Catalyst coprecipitation synthesis device

Abstract

The utility model discloses a catalyst coprecipitation synthesis device, which is of a reactor structure and at least comprises a stirring unit, a reaction unit and a reaction unit, the stirring unit is arranged in the middle in a reactor, comprises a vertically arranged rotating shaft and stirring blades fixed on the rotating shaft, and is used for stirring mixed raw materials of acid and alkali liquor; an aeration head of the aeration unit is arranged in the reactor and right below the stirring unit, and the aeration unit is used for generating nano-scale microbubbles and introducing the nano-scale microbubbles upwards; and the pH value online measuring instrument is arranged below the liquid level in the reactor and is used for measuring the pH value of the mixed liquid in the reactor in real time. According to the utility model, the aeration unit and the stirring unit which are arranged in the reactor are matched for use, so that the mixing of acid-base liquid can be effectively promoted, and meanwhile, the particle size of a precursor is uniform in distribution and moderate in size; the pH value of the reaction system can be dynamically adjusted by dynamically controlling the injection amount of the CO2 microbubbles in the reaction stage and the aging stage.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial catalyst preparation, in particular to a catalyst co-precipitation synthesis device, which is particularly suitable for co-precipitation reaction in preparing multi-component Cu-based catalysts. Background Art

[0002] Multi-component Cu-based catalysts are widely used in a wide range of important industrial reactions, including syngas-to-alcohol synthesis, methanol steam reforming, CO and hydrocarbon oxidation, water-gas shift reactions, and selective hydrogenation of carbonyl compounds. Among the methods for preparing multi-component Cu-based catalysts, coprecipitation is a common method for preparing industrial catalysts due to its simplicity, controllable conditions, and high economic efficiency.

[0003] For example, Chinese patent application CN106732616A discloses a method for preparing a catalyst suitable for large-scale methanol synthesis equipment, belonging to the field of catalytic technology. The preparation method includes: 1) Preparation of a structural additive: Separately prepare a mixed salt solution of metals X and Y and an alkaline solution, preheat them to the coprecipitation reaction temperature, add them concurrently to a precipitation tank, and then age, homogenize, spray-dry, and calcine to obtain the catalyst; 2) Preparation of an active component: Separately prepare a mixed salt solution of Cu and Zn and an alkaline solution, preheat them to the coprecipitation reaction temperature, add them concurrently to another precipitation tank, and then age, homogenize, spray-dry, and calcine to obtain the catalyst; 3) Post-processing: Add a dispersant and a lubricant to the mixture of the structural additive and the active component, and grind, mix, homogenize, and tablet, in sequence, to obtain the methanol synthesis catalyst. The structural additive powder prepared using this method has a spinel structure, which significantly improves the catalyst's catalytic activity, product selectivity, stability, heat resistance, high-temperature performance, and service life.

[0004] This approach, particularly during the coprecipitation preparation of multi-component Cu catalysts, can partially lose the original molecular-level uniformity of the solution due to the varying pH and precipitation rates of different ions. This can lead to severe agglomeration and poor morphological uniformity in the precursor product. The greater the size disparity between precursor particles, the more likely they are to agglomerate during the subsequent catalyst calcination, leading to localized sintering between particles and compromising the catalyst's physical and chemical properties. Therefore, optimizing the coprecipitation process to produce a coprecipitated product with uniform size and distribution is a key challenge in the preparation of multi-component Cu catalysts.

[0005] Therefore, there is an urgent need for a catalyst co-precipitation synthesis device that can not only promote the mixing of acid and base liquids, but also make the precursor particle size distribution uniform and moderate.

[0006] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Utility Model Content

[0007] The purpose of the utility model is to provide a catalyst co-precipitation synthesis device, which can effectively promote the mixing of acid and base liquids through the coordinated use of an aeration unit and a stirring unit arranged in a reactor, while making the precursor particle size distribution uniform and the particle size moderate.

[0008] Another object of the present invention is to dynamically adjust the pH value of the reaction system by dynamically controlling the injection amount of CO2 microbubbles during the reaction stage and the aging stage.

[0009] To achieve the above-mentioned purpose, the utility model provides a catalyst co-precipitation synthesis device, which is a reactor structure and at least includes: a stirring unit, which is arranged in the middle of the reactor and includes a vertically arranged rotating shaft and a stirring blade fixed on the rotating shaft, and is used to stir the mixed raw materials of acid and alkali liquid; an aeration unit, whose aeration head is arranged in the reactor and directly below the stirring unit, and is used to generate and pass nanometer-scale microbubbles upward; a pH value online measuring instrument, which is arranged below the liquid level in the reactor and is used to measure the pH value of the mixed liquid in the reactor in real time.

[0010] Furthermore, in the above technical solution, the pH online measuring instrument can be connected to a pH feedback controller provided outside the reactor, and the pH feedback controller can be used to compare and analyze the real-time pH value and the target value and generate a pH control target value.

[0011] Furthermore, in the above technical solution, the aeration unit may also include: a bubble generator, which is arranged outside the reactor and connected to the aeration head through a gas channel; a gas flow controller, which is arranged in the gas channel, for receiving feedback information from the pH feedback controller, and controlling the aeration flow of CO2 in the reactor by controlling the start and stop of the metering pump.

[0012] Furthermore, in the above technical solution, a distribution tower plate with openings is provided in the reactor at a corresponding position below the acid and alkali solution injection port.

[0013] Furthermore, in the above technical solution, the distribution tower plate can be set at an angle, and the position of the tower plate on one side corresponding to the acid and alkali solution injection port is higher than the position of the tower plate on the other side; the opening density at the higher position of the inclined tower plate is lower than the opening density at the lower position, forming an uneven distribution of openings.

[0014] Furthermore, in the above technical solution, the inclination angle of the distribution tray is preferably 10 to 30°.

[0015] Furthermore, in the above technical solution, the number of acid and alkali solution injection ports is at least two, and the number of distribution tower plates is adapted to the number of acid and alkali solution injection ports.

[0016] Furthermore, in the above technical solution, baffles can be symmetrically arranged on the end sides of the reactor.

[0017] Furthermore, in the above technical solution, there may be multiple aeration heads, which may be evenly spaced along the circumferential direction.

[0018] Furthermore, in the above technical solution, the device can be applied to the co-precipitation process of preparing multi-component Cu-based catalysts.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The utility model can inject CO2 into the reactor in the form of evenly dispersed small bubbles (nanoscale bubbles) through the aeration unit provided in the reactor, so that the reaction system is instantly filled with even microbubbles; further, the coordinated use of the aeration unit and the stirring unit can effectively promote the mixing of the acid and base liquids, while making the precursor particle size uniform and of moderate size;

[0021] 2) The present invention uses a gas flow controller to receive feedback from a pH feedback controller, allowing the pH of the reaction system to be controlled by adjusting the amount of CO2 gas introduced during different stages (i.e., the reaction stage and the aging stage). This means that the gas flow controller can communicate with the pH feedback controller to dynamically start and stop the aeration head, controlling the amount of CO2 gas introduced and thus adjusting the pH. Therefore, the CO2 gas in a microbubble state generated by the aeration head of the present invention can, on the one hand, promote mixing of the raw liquids and inhibit collision and agglomeration of particles in the reaction slurry, thereby improving particle dispersion; on the other hand, it can also regulate the pH of the reaction system, establishing a relationship between the amount of CO2 added and the pH change.

[0022] Can be used in multiple reaction systems;

[0023] 3) The acid and alkali liquid injection port of the utility model is located above the higher side of the inclined tower plate. As the liquid flows from the higher end to the lower end of the inclined surface under the action of gravity, the raw liquid can be injected into the reactor through the distribution tower plate with openings. In order to ensure the uniform flow of the raw liquid when injected into the reactor, sparser holes are opened on the tower plate close to the acid and alkali liquid injection port, and denser holes are opened on the tower plate away from the acid and alkali liquid injection port. This can ensure the flow balance at different positions of the tower plate and promote the dispersion of the raw liquid in the reactor. At the same time, the opening setting of the distribution tower plate can also effectively filter large-sized impurities.

[0024] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the catalyst co-precipitation synthesis device of the present invention.

[0026] Figure 2 yes Figure 1 Schematic diagram of the interior top view.

[0027] Figure 3 It is a schematic diagram of the arrangement of the aeration head of the utility model.

[0028] Figure 4 This is a schematic diagram of the morphology of the precursor particles in Example 1 of the present invention.

[0029] Figure 5 This is a schematic diagram of the morphology of catalyst particles after calcination in Example 1 of the present invention.

[0030] Figure 6 This is a schematic diagram of the precursor particle morphology in Comparative Example 1 of the present invention.

[0031] Figure 7 This is a schematic diagram of the morphology of catalyst particles after calcination in Comparative Example 1 of the present invention.

[0032] Description of main reference numerals:

[0033] 100-reactor;

[0034] 1- stirring unit, 10- motor, 11- rotating shaft, 12- stirring blade, 2- aeration unit, 20- air inlet, 21- aeration head, 22- gas distribution plate, 3- pH value online measuring instrument, 31- pH value feedback controller, 4- distribution tower plate, 41- opening, 5- acid and alkali solution injection port, 6- baffle. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention will be described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation.

[0036] Unless expressly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising” will be understood to include the stated elements or components but not to exclude other elements or components.

[0037] In this document, for ease of description, spatially relative terms such as "below," "beneath," "down," "above," "above," etc. may be used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that the spatially relative terms are intended to encompass different orientations of an object in use or operation in addition to the orientation depicted in the drawings. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above directions. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatially relative terms used herein should be interpreted accordingly.

[0038] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit specific positions or relative relationships. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable with each other.

[0039] like Figures 1 to 3 As shown, the present invention provides a catalyst co-precipitation synthesis device, which is a reactor structure and can be used in the co-precipitation process of preparing a multi-element Cu-based catalyst. It includes at least a stirring unit 1, an aeration unit 2 and a pH value online measuring instrument 3. Among them, the stirring unit 1 is arranged in the middle of the reactor 100, including a vertically arranged rotating shaft 11 and a stirring blade 12 fixed on the rotating shaft 11, which is used to stir the mixed raw materials of the acid and alkali liquid. The aeration unit 2 includes an aeration head 21 (refer to Figure 3 The aeration head 21 is located within the reactor 100, directly below the stirring unit 1, and is used to generate and introduce nano-scale microbubbles (i.e., CO2 gas) upward. The online pH meter 3 is located below the liquid level within the reactor 100 and is used to measure the pH value of the mixed liquid within the reactor in real time.

[0040] The utility model uses an aeration unit arranged in the reactor to inject CO2 into the reactor in the form of evenly dispersed small bubbles, so that the reaction system is instantly filled with even fine bubbles; further, through the coordinated use of the aeration unit and the stirring unit, the mixing of acid and alkali liquids can be effectively promoted, and at the same time, the precursor particle size distribution can be even and the particle size can be moderate.

[0041] Further Figure 1 、 2As shown, the top of the reactor 100 is provided with an acid and alkali solution injection port 5 for injecting the raw material liquid of the acid and alkali solution into the reactor. A raw material storage tank and a conveying pipeline are provided upstream of the acid and alkali solution injection port 5, and the flow rate is controlled by a solenoid valve (the upstream facilities are not shown in the figure). A distribution tray 4 is provided downstream (i.e., inside the reactor). The distribution tray 4 is provided with an opening and is located in the reactor 100 at a corresponding position below the acid and alkali solution injection port 5. Preferably, but not restrictively, the distribution tray 4 can be tilted (the tilt angle is preferably 10 to 30 degrees), that is, the tray position on one side corresponding to the acid and alkali solution injection port 5 is higher than the tray position on the other side (reference Figure 2 , the inclined state is not shown in the figure); the density of openings at the higher position of the inclined tower plate is lower than the density of openings at the lower position, resulting in an uneven distribution of openings. With such a setting, the acid and alkali solution injection port 5 is located above the higher side of the inclined tower plate. As the liquid flows from the higher end of the slope to the lower end under the action of gravity, the raw liquid can be injected into the reactor through the distribution tower plate 4 with openings 41. In order to ensure a uniform flow rate of the raw liquid when it is injected into the reactor, sparser holes are opened on the tower plate close to the acid and alkali solution injection port 5, and denser holes are opened on the tower plate away from the acid and alkali solution injection port 5. This can ensure that the flow rate at different positions of the tower plate is balanced, and promote the dispersion of the raw liquid in the reactor; at the same time, the opening setting of the distribution tower plate can also effectively filter large-sized impurities. Further as Figure 1 、 2 As shown, the number of the acid and alkali solution injection ports 5 is at least two, and the number of the distribution trays 4 is adapted to the number of the acid and alkali solution injection ports. Figure 2 Two acid and alkali solution injection ports 5 are shown, and two distribution trays 4 are installed at the side ends of the reactor 100 and are symmetrically arranged. In addition, baffles 6 can also be symmetrically arranged at the end sides of the reactor 100 to further improve the mixing effect.

[0042] Further Figure 1 As shown, the pH online measuring instrument 3 is connected to a pH feedback controller 31 provided outside the reactor. The pH feedback controller 31 can be used to compare and analyze the real-time pH value and the target value and generate a pH control target value.

[0043] Further Figures 1 to 3 As shown, the number of the aeration head 21 in the aeration unit of the present invention is at least one, preferably multiple and evenly spaced along the circumference. The aeration head 21 can generate microbubbles with a diameter of about 100 to 500 nm. Figure 3The aeration head 21 can be connected to the gas distribution plate 22. In addition to the aeration head 21, the aeration unit 2 also includes a bubble generator and a gas flow controller (not shown). The bubble generator is located outside the reactor and connected to the aeration unit 2 via a gas channel. The gas flow controller is located within the gas channel and is used to receive feedback from the pH feedback controller 31 and control the aeration flow of CO2 within the reactor by controlling the start and stop of the metering pump.

[0044] The CO2 gas of the present invention enters the co-precipitation reactor 100 through the air inlet 20 and is dispersed in the reaction system through the aeration head. Since the gas flow controller can receive feedback information from the pH feedback controller 31, the pH value in the reaction system can be controlled by the amount of CO2 gas introduced at different stages. That is, in the reaction stage, the aeration head can be controlled by the gas flow controller to remain open. In the aging stage, the gas flow controller can communicate with the pH feedback controller to achieve dynamic start and stop of the aeration head, control the amount of CO2 gas introduced, and thus adjust the pH value. Therefore, the CO2 gas in the microbubble state generated by the aeration head of the present invention can, on the one hand, promote the mixing of the raw material liquid, inhibit the collision and agglomeration of particles in the reaction slurry, and thus improve the dispersion of the particles. On the other hand, it can also adjust the pH value of the reaction system, establish the relationship between the amount of CO2 added and the pH change value, and can be used for multiple reaction systems.

[0045] Example 1

[0046] Take the two-component Cu+Cr catalyst as an example:

[0047] 1) Copper nitrate, chromium nitrate, and CTAB were added to a certain volume of deionized water to prepare a mixed solution containing 0.645 mol / L copper nitrate, 0.545 mol / L chromium nitrate, and 4 wt% CTAB as the acid solution. A 1.5 mol / L Na2CO3 solution was prepared as the alkali solution.

[0048] 2) Add 200 mL of bottom water to a 5 L reactor. Install four aeration heads, introducing CO2 at a rate of 20 mL / min per aeration head. The CO2 forms diffusely distributed small bubbles with a diameter of 100-200 nm. Acid and alkali solutions are then added to the reactor in parallel, stirring at 220 rpm / min. Maintain a pH of 6.5 and a temperature of 70°C. The reaction time is controlled to 40 min by adjusting the flow rates of the acid and alkali solutions.

[0049] 3) Continue to introduce CO2 until the coprecipitation reaction is completed and the aging process begins. The aging speed is half the reaction speed, the aging temperature is 80°C, the aging time is 4 hours, and the aging pH is 6.5. During the aging process, the aging pH is observed every 30 minutes and maintained by the introduction of CO2. CO2 is introduced into the reactor in the form of microbubbles with a bubble diameter of 100 to 500 nm and a gas velocity of 40 mL / min. After the aging is completed, the slurry is filtered and washed until the effluent conductivity is ≤200 μs. The filter cake is placed in an oven at 100°C and dried to obtain a precursor.

[0050] 4) The precursor was calcined at 450° C. for 3 h in an air atmosphere to obtain a catalyst powder.

[0051] The particle size and microscopic morphology of the slurry obtained after aging were observed. The particle size distribution is shown in Table 1. The morphology of the precursor particles is shown in Figure 4 The catalyst powder obtained after calcination was characterized by SEM, and the results are shown as follows. Figure 5 shown.

[0052] Table 1 Particle size distribution

[0053] D10(μm) D25(μm) D50(μm) D75(μm) D90(μm) D97(μm) Example 1 3.373 5.716 7.121 8.101 10.05 11.96 Comparative Example 1 3.550 5.810 7.422 9.431 12.43 14.97

[0054] Comparative Example 1

[0055] Take the two-component Cu+Cr catalyst as an example:

[0056] 1) Copper nitrate, chromium nitrate, and CTAB were added to a certain volume of deionized water to prepare a mixed solution containing 0.645 mol / L copper nitrate, 0.545 mol / L chromium nitrate, and 4 wt% CTAB as the acid solution. A 1.5 mol / L Na2CO3 solution was prepared as the alkali solution.

[0057] 2) Add 200 mL of bottom water to a 5 L reactor, then add the acid and alkali solutions concurrently to the reactor with stirring at 220 rpm / min. Maintain the reaction pH at 6.5 and the reaction temperature at 70°C. Adjust the flow rates of the acid and alkali solutions to maintain a reaction time of 40 min.

[0058] 3) After the coprecipitation reaction is complete, the aging process begins. The aging speed is half the reaction speed, the aging temperature is 80°C, the aging time is 4 hours, and the aging pH is 6.5. The pH is monitored every 30 minutes during the aging process and maintained by adding acid. After aging, the slurry is filtered and washed until the effluent conductivity is ≤200 μs. The filter cake is dried in an oven at 100°C to obtain the precursor.

[0059] 4) The precursor was calcined at 450° C. for 3 h in an air atmosphere to obtain a catalyst powder.

[0060] The particle size and microscopic morphology of the slurry obtained after aging were observed. The particle size distribution is shown in Table 1. The morphology of the precursor particles is shown in Figure 6 The catalyst powder obtained after calcination was characterized by SEM, and the results are shown as follows. Figure 7 shown.

[0061] As can be seen from Table 1 above, when the coprecipitation synthesis device of the present invention is used to prepare a Cu-based catalyst, the particle size of the precursor prepared by the coprecipitation process is smaller and the particle size distribution range is narrower. Figures 4 to 7 It can be seen that when the co-precipitation synthesis device of the present utility model is used to prepare a Cu-based catalyst, the structures of the prepared precursor and the calcined catalyst are looser.

[0062] The foregoing descriptions of specific exemplary embodiments of the present invention are for illustrative and illustrative purposes. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations are possible based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize the various exemplary embodiments of the present invention and various options and variations. Any simple modifications, equivalent variations, and modifications made to the above exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A catalyst co-precipitation synthesis device, characterized in that: The device is a reactor structure, comprising: A stirring unit is provided in the middle of the reactor and includes a vertically arranged rotating shaft and a stirring blade fixed on the rotating shaft, and is used to stir the mixed raw materials of the acid and alkali solutions; an aeration unit, wherein the aeration head is arranged in the reactor and directly below the stirring unit, and is used to generate and introduce nanometer-scale microbubbles upward; The pH value online measuring instrument is arranged below the liquid level in the reactor and is used for measuring the pH value of the mixed liquid in the reactor in real time.

2. The catalyst co-precipitation synthesis device according to claim 1, characterized in that: The pH online measuring instrument is connected to a pH feedback controller provided outside the reactor. The pH feedback controller is used to compare and analyze the real-time pH value and the target value and generate a pH control target value.

3. The catalyst co-precipitation synthesis device according to claim 2, characterized in that: The aeration unit further comprises: a bubble generator, which is arranged outside the reactor and connected to the aeration head through a gas channel; The gas flow controller is arranged in the gas channel and is used to receive feedback information from the pH value feedback controller and control the aeration flow of CO2 in the reactor by controlling the start and stop of the metering pump.

4. The catalyst co-precipitation synthesis device according to claim 1, characterized in that: A distribution tower plate with openings is provided in the reactor at a corresponding position below the acid and alkali solution injection port.

5. The catalyst co-precipitation synthesis device according to claim 4, characterized in that: The distribution tray is tilted, and the tray corresponding to the acid and alkali solution injection port is higher than the tray on the other side; the opening density at the higher position of the tilted tray is lower than that at the lower position, forming an uneven distribution of openings.

6. The catalyst co-precipitation synthesis device according to claim 5, characterized in that: The inclination angle of the distribution tray is 10 to 30 degrees.

7. The catalyst co-precipitation synthesis device according to claim 5, characterized in that: The number of the acid and alkali solution injection ports is at least two, and the number of the distribution tower plates is adapted to the number of the acid and alkali solution injection ports.

8. The catalyst co-precipitation synthesis device according to claim 1, characterized in that: Baffles are symmetrically arranged on the end sides of the reactor.

9. The catalyst co-precipitation synthesis device according to claim 1, characterized in that: There are multiple aeration heads, which are evenly spaced along the circumference.

10. The catalyst co-precipitation synthesis device according to claim 1, characterized in that: The device is used in the co-precipitation process of preparing a multi-element Cu-based catalyst.

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