The invention provides a copper-bismuth catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: adding bottom water and carboxymethyl cellulose into a reaction kettle, and heating to reaction temperature; adding an acidified salt solution containing a copper element and a bismuth element and a precipitant solution into the reaction kettle in a parallel flow manner, and stopping adding the raw materials for aging when the residual amount of the salt solution is 2 / 3-5 / 6 of the preparation amount; when the average particle size of the precipitate is detected to be 7-13 microns, adding the raw materials in a parallel flow manner until the prepared salt solution is used up, cooling to 5-10 DEG C, and aging; the pH value of the reaction liquid is 5.0-8.0, the concentration of copper ions in the reaction liquid is lower than 5%, and the copper-bismuth catalyst is moderate in particle size, high in bulk density, small in particle size change before and after ethynylation reaction, long in service life and still high in activity, selectivity and stability after being repeatedly used for multiple times.

Description

Technical Field

[0001] This application belongs to the field of catalyst preparation technology, specifically relating to a copper-bismuth catalyst, its preparation method, and its application. Background Technology

[0002] 1,4-Butynediol (BYD) is an important intermediate in the production of high-value-added chemicals. It possesses excellent surface activity and corrosion inhibition properties, and is widely used in electroplating, agriculture, medicine, and coatings. Furthermore, the BYD molecule contains -OH and -C≡C functional groups, enabling it to react chemically with many substances. 1,4-Butanediol is the main downstream product of 1,4-butynediol, obtained by hydrogenation of 1,4-butynediol. 1,4-Butanediol can be reacted to produce polyurethane (PU), tetrahydrofuran (THF), polybutylene succinate (PBS), γ-butyrolactone (GBL), polytetramethylene glycol (PTMEG), and other chemicals, which are widely used as synthetic intermediates in pharmaceuticals, pesticides, electronics, and other polymer materials. Moreover, the types of downstream products of 1,4-butynediol are constantly being developed, and production volume is expanding simultaneously, forming a high-value-added industrial chain.

[0003] my country has abundant coal resources, sufficient calcium carbide production, and inexpensive formaldehyde. Therefore, the preparation of 1,4-butynediol from acetylene and formaldehyde under the action of a catalyst is the most commonly used industrial method, known as the Reppe process (acetylene-aldehyde method). The Reppe process for synthesizing 1,4-butynediol includes fixed-bed, suspended-bed, and slurry-bed reaction processes. Among these, the slurry-bed process effectively eliminates gradients in heat exchange and mass transfer, making it suitable for large-scale operation and widely used in industrial production. The slurry-bed process generally operates at atmospheric pressure, with the catalyst and product separated by filtration and pressure differential. This requires the catalyst to have a suitable particle size and high mechanical strength. If the particle size is too small, filtration and separation become difficult; if the particle size is too large, the catalyst activity is low, the catalyst strength is poor, and the catalyst's lifespan is reduced.

[0004] Currently, copper-bismuth catalysts are commonly used industrially to produce 1,4-butynediol, where copper is the active component and bismuth is the promoter. Patents CN103157500A, US4288641, and US3920759 report copper-bismuth catalysts supported on SiO2, molecular sieves, and silicon-magnesium composite oxides, respectively. Patent CN102950014A describes a method for preparing a catalyst for 1,4-butynediol production, using nano-silica as a support and employing a precipitation deposition method to load copper and bismuth onto the support. The catalyst prepared by this method exhibits good activity and selectivity. Although the above supported copper-bismuth catalysts have high mechanical strength, wear resistance, and better catalytic activity and lifespan, the support is not stable enough. During the reaction, Si easily detaches from the support into the target product, increasing the ion load in subsequent stages, and generating a large amount of wastewater in subsequent treatment.

[0005] Supportless basic copper carbonate catalysts do not lose Si ions, which can reduce wastewater generation. Patents US4584418, US4107082, and CN105642301 report the preparation of supportless basic copper carbonate catalysts. Although these catalysts are not easily worn, the particles become significantly finer after the reaction, making filtration difficult and causing metal components to be easily lost.

[0006] Patent CN105642303B discloses a method for preparing a copper-bismuth catalyst for the synthesis of 1,4-butynediol. This method uses a two-step process: first, water is added to a reactor in a co-current flow. During precipitation, a silicon source, hydroxypropyl cellulose, and sodium stearate polyoxyethylene ether sulfonate are added for modification. The catalyst is then washed with deionized water containing potassium chloride and subjected to ultrasonic treatment. Finally, it is spray-dried to obtain the copper-bismuth catalyst. Patent CN106669697A discloses a copper-bismuth catalyst for the synthesis of 1,4-butynediol, its preparation method, and its applications. The catalyst has a particle size of at least 85% between 7-20 μm. The catalyst is prepared by a two-stage co-precipitation reaction in different reactors, with dispersant 5040 and glycerol polyoxypropylene polyoxyethylene ether added during the co-precipitation process, followed by spray drying. Patent CN112717945A discloses a catalyst for the synthesis of 1,4-butynediol, its preparation method, and its application. The method includes the following steps: (1) preparing or formulating a slurry containing copper-bismuth composite oxides, wherein the average particle size of the copper-bismuth composite oxides in the slurry is <7 μm; (2) adding a copper-bismuth mixed solution AG-1, a precipitant solution AG-2, and a γ-butyrolactone solution AG-3 to the slurry from step (1) in parallel flow for reaction; (3) after the reaction in step (2) is completed, the catalyst for the synthesis of 1,4-butynediol is obtained after aging, filtration, washing, pulping, and spray drying. However, the existing 1,4-butynediol catalyst preparation process is complex, requiring the addition of various surfactants such as hydroxypropyl cellulose, and also requiring spray drying, which increases costs. Moreover, the catalyst prepared in this way has a low bulk density and insufficient strength, and is easily broken during the reaction process, leading to difficult filtration and a short service life. Summary of the Invention

[0007] The technical problem to be solved by this application is to provide a copper-bismuth catalyst, its preparation method and application. The copper-bismuth catalyst prepared by this application has a moderate particle size, high bulk density and high mechanical strength. The particle size of the catalyst changes little before and after the acetylation reaction. The catalyst has a long life and still has high activity, selectivity and stability after repeated use.

[0008] To solve the above-mentioned technical problems, this application provides a method for preparing a copper-bismuth catalyst, comprising the following steps: Step S1, preparing an acidified salt solution containing copper and bismuth elements, and preparing a precipitant solution; Step S2: Add bottom water and carboxymethyl cellulose to the reactor and heat to the reaction temperature; Step S3: The salt solution and the precipitant solution are added to the reactor in a parallel flow manner to carry out the reaction. When the remaining amount of the salt solution is 2 / 3 to 5 / 6 of the amount prepared in step S1, the addition of the salt solution and the precipitant solution is stopped, and an aging treatment is performed. Step S4: When the average particle size of the precipitate is detected to be 7-13 micrometers, the salt solution and the precipitant solution are added in a co-current manner to react until the salt solution prepared in step S1 is used up. The reaction liquid in the reactor is then cooled by 5-10°C and subjected to aging treatment. Step S5: Filter the reaction solution obtained in step S4 to obtain a precipitate. Wash and dry the precipitate to obtain the copper-bismuth catalyst. In steps S3 and S4, the feed ratio of the salt solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 5.0-8.0, and the amount of bottom water is such that the concentration of copper ions in the reaction solution in steps S3 and S4 is less than 5%.

[0009] Further, in step S1, the step of preparing the salt solution includes: first adding acid to deionized water to prepare an acid solution, then adding copper salt and bismuth salt to the acid solution, and stirring to dissolve.

[0010] Furthermore, the copper salt is selected from at least one of copper chloride, copper nitrate, and copper sulfate; the bismuth salt is selected from at least one of bismuth sulfate, bismuth nitrate, and bismuth acetate; and the acid is selected from at least one of sulfuric acid, nitric acid, and hydrochloric acid.

[0011] Furthermore, based on the total mass of the salt solution, the mass fraction of copper is greater than 5%, and the mass fraction of bismuth is 0.2%-3%.

[0012] Furthermore, the pH of the salt solution is 0-2.0, and the pH of the precipitant solution is 8-12.

[0013] Furthermore, the precipitant in the precipitant solution is selected from at least two of sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, ammonia, and sodium bicarbonate.

[0014] Furthermore, the mass of the carboxymethyl cellulose accounts for 0.3%-9% of the mass of copper in the salt solution.

[0015] Furthermore, the bottom water occupies 1 / 10 to 1 / 2 of the volume of the reactor.

[0016] Furthermore, the reaction temperature and the pH of the reaction solution are the same in steps S3 and S4, and the reaction temperature is 40℃-70℃.

[0017] Furthermore, in step S4, the addition rate of the salt solution and the precipitant solution is 0.5-3 times that in step S3.

[0018] Furthermore, in steps S3 and S4, the aging temperature is 40℃-60℃ and the aging pH value is 5.0-8.0; in step S4, the aging time is 0h-3h.

[0019] Furthermore, in step S5, during washing, the temperature of the washing water is 20℃-60℃; during drying, it is dried in two stages. The temperature of the first drying is 50℃-80℃ and the drying time is 2-10 hours. The temperature of the second drying is 80℃-120℃ and the drying time is 2-10 hours.

[0020] Furthermore, step S2 is carried out under stirring; in step S3, the process of adding salt solution and precipitant solution to the reactor is carried out under stirring, and stirring is stopped when the addition of salt solution and precipitant solution is stopped, and stirring is not required during the aging process; in step S4, the process of adding salt solution and precipitant solution to the reactor and the aging process are both carried out under stirring.

[0021] This application also provides a copper-bismuth catalyst, which is prepared by the above-described preparation method.

[0022] This application also provides the application of the above-mentioned copper-bismuth catalyst in the synthesis of 1,4-butynediol.

[0023] The beneficial effects of this application are: This application uses a co-precipitation method to control the concentration of copper ions and alkaline solution in the reactor, keeping them within a suitable temperature and pH range, and with the synergistic effect of carboxymethyl cellulose, to control the crystal growth rate, thereby forming dense and appropriately sized crystal nuclei, which further grow into copper-bismuth catalyst particles with concentrated particle size and high bulk density. The catalyst particles of this application have concentrated particle size, high bulk density, and high mechanical strength. After multiple acetylation reactions, the catalyst particle size changes little, and it still has high activity, selectivity, and stability, and a long catalyst lifetime. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0025] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components.

[0026] Definitions of other specific words and phrases are provided throughout this disclosure. Those skilled in the art will understand that, in many, if not most, cases, such definitions apply to the prior and future use of the words and phrases thus defined.

[0027] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] This disclosure provides a method for preparing a copper-bismuth catalyst, characterized by comprising the following steps: Step S1: Prepare an acidified salt solution containing copper and bismuth elements, and prepare a precipitant solution. Specifically, the prepared precipitant solution is in excess.

[0029] Step S2: Add bottom water and carboxymethyl cellulose to the reactor and heat to the reaction temperature.

[0030] In step S3, the salt solution and precipitant solution are added to the reactor in a parallel flow manner to carry out the reaction. The feed ratio of the salt solution and precipitant solution is such that the pH of the reaction solution in the reactor is 5.0-8.0. When the remaining amount of salt solution is 2 / 3-5 / 6 of the amount prepared in step S1, the addition of salt solution and precipitant solution is stopped, and an aging treatment is performed. For example, the pH of the reaction solution is 5.0, 6.0, 7.0, or 8.0. Preferably, the pH of the reaction solution in the reactor is 6.0-7.0. The addition of salt solution and precipitant solution is stopped when the remaining amount of salt solution is 2 / 3, 3 / 4, or 5 / 6 of the amount prepared in step S1.

[0031] Specifically, the remaining amount of salt solution can be determined by weighing it in real time or by judging based on the remaining volume. As an example, the salt solution is placed on a weighing balance, and the weight of the remaining salt solution can be determined based on the data displayed on the balance, thus determining when to stop adding salt solution.

[0032] Specifically, during feeding, the salt solution and precipitant solution are added to the reactor using separate flow control devices. For example, metering pumps, peristaltic pumps, regulating valves and flow meters can be used. By controlling the flow rates of the two flow control devices, the reaction liquid in the reactor is maintained at the set pH.

[0033] In step S4, when the average particle size of the precipitate is detected to be 7-13 micrometers, the salt solution and precipitant solution are added in a co-current manner to continue the reaction until the salt solution prepared in step S1 is used up. The feed ratio of the salt solution and precipitant solution is such that the pH of the reaction solution in the reactor is 5.0-8.0. For example, the pH of the reaction solution is 5.0, 6.0, 7.0, or 8.0. Preferably, the pH of the reaction solution in the reactor is 6.0-7.0. After the salt solution is added, the reaction solution in the reactor is cooled by 5-10°C and then subjected to an aging treatment.

[0034] Step S5: Filter the reaction solution obtained in step S4 to obtain a precipitate. Wash and dry the precipitate to obtain a copper-bismuth catalyst.

[0035] The amount of bottom water is such that the concentration of copper ions in the reaction solution during steps S3 and S4 is less than 5%. Preferably, the concentration of copper ions in the reaction solution is less than 3%.

[0036] Specifically, in steps S3 and S4, the pH of the reaction solution is measured by an online pH meter. The feed rates of the salt solution and the precipitant solution can be adjusted by the pH to maintain the reaction solution at a stable pH value.

[0037] Specifically, in step S4, when detecting the particle size of the precipitate in the reaction solution, both offline and online detection methods can be used. Offline detection requires periodic sampling. For example, offline detection methods can include laser diffraction, dynamic light scattering, image analysis, etc. Online detection methods can include online laser particle size analyzers, focused beam reflectance meters, etc.

[0038] The method for preparing the copper-bismuth catalyst provided in the above embodiments of this disclosure uses a co-precipitation method. By controlling the concentration of copper ions and alkaline solution in the reactor, and within a suitable temperature and pH range, and with the synergistic effect of carboxymethyl cellulose, the growth rate of the crystals is controlled, so that dense and appropriately sized crystal nuclei are formed, which further grow into copper-bismuth catalyst particles with concentrated particle size and high bulk density. The catalyst particles of this application have concentrated particle size, high bulk density, and high mechanical strength. After multiple acetylation reactions, the catalyst particle size changes little, and it still has high activity, selectivity and stability, and long catalyst lifetime.

[0039] In some embodiments, step S1, the step of preparing the salt solution includes: first adding acid to deionized water to prepare an acid solution, then adding copper salt and bismuth salt to the acid solution, and stirring to dissolve.

[0040] In some embodiments, the copper salt is selected from at least one of copper chloride, copper nitrate, and copper sulfate; the bismuth salt is selected from at least one of bismuth sulfate, bismuth nitrate, and bismuth acetate; and the acid is selected from at least one of sulfuric acid, nitric acid, and hydrochloric acid.

[0041] In some embodiments, the pH of the salt solution is 0-2.0, and the pH of the precipitant solution is 8-12. For example, the pH of the salt solution is 0, 0.1, 0.5, 1, 1.2, 1.6, 2, etc., and the pH of the precipitant solution is 8, 9.3, 10, 11.6, 12, etc. Preferably, the pH of the salt solution is 0-1.0, and the pH of the precipitant solution is 10-12.

[0042] In some embodiments, based on the total mass of the salt solution, the mass fraction of copper is greater than 5%, and the mass fraction of bismuth is 0.2%-3%. For example, the mass fraction of copper is 5%, 10%, 15%, 19%, etc., and the mass fraction of bismuth is 0.2%, 0.5%, 1%, 2%, 3%, etc. Specifically, the maximum mass fraction of copper is the mass fraction of copper in the saturated solution of the corresponding copper salt. Preferably, the mass fraction of copper is 10%-15%, and the mass fraction of bismuth is 0.3%-2%.

[0043] In some embodiments, the precipitant is selected from at least two of sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, ammonia, and sodium bicarbonate. Preferably, the precipitant is sodium carbonate and sodium bicarbonate. The mass ratio of sodium carbonate to sodium bicarbonate is (0.25-4):1. For example, the mass ratio of sodium carbonate to sodium bicarbonate is 0.25:1, 0.5:1, 1:1, 2:1, 4:1, etc. Preferably, the mass ratio of sodium carbonate to sodium bicarbonate is (0.5-2):1.

[0044] In some embodiments, the mass of carboxymethyl cellulose accounts for 0.3%-9% of the mass of copper in the salt solution. For example, the mass of carboxymethyl cellulose accounts for 0.3%, 0.8%, 2%, 3%, 5%, 7%, 9% of the mass of copper in the salt solution, etc. Preferably, this proportion is 0.8%-4%.

[0045] In some embodiments, the bottom water occupies 1 / 10 to 1 / 3 of the reactor volume. For example, the bottom water occupies 1 / 10, 1 / 5, 1 / 4, 1 / 3, 1 / 2, etc. of the reactor volume. Preferably, the bottom water occupies 1 / 5 to 1 / 3 of the reactor volume.

[0046] In some embodiments, the reaction temperature and pH of the reaction solution are the same in steps S3 and S4, and the reaction temperature is 40℃-70℃. For example, the reaction temperature is 40℃, 50℃, 60℃, 70℃, etc. Preferably, the reaction temperature is 45℃-55℃.

[0047] In some embodiments, the addition rate of the salt solution and precipitant solution in step S4 is 0.5-3 times the addition rate in step S3. For example, this multiple is 0.5 times, 1 time, 2 times, 3 times, etc. Preferably, the addition rate of the salt solution and precipitant solution in step S4 is 1-2 times the addition rate in step S3.

[0048] In some embodiments, the aging temperature in steps S3 and S4 is 40℃-60℃. For example, the aging temperature is 40℃, 45℃, 50℃, 55℃, 60℃, etc. Preferably, the aging temperature is 40℃-50℃. The aging pH value is 5.0-8.0. For example, the aging pH value is 5.0, 6.0, 7.0, 8.0. Preferably, the aging pH value is 6.5-7.5.

[0049] In step S4, the aging time is 0h-3h. Preferably, in step S4, the aging time is 0h-1h.

[0050] In some embodiments, during step S5, the temperature of the washing water is 20℃-60℃, preferably 30℃-40℃. During drying, the process is divided into two stages: the first drying stage is at 50℃-80℃ for 2-10 hours, preferably 50℃-65℃ for 4-8 hours; the second drying stage is at 80℃-120℃ for 2-10 hours, preferably 100℃-110℃ for 4-8 hours. This stepwise drying process, using both low and high temperatures, avoids localized overheating of the catalyst, which could cause decomposition of the catalyst (e.g., basic copper carbonate and basic bismuth carbonate), and also allows for a more compact bonding of the catalyst particles.

[0051] In some embodiments, step S2 is performed with stirring.

[0052] In step S3, the addition of salt solution and precipitant solution to the reactor is carried out with stirring. Stirring is stopped when the addition of salt solution and precipitant solution is stopped. No stirring is required during the aging process. The reason for not stirring during the aging process in step S3 is to obtain dense, small grains, which will serve as nuclei for subsequent growth.

[0053] In step S4, the processes of adding the salt solution and precipitant solution to the reactor and the aging process are both carried out under stirring. In step S4, the stirring during the aging process is to allow the grains to grow, ultimately obtaining copper-bismuth catalyst particles with a suitable particle size and high bulk density.

[0054] This disclosure also provides a copper-bismuth catalyst, which is prepared using the above-described method for preparing copper-bismuth catalysts.

[0055] This disclosure also provides an application of a copper-bismuth catalyst in the synthesis of 1,4-butynediol.

[0056] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Where techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0057] Example 1 Step S1: Dissolve 30g of 68% concentrated nitric acid in 500g of water, and weigh out 510g of copper nitrate trihydrate and 13.5g of bismuth nitrate pentahydrate, adding them to the prepared acid solution and stirring until completely dissolved to obtain an acidified salt solution. Add 150g of sodium carbonate and 180g of sodium bicarbonate to 2000g of water and stir until completely dissolved to obtain a precipitant solution.

[0058] Step S2: Add 700g of deionized water to the reactor, then add 1.1g of carboxymethyl cellulose, and heat to 60°C. Stir continuously after adding carboxymethyl cellulose.

[0059] Step S3: Place the salt solution on a balance. Add the salt solution and precipitant solution to the reactor in parallel using metering pumps. After 0.3 hours of adding the salt solution and precipitant solution, stop adding the salt solution and precipitant solution when the remaining amount of salt solution is 780 grams, and then proceed with aging treatment. During the reaction, maintain the pH of the reaction solution in the reactor at 6.0, and the reaction temperature at 60℃. The aging temperature is 55℃, and the pH is adjusted to 6.5 during aging. Continuous stirring is required during both the reaction and aging processes.

[0060] In step S4, during the aging process, samples were taken from the reactor every 10 minutes to check the average particle size of the precipitate. When the average particle size of the precipitate was found to be 9 micrometers, the salt solution and precipitant solution were added in a co-current manner until the prepared salt solution was used up. The rate of addition of the salt solution and precipitant solution was 1.2 times that in step S3. During the reaction, the pH of the reaction solution in the reactor was maintained at 6.0, and the reaction temperature was 60°C. When the salt solution was used up, the addition of the precipitant solution was stopped. Then, the temperature of the reaction solution in the reactor was lowered to 55°C, and the aging treatment was carried out at 55°C for 0.5 hours. Continuous stirring was required during both the reaction and aging processes.

[0061] Step S5: The reaction solution from step S4 is filtered to obtain a precipitate. The precipitate is washed with deionized water at 40°C until the conductivity of the washing solution is less than 200 μS / cm. Washing is then stopped, and filtration begins. The filter cake is first dried at 60°C for 6 hours, and then dried at 100°C for 6 hours to obtain a copper-bismuth catalyst. Analysis shows that the product contains 66.7% CuO by mass and 2.6% Bi₂O₃ by mass.

[0062] Example 2 Step S1: Dissolve 40 g of 68% concentrated nitric acid in 480 g of water, and weigh out 454 g of copper nitrate trihydrate and 19.2 g of bismuth nitrate pentahydrate, adding them to the prepared acid solution and stirring until completely dissolved to obtain an acidified salt solution. Add 175 g of sodium carbonate and 175 g of sodium bicarbonate to 1960 g of water and stir until completely dissolved to obtain a precipitant solution.

[0063] Step S2: Add 750g of deionized water to the reactor, then add 2.1g of carboxymethyl cellulose, and heat to 55°C. Stir continuously after adding carboxymethyl cellulose.

[0064] Step S3: Place the salt solution on a balance. Add the salt solution and precipitant solution to the reaction vessel in parallel using metering pumps. After 0.5 hours of adding the salt solution and precipitant solution, stop adding 800 grams of salt solution and proceed with aging treatment. Maintain the pH of the reaction solution in the reaction vessel at 6.5 and the reaction temperature at 55°C. The aging temperature is 50°C, and the pH is adjusted to 7.0 during aging. Continuous stirring is required during both the reaction and aging processes.

[0065] In step S4, during the aging process, samples are taken from the reactor every 10 minutes to detect the average particle size of the precipitate. When the average particle size of the precipitate is detected to be 10 micrometers, the salt solution and precipitant solution are added in a co-current manner until the prepared salt solution is used up. The rate of addition of the salt solution and precipitant solution is 1.5 times that in step S3. During the reaction, the pH value of the reaction solution in the reactor is maintained at 6.5, and the reaction temperature is 50°C. When the salt solution is used up, the addition of the precipitant solution is stopped simultaneously. Then, the temperature of the reaction solution in the reactor is reduced to 43°C, and the aging treatment is carried out at 43°C for 0.3 hours. Continuous stirring is required during both the reaction and aging processes.

[0066] Step S5: The reaction solution from step S4 is filtered to obtain a precipitate. The precipitate is washed with deionized water at 30°C until the conductivity of the washing solution is less than 200 μS / cm. Washing is then stopped, and filtration begins. The filter cake is first dried at 50°C for 8 hours, and then dried at 105°C for 8 hours to obtain a copper-bismuth catalyst. Analysis shows that the product contains 63.6% CuO by mass and 3.9% Bi₂O₃ by mass.

[0067] Example 3 Step S1: Dissolve 15g of 68% concentrated nitric acid in 550g of water, and weigh 548g of copper nitrate trihydrate and 9.8g of bismuth nitrate pentahydrate into the prepared acid solution, stirring until completely dissolved to obtain an acidified salt solution. Add 200g of sodium carbonate and 160g of sodium bicarbonate to 2000g of water, stirring until completely dissolved to obtain a precipitant solution.

[0068] Step S2: Add 1000g of deionized water to the reactor, then add 5.2g of carboxymethyl cellulose, and heat to 50°C. Stir continuously after adding carboxymethyl cellulose.

[0069] Step S3: Place the salt solution on a balance. Add the salt solution and precipitant solution to the reactor in parallel using metering pumps. After 0.4 hours of adding the salt solution and precipitant solution, stop adding the salt solution and precipitant solution when the remaining amount of salt solution is 835 grams, and then proceed with aging treatment. During the reaction, maintain the pH of the reaction solution in the reactor at 6.0, and the reaction temperature at 50℃. The aging temperature is 50℃, and the pH is adjusted to 7.0 during aging. Continuous stirring is required during both the reaction and aging processes.

[0070] In step S4, during the aging process, samples were taken from the reactor every 10 minutes to check the average particle size of the precipitate. When the average particle size of the precipitate was found to be 10 micrometers, the salt solution and precipitant solution were added in a co-current manner until the prepared salt solution was used up. The rate of addition of the salt solution and precipitant solution was 1.1 times that in step S3. During the reaction, the pH of the reaction solution in the reactor was maintained at 6.0, and the reaction temperature was 50°C. When the salt solution was used up, the addition of the precipitant solution was stopped. Then, the temperature of the reaction solution in the reactor was lowered to 45°C, and the aging treatment was carried out at 45°C for 0.8 hours. Continuous stirring was required during both the reaction and aging processes.

[0071] Step S5: The reaction solution from step S4 is filtered to obtain a precipitate. The precipitate is washed with deionized water at 35°C until the conductivity of the washing solution is less than 200 μS / cm. Washing is then stopped, and filtration begins. The filter cake is first dried at 55°C for 4 hours, and then dried at 110°C for 8 hours to obtain a copper-bismuth catalyst. Analysis shows that the product contains 70.1% CuO by mass and 1.8% Bi₂O₃ by mass.

[0072] Example 4 Step S1: Dissolve 23.6 g of 68% concentrated nitric acid in 700 g of water, and weigh out 590 g of copper nitrate trihydrate and 18.3 g of bismuth nitrate pentahydrate, adding them to the prepared acid solution and stirring until completely dissolved to obtain an acidified salt solution. Add 120 g of sodium carbonate and 200 g of sodium bicarbonate to 2200 g of water and stir until completely dissolved to obtain a precipitant solution.

[0073] Step S2: Add 1200g of deionized water to the reactor, then add 4.5g of carboxymethyl cellulose, and heat to 60°C. Stir continuously after adding carboxymethyl cellulose.

[0074] Step S3: Place the salt solution on a balance. Add the salt solution and precipitant solution to the reactor in parallel using metering pumps. After 0.4 hours of adding the salt solution and precipitant solution, stop adding 1000 grams of salt solution and proceed with aging. Maintain the pH of the reaction solution in the reactor at 6.5 and the reaction temperature at 60°C. The aging temperature is 55°C, and the pH during aging is 6.5. Continuous stirring is required during both the reaction and aging processes.

[0075] In step S4, during the aging process, samples are taken from the reactor every 10 minutes to detect the average particle size of the precipitate. When the average particle size of the precipitate is detected to be 8 micrometers, the salt solution and precipitant solution are added in a co-current manner until the prepared salt solution is used up. The rate of addition of the salt solution and precipitant solution is twice that in step S3. During the reaction, the pH of the reaction solution in the reactor is maintained at 6.5, and the reaction temperature is 55°C. When the salt solution is used up, the addition of the precipitant solution is stopped simultaneously. Then, the temperature of the reaction solution in the reactor is lowered to 45°C, and the aging treatment is carried out at 45°C for 1.0 hour. Continuous stirring is required during both the reaction and aging processes.

[0076] Step S5: The reaction solution from step S4 is filtered to obtain a precipitate. The precipitate is washed with deionized water at 45°C until the conductivity of the washing solution is less than 200 μS / cm. Washing is then stopped, and filtration begins. The filter cake is first dried at 50°C for 4 hours, and then dried at 100°C for 8 hours to obtain a copper-bismuth catalyst. Analysis shows that the product contains 66.5% CuO by mass and 3.0% Bi₂O₃ by mass.

[0077] Example 5 Step S1: Dissolve 27 g of 68% concentrated nitric acid in 700 g of water, and weigh out 215 g of copper nitrate trihydrate and 5.3 g of bismuth nitrate pentahydrate, adding them to the prepared acid solution and stirring until completely dissolved to obtain an acidified salt solution. Add 120 g of sodium carbonate and 200 g of sodium hydroxide to 2200 g of water and stir until completely dissolved to obtain a precipitant solution.

[0078] Step S2: Add 500g of deionized water to the reactor, then add 5.0g of carboxymethyl cellulose, and heat to 70°C. Stir continuously after adding carboxymethyl cellulose.

[0079] Step S3: Place the salt solution on a balance. Add the salt solution and precipitant solution to the reactor in parallel using metering pumps. After 0.4 hours of adding the salt solution and precipitant solution, stop adding the salt solution and precipitant solution when the remaining amount of salt solution is 640 grams, and then proceed with aging treatment. During the reaction, maintain the pH of the reaction solution in the reactor at 5, and the reaction temperature at 70℃. The aging temperature is 60℃, and the pH during aging is 5. Continuous stirring is required during both the reaction and aging processes.

[0080] In step S4, during the aging process, samples are taken from the reactor every 10 minutes to detect the average particle size of the precipitate. When the average particle size of the precipitate is detected to be 8 micrometers, the salt solution and precipitant solution are added in a co-current manner until the prepared salt solution is used up. The rate of addition of the salt solution and precipitant solution is 0.8 times that in step S3. During the reaction, the pH value of the reaction solution in the reactor is maintained at 5, and the reaction temperature is 60°C. When the salt solution is used up, the addition of the precipitant solution is stopped simultaneously. Then, the temperature of the reaction solution in the reactor is reduced to 50°C, and the aging treatment is carried out at 50°C for 1.0 hour. Continuous stirring is required during both the reaction and aging processes.

[0081] Step S5: The reaction solution from step S4 is filtered to obtain a precipitate. The precipitate is washed with deionized water at 45°C until the conductivity of the washing solution is less than 200 μS / cm. Washing is then stopped, and filtration begins. The filter cake is first dried at 50°C for 4 hours, and then dried at 100°C for 8 hours to obtain a copper-bismuth catalyst. Analysis shows that the product contains 68.9% CuO by mass and 2.5% Bi₂O₃ by mass.

[0082] Example 6 Step S1: Dissolve 60g of 36% concentrated hydrochloric acid in 500g of water, and weigh 365g of anhydrous copper chloride and 40g of bismuth nitrate pentahydrate into the prepared acid solution, stirring until completely dissolved to obtain an acidified salt solution. Add 150g of potassium carbonate and 180g of potassium hydroxide to 1650g of water, stirring until completely dissolved to obtain a precipitant solution.

[0083] Step S2: Add 1200g of deionized water to the reactor, then add 5g of carboxymethyl cellulose, and heat to 40°C. Stir continuously after adding carboxymethyl cellulose.

[0084] Step S3: Place the salt solution on a balance. Add the salt solution and precipitant solution to the reactor in parallel using metering pumps. After 0.3 hours of adding the salt solution and precipitant solution, stop adding the salt solution and precipitant solution when the remaining amount of salt solution is 795 grams, and then proceed with aging treatment. During the reaction, maintain the pH of the reaction solution in the reactor at 8.0, and the reaction temperature at 40℃. The aging temperature is 45℃, and the pH during aging is 8.0. Continuous stirring is required during both the reaction and aging processes.

[0085] In step S4, during the aging process, samples are taken from the reactor every 10 minutes to detect the average particle size of the precipitate. When the average particle size of the precipitate is detected to be 9 micrometers, the salt solution and precipitant solution are added in a co-current manner until the prepared salt solution is used up. The rate of addition of the salt solution and precipitant solution is 1.2 times that in step S3. During the reaction, the pH value of the reaction solution in the reactor is maintained at 8.0, and the reaction temperature is 45°C. When the salt solution is used up, the addition of the precipitant solution is stopped simultaneously. Then, the temperature of the reaction solution in the reactor is lowered to 40°C, and the aging treatment is carried out at 40°C for 0.5 hours. Continuous stirring is required during both the reaction and aging processes.

[0086] Step S5: The reaction solution from step S4 is filtered to obtain a precipitate. The precipitate is washed with deionized water at 40°C until the conductivity of the washing solution is less than 200 μS / cm. Washing is then stopped, and filtration begins. The filter cake is first dried at 60°C for 6 hours, and then dried at 100°C for 6 hours to obtain a copper-bismuth catalyst. Analysis shows that the product contains 63.7% CuO by mass and 5.6% Bi₂O₃ by mass.

[0087] Comparative Example 1 (1) Weigh 576g Cu(NO3)2·3H2O and 30g Bi(NO3)3·5H2O and put them into water containing 25g nitric acid. After they dissolve, make up to 2000ml. (2) Weigh 300g of Na2CO3 and prepare 2000ml of solution. (3) Add 350ml of deionized water to the reactor, heat to 60℃, and stir continuously. (4) Add the acidic solution and the alkaline solution to the reactor in parallel, control the pH of the precipitate to 6.0, and the reaction temperature to 60℃. (5) When 800 ml of the acidic solution from step (1) remains, add 250 g of acidified silica sol to the acidic solution (adjust the pH of the silica sol to 2.0 with nitric acid) and continue the reaction. (6) When 400 ml of the acidic solution from step (1) remains, the catalyst particles larger than 5 μm reach 81%. Add 6.0 g of hydroxypropyl cellulose and 8.0 g of sodium methyl stearate polyoxyethylene ether sulfonate to the reactor at the same time, and continue the reaction. (7) Stop the reaction when the acidic solution is used up, adjust the pH value to 7.0, and at the same time reduce the reaction temperature to 45°C and allow it to stand still for aging. (8) After aging for 2 hours, wash with deionized water at 45°C until no sodium ions are present in the washing solution, then stop washing. (9) Add the filter cake to 800g of water containing 80g of potassium chloride, keep the water temperature at 45℃, and slurry until the material is uniform. Then place it in an ultrasonic generator with an ultrasonic frequency of 60Hz and dry the catalyst using a B-290 spray dryer. The sample composition is as follows: CuO: 52.4%, Bi2O3: 3.7%, SiO2: 20.5%, calculated as CuO and Bi2O3.

[0088] Comparative Example 2 (1) Weigh 715g Cu(NO3)2·3H2O and 30g Bi(NO3)3·5H2O and put them into water containing 25g nitric acid. After they dissolve, make up to 2000ml. (2) Weigh 300g of Na2CO3 and prepare 2000ml of solution. (3) Add 500ml of deionized water to the reactor, then add 14g of dispersant 5040 and 4g of glycerol polyoxypropylene polyoxyethylene ether, stir and heat to 50℃. (4) Add the acidic solution and the alkaline solution to the reactor in parallel, control the pH of the reactants to be 6.0, and the reaction temperature to be 50℃. (5) When 1400 ml of the acidic solution from step (1) remains, stop the reaction and carry out aging. The aging conditions are the same as the reaction conditions, and the aging time is 30 minutes. (6) After aging, 600 mL of the reaction product was transferred to the second reaction vessel using a peristaltic pump to continue the reaction in the second reaction vessel, while maintaining the total volume of the reaction product in the second reaction vessel at 600 mL. Any excess reaction product was transferred to the first reaction vessel using a peristaltic pump. The reaction pH was 6.0, and the reaction temperature was 50°C. When the acidic solution was used up, the reaction was stopped, and the reaction product in the second reaction vessel was transferred to the first reaction vessel. (7) Reduce the temperature to 45°C and age for 1.5 hours. Then wash with 45°C deionized water until no sodium ions are present in the washing solution. (8) Add the filter cake to 580g of water containing 65g of potassium hydroxide and 31g of polyethylene glycol. Control the water temperature at 45℃ and slurry until the material is uniform. Dry the catalyst using a B-290 spray dryer. The sample composition is as follows: CuO: 66.2%, Bi2O3: 4.0%, based on CuO and Bi2O3.

[0089] Comparative Example 3 (1) Prepare a slurry containing copper bismuth composite oxide, wherein the average particle size of the copper bismuth composite oxide in the slurry is 3 μm and the mass content of the copper bismuth composite oxide in the slurry containing copper bismuth composite oxide is 13%. (2) Copper-bismuth mixed solution AG-1, precipitant solution AG-2 and γ-butyrolactone solution AG-3 are added concurrently to the slurry of step (1) for reaction; the copper-bismuth mixed solution has a copper mass concentration of 10% and a bismuth mass concentration of 3% as an element, and the copper and bismuth are derived from the corresponding nitrates; the precipitant is sodium hydroxide, the molar concentration of the precipitant solution is 3.0 mol / L, and the molar concentration of γ-butyrolactone in the γ-butyrolactone solution is 0.7 mol / L; the reaction temperature is 40℃, the flow rate of copper-bismuth mixed solution AG-1 is 150 ml / min, the flow rate of solution AG-3 is 3 ml / min, and the pH value of the reaction is 6.

[0090] (3) After the reaction in step (2) is completed, the catalyst for the synthesis of 1,4-butynediol is obtained by aging, filtering, washing, pulping and spray drying. The aging temperature is 40℃; the aging time is 4h; the mass concentration of the pulping solution is 10%; and the catalyst contains 65wt% copper oxide by weight.

[0091] The performance of the copper-bismuth catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 3 was tested.

[0092] The copper-bismuth catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to acetylation reactions to prepare 1,4-butynediol (BYD). The steps of the acetylation reaction were as follows: 14 g of catalyst and 200 mL of 38% formaldehyde aqueous solution were added to a reaction vessel. Acetylene gas was introduced at a flow rate of 200 mL / min and a partial pressure of 0.02-0.03 MPa. The reaction was carried out at 90 °C for 9 hours. After the reaction was stopped, the catalyst was separated from the reaction solution, and the composition and content of the products were analyzed by gas chromatography.

[0093] Catalyst reuse: After separating the catalyst from the reaction solution following the previous acetylation reaction, the reaction solution was removed from the reactor, while the catalyst remained in the reactor. 200 mL of fresh 38% formaldehyde aqueous solution was added, and acetylene gas was introduced. The reaction conditions remained unchanged, and the reaction was carried out for 9 hours. This process was repeated for a total of 5 reactions. The formaldehyde conversion rate and 1,4-butynediol (BYD) selectivity for each reaction are shown in Tables 1 and 2, respectively.

[0094] Before the acetylation reaction experiment and after five consecutive acetylation reactions, the compact density and particle size of the copper bismuth catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were measured using a laser particle size analyzer. The results are shown in Table 3.

[0095] Table 1. Formaldehyde Conversion Rate

[0096] Table 2. BYD Selectivity

[0097] Table 3. Catalyst Particle Size Distribution

[0098] As shown in Tables 1 and 2, the copper-bismuth catalysts prepared in Examples 1-6 exhibited high methanol conversion and BYD selectivity, and these values ​​remained largely unaffected after five consecutive acetylation reactions. In contrast, the catalysts in Comparative Examples 1-3 showed a significant decrease in both methanol conversion and BYD selectivity after five consecutive reactions. Table 3 shows that the copper-bismuth catalysts prepared in Examples 1-6 had the lowest bulk density (1.59 g / ml), significantly higher than those in Comparative Examples 1-3. Furthermore, the particle size of the copper-bismuth catalysts prepared in Examples 1-6 decreased slightly after five consecutive acetylation reactions, while the particle size of the copper-bismuth catalysts prepared in Comparative Examples 1-3 decreased considerably after five consecutive acetylation reactions, indicating that the copper-bismuth catalyst of this application has a longer service life.

[0099] The text in this disclosure is provided by way of example only to aid in understanding this disclosure. It should not be construed as limiting the scope of this disclosure in any way. Although certain embodiments and examples have been provided, it will be clear to those skilled in the art, based on the content disclosed herein, that changes can be made to the illustrated embodiments and examples without departing from the scope of this disclosure.

[0100] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims.

[0101] Nothing described in this disclosure should be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined only by the claims.

Claims

1. A method for preparing a copper-bismuth catalyst, characterized in that, Includes the following steps: Step S1: Prepare an acidified salt solution containing copper and bismuth elements, and prepare a precipitant solution; Step S2: Add bottom water and carboxymethyl cellulose to the reactor and heat to the reaction temperature; Step S3: The salt solution and the precipitant solution are added to the reactor in a parallel flow manner to carry out the reaction. When the remaining amount of the salt solution is 2 / 3 to 5 / 6 of the amount prepared in step S1, the addition of the salt solution and the precipitant solution is stopped, and an aging treatment is performed. Step S4: When the average particle size of the precipitate is detected to be 7-13 micrometers, the salt solution and the precipitant solution are added in a co-current manner to react until the salt solution prepared in step S1 is used up. The reaction liquid in the reactor is then cooled by 5-10°C and subjected to aging treatment. Step S5: Filter the reaction solution obtained in step S4 to obtain a precipitate. Wash and dry the precipitate to obtain the copper-bismuth catalyst. In steps S3 and S4, the feed ratio of the salt solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 5.0-8.0, and the amount of bottom water is such that the concentration of copper ions in the reaction solution in steps S3 and S4 is less than 5%.

2. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, In step S1, the step of preparing the salt solution includes: first adding acid to deionized water to prepare an acid solution, then adding copper salt and bismuth salt to the acid solution and stirring to dissolve.

3. The method for preparing the copper-bismuth catalyst according to claim 2, characterized in that, The copper salt is selected from at least one of copper chloride, copper nitrate, and copper sulfate; The bismuth salt is selected from at least one of bismuth sulfate, bismuth nitrate, and bismuth acetate; The acid is selected from at least one of sulfuric acid, nitric acid, and hydrochloric acid.

4. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, Based on the total mass of the salt solution, the mass fraction of copper is greater than 5%, and the mass fraction of bismuth is 0.2%-3%.

5. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, The pH of the salt solution is 0-2.0, and the pH of the precipitant solution is 8-12.

6. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, The precipitant in the precipitant solution is selected from at least two of sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, ammonia, and sodium bicarbonate.

7. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, The mass of the carboxymethyl cellulose accounts for 0.3%-9% of the mass of copper in the salt solution.

8. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, The bottom water accounts for 1 / 10 to 1 / 2 of the volume of the reactor.

9. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, In steps S3 and S4, the reaction temperature and the pH of the reaction solution are the same, and the reaction temperature is 40℃-70℃.

10. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, In step S4, the addition rate of the salt solution and the precipitant solution is 0.5-3 times that in step S3.

11. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, In steps S3 and S4, the aging temperature is 40℃-60℃ and the aging pH value is 5.0-8.

0. In step S4, the aging time is 0h-3h.

12. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, In step S5, the temperature of the washing water is 20℃-60℃ during washing; The drying process is carried out in two stages. The first drying temperature is 50℃-80℃ and the drying time is 2-10 hours. The second drying temperature is 80℃-120℃ and the drying time is 2-10 hours.

13. The method for preparing the copper-bismuth catalyst according to claim 1, characterized in that, Step S2 is carried out while stirring; In step S3, the process of adding the salt solution and the precipitant solution to the reaction vessel is carried out under stirring. When the addition of the salt solution and the precipitant solution is stopped, stirring is stopped. No stirring is required during the aging process. In step S4, the process of adding the salt solution and the precipitant solution to the reaction vessel and the aging process are both carried out under stirring.

14. A copper-bismuth catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-13.

15. The use of the copper bismuth catalyst of claim 14 in the synthesis of 1,4-butynediol.

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