Device and method for high-throughput preparation of nano-catalyst
The three-dimensional channel chip design for nanoparticle synthesis addresses size and shape control issues in metal nanoparticle production, achieving narrow distribution and high-throughput manufacturing of complex nanostructures with improved catalytic performance.
Patent Information
- Application Number
- CN202510424900.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2025-07-15
AI Technical Summary
The prior art is difficult to achieve precise control of the size and morphology of metal nanoparticles, resulting in excessively wide particle distribution and poor batch reproducibility. It is difficult for traditional methods to meet the preparation needs of high-quality monodispersed nanoparticles and multi-level structures.
The high-throughput, integrated three-dimensional channel chip design is adopted to accurately control the reaction conditions, and the controllable nucleation and growth of nanoparticles are achieved in the microchannel. The flow type is regulated using a helical and diamond hedge mixing system to ensure uniform droplet size and improve mixing efficiency through a multi-stage channel structure.
The nanoparticles have extremely narrow size distribution and high repeatability, and can prepare composite nanocatalysts with high activity and high selectivity, which improves production flux and batch stability, and solves the problem of preparation of complex structure nanocatalysts.
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Figure CN120305902A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of chemical catalysis, and particularly relates to an apparatus and method for high-throughput preparation of nano-catalysts. Background Art
[0002] Metal nano-materials have been widely used in the catalytic field due to their good catalytic activity and optical properties. Among them, metal nanoparticles (NPs) exhibit more excellent catalytic performance due to their large specific surface area. Since the properties of nanoparticles are highly correlated with their size and morphology, it is crucial to prepare monodisperse nanoparticles with controllable morphology and size and high homogeneity on demand.
[0003] Currently, common methods for preparing metal nano-materials include nano-precipitation, sol-gel, liquid-phase reduction, etc. It is usually difficult to precisely control the nucleation and growth processes, resulting in a too wide size distribution of nanoparticles and poor reproducibility between batches. In addition, the amplification method of increasing the reactor volume will exacerbate the mass transfer limitation, leading to the generation of polydisperse nanoparticles due to insufficient mixing, and it is difficult to meet the actual application requirements. Therefore, there are great challenges in the field of preparing high-quality monodisperse NPs and complex nano-hybrid materials with multi-level structures under traditional processes.
[0004] Since the rise of micro-chemical technology in the 1990s, a large amount of research work has been devoted to the preparation of nanoparticles by microfluidic control. Compared with the traditional batch method, the high specific area of the micro-reactor enhances the heat transfer and mass transfer performance; the transportation process at the micron scale greatly shortens the characteristic time, and some reactions that cannot be controlled or are limited by mass transfer in traditional reactors can be easily realized. In addition, it also has the advantages of controllable reaction process and compatibility with on-line analysis. In the microfluidic system, the nucleation and growth stages of nanoparticles can be effectively defined, enabling precise control of particle size, size distribution, and morphology, and improving reproducibility, providing an ideal platform for exploring and developing new functional nanoparticles. Currently, researchers have used microfluidic technology to achieve the controllable preparation of nanoparticles of different categories (organic, inorganic, composite), different sizes (0 - 10 nm, 10 - 100 nm, 100 - 1000 nm), and different morphologies (spherical, rod-shaped, triangular prism, cube, etc.). In addition, by designing a microfluidic reactor with multi-dimensional precision and a channel structure, nano-catalysts with complex structures, high activity, and high stability can be prepared. For example, Shen et al. (Shen X, Song Y, Li S, et al. RSC Advances , 2014, 4, 34179) prepared a programmed transparent microfluidic chip (C-SPMPs), and successfully observed the four stages of reaction, nucleation, growth, and termination during the formation of NPs through the change of the fluid color in the microchannel; Zhang et al. (Zhang D, Wu F, Peng M, et al.Journal of the American Chemical Society , 2015, 137(19), 6263) Precise segmented temperature control was applied to the particle formation stage in a microfluidic reactor to controllably synthesize different phase intermetallic compounds of Pt / Bi. At present, droplet microfluidic technology still has problems such as complex operation and integration, and is not easy to scale up for production, with certain technical limitations. Summary of the Invention
[0005] The present invention proposes a device and method for high-throughput preparation of nano-catalysts. A high-throughput and highly integrated three-dimensional channel chip design is adopted, and through precise control of reaction conditions, a controllable nucleation and growth process of nanoparticles in microchannels is achieved.
[0006] To achieve the above objectives, the present invention adopts the following technical solutions: A device for high-throughput preparation of nano-catalysts, which successively includes a liquid phase distribution layer, a multiphase emulsification reaction layer, and a droplet unit collection layer from top to bottom.
[0007] The liquid phase distribution layer is provided with a metal salt solution input port, an oil phase solution input port, a reduction phase solution input port, and a micro-droplet output port. Among them, the metal salt solution input port is successively connected with a mixing channel and a multi-pipeline distribution channel in the liquid phase distribution layer. Each distribution channel can perform liquid phase transmission and distribution, and the outlet of the distribution channel is connected to the multiphase emulsification reaction layer; the oil phase solution input port and the reduction phase solution input port are directly connected to the multiphase emulsification reaction layer.
[0008] The multiphase emulsification reaction layer includes a reduction phase multi-stage distribution channel, an oil phase multi-stage distribution channel, a metal salt solution multi-stage distribution channel, a co-directional collision mixing channel, and a micro-reaction channel; the reduction phase multi-stage distribution channel and the metal salt solution multi-stage distribution channel are respectively connected to the co-directional collision mixing channel. When the reduction phase solution and the metal salt solution are input into the co-directional collision mixing channel, they are mixed in a co-directional collision manner. After forming a dispersed phase fluid in the co-directional collision mixing channel, it converges and shears with the oil phase distribution channel, and then is connected to the micro-reaction channel. The micro-reaction channel is connected to the droplet unit collection layer through a micro-droplet distribution connection port; the multiphase emulsification reaction layer is used for the convergence and shearing of multi-path continuous phase liquid and dispersed phase liquid. After emulsifying into droplets, continuous distribution and regulation are carried out through the micro-reaction channel.
[0009] The droplet unit collection layer includes an annular collection channel and an outlet channel. At the micro-droplet distribution connection port, the micro-droplets are divided into two flow directions for collection. The temperature of the entire micro-droplet generation process can be controlled. Finally, nano-catalysts are prepared through centrifugation, washing, and drying steps.
[0010] In the above-described device, the mixing channels in the liquid-phase distribution layer are one or more of spiral channels, laminar mixing channels, Tesla channels, herringbone channels, and droplet mixing channels, and the multi-pipeline distribution channels adopt a multi-stage dendritic fractal channel structure to evenly divide the metal salt solution into multiple equal parts.
[0011] The oil-phase solution distribution channel is an N-stage distribution flow channel, where N≥2; the mixing channel for the reducing-phase solution and the metal salt solution is a 2N-stage distribution flow channel, where N≥2.
[0012] The micro-reaction channel structure is one or more of a fluid focusing structure, a heart-shaped structure, a co-directional flow splitting structure, an axial stepped structure, and a volume amplification structure.
[0013] The micro-reaction channel includes N stages, where N≥2. The merged micro-reaction channel is connected to the droplet unit collection layer in a single stage and then accesses the annular channel to output micro-liquid fluids bidirectionally.
[0014] The width of all channels is 0.01 - 50 mm, the height is 0.01 - 50 mm, and the pore diameters for liquid-phase input and output are 0.1 - 100 mm.
[0015] The temperature control method of the droplet unit collection layer is contact heating or non-contact heating, including one or more of metal block heating, thin-film heating, electromagnetic induction heating, infrared radiation heating, and thermoelectric heating.
[0016] One or more of hot pressing, gluing, laser welding, anodic bonding, and plasma bonding are used for encapsulation bonding between layers.
[0017] A method for high-throughput preparation of nano-catalysts using the above device includes the following steps: First, pump the metal salt solution into the metal salt solution input port. It flows through the mixing channel and the multi-stage dendritic distribution channel in the liquid-phase distribution layer for uniform distribution. Each distribution channel can perform independent liquid-phase transmission. Subsequently, the oil-phase solution and the reducing-phase solution are respectively introduced into the oil-phase solution input port and the reducing-phase solution input port, and directly connected to the connection channel of the multi-phase emulsification layer for continuous liquid-phase distribution. Among them, the metal salt solution and the reducing-phase solution flowing down are strongly mixed in a co-directional collision mixing channel in a co-directional collision manner, and then sheared into droplets in the oil-phase multi-stage distribution channel and continue to flow into the micro-reaction channel for nucleation, growth, and reaction of nanoparticles. They enter the droplet collection layer through the micro-droplet distribution connection port, are divided into two streams in the annular channel for droplet transportation, extending the reaction growth time of the nanoparticles. Finally, the micro-droplets of the nanoparticles are collected at the micro-droplet output port, and finally, a highly active and highly selective nano-catalyst is obtained through centrifugation, washing, and drying.
[0018] Advantages: The present invention provides an apparatus and method for high-throughput preparation of nano-catalysts, which have the following advantages compared with the prior art: (1) During the high-throughput preparation of nano-catalysts, through a helical and diamond-shaped counter-flow mixing system, the flow patterns of eddy current and laminar flow are regulated by means of the microstructure design of the pipeline, realizing the dynamic selection of turbulent flow and plug flow streamlines, enabling spatio-temporal resolution at each forming and growing stage of nano-particles, optimizing the breakage and generation mechanisms of micro-droplets, and achieving controllable assembly and modification of particles; (2) Precise control of the micro-droplet size is ensured to guarantee the uniformity of droplet size, with the coefficient of variation (CV) being reduced to less than 1%, far higher than 35% of the traditional batch synthesis method. By precisely controlling the reaction conditions, the growth kinetics of nano-particles can be manipulated, promoting uniform nucleation and growth, and obtaining nano-particles with an extremely narrow size distribution, thereby achieving precise control of the size and morphology of nano-particles; (3) It is possible to prepare high-throughput composite nano-catalysts of multi-metal nano-particles. The alloy effect, electronic effect, etc. of multi-metal composite nano-materials can significantly improve the catalytic performance of nano-particles, solving the cumbersome preparation process of nano-catalysts with complex structures. Directly controlling the processing conditions precisely at the nano-scale and microscopic level, regulating the structures of different components, and obtaining composite nano-catalysts with high activity and high selectivity; (4) The monodisperse droplets generated by the channel have high mixing efficiency. The oil phase encapsulation effectively solves the problems of channel blockage and nano-particle aggregation, with good repeatability and high batch stability of the generated nano-particles; (5) The present invention uses a ring-shaped parallel distribution channel structure with a higher channel density to achieve high-throughput preparation of unit / multi-metal nano-catalysts. Compared with the traditional process, the throughput under the same volume is increased by at least two orders of magnitude. Through the integration of a three-dimensional stereoscopic chip, its production throughput can be further improved; (6) For different liquid-liquid phase systems, such as the preparation system of hydrogels and the multi-channel reaction system of liquid-liquid phases, they can all be introduced into the three-dimensional stereoscopic chip device designed in the present invention for operation, realizing the liquid-liquid homogeneous reaction process of different structured droplets, with a certain degree of universality; (7) The device of the present invention has the characteristics of small size and integratability. The entire preparation process can precisely control the reaction conditions, realizing continuous, green and low-consumption large-scale production. Description of the Drawings
[0019] Figure 1 It is a schematic structural diagram of a three-dimensional stereoscopic device for high-throughput preparation of nano-catalysts in an embodiment of the present invention; Figure 2 It is a plan view of a three-layer structure device for high-throughput preparation of nano-catalysts in an embodiment of the present invention; Figure 3Schematic three-dimensional pipeline diagram of the device for high-throughput preparation of nano-catalysts in the embodiments of the present invention; Figure 4 Schematic diagram of the multi-stage distribution structure of the oil phase in the embodiments of the present invention; Figure 5 Schematic diagram of the multi-stage distribution structure of the reduction phase in the embodiments of the present invention; Figure 6 Schematic diagram of the structures of different mixing devices in the liquid phase distribution layer in the embodiments of the present invention; Figure 7 Comparison chart of the particle size distributions of the nanoparticles prepared by the traditional batch method and the micro-droplet method in the embodiments of the present invention; Figure 8 Process diagram of the generation of high-throughput micro-droplets converging at the distribution interface in the embodiments of the present invention; Figure 9 Characterization structure diagram of the activity, selectivity and stability of the Pd / Mn binary nano-catalyst prepared in Embodiment 5 of the present invention; Figure 10 Selectivity comparison chart of the ruthenium / copper / cobalt ternary nano-carbon supported catalyst prepared in Embodiment 4 of the present invention and various traditional catalysts; Among them, a - liquid phase distribution layer, b - multi-phase emulsification layer, c - droplet unit collection layer, 1 - metal salt solution input port, 2 - oil phase solution input port, 3 - reduction phase solution input port, 4 - mixing channel, 5 - micro-droplet output port, 6 - micro-reaction channel, 7 - co-directional collision mixing channel, 8 - micro-droplet distribution connection port, 9 - oil phase multi-stage distribution channel, 10 - reduction phase multi-stage distribution channel, 11 - metal salt solution multi-stage distribution channel. Detailed implementation manners
[0020] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments: As Figure 1 and Figure 2 shown, a device for high-throughput preparation of nano-catalysts is assembled and bonded by three chips with micro-channel structures. Encapsulation bonding is carried out between layers by one or several of hot pressing, gluing, laser welding, anodic bonding, and plasma bonding; it includes a liquid phase distribution layer a, a multi-phase emulsification reaction layer b, and a droplet unit collection layer c, and through holes are interconnected at the outlets of each layer.
[0021] The liquid phase distribution layer a is provided with a metal salt solution input port 1, an oil phase solution input port 2, a reduction phase solution input port 3, and a micro-droplet output port 5. Among them, the metal salt solution input port 1 is sequentially connected with a mixing channel 4 and a multi-stage dendritic distribution channel in the liquid phase distribution layer a. Each distribution channel can perform liquid phase transmission and distribution, and the outlet of the distribution channel is connected to the multi-phase emulsification reaction layer b; the oil phase solution input port 2 and the reduction phase solution input port 3 are directly connected to the multi-phase emulsification reaction layer.
[0022] The multiphase emulsification reaction layer b includes a reduction-phase multi-stage distribution channel 10, an oil-phase multi-stage distribution channel 9, a metal salt solution multi-stage distribution channel 11, a co-directional collision mixing channel 7, and a micro reaction channel 6. The oil-phase solution input port 2 is connected to the oil-phase multi-stage distribution channel 9, the reduction-phase solution input port 3 is connected to the reduction-phase multi-stage distribution channel 10, and the outlets of the multi-stage dendritic distribution channels are connected to the metal salt solution multi-stage distribution channel 11. The reduction-phase multi-stage distribution channel 10 and the metal salt solution multi-stage distribution channel 11 are respectively connected to the co-directional collision mixing channel 7. When the reduction-phase solution and the metal salt solution are input into the co-directional collision mixing channel 7, they are mixed in a co-directional collision manner, and after forming a dispersed-phase fluid in the co-directional collision mixing channel 7, they converge and shear with the oil-phase multi-stage distribution channel 9, and then are connected to the micro reaction channel 6. The micro reaction channel 6 is connected to the droplet unit collection layer c through the micro-droplet distribution connection port 8. The multiphase emulsification reaction layer b is used for the convergence and shearing of multi-path continuous-phase liquid and dispersed-phase liquid. After emulsifying into droplets, continuous distribution regulation is carried out through the micro reaction channel 6.
[0023] The droplet unit collection layer c includes an annular collection channel and an outlet channel. At the micro-droplet distribution connection port 8, the micro-droplets are divided into two annular flow directions and flow to the outlet channel for collection through the micro-droplet output port 5. The temperature of the entire micro-droplet generation process can be controlled.
[0024] As Figure 6 shown, the mixing channel 4 is one or more of a spiral channel, a laminar flow mixing channel, a Tesla channel, a herringbone channel, and a droplet mixing channel.
[0025] The oil-phase multi-stage distribution channel is an N-stage distribution channel, N≥2; the reduction-phase multi-stage distribution channel 10 and the metal salt solution multi-stage distribution channel 11 are 2N-stage distribution channels, N≥2.
[0026] The structure of the micro reaction channel 6 is one or more of a fluid focusing structure, a heart-shaped structure, a co-directional diversion structure, an axial step structure, and a volume amplification structure.
[0027] The micro reaction channel 6 includes N channels, N≥2. The converged micro reaction channel is connected to the droplet unit collection layer in a single stage, and then is connected to an annular channel to output the micro liquid fluid bidirectionally.
[0028] The width of all channels is 0.01 - 50 mm, the height is 0.01 - 50 mm, and the pore diameter of the liquid-phase input and output is 0.1 - 100 mm.
[0029] The temperature control method of the droplet unit collection layer c is contact heating or non-contact heating, including one or more of metal block heating, thin film heating, electromagnetic induction heating, infrared radiation heating, and thermoelectric heating.
[0030] Figure 3 shows a specific three-dimensional pipeline schematic diagram, which is shown with the metal salt solution distribution channel being 2N levels (N = 20). The above figure shows the specific pipeline structure from the liquid phase distribution layer a to the multiphase emulsification reaction layer b. Among them, the metal salt solution that is distributed into 40 channels by the multi-level distribution channel 11 of the metal salt solution flows towards the second-layer interface, belonging to the innermost annular flow unit, as Figure 5 shown. The reduction phase multi-level distribution channel 10 also distributes the reduction phase solution into 40 channels, and undergoes strong mixing and mass transfer with the metal salt solution in the co-directional collision mixing channel 7, as Figure 4 shown. The oil phase multi-level distribution channel 9 distributes the oil phase solution into 20 channels, and then shears the liquid phase after mixing in the co-directional collision mixing channel 7, and transports it to the subsequent micro-reaction channel 6 and the micro-droplet connection port 8. The following figure shows the specific pipeline structure from the multiphase emulsification reaction layer b to the droplet unit collection layer c. The micro-droplets transported down by the micro-droplet distribution connection port 8 are directly connected upward to the liquid phase distribution layer of the first layer through the double-path transportation of the annular pipeline, and are collected as droplets at the micro-droplet output port 5.
[0031] All solution inputs are injected through at least one of a plunger pump, an injection pump, and a hydraulic pump, and the flow rate can be precisely controlled. The process of preparing a nanocatalyst using the above device is as follows: First, pump the metal salt solution into the metal salt solution input port 1, and flow through the mixing channel 4 and the multi-level dendritic distribution channel in the liquid phase distribution layer a for uniform distribution. Each distribution channel can perform separate liquid phase transmission. Subsequently, the oil phase solution and the reduction phase solution are respectively introduced into the oil phase solution input port 2 and the reduction phase solution input port 3, and are directly connected to the connection channel of the multiphase emulsification layer b for continuous liquid phase distribution. Among them, the metal salt solution and the reduction phase solution flowing down are strongly mixed in the co-directional collision mixing channel 7, and then sheared into droplets in the oil phase multi-level distribution channel 9, and continue to flow into the micro-reaction channel 6 for nucleation, growth, and reaction of nanoparticles. They enter the droplet collection layer c through the micro-droplet distribution connection port 8, and are divided into two streams in the annular channel for droplet transportation, extending the reaction growth time of the nanoparticles. Finally, the micro-droplets of the nanoparticles are collected at the micro-droplet output port 5, and finally, a highly active and highly selective nanocatalyst is obtained through centrifugation, washing, and drying. Example 1
[0032] This example provides a method for high-throughput preparation of a nanocatalyst. The device is made of polydimethylsiloxane, and each micro-sized channel is engraved by soft lithography, and the three-layer structure is encapsulated by plasma bonding.
[0033] For the high-throughput preparation of a nanocatalyst, taking 20 oil phase channels as an example: Prepare an aqueous solution of ruthenium(III) chloride trihydrate with a mass concentration of 12.8%. Together with sodium borohydride, they are used as the metal salt solution dispersion phase and the reducing phase solution dispersion phase, and are respectively injected into the metal salt solution inlet 1 and the reducing phase solution inlet 3 through a high-precision syringe pump. The flow rate of the syringe pump is controlled at 50 mL / h. The methyl silicone oil containing 2% pyrrolidone is directly input into the oil phase solution inlet 2 as the oil phase solution, and is divided into 20 channels and flows into the second layer. The flow rate of the syringe pump is controlled at 200 mL / h. The temperature of the reaction device is controlled at 50 °C by means of film heating. Ruthenium(III) chloride trihydrate undergoes strong diffusion in the droplet mixing channel of the first layer, is evenly distributed through the multi-channel dendritic channel, and is continuously introduced into the second layer through 40 channels. It collides and mixes with an equal amount of reducing phase solution in the co-directional collision mixing channel 7 for reduction, flows along with the liquid, and is sheared into droplets at the oil phase distribution port, and directly enters the microreaction channel for a long-term reaction. After the droplets converge, they flow into the third layer, and the reaction time is further extended through the annular channel to control the nucleation of nanoparticles. After the growth is stable, the microdroplets are collected at the outlet, and most of the liquid is removed by centrifugation. The collected nanoparticles are successively washed with n-hexane and ethanol, and finally dried in an oven at 110 °C to prepare the ruthenium-based nanocatalyst.
[0034] Among them, the mixable channel structures that can be designed in the liquid phase distribution layer are as Figure 1 shown, and corresponding selections can be made according to the properties of the metal salt solution and the required mixing degree. For example, for a metal salt solution with a higher concentration, a Tesla mixer channel and a herringbone mixer channel can be selected. If the metal salt solution is easily soluble in the solvent and the system is not viscous, a spiral mixing or laminar mixing method can be used for slow mixing and flowing of the fluid. Example 2
[0035] This example provides a method for high-throughput preparation of nanocatalysts. The device is made of polymethyl methacrylate, and each micro-sized channel is engraved by laser engraving, and the three-layer structure is encapsulated by laser welding.
[0036] For the high-throughput preparation of nanocatalysts, taking 20 oil phase channels as an example: Prepare an aqueous solution of chloroplatinic acid with a mass concentration of 12.8%, and use hydrazine hydrate as the metal salt solution dispersion phase and the reducing phase solution dispersion phase. Inject them into the metal salt solution inlet 1 and the reducing phase solution inlet 3 respectively through a high-precision syringe pump. The flow rates of the syringe pumps are controlled at 50 mL / h and 25 mL / h respectively. Use perfluoropolyether containing 2% polyvinyl alcohol as the oil phase solution and directly input it into the oil phase solution inlet 2. It is divided into 20 channels and flows into the second layer. The flow rate of the syringe pump is controlled at 200 mL / h. Use thermoelectric heating to control the temperature of the reaction device at 30 °C. Ruthenium chloride trihydrate and chloroplatinic acid undergo strong diffusion mixing in the droplet mixing channel of the first layer, and are evenly distributed through the multi-channel dendritic channel. It is divided into 40 channels and continuously introduced into the second layer, and undergoes collision mixing and reduction with an equal amount of reducing phase solution in the co-directional collision mixing channel 7. It flows along with the liquid and is sheared into droplets at the oil phase distribution port, and directly enters the microreaction channel for a long-term reaction. After the droplets converge, they flow into the third layer, and the reaction time is further extended through the annular channel to control the nucleation of nanoparticles. After the growth is stable, the microdroplets are collected at the outlet, and most of the liquid is removed by centrifugation. The collected nanoparticles are successively washed with a demulsifier PFO (perfluorooctanol) and ethanol, and finally dried in an oven at 110 °C to prepare a platinum-based nanocatalyst.
[0037] Under the same parameter conditions, the preparation of platinum nanoparticles using microdroplets and the traditional batch method in a kettle was tested, as Figure 7 shown. The average particle size of the platinum nanoparticles prepared by microdroplets is 160 nm, the PDI coefficient is 0.312, and the monodispersity degree is relatively high. While the particle size of the nanoparticles prepared by the traditional batch method is uncontrollable, the particle size of the nanoparticles is 570 nm, and the PDI coefficient reaches 0.963. The particle size is relatively dispersed and cannot maintain the uniformity of the nanoparticle size. And the size distribution coefficient of the nanoparticles is positively correlated with the actual catalytic effect. There are great advantages in preparing highly active nanoparticles by microdroplets. Example 3
[0038] This example provides a method for high-throughput preparation of nanocatalysts. The device is made of polycarbonate, and each micro-sized channel is engraved by laser engraving, and the three-layer structure is encapsulated by hot pressing.
[0039] For the high-throughput preparation of nanocatalysts, taking 20 oil phase channels as an example: Prepare a mixed aqueous solution containing ruthenium chloride hexahydrate with a mass concentration of 12.8% and copper nitrate with a mass concentration of 12.8%. Together with sodium borohydride, they are used as the metal salt solution dispersion phase and the reducing phase solution dispersion phase, and are respectively injected into the metal salt solution inlet 1 and the reducing phase solution inlet 3 through a high-precision syringe pump. The flow rates of the syringe pumps are respectively controlled at 50 mL / h and 50 mL / h. Perfluoropolyether containing 2% polyethylene glycol is directly input into the oil phase solution inlet 2 as the oil phase solution, and flows into the second layer through 20 channels. The flow rate of the syringe pump is controlled at 150 mL / h, and the temperature of the reaction device is controlled at 60 °C by means of thermoelectric heating. Ruthenium chloride trihydrate and copper nitrate are strongly diffused and mixed in the droplet mixing channel of the first layer, and are evenly distributed through the multi-channel dendritic channel, and are continuously introduced into the second layer through 40 channels. They collide and mix with an equal amount of reducing phase solution in the co-directional collision mixing channel 7 for reduction. They flow along with the liquid and are sheared into droplets at the oil phase distribution port, and directly enter the micro-reaction channel for a long-term reaction. After the droplets converge, they directly gather and flow into the third layer, and the reaction time is further extended through the annular channel to control the nucleation of nanoparticles. After the growth is stable, the micro-droplets are collected at the outlet, and most of the liquid is removed by centrifugation. The collected nanoparticles are successively washed with a demulsifier PFO (perfluorooctanol) and ethanol, and finally dried in an oven at 110 °C to prepare a ruthenium / copper bimetallic nanocatalyst. Example 4
[0040] This example provides a device and method for high-throughput preparation of nanocatalysts. The device preparation material is selected as glass, and each micro-sized channel is engraved by laser engraving, and a three-layer structure is encapsulated by anodic bonding.
[0041] For the high-throughput preparation of nanocatalysts, taking 20 oil phase channels as an example: Prepare a mixed aqueous solution containing ruthenium(III) chloride hexahydrate with a mass concentration of 12.8%, copper(II) nitrate with a mass concentration of 8%, and cobalt(II) nitrate with a mass concentration of 8%. Together with sodium borohydride, they are used as the dispersed phase of the metal salt solution and the dispersed phase of the reducing phase solution. They are respectively injected into the metal salt solution inlet 1 and the reducing phase solution inlet 3 through a high-precision syringe pump. The flow rates of the syringe pumps are respectively controlled at 25 mL / h and 25 mL / h. Perfluoropolyether containing 2% polyethylene glycol is directly input into the oil phase solution inlet 2 as the oil phase solution, and it flows into the second layer through 20 channels. The flow rate of the syringe pump is controlled at 100 mL / h. The temperature of the reaction device is controlled at 80 °C by electromagnetic induction heating. Ruthenium(III) chloride hexahydrate, copper(II) nitrate, and cobalt(II) nitrate undergo strong diffusion mixing in the droplet mixing channel of the first layer, are evenly distributed through the multi-channel dendritic channels, and are continuously introduced into the second layer through 40 channels. They undergo collision mixing and reduction with an equal amount of the reducing phase solution in the co-directional collision mixing channel 7, flow along with the liquid, and are sheared into droplets at the oil phase distribution port, and directly enter the micro-reaction channel for a long-term reaction. After the droplets converge, they directly flow into the third layer, and the reaction time is further extended through the annular channel to control the nucleation of nanoparticles. After the growth is stable, the micro-droplets are collected at the outlet, and most of the liquid is removed by centrifugation. The collected nanoparticles are successively washed with a demulsifier PFO (perfluorooctanol) and ethanol, and finally dried in an oven at 110 °C to prepare ruthenium / copper / cobalt ternary metal nanoparticles.
[0042] The prepared ruthenium / copper / cobalt ternary metal nanoparticles are loaded on the sphere C support and applied to the experiment of oxidizing 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid (FDCA) with the aid of a fixed-bed reactor. Under the reaction conditions of 2 MPa, 90 °C, and an oxygen flow rate of 50 sccm, the FDCA yield can be as high as 85%, and the selectivity can reach 98%. As Figure 10 shown, the catalysts for the conventional oxidation of HMF to FDCA are compared, including zinc oxide, copper oxide, copper / cobalt bimetal, ruthenium supported on alumina, and ruthenium supported on carbon catalysts. Conventional nano-catalysts or supported catalysts will produce too many by-products. However, when the ruthenium / copper / cobalt ternary metal nanoparticles are loaded on the sphere C catalyst, compared with conventional ruthenium-based and non-precious metal binary catalysts, the generation amounts of impurities such as FFCA and DFF are reduced, and the whole oxidation reaction is more inclined to the formation of the final product FDCA. By preparing ternary nanoparticles through micro-droplets, the catalytic activity and selectivity can be greatly improved, and the catalyst stability time is greatly enhanced. The continuous reaction lasts for 1 week, and the activity basically does not decrease significantly. Example 5
[0043] This embodiment provides an apparatus and a method for high-throughput preparation of nano-catalysts. The material used for the apparatus is polydimethylsiloxane, and each micro-sized channel is etched by soft lithography, and a three-layer structure is encapsulated by plasma bonding.
[0044] For the high-throughput preparation of nano-catalysts, taking 20 oil-phase channels as an example: Prepare a mixed aqueous solution containing palladium chloride with a mass concentration of 12.8% and manganese nitrate with a mass concentration of 10%, and use it together with sodium borohydride as the metal salt solution dispersion phase and the reducing phase solution dispersion phase. They are respectively injected into the metal salt solution input port 1 and the reducing phase solution input port 3 through high-precision injection pumps. The flow rates of the injection pumps are respectively controlled at 50 mL / h and 25 mL / h. Perfluoropolyether containing 2% polyethylene glycol is directly input into the oil-phase solution input port 2 as the oil-phase solution, and it flows into the second layer through 20 channels. The flow rate of the injection pump is controlled at 100 mL / h, and the temperature of the reaction device is controlled at 60 °C by electromagnetic induction heating. Palladium chloride and manganese nitrate are strongly diffused and mixed in the droplet mixing channel of the first layer, and are uniformly distributed through the multi-channel dendritic channels, and are continuously introduced into the second layer through 40 channels. They are colliding and mixing with an equal amount of reducing phase solution in the co-directional collision mixing channel 7 for reduction, flowing along with the liquid and being sheared into droplets at the oil-phase distribution port, and directly entering the micro-reaction channel for a long-term reaction. After the droplets converge, they directly flow into the third layer, and the reaction time is further extended through the annular channel to control the nucleation of nanoparticles. After the growth is stable, the micro-droplets are collected at the outlet, and most of the liquid is removed by centrifugation. The collected nanoparticles are successively washed with a demulsifier PFO (perfluorooctanol) and ethanol, and finally dried in an oven at 110 °C to prepare a palladium / manganese binary metal nano-catalyst. We measured the activity, selectivity and stability of the prepared palladium / manganese binary metal nano-catalyst through the nitrobenzene hydrogenation experiment. As Figure 9 shown, when the number of cycles reaches 6 times, the activity and selectivity of the hydrogenation reaction can still be maintained above 90%, and there is no phenomenon of the active center of the conventional catalyst falling off and deactivating. In addition, the nano-catalyst after multiple reactions can be reactivated by continuous washing and baking, continuously improving the utilization rate of the catalyst and reducing the overall catalyst usage cost.
[0045] The above are only the preferred embodiments of the present invention, which will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements made all belong to the protection scope of the present invention.
Claims
1. An apparatus for high-throughput preparation of a nanocatalyst, characterized in that, From top to bottom, there are a liquid phase distribution layer, a multiphase emulsification reaction layer, and a droplet unit collection layer for encapsulation bonding in sequence. The liquid phase distribution layer is provided with a metal salt solution input port, an oil phase solution input port, a reducing phase solution input port, and a micro-droplet output port. Among them, the metal salt solution input port is sequentially connected with a mixing channel and a multi-pipeline distribution channel in the liquid phase distribution layer. Each distribution channel can perform liquid phase transmission and distribution, and the outlet of the distribution channel is connected to the multiphase emulsification reaction layer. The oil phase solution input port and the reducing phase solution input port are directly connected to the multiphase emulsification reaction layer. The multiphase emulsification reaction layer includes a reducing phase multi-stage distribution channel, an oil phase multi-stage distribution channel, a metal salt solution multi-stage distribution channel, a co-directional collision mixing channel, and a micro-reaction channel. The reducing phase multi-stage distribution channel and the metal salt solution multi-stage distribution channel are respectively connected to the co-directional collision mixing channel. When the reducing phase solution and the metal salt solution are input into the co-directional collision mixing channel, they are mixed in a co-directional collision manner. After forming a dispersed phase fluid in the co-directional collision mixing channel, it converges and shears with the oil phase multi-stage distribution channel, and then accesses the micro-reaction channel. After the micro-reaction channels converge, they are connected to the droplet unit collection layer in a single stage; the droplet unit collection layer generates micro-droplets and outputs them through the micro-droplet output port.
2. The device for high-throughput preparation of a nano-catalyst according to claim 1, characterized in that, The droplet unit collection layer includes an annular collection channel and an outlet channel. At the micro-droplet distribution connection port, the micro-droplets are divided into two flow directions.
3. The device for high-throughput preparation of nano-catalysts according to claim 1, characterized in that, The mixing channel in the liquid phase distribution layer is one or several of a spiral channel, a laminar flow mixing channel, a Tesla channel, a herringbone channel, and a droplet mixing channel.
4. The device for high-throughput preparation of nano-catalysts according to claim 1 or 3, characterized in that, The multi-pipeline distribution channel adopts a multi-stage dendritic fractal channel structure.
5. The device for high-throughput preparation of nano-catalysts according to claim 1, characterized in that, The oil phase solution multi-stage distribution channel is an N-stage distribution flow channel, and the mixing channel of the reducing phase solution and the metal salt solution is a 2N-stage distribution flow channel, where N≥2.
6. The device for high-throughput preparation of nano-catalysts according to claim 1, wherein The structure of the micro-reaction channel is one or several of a fluid focusing structure, a heart-shaped structure, a co-directional diversion structure, an axial step structure, and a volume amplification structure.
7. The device for high-throughput preparation of a nano-catalyst according to claim 1 or 6, characterized in that, The micro-reaction channel includes N channels, where N≥2.
8. The device for high-throughput preparation of nano-catalysts according to claim 1, characterized in that, The width of all channels is 0.01 - 50 mm, the height is 0.01 - 50 mm, and the pore diameter of the liquid phase input and output is 0.1 - 100 mm.
9. The device for high-throughput preparation of nano-catalysts according to claim 1, characterized in that, The droplet unit collection layer can be temperature-controlled.
10. A method for high-throughput preparation of a nanocatalyst using the device according to any one of claims 1-9, characterized in that, It includes the following steps: First, pump the metal salt solution into the metal salt solution input port. It flows through the mixing channel and the multi-stage dendritic distribution channels in the liquid phase distribution layer for uniform distribution successively. Each distribution channel can conduct independent liquid phase transmission. Subsequently, pump the oil phase solution and the reducing phase solution into the oil phase solution input port and the reducing phase solution input port respectively, which are directly connected to the connection channels of the multiphase emulsification layer for continuous liquid phase distribution. Among them, the flowing-down metal salt solution and reducing phase solution are powerfully mixed in the co-directional collision mixing channel in a co-directional collision manner, and then sheared into droplets in the oil phase multi-stage distribution channel, and continue to flow into the micro reaction channel for nucleation, growth and reaction of nanoparticles. Then, they enter the droplet collection layer through the micro-droplet distribution connection port, and are divided into two streams in the annular channel for droplet transportation, extending the reaction growth time of nanoparticles. Finally, the micro-droplets of nanoparticles are collected at the micro-droplet output port, and finally high-activity and high-selectivity nano-catalysts are obtained through centrifugation, washing and drying.