System and method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol

Abstract

This invention discloses a system and method for producing 1,4-butanediol from 1,4-butynediol by hydrogenation. The system includes a buffer tank, a hydrogenation reactor, an ejector, a magnetic capture separator, and an optional hydrocyclone. The material outlet of the buffer tank is connected to both the first inlet of the hydrogenation reactor and the first inlet of the ejector. The outlet of the ejector is connected to the second inlet of the hydrogenation reactor. The outlet of the hydrogenation reactor is connected to the inlet of the magnetic capture separator. The inlet of the magnetic capture separator is located at its lower part, and its lower outlet is connected to the second inlet of the ejector. The outlet of the magnetic capture separator is connected to the inlet of the hydrocyclone, and its outlet is located at the top of the hydrocyclone. This system and method enable continuous recycling of the catalyst, improving catalyst utilization efficiency and reducing catalyst consumption.

Description

Technical Field

[0001] This invention relates to the field of 1,4-butanediol preparation technology, and more specifically to a system and method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol. Background Technology

[0002] 1,4-Butanediol is an important basic organic chemical and fine chemical raw material with a wide range of applications. Its derivatives are high-value-added fine chemical products, widely used as solvents, in pharmaceuticals, cosmetics, plasticizers, curing agents, pesticides, rust removers, artificial leather, fibers, and engineering pigments. 1,4-Butanediol is also widely used as a raw material in the manufacture of tetrahydrofuran (THF), γ-butyrolactone (GBL), and N-methylpyrrolidone (NMP).

[0003] Currently, over 80% of 1,4-butanediol is produced via the Reppe process. Developed in 1930 by W. Reppe and others at Farben in Germany, the Reppe process was first industrialized by BASF in 1940. This method uses acetylene and formaldehyde as raw materials, first synthesizing 1,4-butynediol in the presence of a copper catalyst, then hydrogenating the 1,4-butynediol to produce 1,4-butanediol. The Reppe process technology can be divided into the classic high-pressure process, the medium-pressure process (collectively referred to as the high-pressure process), and the modified low-pressure process. Several companies worldwide possess Reppe process technology. Since 2009, influenced by factors such as the gradual decrease in technological barriers, the rapid development of downstream derivatives of 1,4-butanediol, and the uneven geographical distribution of domestic production enterprises, my country's 1,4-butanediol industry has entered a period of rapid development. Several companies, including Shaanxi Bidio Chemical Co., Ltd., Nanjing Lanxing Chemical New Materials Co., Ltd., Henan Kaixiang Fine Chemical Co., Ltd., and Sinopec Great Wall Energy & Chemical Ningxia Branch, have successively built or expanded production facilities. In these projects, the Reppe method holds an absolute advantage due to its relatively low cost (using coal as raw material).

[0004] By the end of 2016, China's 1,4-butanediol production capacity had exceeded 2.0 Mt, making it the world's largest producer of 1,4-butanediol. Although the expansion of 1,4-butanediol production capacity has stimulated the output of downstream industries such as resins and spandex, the overall apparent consumption of 1,4-butanediol is optimistically estimated at around 800 kt. Clearly, even assuming an average operating rate of 70%, there is a significant overcapacity of 1,4-butanediol in China. Currently, the maleic anhydride process is largely shut down due to cost pressures. "In an era of overcapacity, cost reduction" has become a consensus among 1,4-butanediol companies, who are reducing production costs by using domestically produced catalysts to replace imported ones, improving processes, and strengthening production management.

[0005] From a technical perspective, the Reppe process for 1,4-butanediol synthesis is now relatively mature. Catalysts for the hydrogenation of 1,4-butynediol to 1,4-butanediol have been developed into various commercial products. These catalysts are mainly reported in patent form, and due to the confidentiality of the technology, the preparation technology is controlled by a few foreign companies. Currently, in the 1,4-butanediol preparation process, the two-stage medium-pressure hydrogenation process proposed in CN1040530C involves intermittent recycling of the catalyst, resulting in low catalyst utilization and high catalyst consumption because the catalyst cannot be continuously recycled. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of existing technologies, such as the inability to continuously recycle catalysts, low catalyst utilization, and high catalyst consumption, and to provide a system and method for the hydrogenation of 1,4-butynediol to produce 1,4-butanediol. The system and method of this invention enable continuous recycling of the catalyst, thereby improving catalyst utilization efficiency and reducing catalyst consumption.

[0007] To achieve the above objectives, a first aspect of the present invention provides a system for the hydrogenation of 1,4-butynediol to produce 1,4-butanediol, wherein the hydrogenation catalyst used is a magnetically separable catalyst. The system includes: a buffer tank, a hydrogenation reactor, an ejector, a magnetic capture separator, and an optional hydrocyclone. The buffer tank includes a feed inlet, a fresh catalyst replenishment inlet, and a material outlet. The material outlet of the buffer tank is connected to both the first feed inlet of the hydrogenation reactor and the first feed inlet of the ejector. The outlet of the ejector is connected to the second feed inlet of the hydrogenation reactor. The outlet of the hydrogenation reactor is connected to the feed inlet of the magnetic capture separator. The feed inlet of the magnetic capture separator is located at the lower part of the magnetic capture separator. The lower outlet of the magnetic capture separator is connected to the second feed inlet of the ejector. The outlet of the magnetic capture separator is connected to the feed inlet of the hydrocyclone. The outlet of the hydrocyclone is located at the top of the hydrocyclone.

[0008] A second aspect of the present invention provides a method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol, which employs the aforementioned system, the method comprising:

[0009] An aqueous solution of 1,4-butynediol and optionally a fresh hydrogenation catalyst are fed into the hydrogenation reactor via the injector, and a hydrogenation reaction is carried out under the action of the hydrogenation catalyst to obtain a reaction mixture.

[0010] The reaction mixture is subjected to a first separation using a magnetic capture separator to obtain a first separated liquid. The first separated liquid is then post-treated to obtain 1,4-butanediol product. All or part of the separated hydrogenation catalyst is returned to the hydrogenation reactor via the injector for recycling.

[0011] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0012] 1) The system and method of the present invention utilize a combination of a magnetic capture separator, an ejector and a hydrocyclone to separate the catalyst from the 1,4-butanediol aqueous solution. In the magnetic capture separator, the catalyst particles are captured by the magnetic field, resulting in good fluidity and stable operation. After the catalyst is washed with washing water, it is returned to the reactor, reducing the impact of reaction products on the reaction, enabling continuous operation, convenient maintenance and low cost.

[0013] 2) The system and method of the present invention enable the continuous recycling of catalysts, which can improve the utilization efficiency of catalysts and reduce catalyst consumption.

[0014] 3) The system and method of the present invention can change the catalyst concentration of the reaction system and control the hydrogenation effect by changing the catalyst circulation rate, without the need to add or remove fresh catalyst, and have good operational flexibility and raw material adaptability. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of a system for producing 1,4-butanediol by hydrogenation of 1,4-butynediol according to one embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of a magnetic capture separator provided in one embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the structure of an injector provided in one embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram of the structure of a hydrocyclone separator provided in one embodiment of the present invention. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] The first aspect of this invention provides a system for the hydrogenation of 1,4-butynediol to produce 1,4-butanediol, wherein the hydrogenation catalyst used is a magnetically separable catalyst, such as... Figure 1-4 As shown, the system includes: a buffer tank A, a hydrogenation reactor B, an ejector F, a magnetic capture separator C, and an optional hydrocyclone separator D; wherein, the buffer tank A includes a 1,4-butynediol aqueous solution feed inlet A1, a fresh catalyst replenishment inlet A2, and a material outlet A3. The material outlet A3 of the buffer tank is connected via a feed pump E to the first feed inlet B1 of the hydrogenation reactor B and the first feed inlet F1 of the ejector F, respectively. The outlet F2 of the ejector F is connected to the second feed inlet B2 of the hydrogenation reactor. The outlet B3 of the hydrogenation reactor is connected to the inlet C1 of the magnetic capture separator C; the inlet C1 of the magnetic capture separator C is located at the lower part of the magnetic capture separator C; the lower outlet C2 of the magnetic capture separator C is connected to the second inlet F3 of the ejector F; the outlet C3 of the magnetic capture separator C is connected to the inlet D1 of the hydrocyclone separator D; and the outlet D2 of the hydrocyclone separator D is located at the top of the hydrocyclone separator D and is used to discharge 1,4-butanediol aqueous solution.

[0021] This invention integrates magnetic capture, aggregation, and washing functions, reduces the magnetic field requirements, broadens the range of operating parameters, and is the first to be applied in the production of 1,4-butanediol.

[0022] The system of this invention combines a magnetic capture separator with an injector and other equipment, enabling continuous recycling of the catalyst in the hydrogenation of 1,4-butynediol to 1,4-butanediol. It features a short process, simple equipment, and continuous operation, avoiding the drawbacks of intermittent operation and pressure reduction / increase operation of catalyst capture and transportation.

[0023] In this invention, a hydrocyclone separator is optional, but it is preferred to add one in order to further improve the catalyst separation degree.

[0024] In this invention, the buffer tank serves two purposes: first, to stabilize the flow rate of the feedstock 1,4-butynediol into the hydrogenation reactor; and second, to ensure uniform mixing of the feedstock 1,4-butynediol with the fresh hydrogenation catalyst when fresh catalyst replenishment is required. The hydrogenation reactor is used to realize the hydrogenation reaction of 1,4-butynediol.

[0025] The injector of the present invention can be used in high-pressure environments and with high-concentration slurry inlet concentrations. It has a slurry flow rate regulation function to meet the process requirements for catalyst concentration regulation in the reaction system.

[0026] The working fluid used in the injector of this invention is derived from an aqueous solution of 1,4-butynediol, and the pressure only needs to meet the operating requirements of the injector. The injector of this invention is a hydraulic injector, vertically installed in the gas phase space at the top of the hydrogenation reactor. After the working fluid and catalyst slurry are mixed in the mixing chamber, they are directly fed into the hydrogenation reactor. The basic structure of the injector is as follows: Figure 3 As shown.

[0027] This invention utilizes the principle of kinetic-static energy conversion in a Venturi tube. When a high-pressure working fluid is injected through a nozzle, its kinetic energy increases while its pressure energy decreases, creating a relatively low-pressure zone (mixing chamber). This zone draws in the liquid to be absorbed, which is then mixed and fed into a narrowing pipe section. The pipe diameter gradually increases, the flow velocity gradually decreases, and the pressure gradually increases, thus achieving the transport of a high-concentration solid slurry. The working fluid originates from a 1,4-butynediol aqueous solution, while the absorbed slurry is from a magnetic capture separator. Due to the pressure difference between the mixing chamber and the magnetic capture separator, the high-concentration slurry is "drawn in" by the low-pressure zone. By controlling the flow rate of the working fluid, this pressure difference can be controlled, thereby adjusting the flow rate of the "drawn in" slurry and controlling the slurry transport, thus controlling the catalyst concentration in the reactor.

[0028] The magnetic capture separator used in this invention uses an external magnetic field for liquid-solid separation. The magnetic field is generated by a magnetic induction coil that is looped around the outside of the device, which can separate the magnetically separable catalyst from the fluid.

[0029] The hydrocyclone separator of this invention is located after the magnetic capture separator. The 1,4-butanediol aqueous solution exiting from the top of the magnetic capture separator enters the hydrocyclone separator. A small amount of solid particles entering the hydrocyclone separator are concentrated again at its bottom and flow out in slurry form, continuously flowing to the reaction feed buffer tank, and then being pumped back to the reaction system for recycling via a raw material feed pump. The hydrocyclone separator used in this invention is a device of hydrocyclone separation technology. Based on the hydrocyclone theory of fluid mechanics, it employs guiding, diversion, and eddy suppression techniques, using a liquid as the carrier medium. The suspension is tangentially input into the hydrocyclone chamber under high pressure. Based on the difference in specific gravity and particle size, the particles and liquid are separated through swirling flow. The structure of the hydrocyclone separator is as follows... Figure 4 As shown, the equipment has an inlet D1, a clarified liquid outlet D2, and a mixed slurry outlet D3. According to the design, it can separate solid particles of 1-120μm, with an inlet slurry concentration ≤30wt% and a throughput range of 10-20m³. 3 / h, corresponding to an inlet and outlet pressure difference of 0.2-0.5MPa. When the throughput is 15m³ / h. 3At a rate of / h, the pressure difference is approximately 0.45 MPa. The turbid liquid discharged from the bottom of the hydrocyclone separator has a catalyst content related to the feed catalyst concentration level, approximately 0-20 wt%, while the catalyst content of the clear liquid is <6 ppmwt (referring to catalyst particle size of 80-120 mesh). According to measurements, when the bottom pore size is... At that time, its turbidity flow rate remained constant within the operating range, approximately 2-3.5 L / min.

[0030] In this invention, the injector, magnetic capture separator, and hydrocyclone all operate continuously. The catalyst solid-liquid separation and circulation system, composed of the injector, magnetic capture separator, and hydrocyclone, serves two purposes: first, to perform solid-liquid separation of the hydrogenated 1,4-butanediol aqueous solution; and second, to achieve continuous catalyst recycling. In existing processes for hydrogenating 1,4-butynediol to 1,4-butanediol, the catalyst is mostly used in a single-pass or intermittent circulation manner. This results in either very low catalyst utilization or complex and costly recycling operations. This invention achieves continuous catalyst recycling, thereby improving catalyst utilization efficiency and reducing catalyst consumption.

[0031] In some embodiments of the present invention, such as Figure 2 As shown, the magnetic capture separator C includes:

[0032] A vertical container 1 includes an upper cylinder 11 and a lower cylinder 12; the top of the upper cylinder 11 is provided with a clear liquid outlet N2 for discharging the clear liquid after the catalyst is separated; the side wall of the lower cylinder 12 is provided with a slurry inlet N7 for adding slurry containing the catalyst.

[0033] At least two electromagnetic coils 2 are respectively looped around the outside of the upper cylinder 11 and arranged along the axial direction of the upper cylinder 11; and

[0034] The central tube 3 is located at the bottom of the lower cylinder 12 and extends into the interior of the lower cylinder 12; a washing water inlet N10 is provided at the bottom of the central tube 3; and a catalyst outlet N8 is also provided on the central tube 3 for discharging the separated catalyst.

[0035] The magnetic capture separator of the present invention comprises at least two Helmholtz coils, each independently connected to a transformer. The Helmholtz coils provide a magnetic field, which captures and aggregates the magnetic catalyst under the influence of the magnetic field. The catalyst then flows out of the central tube under gravity, and new catalyst continuously flows out of the central tube as the catalyst flows out.

[0036] In this invention, the effect of magnetic separation on solid catalyst particles comes from two aspects. One is the presence of a magnetic medium, such as iron, which can be attracted by a magnet. Preferably, the solid catalyst particles are larger than 100 mesh and have a significantly higher density than the liquid (i.e., a settling time of less than 20 seconds in a static liquid). Typical examples include industrial-grade Raney nickel and amorphous nickel particles. The other factor is the upward fluid velocity. Simultaneously, the density of the solid particles must be greater than that of the fluid, thus the solid naturally has the property of settling in a static fluid. When the upward flow velocity of the fluid exceeds the initial fluidization velocity of the bed, the bed expands, and the particles tend to fluidize. At this point, turning on the magnetic field causes the bed to immediately tighten, requiring an even higher flow velocity to expand and fluidize again. Therefore, the magnetic field significantly increases the initial fluidization velocity of the bed, thereby increasing the processing air velocity and reducing equipment size. The magnetic capture separator of this invention can simultaneously perform capture, washing, and high-concentration slurry transport operations.

[0037] In this invention, the upper cylinder 11 and the lower cylinder 12 are connected by a flange 13.

[0038] In this invention, the washing water inlet N10 is located at the bottom of the central tube 3, through which process water can be introduced to wash away the reaction products adhering to the catalyst surface, thereby reducing the pollution of the reaction system during recycling.

[0039] In this invention, the catalyst is a magnetically separable catalyst, specifically a solid particle containing magnetic material. Preferably, the magnetic capture separator C of this invention can capture and recover fine catalyst particles, and preferably the catalyst particle size is greater than 100 mesh.

[0040] The magnetic capture separator C of the present invention, such as Figure 1 As shown, it also includes pressure gauge mounting port K1, pressure gauge mounting port K3, and thermometer mounting port K2, as well as other auxiliary instrument ports.

[0041] In some embodiments of the present invention, the length-to-diameter ratio of the vertical container is 4-8:1, for example, 4:1, 5:1, 6:1, 7:1, 8:1, and any value within the range of any two values, preferably 5-6:1.

[0042] In some embodiments, the height Dk of the vertical container is 3-10m, preferably 5-7m.

[0043] In some embodiments of the present invention, the ratio of the length of the upper cylinder to the length of the lower cylinder is 5-9:1, for example, 5:1, 6:1, 7:1, 8:1, 9:1, and any value within the range of any two values, preferably 6-8:1.

[0044] In some embodiments of the present invention, the length-to-diameter ratio of the central tube is 4-12:1, for example, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, and any value within the range of any two values, preferably 6-10:1. The length-to-diameter ratio of the central tube must meet the washing requirements; if it is too short, the washing will not be sufficient; if it is too long, installation will be inconvenient.

[0045] In some embodiments of the present invention, the ratio of the diameter of the central tube to the diameter of the lower cylinder is 0.05-0.3:1, for example, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, and any value within the range of any two values, preferably 0.1-0.25:1. If the ratio of the diameter of the central tube to the diameter of the lower cylinder is too large, the catalyst separation degree is low and the washing liquid volume is large; if the ratio of the diameter of the central tube to the diameter of the lower cylinder is too small, the catalyst is not easy to flow out from the central tube.

[0046] In some embodiments of the present invention, the diameter of the upper cylinder is the same as the diameter of the lower cylinder.

[0047] In some embodiments of the present invention, the upper opening of the central tube is higher than the liquid inlet.

[0048] In this invention, the length of the central tube must first meet the washing requirements. If the central tube is too short, washing will be insufficient; if the central tube is too long, installation will be inconvenient. If the feed inlet is too high, the area below the feed inlet will become a fluid dead zone, resulting in wasted space. Furthermore, for smaller central tubes (e.g., 25mm diameter), the flushing effect at the feed inlet can prevent catalyst bridging at the central tube inlet, thus preventing the catalyst from exiting the central tube. For larger diameters (greater than 50mm), the flushing effect can be ignored.

[0049] In some preferred embodiments of the present invention, the upper opening of the central tube is 30-200 mm higher than the liquid inlet, for example, any value in the range of 30 mm, 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, and any two of these values, preferably 50-150 mm higher.

[0050] In this invention, the bottom of the lower cylinder 12 is also provided with a catalyst discharge outlet N9, which is used to completely discharge the catalyst during shutdown and accident handling. The top of the upper cylinder 11 is also provided with a fresh catalyst replenishment port N1, and a fresh catalyst feeding pipeline is provided at the fresh catalyst replenishment port N1, which extends into the interior of the upper cylinder 11 for adding fresh catalyst.

[0051] In this invention, after the catalyst is discharged, fresh catalyst needs to be added to maintain the catalyst interface position in the magnetic separator. The catalyst in the magnetic separator can be maintained in quantity and activity through intermittent input and output, or through continuous input and output to maintain catalyst balance. Both methods require that fresh catalyst be added to the system promptly before the catalyst becomes deactivated; otherwise, the hydrogenation quality will not meet requirements. Simultaneously, a catalyst discharge line is arranged at the bottom of the magnetic separator for completely discharging the catalyst from the magnetic separator when necessary, typically used during shutdowns and accident handling.

[0052] In some embodiments of the present invention, the magnetic capture separator comprises 2-16 electromagnetic coils, for example, any value within the range of 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, or any two of these values, preferably 4-10 electromagnetic coils. Adjacent groups of electromagnetic coils are of the same size, and the magnetic field strength can be adjusted according to the actual separation situation.

[0053] In this invention, the current and voltage of the electromagnetic coils are supplied by two cabinets respectively. Each group consists of 2-4 electromagnetic coils and one cabinet. The voltage is adjusted between 50V and 200V, and the current is controlled by adjusting the voltage to keep the current constant at 10-14A.

[0054] In this invention, the basic structure of the magnetic capture separator is as follows: Figure 2 As shown, 2-16 Holmes magnetic induction coils are looped around a cylindrical container with a high aspect ratio. The size of the magnetic capture separator can be designed according to the amount of hydrogenation catalyst in the hydrogenation reactor, and the volume of the magnetic capture separator is approximately 1-2 times the volume required for the amount of hydrogenation catalyst in the hydrogenation reactor.

[0055] In some embodiments of the present invention, the interval between two adjacent sets of electromagnetic coils is 0.5-5m, for example, 0.5m, 1m, 2m, 3m, 4m, 5m, and any value in the range of any two values, preferably 1-4m.

[0056] In some embodiments of the present invention, the height Db of each set of electromagnetic coils is 0.1-1m, for example, 0.1m, 0.2m, 0.3m, 0.4m, 0.5m, 0.6m, 0.7m, 0.8m, 0.9m, 1m, and any value within the range of any two values, preferably 0.4-0.8m.

[0057] In some embodiments of the present invention, the inner diameter of each set of electromagnetic coils is 0.5-3m, for example, 0.5m, 0.8m, 1m, 1.5m, 2m, 2.5m, 3m, or any value within the range of any two values; the outer diameter is 1.0-4m, for example, 1m, 1.5m, 2m, 2.5m, 3m, 3.5m, 4m, or any value within the range of any two values.

[0058] In some embodiments of the present invention, each set of electromagnetic coils 2 is provided with a water inlet N3a and a water outlet N3b to reduce the temperature of the electromagnetic coils so as to ensure that the operating temperature of the electromagnetic coils is 40-70°C.

[0059] In this invention, water is introduced into the inlet of each electromagnetic coil and discharged from the outlet to cool the electromagnetic coil and dissipate the heat generated by the electromagnetic coil in a timely manner.

[0060] In this invention, a thermocouple is embedded in the middle of the electromagnetic coil to detect the temperature rise. The electromagnetic coil is cooled according to the temperature rise. Forced water cooling can be used, with cooling water entering from N3a and exiting from N3b after heat extraction.

[0061] In this invention, the magnetic capture separator C further includes a current sensor for monitoring the current in each electromagnetic coil. A current alarm is mounted on the current sensor, and the current alarm is set to a value of 6A-10A.

[0062] In this invention, when a low current alarm is triggered, to prevent the catalyst inside the magnetic capture separator from being carried out due to demagnetization, an interlock action is activated to shut off the valve and stop the discharge. The cause of the low current is quickly identified, the fault is promptly eliminated, and normal operation is restored.

[0063] In some embodiments of the invention, the magnetic capture separator C further includes a current sensor for monitoring the current in each electromagnetic coil.

[0064] In some embodiments of the present invention, a current alarm is provided on the current sensor, and the current alarm is set to 6A-10A.

[0065] In this invention, when a low current alarm is triggered, to prevent the catalyst in the magnetic capture separator C from being carried out due to demagnetization, an interlock action is activated to shut off the valve and stop the discharge. The cause of the low current is quickly identified, the fault is promptly eliminated, and normal operation is restored.

[0066] In some embodiments of the present invention, such as Figure 1 and Figure 3As shown, the first feed port F1 of the injector F is located at the top of the injector F, the second feed port F3 of the injector F is located at the upper part of the injector F and the second feed port F3 is perpendicular to the first feed port F1, and the discharge port F2 of the injector F is located at the bottom of the injector F.

[0067] In this invention, the flow rate out of the injector = the catalyst flow rate entering the injector from the magnetic separator + the working fluid flow rate of the injector.

[0068] This invention utilizes an ejector under conditions of high slurry inlet concentration and pressure, featuring a method for regulating slurry flow rate and an anti-clogging mechanism and structural design for the ejector. The ejector of this invention functions as both a slurry flow rate regulator and a catalyst concentration regulator in the reaction system. By employing the ejector, high-concentration, high-inlet-pressure slurry transport is achieved, reducing the number of equipment and the process flow. This invention combines the ejector with a magnetic capture separator, representing the essence of solid capture, solid-liquid transport, control, and reaction concentration control.

[0069] Considering the equipment installation, the parts of the ejector that might require casting are placed inside the reactor, sharing the same pressure as the reaction system, thus not functioning as a pressure vessel. The parts extending out of the reactor are all machined, and their construction and manufacturing according to pressure vessel specifications present no difficulties.

[0070] The hydrogenation reactor used in this invention is designed to maintain a uniform dispersion of catalyst particles smaller than 50 micrometers, while ensuring that the gas retention rate in the liquid is maintained between 5-10%. The hydrogenation reactor can be selected from stirred tank or straight-tube slurry bed types. The gas-liquid separation residence time in the reactor is approximately 15-30 minutes. The reactor is equipped with a propeller-type agitator, and the agitator uses a magnetic seal or mechanical seal. An aqueous solution of 1,4-butynediol is used as the coolant or sealing fluid. The stirring effect is enhanced by installing four baffles along the inner wall of the stirred tank.

[0071] In some embodiments of the present invention, the hydrogenation reactor is a slurry bed reactor; preferably, the number of hydrogenation reactors is one or more connected in series, more preferably two to three connected in series.

[0072] For the production of 1,4-butanediol, the tandem process can select a reactant concentration distribution that results in a higher reaction rate and a smaller equipment volume. For the production of 1,4-butenediol as a secondary product, the tandem process can extract the intermediate product in a reactor with the highest concentration of 1,4-butenediol and a lower concentration of byproducts, thus obtaining corresponding benefits.

[0073] In some embodiments of the present invention, such as Figure 1As shown, the hydrogenation reactor B is also provided with a hydrogen inlet B4 and a post-reaction gas outlet B5; the bottom outlet D3 of the hydrocyclone D is connected to the buffer tank A, and a catalyst outlet D4 is also provided on the connecting pipe between the bottom outlet D3 of the hydrocyclone D and the buffer tank A.

[0074] In some embodiments of the present invention, a set of separation devices is formed by one ejector F, one magnetic capture separator C, and one optional hydrocyclone separator D; the system includes one or more sets of parallel separation devices.

[0075] The number of parallel separation units in this invention can be determined by the size of the magnetic separator used, the amount of catalyst to be processed, and the amount of reactants.

[0076] A second aspect of the present invention provides a method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol, which employs the aforementioned system, such as... Figure 1 As shown, the method includes:

[0077] An aqueous solution of butynediol and optionally a fresh hydrogenation catalyst are fed into the hydrogenation reactor B via the injector F. Under the action of the hydrogenation catalyst, a hydrogenation reaction is carried out to obtain a reaction mixture.

[0078] The reaction mixture is subjected to a first separation in a magnetic capture separator C to obtain a first separated liquid. The first separated liquid is then post-treated to obtain 1,4-butanediol product. All or part of the separated hydrogenation catalyst is returned to the hydrogenation reactor B via the injector F for recycling.

[0079] In this invention, the reaction mixture is a mixture of the reaction product after the hydrogenation reaction of 1,4-butynediol and the hydrogenation catalyst, including 1,4-butanediol, hydrogenation catalyst, water, and a small amount of by-reaction products including ∑C3ol, ∑C4ol, etc.

[0080] In this invention, fresh hydrogenation catalyst can be added along with the raw material through the fresh catalyst replenishment port A2 in the buffer tank, or through the fresh catalyst replenishment port N1 of the magnetic capture separator, and then sent into the reactor through an injector.

[0081] The catalyst used in this invention has the characteristics of being magnetizable, fine-particle, high-density, and flowing with the reactants. A technical route integrating catalyst capture, catalyst washing, and catalyst transportation and recycling has been designed to achieve continuous operation.

[0082] High-concentration solid particle transport can damage the mechanical seals of pumps. The higher the concentration, the greater the chance of damage; the higher the pressure, the greater the damage. Typically, centrifugal pumps require the solid slurry concentration not to exceed 15%, with some exceptions allowing 25%, but operation is at or near atmospheric pressure. Therefore, existing technologies struggle to achieve solid-liquid transport under high concentration and high inlet pressure. Existing methods primarily employ continuous capture and intermittent release mechanisms. Some can achieve high-pressure capture, but release requires a return to low pressure. This invention achieves the capture, washing, and transport of high-concentration slurries (20-30%) under high pressure, while maintaining continuity in all unit operations.

[0083] This invention uses a catalyst containing magnetizable components as the hydrogenation catalyst, which is for single-use. The catalyst concentration in the slurry-bed reaction system is between 1% and 5%. The amount of deactivation depends on the reaction system; for this process, the total amount of deactivation and loss is generally considered to be 0.02 kg / ton of processing capacity. Continuous or intermittent replenishment of this loss can maintain constant hydrogenation efficiency. If the reaction effect is unsatisfactory, the amount of catalyst replenished needs to be increased, and a corresponding amount of recycled catalyst needs to be removed. Recycling the hydrogenation catalyst is more reasonable and economical than the traditional single-use approach.

[0084] In this invention, the role of hydrocyclone separation is to further improve the separation degree of the catalyst. If the requirements for catalyst separation are not very high, hydrocyclone separators may not be used.

[0085] In some embodiments of the present invention, the post-processing includes: subjecting the first separated liquid to a second separation via the hydrocyclone D to obtain a second separated liquid; then refining the second separated liquid to obtain 1,4-butanediol product, and returning all or part of the separated hydrogenation catalyst to the buffer tank A.

[0086] Specifically, such as Figure 1As shown, an aqueous solution of 1,4-butynediol enters buffer tank A through a feed pipeline. In buffer tank A, various materials are dispersed and mixed. Then, a portion is pumped by pump E into hydrogenation reactor B, and the remaining portion into ejector F. Hydrogen gas is piped into hydrogenation reactor B, where a hydrogenation reaction takes place. The resulting aqueous solution of 1,4-butynediol containing solid particulate catalyst enters magnetic capture separator C through a pipeline. The gas produced after the reaction is discharged through a pipeline; this gas contains a large amount of hydrogen and can be recycled using a circulating compressor (not shown in the diagram). The solid catalyst and a small amount of liquid enter ejector F from the bottom of the magnetic capture separator and are directly returned to hydrogenation reactor B. The effluent from the top of magnetic capture separator C, containing a small amount of solid catalyst, enters hydrocyclone D through a pipeline. The clarified aqueous solution of 1,4-butynediol is sent to downstream units through the top pipeline of the hydrocyclone, while the turbid liquid containing solid catalyst is returned to buffer tank A through a pipeline. When the catalyst activity is very low, fresh catalyst can be added to buffer tank A through the pipeline, and low-activity catalyst can be taken out intermittently or continuously through the pipeline.

[0087] The magnetic capture separator of this invention can capture and aggregate magnetically separable catalysts from fluids, thereby separating the hydrogenation catalyst from the fluid and clarifying the fluid. Its main working principle is as follows: Fluid containing solid catalyst particles enters the magnetic capture separator and passes through a dense magnetic field zone from bottom to top. The solid catalyst particles are aggregated into a specific state under the combined action of the magnetic field and the fluid. In this state, the solid catalyst particles gradually aggregate into clusters under the influence of the magnetic field. After reaching a certain weight, they settle downwards under gravity. Throughout this process, the solid catalyst particles are in a relatively stable state of motion. Finally, the solid catalyst particles captured and aggregated by the magnetic field are led out through a central tube, washed, and returned directly to the hydrogenation reactor from the catalyst outlet. The clarified liquid continues to flow upwards from the top clarified liquid outlet. This process achieves continuous separation and washing of catalyst particles, resulting in high catalyst recovery and simple operation.

[0088] In this invention, most of the catalyst is separated by the magnetic capture separator, with only a small portion entering the hydrocyclone separator for further separation. Through this two-step separation process using both the magnetic capture separator and the hydrocyclone separator, almost all of the catalyst can be recovered and recycled. This method enables continuous catalyst capture and transport under high pressure and high concentration, with adjustable flow rate.

[0089] When the catalyst activity is very low, remove the deactivated catalyst and replenish it with fresh catalyst at the same time.

[0090] According to the method for continuous cyclic production of 1,4-butanediol provided by the present invention, the concentration of the catalyst in the hydrogenation reactor can be flexibly adjusted as needed. In principle, when the quality of the raw material is poor or an improved hydrogenation effect is required, the catalyst concentration often needs to be increased. In existing 1,4-butanediol production processes, increasing the catalyst concentration can only be achieved by increasing the amount of fresh catalyst added. Since the catalyst is used only once, catalyst consumption is therefore high. The method of the present invention achieves this by changing the continuous circulation rate of the catalyst, avoiding the problem of significantly increasing the amount of fresh catalyst used, thus providing good operational flexibility and raw material adaptability. The adjustment of the catalyst concentration needs to consider various factors such as raw material quality, hydrogenation effect, catalyst performance, and the separation effect of magnetic separation and hydrocyclone separators. The catalyst concentration range is generally 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any value within any range of two such values.

[0091] In some embodiments of the present invention, the first separation liquid is an aqueous solution of 1,4-butanediol containing a small amount of hydrogenation catalyst, wherein the concentration of the hydrogenation catalyst in the first separation liquid is 0-0.5 wt%, for example 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, and any value within the range of any two values.

[0092] In some embodiments of the present invention, the second separation liquid is an aqueous solution of 1,4-butanediol containing a small amount of hydrogenation catalyst, wherein the concentration of the hydrogenation catalyst in the second separation liquid is 0-0.2 wt%, for example 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, and any value within the range of any two values.

[0093] In this invention, the lower the concentration of the hydrogenation catalyst, the better, as it will not waste the catalyst and the product purity will be higher. However, the lower the catalyst concentration, the more stringent the separation conditions are and the higher the cost. The separation conditions are balanced while meeting the product requirements.

[0094] Key parameters of the method of this invention include: catalyst concentration in the reaction system (related to slurry concentration, slurry flow rate, and reactant flow rate), reaction temperature (related to catalyst concentration, hydrogen flow rate, and 1,4-butynediol concentration), reaction pressure (related to hydrogen flow rate and hydrogen emission), and catalyst holdup in the reaction system (related to liquid phase volume, catalyst concentration, magnetic field strength of the magnetic capture separator, liquid hourly space velocity of the magnetic capture separator, and liquid-solid bed volume of the magnetic capture separator). Controlling and maintaining the catalyst concentration in the reaction system is a challenge in this method. This invention controls the working fluid of the ejector pump to originate from the reactant or reaction liquid. The magnitude of this flow does not affect the reaction effect, but it has a significant effect on reducing the slurry concentration at the ejector outlet and on regulating the inlet slurry flow rate. Therefore, the ejector acts as a regulator of the slurry flow rate and, consequently, a regulator of the catalyst concentration in the reaction system. Adjusting the catalyst concentration according to the reaction effect can be achieved by adjusting the working fluid of the ejector.

[0095] In some embodiments of the present invention, depending on the activity level of the hydrogenation catalyst, the used hydrogenation catalyst is removed and / or fresh hydrogenation catalyst is added, wherein the removal is instantaneous and continuous or intermittent and periodic, and the addition is instantaneous and continuous or intermittent and periodic.

[0096] In this invention, excluding deactivation and loss, the catalyst recycling rate is 100%. The amount of deactivation is related to the reaction system; for this process, the total amount of deactivation and loss is generally considered to be 0.02 kg / ton of processing capacity. Continuous or intermittent replenishment of this loss can maintain constant hydrogenation efficiency. If the reaction effect is unsatisfactory, the catalyst replenishment amount needs to be increased, and a corresponding amount of recycled catalyst needs to be removed. It cannot be guaranteed that all removed catalyst is deactivated, but it is certainly more reasonable and economical than the traditional method of single-use.

[0097] In some embodiments of the present invention, the concentration of the 1,4-butynediol aqueous solution is 25-60 wt%, for example, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, and any value within a range of any two values.

[0098] The effect of the mass fraction of 1,4-butynediol on catalytic performance was investigated under reaction conditions of 2.0 MPa, pH = 8.5, and reaction temperature of 60-70℃. Two 1,4-butynediol feedstocks were used: one was a 1,4-butynediol solution with a mass fraction of approximately 40% from the production unit of the Ningxia branch; the other was purchased 1,4-butynediol solid (mass fraction 99%). Two methods were used to obtain 1,4-butynediol solutions of different concentrations: one method involved diluting the 1,4-butynediol solution with deionized water, and the other involved diluting it with industrial 1,4-butynediol product (mass fraction 99%).

[0099] The effects of a 1,4-butynediol mass fraction of 10%-50% on the selectivity of 1,4-butynediol and the selectivity of byproducts n-butanol, hydroxybutyraldehyde, and TBA are as follows: The lower the 1,4-butynediol mass fraction, the higher the 1,4-butanediol selectivity and the fewer byproducts generated; when the butynediol mass fraction is low, the byproduct n-butanol can be maintained at a low level; when the raw material mass fraction is greater than 30%, the butanediol selectivity decreases significantly. Considering all factors, a 1,4-butynediol mass fraction of 25%-40% in the reaction solution is optimal, but not limited to this concentration. Therefore, the advantage is that higher 1,4-butanediol selectivity results in fewer byproducts.

[0100] In some embodiments of the present invention, during the hydrogenation reaction, the amount of gas retained in the liquid is controlled to be 5-10 wt%, for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, and any value within the range of any two values.

[0101] The hydrogenation reaction is designed to require a certain amount of gas retention to proceed. Studies have shown that 5-10% is sufficient to sustain the hydrogenation reaction.

[0102] In some embodiments of the present invention, during the hydrogenation reaction, the concentration of the hydrogenation catalyst is controlled to be 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and any value within the range of any two values.

[0103] In some embodiments of the present invention, the hydrogenation catalyst is a solid particle containing magnetic material, preferably a nickel catalyst, an amorphous alloy catalyst with nickel as the main active component, or a supported catalyst with nickel and iron as the main active components.

[0104] In some embodiments of the present invention, the particle size of the hydrogenation catalyst is greater than 100 mesh. Preferably, the particle size of the hydrogenation catalyst is 5-150 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 50 μm, 80 μm, 100 μm, 130 μm, 150 μm, and any value within the range of any two values, preferably 30-100 μm.

[0105] The hydrogenation catalyst used in this invention is a solid particulate catalyst with a certain particle size that can be magnetized, preferably a highly hydrogenation-active amorphous nickel catalyst. To eliminate the influence of internal diffusion on reactant concentration and rate, catalyst particles with a particle size of less than 80 μm are selected, preferably less than 50 μm.

[0106] In some embodiments of the present invention, the reaction conditions for the hydrogenation reaction are: temperature of 40-70°C, preferably 50-60°C; pressure of 1-4 MPa, preferably 2-3 MPa; pH value greater than 7, preferably 7-9; residence time of 4-8 h, preferably 5-7 h.

[0107] In this invention, the hydrogenation reaction temperature significantly affects the product yield and has a substantial impact on byproduct formation. Therefore, to minimize byproduct generation, while ensuring complete conversion of 1,4-butynediol, the temperature should be controlled as low as possible below 40-70°C, preferably 50-60°C, to achieve greater selectivity for the target product, 1,4-butanediol. The reaction pressure is generally 1-4 MPa, preferably 1.5-3 MPa. Higher reaction pressure can accelerate the reaction rate and reduce byproduct formation, but higher pressure also increases equipment investment. The reaction residence time is related to the reaction temperature, reaction pressure, and catalyst concentration, and is generally 4-8 hours, which can be adjusted according to specific circumstances.

[0108] All pressures in this invention are gauge pressures.

[0109] According to a particularly preferred embodiment of the present invention, a method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol using a continuously circulating catalyst includes the following steps:

[0110] (1) The 1,4-butynediol aqueous solution from the upstream is prepared and sent to the hydrogenation reactor. It is in contact with hydrogen in the presence of a magnetizable solid particle hydrogenation catalyst. The hydrogenation reaction is carried out at a temperature of 40-70℃, a pressure of 1-4MPa, a residence time of 4-8h, and a catalyst concentration of 1-5wt%.

[0111] (2) After hydrogenation, the 1,4-butanediol aqueous solution containing solid particulate catalyst is first introduced into the lower part of the magnetic capture separator. The catalyst particles are concentrated in the magnetic field area of ​​the magnetic capture separator. The solid content depends on the magnetic field strength and is about 15-45%. It is led out from the washing channel to the mixing chamber inlet of the ejector and fed into the reactor under the action of the ejector working fluid. The 1,4-butanediol aqueous solution containing a small amount of catalyst particles exiting from the top of the magnetic capture separator enters the hydrocyclone separator. The small amount of solid particles are concentrated at the bottom and flow out in the form of turbid liquid. It flows continuously into the buffer tank and is sent to the hydrogenation reactor for recycling by the feed pump. The clear liquid is the 1,4-butanediol aqueous solution after hydrogenation reaction. After appropriate filtration to remove trace particles, it is sent to the subsequent system. The magnetic capture separator, ejector and hydrocyclone separator are all continuously operated.

[0112] (3) Based on the activity level of the catalyst, the deactivated catalyst is taken out and sent to the catalyst settling tank for settling and solid-liquid separation. All the solid part of the catalyst is unloaded into the transport vehicle or the tank, thus completing the unloading of the deactivated catalyst from the system.

[0113] The raw material used in this invention is an aqueous solution of 1,4-butynediol with a mass fraction of 25%-60% and an alkaline pH. The lower the mass fraction of 1,4-butynediol, the higher the selectivity of 1,4-butanediol and the fewer byproducts generated. When the mass fraction of 1,4-butynediol is low, the byproduct n-butanol can be maintained at a low level. When the mass fraction of the raw material is greater than 30%, the selectivity of 1,4-butanediol decreases significantly. Alkaline conditions are beneficial to the formation of 1,4-butanediol and the reduction of byproducts.

[0114] In step (2), the 1,4-butanediol aqueous solution containing solid particulate catalyst after hydrogenation is introduced into the lower part of the magnetic capture separator, passing through the magnetic field zone from bottom to top. The catalyst aggregates under the combined action of the magnetic field and the fluid, resulting in the 1,4-butanediol aqueous solution containing only a small amount of solid catalyst. The amount of catalyst in the magnetic capture separator serves as the buffer for the entire cycle, acting as a buffer for catalyst circulation and being retained. The 1,4-butanediol aqueous solution flows out from the top of the magnetic capture separator and into the hydrocyclone separator.

[0115] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0116] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0117] In the following examples, the catalyst used is an amorphous high-hydrogenation-activity nickel catalyst, the specifications of which are shown in Table 1. Figure 2The data for the magnetic capture separator shown are in Table 2, such as... Figure 3 The data for the injectors shown are in Table 3, such as... Figure 4 The data for the hydrocyclone separator shown are in Table 4, the magnetic separation design conditions are in Table 5, and the electromagnetic coil design conditions are in Table 6.

[0118] Table 1 Specifications of Amorphous Catalysts

[0119]

[0120] Table 2 Specifications of magnetic capture separators, in mm.

[0121] Da Db Dc Dd De Df Dg Dh Di 3320 680 400 200 150 800 300 700 1600 Dj Dk Dl Dm Dn Do Dp Dq 2800 5590 670 200 1000 2100 1200 100

[0122] Table 3. Specifications of the injector, in mm.

[0123] Da Db Dc Dd De Df Dg Dh 15.4 9.0 10 70 12 4.5 3.0 13 Di Dj Dk Dl Dm Dn Do 8 54 35 20 17.1 156.5 30.3

[0124] Table 4 Specifications of hydrocyclones, in mm

[0125] Da Db Dc Dd 1576 150 230 120

[0126] Table 5. Design conditions data for magnetic separators

[0127]

[0128] Table 6. Electromagnetic Coil Design Conditions Data

[0129] project Electromagnetic coil design conditions Operating temperature (ambient), °C 60 Operating cycle, h / a 7200 Magnetic field induction intensity, Gauss 600 Magnetic field voltage, V Adjustable, 380V rectified to 330V Current, A 12 Coil inner diameter, mm 1200 Coil outer diameter, mm 2100 Number of coils, 4 Height of each coil, mm 650 Coil mounting spacing, mm 300 electromagnetic coil material Copper Power, kW 3.2 Coil weight / piece, kg 44600 Connection method Four coils are connected in parallel, in pairs.

[0130] Example 1

[0131] This embodiment illustrates the effect of the magnetic capture separator, ejector, and hydrocyclone separator used in this invention on solid-liquid separation.

[0132] like Figure 1 As shown, a purified 1,4-butynediol aqueous solution from the upstream unit, with a 1,4-butynediol concentration of 53.8 wt%, a temperature of 55 °C, a pressure of 1.899 MPa, and a flow rate of 8610 kg / h, enters buffer tank A. In buffer tank A, it is mixed with process water and sodium hydroxide solution to prepare a reaction feedstock with a 1,4-butynediol concentration of 50 wt% and a pH of 8.5. The prepared feedstock is then pumped into hydrogenation reactor B, where it reacts with hydrogen at a reaction temperature of 55 °C, a pressure of 2 MPa, and a hydrogenation catalyst concentration of 2 wt% for 6 hours. The results are as follows:

[0133] The conversion rate of 1,4-butynediol was 100 wt%, the selectivity of 1,4-butanediol was 91.4 wt%, the concentration of hydrogenation catalyst in the 1,4-butanediol aqueous solution exiting the top of the magnetic capture separator was 0.02 wt%, and the concentration of hydrogenation catalyst in the 1,4-butanediol aqueous solution exiting the hydrocyclone was 0.01 wt%. The results show that almost all the catalyst was separated from the 1,4-butanediol aqueous solution after passing through the magnetic capture separator and the hydrocyclone, and the catalyst was continuously recycled back to the reactor.

[0134] Example 2

[0135] The method for hydrogenating 1,4-butanediol according to Example 1 was adopted, except that a hydrocyclone was not used, and the concentration of hydrogenation catalyst in the 1,4-butanediol aqueous solution exiting from the top of the magnetic capture separator was 0.02 wt%. This demonstrates that multiple separations using both magnetic separators and hydrocyclones can further improve the degree of catalyst separation.

[0136] Example 3-12

[0137] Examples 3-12 illustrate the effect of the washing water flow rate on the concentration of the reaction product at the bottom outlet of the magnetic separator.

[0138] The catalyst was hydrogenated to produce 1,4-butanediol according to the method in Example 1. Different flow rates of washing water were introduced to wash the catalyst, and the results are shown in Table 7.

[0139] Table 7

[0140]

[0141]

[0142] As shown in Table 7, the data from Examples 3-7 indicate that when the amount of washing water is too small, the catalyst washing effect is poor; as the amount of washing water increases, the catalyst washing effect gradually improves. The data from Examples 8-12 show that when the amount of washing water exceeds a certain value, the catalyst washing effect tends to stabilize. Furthermore, excessive washing water will increase the energy consumption of the subsequent product purification system. Therefore, provided that the washing is thorough, it is unnecessary to continuously introduce washing water.

[0143] When no washing liquid is introduced, some of the reaction products at the bottom of the magnetic separator adhere to the catalyst and return to the reactor. These reaction products will affect the hydrogenation reaction effect, indicating that it is necessary to wash the catalyst during the catalyst recycling process. This invention achieves catalyst washing simply and ingeniously by setting a central tube in the magnetic separator and introducing washing water for washing, eliminating the need for an external washing device and reducing the equipment process.

[0144] Examples 13-16

[0145] Examples 13-16 illustrate the effect of the working fluid flow rate of the injector used in this invention on the control of catalyst concentration in the reactor.

[0146] The method of Example 1 was used to produce 1,4-butanediol by hydrogenation, with different working fluid flow rates of different injectors. The results are shown in Table 8.

[0147] Table 8

[0148]

[0149] As can be seen from Table 8, adjusting the flow rate of the injector working fluid can effectively control the concentration of the catalyst entering the reactor, thereby controlling the reaction process.

[0150] Comparative Example 1

[0151] In the process of preparing butanediol using two-stage medium-pressure hydrogenation of butynediol in patent CN1040530C, most of the catalyst in the material after the first stage hydrogenation is separated by sedimentation and returned to the reactor. A small amount of catalyst is suspended in the reaction liquid and separated again by filtration through a catalyst filter. The filtered material is pumped into the second stage hydrogenation reactor by a high-pressure metering pump for reaction. The catalyst separation in the whole process is intermittent and the operation is complicated.

[0152] Comparative Example 2

[0153] Patent CN103846161B, which uses the same catalytic system, separates the catalyst by intermittently switching the electromagnet on and off. The energizing time is maintained at 2-1800s, and the de-energizing time is maintained at 1-1200s. This requires frequent switching on and off, resulting in high energy consumption. Furthermore, the material after magnetic separation needs to be further separated by a filter, making the process long and the operation complex.

[0154] The results above show that Example 1 of the present invention utilizes a combination of a magnetic capture separator, a hydrocyclone separator, and an ejector pump to separate the catalyst from the 1,4-butanediol aqueous solution. In the magnetic capture separator, the catalyst particles are trapped by a magnetic field, resulting in good fluidity, stable operation, and continuous catalyst recycling, thus improving catalyst utilization efficiency and reducing catalyst consumption. Example 2 of the present invention changes the catalyst circulation rate by altering the working fluid volume of the ejector, thereby changing the catalyst concentration in the reaction system and controlling the hydrogenation effect. It does not require adding or removing fresh catalyst, offering excellent operational flexibility and raw material adaptability. Example 3 of the present invention demonstrates that the combination of a magnetic separator and a hydrocyclone separator can further improve the catalyst separation degree and separation effect. Example 4 of the present invention shows that adding a central tube to the magnetic separator structure and introducing washing water to wash the catalyst before returning it to the reactor reduces the impact of reaction products on the reaction, allows for continuous operation without backwashing, and is convenient to maintain and low in cost. Compared with Comparative Examples 1 and 2, the system and method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol proposed in this invention have significantly better effects.

[0155] The preferred 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, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A system for the hydrogenation of 1,4-butynediol to produce 1,4-butanediol, wherein the hydrogenation catalyst used is a magnetically separable catalyst, characterized in that, The system includes: a buffer tank, a hydrogenation reactor, an ejector, a magnetic capture separator, and a hydrocyclone separator; wherein, the buffer tank includes a feed inlet, a fresh catalyst replenishment inlet, and a material outlet; the material outlet of the buffer tank is connected to the first feed inlet of the hydrogenation reactor and the first feed inlet of the ejector, respectively; the discharge outlet of the ejector is connected to the second feed inlet of the hydrogenation reactor; the liquid outlet of the hydrogenation reactor is connected to the feed inlet of the magnetic capture separator; the feed inlet of the magnetic capture separator is located at the lower part of the magnetic capture separator; the lower discharge outlet of the magnetic capture separator is connected to the second feed inlet of the ejector; the liquid outlet of the magnetic capture separator is connected to the feed inlet of the hydrocyclone separator; and the liquid outlet of the hydrocyclone separator is located at the top of the hydrocyclone separator. The magnetic capture separator includes: A vertical container includes an upper cylinder and a lower cylinder; the top of the upper cylinder is provided with a clear liquid outlet for discharging the clear liquid after the catalyst is separated; the side wall of the lower cylinder is provided with a slurry inlet for adding slurry containing the catalyst. At least two electromagnetic coils are respectively looped around the outside of the upper cylinder and arranged along the axial direction of the upper cylinder; and A central tube is located at the bottom of the lower cylinder and extends into the interior of the lower cylinder; a washing water inlet is provided at the bottom of the central tube; a catalyst outlet is also provided on the central tube for discharging the separated catalyst.

2. The system according to claim 1, wherein, The length-to-diameter ratio of the vertical container is 4-8:1; And / or, the ratio of the length of the upper cylinder to the length of the lower cylinder is 5-9:1; And / or, the length-to-diameter ratio of the central tube is 4-12:1; And / or, the ratio of the diameter of the central tube to the diameter of the lower cylinder is 0.05-0.3:1; And / or, the diameter of the upper cylinder is the same as the diameter of the lower cylinder; And / or, the upper opening of the central tube is higher than the slurry inlet.

3. The system according to claim 2, wherein, The upper opening of the central tube is 30-200 mm higher than the slurry inlet.

4. The system according to claim 3, wherein, The upper opening of the central pipe is 50-150 mm higher than the slurry inlet.

5. The system according to claim 1 or 2, wherein, The magnetic capture separator includes 2-16 electromagnetic coils.

6. The system according to claim 5, wherein, The interval between two adjacent sets of electromagnetic coils is 0.5-5m.

7. The system according to claim 6, wherein, The height Db of each electromagnetic coil is 0.1-1m.

8. The system according to any one of claims 1 or 2, wherein, The first feed inlet of the injector is located at the top of the injector, the second feed inlet is located at the upper part of the injector and is perpendicular to the first feed inlet, and the discharge outlet of the injector is located at the bottom of the injector; And / or, the hydrogenation reactor is a slurry bed reactor; And / or, the hydrogenation reactor is further provided with a hydrogen inlet and a post-reaction gas outlet; the connecting pipe between the bottom outlet of the hydrocyclone and the buffer tank is further provided with a catalyst outlet; And / or, a group of separation devices consisting of one of the ejectors, one of the magnetic capture separators, and one of the hydrocyclones; the system includes one or more groups of parallel separation devices.

9. The system according to claim 8, wherein, The number of hydrogenation reactors is one or more connected in series.

10. The system according to claim 9, wherein, The number of hydrogenation reactors is 2-3 connected in series.

11. A method for producing 1,4-butanediol by hydrogenation of 1,4-butynediol, characterized in that, The method using the system according to any one of claims 1-10 includes: An aqueous solution of 1,4-butynediol is fed into the hydrogenation reactor via the injector, and a hydrogenation reaction is carried out under the action of the hydrogenation catalyst to obtain a reaction mixture. The reaction mixture is subjected to a first separation using a magnetic capture separator to obtain a first separated liquid. The first separated liquid is then post-treated to obtain 1,4-butanediol product. All or part of the separated hydrogenation catalyst is returned to the hydrogenation reactor via the injector for recycling.

12. The method according to claim 11, wherein, The post-processing includes: subjecting the first separated liquid to a second separation via the hydrocyclone to obtain a second separated liquid; then refining the second separated liquid to obtain 1,4-butanediol product, and returning all or part of the separated hydrogenation catalyst to the buffer tank.

13. The method according to claim 12, wherein, The first separation solution is an aqueous solution of 1,4-butanediol containing a small amount of hydrogenation catalyst, wherein the concentration of the hydrogenation catalyst in the first separation solution is 0-0.5 wt%. And / or, the second separation liquid is an aqueous solution of 1,4-butanediol containing a small amount of hydrogenation catalyst, wherein the concentration of hydrogenation catalyst in the second separation liquid is 0-0.2 wt%.

14. The method according to claim 11 or 12, wherein, Depending on the activity level of the hydrogenation catalyst, the used hydrogenation catalyst is removed and / or fresh hydrogenation catalyst is added. The removal is carried out in an instantaneous continuous or intermittent periodic manner, and the addition is carried out in an instantaneous continuous or intermittent periodic manner.

15. The method according to claim 11 or 12, wherein, The concentration of the 1,4-butynediol aqueous solution is 25-60 wt%. And / or, during the hydrogenation reaction, the amount of gas retained in the liquid is controlled to be maintained at 5-10 wt%; And / or, during the hydrogenation reaction, the concentration of the hydrogenation catalyst is controlled to be 1-5 wt%; And / or, the hydrogenation catalyst is a solid particle containing magnetic material.

16. The method according to claim 15, wherein, The hydrogenation catalyst is a nickel catalyst, an amorphous alloy catalyst with nickel as the main active component, or a supported catalyst with nickel and iron as the main active components. And / or, the particle size of the hydrogenation catalyst is greater than 100 mesh.

17. The method according to claim 11 or 12, wherein, The reaction conditions for the hydrogenation reaction are: temperature 40-70℃, pressure 1-4MPa, pH value greater than 7, and residence time 4-8h.

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