Mass production method of supported noble metal catalyst

Abstract

The invention provides a mass production method of a supported noble metal catalyst. The mass production method comprises the following steps: preparing a noble metal and / or noble metal precursor solution: mixing the noble metal and / or noble metal precursor with a high-boiling-point organic solvent; preparing a protective layer on the outer surface of the carrier: mixing the carrier, water and an organic solvent together to obtain a turbid liquid 1; loading a noble metal and / or a noble metal precursor on a carrier; adding the noble metal and / or noble metal precursor solution into the turbid liquid 1 to obtain turbid liquid 2; modifying a solid material by charges: adding a charge modifier into the turbid liquid 2 to form particles with charges so as to obtain turbid liquid 3; if the carrier is loaded with the noble metal precursor, the mass production method of the supported noble metal catalyst further comprises the following steps: reducing the noble metal precursor: adding a reducing solution into the turbid liquid 3 to obtain turbid liquid 4; and filtering: filtering the turbid liquid 3 or the turbid liquid 4, and washing with water to obtain the supported noble metal catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation methods, and more specifically relates to a method for mass production of supported noble metal catalysts. Background Art

[0002] With the rapid development of the times, the Internet of Things (IoT), where everything is connected, is profoundly affecting people's lives in an unprecedented manner. The IoT uses sensors based on various principles to build a perception layer to obtain underlying information. The indicators that these sensors can detect cover physical and chemical quantities, just like the "eyes" and "antennae" of the IoT, providing vital basic data for the IoT system.

[0003] Nowadays, the Internet of Things has been widely used in various fields of production and life. In factories, mining, hospitals, schools and other crowded places, the content of toxic and harmful gases is closely related to the safety of people's lives and property. The centralized monitoring achieved through the Internet of Things and big data technology can play an excellent early warning role and provide strong support for ensuring the safety of personnel and property.

[0004] Among many gas sensors, gas sensors based on electrochemical principles have been widely used due to their significant advantages such as rapid response, high cost performance, strong robustness, and good adaptability to environmental temperature and humidity. In gas sensors based on electrochemical principles, catalysts are the core components for chemical reactions. At present, precious metal catalysts are widely used in the industry, and the particle size of precious metal catalysts with excellent performance is usually 3 to 5nm. However, the smaller the particle size of the catalyst, the more likely it is to agglomerate when the particles collide due to its own strong activity during the preparation process.

[0005] my country started relatively late in catalyst research, especially when catalysts are mass-produced, the overall performance often decreases due to catalyst agglomeration. Summary of the invention

[0006] In order to solve the problem that the catalyst preparation method in the prior art is easy to agglomerate and lead to a decrease in catalyst performance during large-scale mass production, the present invention aims to develop a mass production method for supported precious metal catalysts, and the precious metal catalysts prepared by this method can be mass-produced.

[0007] A method for mass production of a supported noble metal catalyst comprises the following steps:

[0008] Preparing a noble metal and / or a noble metal precursor solution: mixing the noble metal and / or the noble metal precursor with a high boiling point organic solvent to prepare the noble metal and / or the noble metal precursor solution;

[0009] Preparing a protective layer on the outer surface of the carrier: mixing the carrier, water and an organic solvent together to obtain a suspension 1;

[0010] Loading the precious metal and / or the precious metal precursor onto the carrier: adding the precious metal and / or the precious metal precursor solution into the suspension 1 at a precious metal loading of 10% to 80% to obtain a suspension 2 containing a solid material;

[0011] Charge-modified solid material: adding a charge modifier to the above suspension 2 to form charged particles to obtain suspension 3;

[0012] If the carrier carries a noble metal precursor, the method for mass production of the supported noble metal catalyst further comprises: reducing the noble metal precursor: adding an appropriate amount of reducing liquid to the suspension 3 to generate catalyst particles to obtain a suspension 4;

[0013] Filtration: Filter the suspension 3 or the suspension 4, and wash with water to obtain the precious metal catalyst.

[0014] Furthermore, the precious metal is one or more of platinum, palladium, ruthenium, iridium, and gold; the precious metal precursor is one or more of chloroplatinic acid, palladium dichloride, ruthenium trichloride, potassium chloroaurate, and iridium chloride.

[0015] Furthermore, the high boiling point organic solvent is one or more of ethylene glycol, diethylene glycol, propylene glycol ether, glycerol, diethylene glycol, diethyl oxalate, and propylene glycol.

[0016] Furthermore, the concentration of the noble metal in the noble metal and / or the noble metal precursor is 0.2 to 20 mmol / L.

[0017] Furthermore, the carrier, water, and organic solvent are mixed together in a ratio of 0.001:1:1 to 0.01:1:1 to obtain suspension 1.

[0018] Furthermore, the carrier is one or more of carbon particles with a size ranging from 20 to 200 nm, graphene, carbon nanotubes, molecular sieves, and ceramic materials; preferably, the organic solvent is one or more of ethylene glycol, diethylene glycol, propylene glycol ether, glycerol, diethylene glycol, diethyl oxalate, and propylene glycol.

[0019] Furthermore, after the noble metal and / or noble metal precursor solution is added to the suspension 1, it is continuously stirred at a speed of 200 to 900 rpm and a temperature of 40 to 150°C to mix the new solution evenly, thereby obtaining a suspension 2 containing the solid material.

[0020] Furthermore, the charge modifier is one or more of a sodium bicarbonate aqueous solution, a sodium carbonate aqueous solution, a sodium hypochlorite aqueous solution, and a sodium sulfite aqueous solution; preferably, the added amount of the charge modifier is 1 to 5 times the molar amount of the noble metal.

[0021] Furthermore, in the step of reducing the precious metal precursor: before adding a proper amount of reducing solution into the suspension 3, the suspension 3 is first heated to 40-80°C.

[0022] Furthermore, the reducing liquid is prepared by the following steps: adding a small molecule reducing agent to a high viscosity organic solvent to dissolve it into the reducing liquid; preferably, the small molecule reducing agent is one or more of sodium formate, sodium borohydride, sodium sulfite, and formaldehyde; preferably, the concentration of the small molecule reducing agent is 0.3-20 mmol / L; preferably, the high viscosity organic solvent is one or more of glycerol, diethylene glycol, diethyl oxalate, propylene glycol, and diethylene glycol.

[0023] The mass production method of a supported precious metal catalyst provided by the present invention is significantly innovative and efficient. When studying the large-scale preparation process of the catalyst, the optimal ratio relationship between the precursor, the reducing agent and the organic solvent is explored. In order to prevent the intermediate from agglomerating and causing a significant reduction in yield, the present invention prepares a protective layer on the outer surface of the carrier to generate a structure with a pre-anchored microscopic barrier, giving the intermediate the property of electrically repelling each other, effectively avoiding their mutual aggregation. In terms of environmental protection, the present invention abandons the traditional practice of using a large amount of organic solvents and innovatively adopts a water suspension method, which not only solves the problem of environmental pollution, but also optimizes the preparation process. In the constructed water system, by increasing the amount of solvent used and reducing the catalyst concentration, the microscopic collision distance between the catalyst particles is increased, thereby minimizing or even eliminating the occurrence of catalyst agglomeration.

[0024] In addition, in order to further reduce the activity of intermediates and catalysts and reduce the possibility of collision between them, an appropriate amount of viscosity agent is added to the water system. In this way, the particle characteristics of the catalysts produced on a large scale can be ensured to be highly consistent with those in the laboratory small batch preparation stage, which effectively guarantees the quality stability and performance reliability of the catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a microscopic photograph of a single 5 kg noble metal catalyst prepared according to the method in Example 1. DETAILED DESCRIPTION

[0026] A large number of catalyst preparation methods have been reported in the literature, among which the more typical ones are:

[0027] US Patent US6689505B1: The preparation method of platinum / carbon catalyst disclosed in this patent uses water as dispersion liquid and performs reduction reaction under medium temperature and weak alkaline environment. Specifically, the noble metal precursor is added to the dispersion liquid with a temperature of 90°C and pH=9, and then sodium formate is used as the reducing liquid to finally obtain the supported noble metal catalyst.

[0028] Chinese Patent (Application No. 02118282.5): This patent effectively reduces the loss of precious metals during the preparation and post-processing process by introducing halides such as halogenated ammonium as anchoring agents during the catalyst preparation process.

[0029] US Patent No. 6,686,308B2 discloses a method for preparing a noble metal catalyst by using ethylene glycol as both a reducing agent and a dispersing agent. The prepared catalyst has the advantage of small particles.

[0030] US Patent No. 6703150B2: This patent discloses a method for preparing a catalyst by reduction using 7% hydrogen.

[0031] Chinese Patent 200410028129.X: The method disclosed in this patent is to use ethylene glycol as a dispersant and sodium formate as a reducing agent to prepare a precious metal catalyst. This method has outstanding advantages such as uniform particles, simple operation, and high raw material utilization.

[0032] When preparing precious metal catalysts, all of the above methods adopt the "precious metal precursor + reducing agent" model, use organic solvents to create a reaction microenvironment, and promote chemical reactions through a one-step method under high temperature and / or high pressure conditions. However, this method has obvious disadvantages. The reaction rate is too fast under high temperature and / or high pressure conditions, which makes the generation and agglomeration of intermediates difficult to control. In the process of large-scale production, there are still many problems, such as how to achieve uniform distribution of temperature and pressure in the microenvironment inside the solvent, how to ensure uniform ratio of precursors and reducing agents at the molecular level, etc. At the same time, the generated intermediates are prone to collide and combine with each other to generate by-products in mass production, resulting in the yield of mass-produced catalysts being much lower than the yield of small-scale laboratory production. In addition, the surface energy and activity of the generated nano-scale catalyst particles are extremely high, and agglomeration is very likely to occur during the collision process, which leads to the increase of catalyst particles and changes in crystal form, and ultimately greatly reduces the detection performance of the catalyst.

[0033] The mass production method of a supported precious metal catalyst provided by the present invention is significantly innovative and efficient. When studying the large-scale preparation process of the catalyst, the optimal ratio relationship between the precursor, the reducing agent and the organic solvent is explored. In order to prevent the intermediate from agglomerating and causing a significant reduction in yield, the present invention prepares a protective layer on the outer surface of the carrier to generate a structure with a pre-anchored microscopic barrier, giving the intermediate the property of electrically repelling each other, effectively avoiding their mutual aggregation. In terms of environmental protection, the present invention abandons the traditional practice of using a large amount of organic solvents and innovatively adopts a water suspension method, which not only solves the problem of environmental pollution, but also optimizes the preparation process. In the constructed water system, by increasing the amount of solvent used and reducing the catalyst concentration, the microscopic collision distance between the catalyst particles is increased, thereby minimizing or even eliminating the occurrence of catalyst agglomeration.

[0034] In addition, in order to further reduce the activity of intermediates and catalysts and reduce the possibility of collision between them, an appropriate amount of viscosity agent is added to the water system. In this way, the particle characteristics of the catalysts produced on a large scale can be ensured to be highly consistent with those in the laboratory small batch preparation stage, which effectively guarantees the quality stability and performance reliability of the catalysts.

[0035] A method for mass production of a supported noble metal catalyst comprises the following steps:

[0036] S1. Preparing a noble metal and / or a noble metal precursor solution: mixing a noble metal and / or a noble metal precursor with a high boiling point organic solvent to prepare a noble metal and / or a noble metal precursor solution.

[0037] In the present invention, the noble metal may be one or more of platinum, palladium, ruthenium, iridium, gold, and other potentially applicable noble metals. The noble metal precursor may be one or more of chloroplatinic acid, palladium dichloride, ruthenium trichloride, potassium chloroaurate, iridium chloride, and other potentially applicable noble metal precursors.

[0038] In the present invention, the high boiling point organic solvent is a water-insoluble solvent, which can be one or more of ethylene glycol, diethylene glycol, propylene glycol ether, glycerol, diethylene glycol, diethyl oxalate, and propylene glycol. The boiling point range of the high boiling point solvent in the present invention is above 150°C.

[0039] The concentration of the precious metal and / or the precious metal precursor in the precious metal and / or the precious metal precursor solution is determined according to the type of precious metal and the difficulty of agglomeration. In the present invention, the concentration of the precious metal in the precious metal and / or the precious metal precursor is 0.2 to 20 mmol / L. For example, gold nanoparticles are the most prone to self-agglomeration among all precious metal nanoparticles, so it is suitable to select an extremely low concentration, such as 0.2 to 5 mmol / L; ruthenium particles are extremely small and difficult to agglomerate or settle, so they are suitable for a higher concentration, so as to increase the chance of intermolecular collision and accelerate the sedimentation rate of the produced catalyst, such as 15 to 20 mmol / L.

[0040] S2. Preparing a protective layer on the outer surface of the carrier: mixing the carrier, water and an organic solvent in a weight ratio of 0.001:1:1 to 0.01:1:1 to obtain a suspension 1.

[0041] In the present invention, the carrier may be one or more of carbon particles, graphene, carbon nanotubes, molecular sieves, and ceramic materials with a size ranging from 20 to 200 nm.

[0042] In the present invention, the organic solvent is a water-insoluble solvent and may be one or more of ethylene glycol, diethylene glycol, propylene glycol ether, glycerol, diethylene glycol, diethyl oxalate, and propylene glycol.

[0043] The 1:1 configuration of water and organic solvent can ensure the uniformity of the water wall. The above ratio needs to be determined according to the precious metal loading. It should be noted that the carrier concentration should not be too high, so as to avoid the phenomenon that the carrier is too much and cannot be isolated by the water wall and solvent. If the precious metal content in the final supported precious metal catalyst is low, a ratio with a higher carrier content concentration can be selected within the above ratio range, so that agglomeration will not occur; if the precious metal loading in the final supported precious metal catalyst is high, it is necessary to select an extremely low carrier loading to increase the relative amount of solvent to avoid collision and agglomeration. Since water and organic solvents are immiscible, and the carrier can form an infiltration effect in the organic solvent but not in the water, a protective layer with water as the isolation wall will be formed, and the carriers infiltrated by the organic solvent are separated by a shielding cover formed by a microscopic water wall, and the distance is greatly enhanced.

[0044] S3. Loading the precious metal and / or precious metal precursor onto the carrier: adding the precious metal and / or precious metal precursor solution into the suspension 1 at a precious metal loading of 10% to 80% to obtain a suspension 2 containing solid materials (the solid materials include precious metals and / or precious metal precursors, and carriers).

[0045] Specifically, the noble metal and / or noble metal precursor solution is added to the suspension 1 according to the noble metal loading, and a high-speed stirrer is used to continuously stir at a speed of 200 to 900 rpm and a temperature of 40 to 150° C. to mix the new solution evenly, and obtain a suspension 2 containing solid materials (solid materials include noble metals and / or noble metal precursors, carriers). For noble metals such as gold that are very easy to reduce and agglomerate, high speed and low temperature are suitable. Low temperature can slow down the reaction activity and avoid the reaction from being too violent to generate macromolecules. High-speed stirring can increase the distance between molecules, reduce the possibility of collision, and avoid agglomeration. For materials that are difficult to reduce, such as ruthenium and iridium, low-speed stirring and high-temperature reduction are suitable to speed up the reaction rate.

[0046] S4. Charge-modified solid material: Add a charge modifier to the above suspension 2 to form charged particles to obtain suspension 3.

[0047] In the present invention, the charge modifier can be one or more of a sodium bicarbonate aqueous solution, a sodium carbonate aqueous solution, a sodium hypochlorite aqueous solution, and a sodium sulfite aqueous solution. Specifically, the charge modifier is added to the above suspension 2, and the amount of the charge modifier added is 1 to 5 times the molar amount of the noble metal to ensure that all noble metals and / or noble metal precursors can be effectively charge modified.

[0048] Then, stirring is continued at a speed of about 1200 rpm to form charged particles to obtain suspension 3. Since the particles are uniformly charged with the same charge, there is a phenomenon of electrical mutual repulsion between each other, and the distance between the particles is further increased, which can effectively avoid the phenomenon of agglomeration.

[0049] If the carrier is loaded with a noble metal precursor, the above-mentioned method for mass production of supported noble metal catalysts further includes:

[0050] S41. Reduction of precious metal precursors: heating the above suspension 3 to 40-80°C; adding 0.3-20 mmol / L of a small molecule reducing agent into a high-viscosity organic solvent to dissolve it into a reducing solution; adding an appropriate amount of reducing solution to the above suspension 3, the small molecule reducing agent in the reducing solution can pass through the barrier water wall to reach the precious metal precursor to undergo a reduction reaction, thereby generating catalyst particles and obtaining a suspension 4.

[0051] If the carrier carries a precious metal, the above step S41 is not necessary.

[0052] Specifically, the above suspension 3 is heated to 40-80°C. When the temperature reaches above 40°C, 0.3-20 mmol / L of a small molecule reducing agent is added to a high-viscosity organic solvent to dissolve into a reducing solution. In the present invention, the small molecule reducing agent can be dissolved in water and an organic solvent, for example, it can be one or more of sodium formate, sodium borohydride, sodium sulfite, and formaldehyde. In the present invention, the high-viscosity organic solvent can be one or more of glycerol, diethylene glycol, diethyl oxalate, propylene glycol, and diethylene glycol. The present invention adopts reduction under low temperature conditions, which reduces the reaction rate and facilitates the generation of small-particle precious metal catalysts. At the same time, the organic solvent has high viscosity at low temperatures and a strong drag effect, which is conducive to preventing agglomeration.

[0053] Add an appropriate amount of reducing liquid to the above suspension 3. The small molecule reducing agent in the reducing liquid can pass through the barrier water wall to reach the precious metal precursor to undergo a reduction reaction, generate catalyst particles, and obtain suspension 4. The high-viscosity organic solvent in the reducing liquid is dispersed in the entire reaction liquid, which can implement a wrapping and dragging effect on the catalyst particles generated by the reaction, reduce the activity of the generated catalyst particles, and prolong the collision time, thereby reducing the possibility of catalyst particle agglomeration to a minimum. After the reaction is completed, the suspension 4 is rapidly cooled in an ice bath overnight to further reduce the probability of collision of the catalyst particles.

[0054] S5, filtration: filtering the suspension 3 or the suspension 4, and washing with water to obtain the noble metal catalyst.

[0055] The noble metal catalyst prepared by the method of the present invention has good selectivity, the process is controllable, and the preparation of targeted catalysts for different gases can be realized. The gas sensor prepared by the above catalyst is significantly superior to the products sold in the industry in terms of selectivity. The technical solution of the present invention will be further described in detail below in conjunction with specific embodiments.

[0056] Example 1

[0057] S1. Prepare a noble metal precursor solution: select chloroplatinic acid as a noble metal precursor, mix it with ethylene glycol, and prepare a solution with a concentration of 5 mmol / L.

[0058] S2. Preparing a protective layer on the outer surface of the carrier: mixing carbon particles with a size of 50 nm, water, and ethylene glycol in a ratio of 0.005:1:1 to obtain a suspension 1.

[0059] S3. Loading the precious metal precursor onto the carrier: adding the above-prepared chloroplatinic acid solution into the suspension 1 at a precious metal loading of 70%, and continuously stirring at a speed of 500 rpm and a temperature of 80° C. using a high-speed stirrer to obtain a suspension 2 containing a solid material.

[0060] S4. Charge-modified solid material: add sodium bicarbonate aqueous solution as a charge modifier to suspension 2 in an amount three times the molar amount of the noble metal, and continue stirring at a speed of 1200 rpm to obtain suspension 3.

[0061] S41. Reduction of precious metal precursors: heat suspension 3 to 60°C, add 10 mmol / L sodium formate to propylene glycol to dissolve into a reducing solution, add an appropriate amount of the reducing solution to suspension 3 to obtain suspension 4. After the reaction is completed, rapidly cool suspension 4 in an ice bath overnight.

[0062] S5, filtration: Filter the suspension 4, and wash with water to obtain the noble metal catalyst.

[0063] Example 2

[0064] S1. Prepare a noble metal precursor solution: use palladium dichloride as a noble metal precursor, mix it with diethylene glycol, and prepare a solution with a concentration of 8 mmol / L.

[0065] S2. Preparing a protective layer on the outer surface of the carrier: mixing carbon nanotubes with a size of 100 nm, water and diethylene glycol in a ratio of 0.003:1:1 to obtain a suspension 1.

[0066] S3. Loading the precious metal precursor onto the carrier: adding the palladium dichloride solution into the suspension 1 at a precious metal loading of 30%, using a high-speed stirrer to continuously stir at a speed of 400 rpm and a temperature of 100° C. to obtain a suspension 2 containing a solid material.

[0067] S4. Charge-modified solid material: add sodium carbonate aqueous solution as a charge modifier to suspension 2 in an amount twice the molar amount of the noble metal, and continue stirring at a speed of 1200 rpm to obtain suspension 3.

[0068] S41. Reduction of precious metal precursors: heat suspension 3 to 70°C, add 15 mmol / L sodium borohydride to diethylene glycol to dissolve into a reducing solution, add an appropriate amount of the reducing solution to suspension 3 to obtain suspension 4. After the reaction is completed, rapidly cool suspension 4 in an ice bath overnight.

[0069] S5, filtration: Filter the suspension 4, and wash with water to obtain the noble metal catalyst.

[0070] Example 3

[0071] S1. Preparing a noble metal precursor solution: using potassium chloroaurate as a noble metal precursor, mixing it with propylene glycol ether to prepare a solution with a concentration of 3 mmol / L.

[0072] S2. Preparing a protective layer on the outer surface of the carrier: mixing graphene with a size of 80 nm, water, and propylene glycol ether in a ratio of 0.008:1:1 to obtain a suspension 1.

[0073] S3. Loading the precious metal precursor onto the carrier: adding potassium chloroaurate solution into the suspension 1, using a high-speed stirrer to continuously stir at a speed of 700 rpm and a temperature of 60° C. to obtain a suspension 2 containing a solid material.

[0074] S4. Charge-modified solid material: add sodium hypochlorite aqueous solution as a charge modifier to suspension 2 in an amount of 4 times the molar amount of the noble metal, and continue stirring at a speed of 1200 rpm to obtain suspension 3.

[0075] S41. Reduction of precious metal precursors: heat suspension 3 to 50°C, add 8 mmol / L sodium sulfite to diethyl oxalate to dissolve it into a reducing solution, add an appropriate amount of the reducing solution to suspension 3 to obtain suspension 4. After the reaction is completed, rapidly cool suspension 4 in an ice bath overnight.

[0076] S5, filtration: Filter the suspension 4, and wash with water to obtain the noble metal catalyst.

[0077] Example 4

[0078] S1. Prepare a noble metal precursor solution: use ruthenium trichloride as a noble metal precursor, mix it with propylene glycol, and prepare a solution with a concentration of 18 mmol / L.

[0079] S2. Preparing a protective layer on the outer surface of the carrier: mixing a molecular sieve with a size of 150 nm, water, and glycerol in a ratio of 0.006:1:1 to obtain a suspension 1.

[0080] S3. Loading the precious metal precursor onto the carrier: adding ruthenium trichloride solution into the suspension 1 at a precious metal loading of 40%, using a high-speed stirrer to continuously stir at a speed of 300 rpm and a temperature of 120° C. to obtain a suspension 2 containing a solid material.

[0081] S4. Charge-modified solid material: add sodium sulfite aqueous solution as a charge modifier to suspension 2 in an amount three times the molar amount of the noble metal, and continue stirring at a speed of 1200 rpm to obtain suspension 3.

[0082] S41. Reduction of precious metal precursors: heat suspension 3 to 75°C, add 12 mmol / L formaldehyde to diethylene glycol to dissolve it into a reducing solution, add an appropriate amount of the reducing solution to suspension 3 to obtain suspension 4. After the reaction is completed, rapidly cool suspension 4 in an ice bath overnight.

[0083] S5, filtration: Filter the suspension 4, and wash with water to obtain the noble metal catalyst.

[0084] Example 5

[0085] S1. Preparing a noble metal precursor solution: selecting iridium chloride as a noble metal precursor, mixing it with diethylene glycol, and preparing a solution with a concentration of 12 mmol / L.

[0086] S2. Preparing a protective layer on the outer surface of the carrier: mixing a ceramic material with a size of 120 nm, water, and diethylene glycol in a ratio of 0.004:1:1 to obtain a suspension 1.

[0087] S3. Loading the precious metal precursor onto the carrier: adding the iridium chloride solution into the suspension 1 at a precious metal loading of 80%, and continuously stirring at a speed of 600 rpm and a temperature of 90° C. using a high-speed stirrer to obtain a suspension 2 containing a solid material.

[0088] S4. Charge-modified solid material: add sodium bicarbonate aqueous solution as a charge modifier to the suspension 2, the added amount being 2.5 times the molar amount of the noble metal, and continue stirring at a speed of 1200 rpm to obtain a suspension 3.

[0089] S41. Reduction of precious metal precursors: heat suspension 3 to 65°C, add 10 mmol / L sodium formate to propylene glycol to dissolve into a reducing solution, add an appropriate amount of the reducing solution to suspension 3 to obtain suspension 4. After the reaction is completed, rapidly cool suspension 4 in an ice bath overnight.

[0090] S5, filtration: Filter the suspension 4, and wash with water to obtain the noble metal catalyst.

[0091] Example 6

[0092] S1. Preparing a precious metal solution: Weigh an appropriate amount of platinum powder and add it to glycerol. Since platinum is relatively difficult to agglomerate, its concentration in the solution can be controlled at 10 mmol / L. The platinum powder is fully dispersed in glycerol by ultrasonic dispersion or other methods to obtain a uniform precious metal solution.

[0093] S2. Preparing a protective layer on the outer surface of the carrier: Select carbon nanotubes with a size of 80 nm as the carrier, and mix the carbon nanotubes, water, and propylene glycol in a ratio of 0.005:1:1. Since water and propylene glycol are immiscible, and carbon nanotubes can form an infiltration effect in propylene glycol but not in water, a protective layer with water as a separation wall is formed to obtain a suspension 1.

[0094] S3, loading the precious metal onto the carrier: adding the platinum glycerol solution prepared above to the suspension 1 at a precious metal loading of 10%. Using a high-speed stirrer, continuously stir at a speed of 600 rpm and a temperature of 90° C. to mix the solution evenly, and obtain a suspension 2 containing solid materials (including platinum and the carrier).

[0095] S4, charge-modified solid material: add sodium carbonate aqueous solution as charge modifier to suspension 2, the amount of charge modifier added is 3 times the molar amount of precious metal. Continue stirring at a speed of 1200 rpm to make the particles uniformly charged with the same charge, and there is electrical repulsion between each other, and the distance between particles is further increased to obtain suspension 3, effectively avoiding agglomeration.

[0096] S5, filtration: The suspension 3 is directly filtered, and then repeatedly washed with deionized water to remove residual impurities and unreacted substances, and finally a supported platinum noble metal catalyst is obtained. During the preparation process of the catalyst, the agglomeration of noble metal particles is effectively reduced through the fine control of each step, ensuring the performance and quality of the catalyst.

[0097] Experimental Example 1

[0098] The microscopic photograph of a single 5 kg noble metal catalyst prepared according to the method in Example 1 was tested by scanning electron microscopy, as shown in FIG. Figure 1 As shown by Figure 1 It can be seen that the precious metal catalyst particles prepared at the 5kg pilot scale are evenly distributed without agglomeration.

[0099] Experimental Example 2

[0100] A carbon monoxide sensor was made using the noble metal catalyst prepared in Example 1. Its sensitivity to carbon monoxide, 705 silicone rubber and freon was tested and shown in Table 1.

[0101] Table 1 Comparison of the sensitivity of the sensor of the present invention and commercially available sensors to carbon monoxide, 705 silicone rubber and freon

[0102]

[0103] The sensitivity of the sensor of the present invention to carbon monoxide (3.2nA / ppm) is significantly higher than that of commercially available sensors (2.1nA / ppm), indicating that the carbon monoxide sensor made of the precious metal catalyst of the present invention can generate a larger current response when detecting carbon monoxide and is more sensitive to carbon monoxide detection.

[0104] The sensitivity of the sensor of the present invention to 705 silicone rubber is only 0.04nA / ppm, and the relative sensitivity is 1%, indicating that the sensor of the present invention is minimally interfered by 705 silicone rubber and has better anti-interference ability. The sensitivity of the commercial sensor to 705 silicone rubber is 2nA / ppm, and the relative sensitivity (S silicone rubber / SCO*100%) is 96%, indicating that the commercial sensor is greatly interfered by 705 silicone rubber.

[0105] The sensitivity of the sensor of the present invention to Freon (R32) is 0.03nA / ppm, and the relative sensitivity is 1%, which indicates that the sensor of the present invention is also very little disturbed by Freon, and can detect carbon monoxide more accurately in a complex environment without being affected by Freon. The sensitivity of the commercial sensor to Freon (R32) is 0.4nA / ppm, and the relative sensitivity (SR32 / SCO*100%) is 19%, indicating that the commercial sensor will be disturbed to a certain extent in the presence of Freon.

[0106] In summary, the carbon monoxide sensor made of the precious metal catalyst of the present invention is superior to commercially available sensors in carbon monoxide detection sensitivity, and also performs well in resisting interference from 705 silicone rubber and Freon, and has higher accuracy and reliability.

[0107] Experimental Example 3

[0108] A hydrogen sulfide sensor was made using the noble metal catalyst prepared in Example 1. Its sensitivity to hydrogen sulfide, carbon monoxide and alcohol was tested and shown in Table 2.

[0109] Table 2 Comparison of the sensitivity of the sensor of the present invention and commercially available sensors to hydrogen sulfide, carbon monoxide, and alcohol

[0110]

[0111] The sensitivity of the sensor of the present invention to hydrogen sulfide (62nA / ppm) is significantly higher than that of commercially available sensors (39nA / ppm), indicating that the sensor of the present invention is more sensitive in detecting hydrogen sulfide and can more effectively capture changes in the concentration of hydrogen sulfide.

[0112] The sensor of the present invention is only 1.2nA / ppm, while the commercially available sensor has a sensitivity to carbon monoxide of 24nA / ppm. Although the carbon monoxide sensitivity of the sensor of the present invention is lower than that of the commercially available sensor, in terms of resistance to interference from 705 silicone rubber, the relative sensitivity (S silicone rubber / SCO*100%) of the sensor of the present invention is 2%, which is much lower than 60% of the commercially available sensor. This indicates that the sensor of the present invention is minimally interfered by 705 silicone rubber during carbon monoxide detection and has better selectivity and stability.

[0113] The sensitivity of the sensor of the present invention to alcohol is only 0.3nA / ppm, and the relative sensitivity is 0.5%, which shows that the sensor of the present invention is minimally interfered by alcohol and can detect the target gas more accurately in an environment where alcohol exists without misjudgment due to alcohol interference. The sensitivity of commercial sensors to alcohol is as high as 47nA / ppm, and the relative sensitivity (SR32 / SCO*100%) is 120%, indicating that commercial sensors are seriously interfered by alcohol.

[0114] In summary, the sensor of the present invention has advantages in hydrogen sulfide detection sensitivity. At the same time, in terms of carbon monoxide and alcohol detection, although the sensitivity values ​​may not be advantageous, it performs well in anti-interference ability, can detect target gases more accurately in complex environments, and has higher reliability and practicality.

[0115] The details shown herein are presented as examples only and for the purpose of illustrative discussion of preferred embodiments of the invention, and are presented for the purpose of providing what is believed to be the most useful and easy-to-understand description of aspects of the principles and concepts of various embodiments of the invention. In this regard, no attempt is made to show the structural details of the invention in more detail than is necessary for a basic understanding of the invention, and the description in conjunction with the accompanying drawings and / or examples makes it clear to those skilled in the art how several forms of the invention are embodied in practice. Therefore, before describing the disclosed methods and apparatus, it should be understood that the aspects described herein are not limited to specific embodiments, instruments or configurations, and therefore can certainly be changed. It should also be understood that the terms used herein are only for the purpose of describing specific aspects, and are not intended to be limiting unless expressly defined herein.

[0116] The terms "a", "an", "the" and similar references used in the context of describing the present invention (especially in the context of the claims below) should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each individual value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. It will be further understood that the endpoints of each range are significant not only in relation to the other endpoints, but also independently of the other endpoints.

[0117] All methods described herein can be performed in the order of any suitable steps, unless otherwise indicated herein or clearly contradictory to the context. The use of any and all embodiments provided herein, or exemplary language (e.g., "such as") is intended only to better illustrate the present invention and does not set limitations on the scope of the present invention otherwise claimed. No language in the specification should be interpreted as indicating any unclaimed elements essential to the practice of the present invention.

[0118] Unless the context clearly requires otherwise, throughout the specification and claims, the wording 'comprising

[0119] The terms "herein," "above," and "below," and words of similar meaning, when used in this application, shall refer to this application as a whole and not to any particular portion of this application.

[0120] As will be understood by one of ordinary skill in the art, each embodiment disclosed herein may comprise, consist essentially of, or consist of the specifically identified elements, steps, ingredients, or components thereof. As used herein, the transitional terms "comprise" or "comprises" are meant to include, but are not limited to, and permit the inclusion of unspecified elements, steps, ingredients, or components, even in large quantities. The transitional phrase "consisting of" excludes any unspecified elements, steps, ingredients, or components. The transitional phrase "consisting essentially of" limits the scope of the embodiment to the identified elements, steps, ingredients, or components and those that do not materially affect the embodiment.

[0121] Unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0122] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors resulting from the standard deviation found in their respective testing measurements.

[0123] The grouping of the optional elements or embodiments of the invention disclosed herein should not be construed as limiting. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements present herein. It is expected that one or more members of the group may be included in the group, or deleted from the group, due to convenience and / or patentable reasons. When any such inclusion or deletion occurs, it is considered that the specification contains the modified group, and therefore satisfies the written description of all Markush groups used in the appended claims.

[0124] Some embodiments of the present invention are described herein, including the best mode known to the inventor for carrying out the present invention. Of course, for those skilled in the art, when reading the foregoing description, variations of the embodiments described will become clear. The inventor expects that a skilled person will adopt such variations as appropriate, and the inventor intends to practice the present invention in a manner other than the specific description herein. Therefore, the present invention includes all modifications and equivalents of the subject matter recorded in the appended claims as allowed by applicable law. In addition, the present invention includes any combination of the elements described above in all possible variants thereof, unless otherwise indicated herein or clearly contradictory to the context.

[0125] Throughout this specification, a number of patents and printed publications are cited. Each of the cited references and printed publications is incorporated herein by reference in its entirety.

[0126] In addition, it should be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that may be adopted are within the scope of the present invention. Therefore, by way of example, but not as a limitation, alternative configurations of the present invention may be used consistent with the teachings herein. Therefore, the present invention is not limited to what is precisely shown and described.

Claims

1. A method for mass production of a supported noble metal catalyst, characterized in that: The following steps are involved: Preparing a noble metal and / or a noble metal precursor solution: mixing the noble metal and / or the noble metal precursor with a high boiling point organic solvent to prepare the noble metal and / or the noble metal precursor solution; Preparing a protective layer on the outer surface of the carrier: mixing the carrier, water and an organic solvent together to obtain a suspension 1; Loading the precious metal and / or the precious metal precursor onto the carrier: adding the precious metal and / or the precious metal precursor solution into the suspension 1 at a precious metal loading of 10% to 80% to obtain a suspension 2 containing a solid material; Charge-modified solid material: adding a charge modifier to the above suspension 2 to form charged particles to obtain suspension 3; If the carrier carries a noble metal precursor, the method for mass production of the supported noble metal catalyst further comprises: reducing the noble metal precursor: adding an appropriate amount of reducing liquid to the suspension 3 to generate catalyst particles to obtain a suspension 4; Filtration: Filter the suspension 3 or the suspension 4, and wash with water to obtain the precious metal catalyst.

2. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: The noble metal is one or more of platinum, palladium, ruthenium, iridium and gold; the noble metal precursor is one or more of chloroplatinic acid, palladium dichloride, ruthenium trichloride, potassium chloroaurate and iridium chloride.

3. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: The high boiling point organic solvent is one or more of ethylene glycol, diethylene glycol, propylene glycol ether, glycerol, diethylene glycol, diethyl oxalate, and propylene glycol.

4. The method for mass production of supported noble metal catalysts according to any one of claims 1 to 3, characterized in that: The concentration of the noble metal and / or the noble metal precursor is 0.2-20 mmol / L.

5. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: The carrier, water and organic solvent are mixed together in a weight ratio of 0.001:1:1 to 0.01:1:1 to obtain a suspension 1.

6. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: The carrier is one or more of carbon particles with a size ranging from 20 to 200 nm, graphene, carbon nanotubes, molecular sieves, and ceramic materials; preferably, the organic solvent is one or more of ethylene glycol, diethylene glycol, propylene glycol ether, glycerol, diethylene glycol, diethyl oxalate, and propylene glycol.

7. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: After the noble metal and / or noble metal precursor solution is added to the suspension 1, it is continuously stirred at a speed of 200 to 900 rpm and a temperature of 40 to 150°C to mix the new solution evenly, thereby obtaining a suspension 2 containing the solid material.

8. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: The charge modifier is one or more of a sodium bicarbonate aqueous solution, a sodium carbonate aqueous solution, a sodium hypochlorite aqueous solution, and a sodium sulfite aqueous solution; preferably, the added amount of the charge modifier is 1 to 5 times the molar amount of the noble metal.

9. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: In the step of reducing the precious metal precursor: before adding an appropriate amount of reducing solution into the suspension 3, the suspension 3 is first heated to 40-80°C.

10. The method for mass production of supported noble metal catalysts according to claim 1, characterized in that: The reducing liquid is prepared by the following steps: adding a small molecule reducing agent into a high viscosity organic solvent to dissolve into the reducing liquid; preferably, the small molecule reducing agent is one or more of sodium formate, sodium borohydride, sodium sulfite, and formaldehyde; preferably, the concentration of the small molecule reducing agent is 0.3-20 mmol / L; preferably, the high viscosity organic solvent is one or more of glycerol, diethylene glycol, diethyl oxalate, propylene glycol, and diethylene glycol.

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