Platinum-cerium bimetallic catalyst as well as preparation method and application thereof
By using platinum cerium bimetallic catalyst in the Anthracene method and anchoring metal atoms using the domain-limiting action of molecular sieve, the problem of platinum mesh catalysts being easily oxidized and sensitive to elements at high temperatures is solved, and high-efficiency and low-energy consumption of hydrogen cyanic acid production is achieved, and the yield of hydrogen cyanic acid is significantly improved.
Patent Information
- Application Number
- CN202311660079.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-06
- Publication Date
- 2025-06-06
AI Technical Summary
The platinum mesh catalyst used in the existing Anthracite method is prone to oxidation loss at high temperatures and is sensitive to elements such as sulfur and phosphorus, resulting in the deactivation of the catalyst, and the reaction conditions are harsh and the energy consumption is high.
The platinum cerium bimetallic catalyst is used to anchor metal atoms through the domain-limiting action of the molecular sieve, which improves the strength and reaction activity of the catalyst, reduces the reaction temperature and reduces energy consumption. The catalyst consists of MFI-type titanium silicon molecular sieve TS-1 support and platinum and cerium metals. Platinum elements account for 0.1-6% of the total mass and cerium elements account for 0.1-5%.
The strength and reaction activity of the catalyst are significantly improved, the reaction temperature and energy consumption are reduced, and the yield of hydrocyanic acid is greater than 60%, which is much higher than the 42.5% of the commercially available platinum mesh catalysts.
Smart Images
Figure BDA0004589961830000091 
Figure BDA0004589961830000101
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of industrial catalysis, and in particular relates to a platinum-cerium bimetallic catalyst, a preparation method and application thereof. Background Art
[0002] Hydrocyanic acid, with the molecular formula HCN, is an important chemical raw material, mainly used to produce sodium cyanide, methionine, MMA, etc. It has a wide range of uses. Hydrocyanic acid is a highly toxic chemical and cannot be transported over long distances, so all products involving cyanide must be used near the hydrocyanic acid plant. The main production processes for hydrocyanic acid include the methanol method, the methane method, the BMA method, and the acrylonitrile by-product method.
[0003] The methane method, also known as the Anscher method, uses methane (natural gas), ammonia, and air as raw materials. Under a certain temperature and catalyst, after absorption and distillation, the finished product of hydrocyanic acid is obtained. The Anscher method needs to be carried out under the conditions of 0.049-0.075MPa and 1050-1200℃, which are relatively harsh conditions. In addition, the Anscher method catalyst is an expensive platinum mesh catalyst, and the platinum mesh catalyst is easily oxidized to volatile PtO above 850℃. 2 , resulting in catalyst loss. In addition, the platinum mesh catalyst will undergo irreversible catalyst deactivation after contacting elements such as sulfur and phosphorus, so this reaction has high requirements for raw material purity. Summary of the invention
[0004] In view of the above-mentioned problems, the present invention provides a novel platinum-cerium bimetallic catalyst. Specifically, it is a novel platinum-based catalyst used in the preparation of hydrocyanic acid by the Angle method and a preparation method thereof. The catalyst anchors metal atoms through the confinement effect of the molecular sieve, greatly improving the strength of the catalyst. Through the synergistic effect of cerium metal, the reaction activity of the catalyst is improved, the reaction temperature is reduced, and the energy consumption is reduced.
[0005] Another object of the present invention is to provide the application of the platinum-cerium bimetallic catalyst.
[0006] In order to achieve the above invention object, the technical solution of the present invention is as follows:
[0007] A platinum-cerium bimetallic catalyst is an MFI type catalyst with a core-shell structure, wherein the inner core is PtCe@TS-1 and the outer shell is S-1, wherein the platinum element accounts for 0.1-6% of the total mass of the catalyst and the cerium element accounts for 0.1-5% of the total mass of the catalyst.
[0008] On the other hand, the preparation method of the aforementioned platinum-cerium bimetallic catalyst comprises the following steps:
[0009] (1) Preparation of the catalyst core PtCe@TS-1 by hydrothermal synthesis;
[0010] (2) The catalyst core is mixed with silica sol, and the surface silicon source is crystallized into S-1 at high temperature using template vapor in a crystallization kettle, thereby finally obtaining the platinum-cerium bimetallic catalyst.
[0011] In some specific embodiments, the TS-1 described in step (1) is a titanium silicalite molecular sieve having an MFI structure.
[0012] In some specific embodiments, the hydrothermal synthesis method in step (1) for preparing the catalyst core PtCe@TS-1 is as follows: adding a titanium source, a silicon source, a template, a platinum salt, and a cerium salt into a reactor and stirring, and then placing the mixture in a crystallization kettle for crystallization to obtain a catalyst core.
[0013] In some specific embodiments, the titanium source is selected from at least one of titanium dioxide, tetrabutyl titanate, tetraethyl titanate, and titanium isopropoxide; and / or
[0014] The silicon source is selected from one or more of methyl orthosilicate, ethyl orthosilicate, tetrabutyl silicate, nano-scale silica sol, and white carbon black; and / or
[0015] The template agent is selected from one or more of n-butylamine, triethylamine, ammonia water, hexamethylenediamine, tetrapropylammonium hydroxide and tetrapropylammonium bromide; and / or
[0016] The platinum salt is selected from at least any one of tetraammine platinum nitrate, platinum acetylacetonate, platinum nitrate, platinum sulfate, and platinum chloride; and / or
[0017] The cerium salt is selected from one or more of cerium nitrate, cerium isopropoxide and cerium sulfate.
[0018] In some specific embodiments, the molar ratio of the silicon source to the template is 0.2-5:1, and the molar ratio of the titanium source to the template is 0.01-0.5:1; and / or
[0019] The amount of the platinum salt added is 0.2-8% of the mass of silicon in the silicon source, calculated on the mass of the platinum element; and / or
[0020] Calculated by the mass of cerium element, the added amount of the cerium salt is 0.2-6% of the mass of silicon in the silicon source.
[0021] In some specific implementation schemes, the template is first configured into a 10-50wt% aqueous solution, and a titanium source and a silicon source are added in a 60-90°C water bath under stirring; after the addition is completed, stirring is continued for 20-60 minutes; then platinum salt and cerium salt are added, and stirring is continued for 10-30 minutes; the solution is placed in a crystallization kettle and crystallized at 150-200°C for 24-72 hours; after crystallization is completed, the solution is dried and calcined at 400-600°C for 4-6 hours to obtain PtCe@TS-1.
[0022] In some specific embodiments, the mass ratio of the catalytic core to the silica sol in step (2) is 1:2-5;
[0023] Preferably, step (2) is: a) mixing the catalytic core with silica sol, drying in a water bath at 50-80° C. while stirring until dried, and then grinding into fine powder for later use;
[0024] b) Take a crystallization kettle, which is equipped with a tray, and the bottom of the kettle is filled with a template solution. The tray supports the fine powder of step a) above the template liquid surface, and then crystallizes at 120-180° C. for 24-72 hours, and then calcines at 450-540° C. for 4-8 hours to obtain a catalyst.
[0025] In another aspect, the use of the aforementioned platinum-cerium bimetallic catalyst or the platinum-cerium bimetallic catalyst prepared by the aforementioned preparation method in the production of hydrocyanic acid by the methane process;
[0026] Preferably, a fixed bed reactor is used for evaluation, the reaction temperature is 600°C, and the space velocity is 1500h -1 , the feed ratio of methane: ammonia: air is 1:1.1:24.
[0027] In some specific embodiments, when the platinum-cerium bimetallic catalyst is used in the reaction of preparing hydrocyanic acid from methane, the yield of hydrocyanic acid is greater than 60%.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] The catalyst of the present invention uses titanium silicon molecular sieve TS-1 with MFI structure as a carrier, and anchors platinum and cerium metals at defect sites inside the molecular sieve through the confinement effect of the molecular sieve, thereby achieving high dispersion of the metals, thereby avoiding the loss of precious metals and greatly improving the strength of the catalyst. Through the synergistic effect of platinum and cerium bimetallics, the reaction activity of the catalyst is improved, the reaction temperature is reduced, and energy consumption is reduced.
[0030] The platinum-cerium bimetallic catalyst of the present invention is applied to the hydrocyanic acid production reaction of methane process, and the yield of hydrocyanic acid is greater than 60%, which is much higher than 42.5% of the commercially available platinum mesh catalyst. DETAILED DESCRIPTION
[0031] In order to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. For those who do not specify specific conditions in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer.
[0032] A platinum-cerium bimetallic catalyst, which is an MFI-type catalyst with a core-shell structure, wherein the core is PtCe@TS-1 and the outer shell is S-1, wherein the platinum element accounts for 0.1-6% of the total mass of the catalyst, for example, 0.1%, 0.25%, 0.5%, 0.7%, 1%, 1.3%, 1.5%, 2%, 2.5%, 3%, 3.6%, 4%, 4.7%, 5%, 5.6%, 6%, etc., and the cerium element accounts for 0.1-5%, for example, 0.1%, 0.25%, 0.5%, 0.7%, 1%, 1.3%, 1.5%, 2%, 2.5%, 3%, 3.6%, 4%, 4.7%, 5%, etc.
[0033] Among them, PtCe@TS-1 means that platinum and cerium bimetallic catalysts are loaded on a titanium silicon molecular sieve carrier. Since the titanium silicon molecular sieve has an MFI configuration, the platinum-cerium bimetallic catalyst can be considered as an MFI type catalyst. The platinum-cerium bimetallic catalyst of the present invention grows a silicon shell layer (S-1) on the surface of the core PtCe@TS-1 in situ.
[0034] Specifically, there is no particular limitation on the preparation method of the platinum-cerium bimetallic catalyst of the present invention. Those skilled in the art will understand that as long as the platinum-cerium bimetallic catalyst meets the aforementioned performance characteristics, a high conversion rate can be achieved in the methane process to hydrogen cyanide reaction, regardless of the method used for its preparation.
[0035] Exemplarily, a method for preparing the aforementioned platinum-cerium bimetallic catalyst is provided below, comprising the following steps, but does not constitute any limitation:
[0036] (1) Synthesize the highly metal-dispersed catalyst core PtCe@TS-1 by hydrothermal synthesis;
[0037] (2) The core is mixed with silica sol, and the surface silicon source is crystallized into S-1 at high temperature in a crystallization reactor using template vapor to finally obtain a catalyst.
[0038] The catalyst of the present invention contains 0.1-6% of the total mass of platinum and 0.1-5% of the total mass of cerium. When the catalyst is used in the reaction of preparing hydrocyanic acid by Angle method, the yield of hydrocyanic acid is greater than 60%.
[0039] In the present invention, the TS-1 mentioned in step (1) is a titanium silicon molecular sieve having an MFI structure. The so-called high dispersion of metals means that the platinum and cerium metals are anchored at the defect sites inside the molecular sieve through the confinement effect of the molecular sieve, thereby avoiding the loss of precious metals.
[0040] In the present invention, step (1) is to prepare PtCe@TS-1 by a hydrothermal synthesis method. Specifically, for example, a titanium source, a silicon source, a template, a platinum salt, and a cerium salt are added to a beaker and stirred, and then placed in a crystallization kettle for crystallization to obtain a finished product.
[0041] The titanium source used is, for example, any one or more of titanium dioxide, tetrabutyl titanate, tetraethyl titanate, and titanium isopropoxide;
[0042] The silicon source is selected from one or more of methyl orthosilicate, ethyl orthosilicate, tetrabutyl silicate, nano-scale silica sol, and white carbon black;
[0043] The template used is, for example, one or more of n-butylamine, triethylamine, ammonia water, hexamethylenediamine, tetrapropylammonium hydroxide, and tetrapropylammonium bromide;
[0044] The platinum salt used is, for example, any one of tetraammine platinum nitrate, platinum acetylacetonate, platinum nitrate, platinum sulfate, and platinum chloride;
[0045] The cerium salt used is, for example, any one of cerium nitrate, cerium isopropoxide, and cerium sulfate.
[0046] In a preferred embodiment of the present invention, the catalyst core PtCe@TS-1 is prepared as follows: first, the template is configured into an aqueous solution with a mass fraction of 10-50%, for example, 20%, 30%, 40%, etc., preferably 20-40%; in a water bath at 60-90°C (for example, 65°C, 70°C, 75°C, 80°C, 85°C), a titanium source and a silicon source are added under stirring; wherein the molar ratio of the silicon source to the template is 0.2-5:1, for example, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, etc., and the molar ratio of the titanium source to the template is 0.01-0.5:1, for example, 0.01:1, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.3:1, 0.4:1, etc. After the addition is completed, stirring is continued for 30 minutes; then a certain amount of platinum salt and cerium salt are added, for example, by element mass, platinum accounts for 0.2-8% of the total silicon mass in the silicon source, and cerium accounts for 0.2-6% of the total silicon mass; stirring is continued for 30 minutes, loaded into a crystallization kettle, and crystallized at 150-200°C for 24-72 hours, for example, crystallized at 160°C, 170°C, 180°C, 190°C for 25h, 28h, 30h, 35h, 36h, 40h, 48h, 50h, 56h, 60h, 65h, 70h, etc. After crystallization is completed, it is dried and calcined at 540°C for 4h to obtain PtCe@TS-1.
[0047] In the present invention, the core-shell structure is prepared by dry gel conversion. The catalyst core PtCe@TS-1 is mixed with silica sol in a mass ratio of 1:2 to 5, such as 1:2, 1:3, 1:4, etc., and stirred in an open water bath at 80°C until dried, and then ground into fine powder for use. Take a crystallization kettle, which is equipped with a tray, and the bottom of the kettle is equipped with a template solution. The tray supports the fine powder above the template liquid surface, and then crystallizes at 120-180°C for 24-72h, for example, at 130°C, 140°C, 150°C, 160°C, 170°C, 180°C for 25h, 28h, 30h, 35h, 36h, 40h, 48h, 50h, 56h, 60h, 65h, 70h, etc., and calcines at 450-540°C for 4-8h, for example, at 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C for 5h, 6h, 7h, etc., to obtain a catalyst.
[0048] The template agent is, for example, one or more of n-butylamine, triethylamine, ammonia water, hexamethylenediamine, tetrapropylammonium hydroxide, and tetrapropylammonium bromide; preferably, the template agent is the same as the template agent used in step (1).
[0049] In the present invention, the prepared catalyst is analyzed by ICP, and the platinum element accounts for 0.1-6% of the total mass, and the cerium element accounts for 0.1-5% of the total mass.
[0050] In the present invention, the prepared catalyst is applied to the methane process to produce hydrocyanic acid. Specifically, a fixed bed reactor is used for evaluation, the reaction temperature is 600°C, the space velocity is 1500h -1 , the feed ratio of methane: ammonia: air is 1:1.1:24.
[0051] The present invention is further explained below by more specific embodiments. The present invention is not limited to the scope of the embodiments, but also includes any other changes within the scope of the rights claimed by the present invention.
[0052] The raw materials used in the embodiments of the present invention are not particularly described and can be purchased through conventional channels in the market.
[0053] The reaction product is absorbed by alkaline solution and the cyanide concentration is titrated by silver nitrate titration.
[0054] The elemental composition of the catalyst was analyzed by inductively coupled plasma spectrometry (ICP).
[0055] Example 1
[0056] Take 300g water and 69g tetrapropylammonium bromide, mix them, stir at 60℃, add 53.94g ethyl orthosilicate and 11.82g tetrabutyl titanate, stir for 30min. Then add 0.369g tetraammine platinum nitrate and 0.39g cerium isopropoxide, continue stirring for 30min. Then put it in a crystallization kettle, crystallize at 160℃ for 48h, and calcine at 540℃ for 4h to obtain the inner core.
[0057] Then take 5g of the core and 10g of silica sol, mix them, stir at 80℃ until dry. After grinding, place them on a tray in a crystallization kettle, add n-butylamine as a template under the tray. Crystallize at 180℃ for 72h, and calcine at 450℃ for 4h. Catalyst A is obtained.
[0058] Example 2
[0059] Take 300g water and 60g tetrapropylammonium hydroxide, mix them, stir at 80℃, add 3.54g white carbon black and 4.73g titanium dioxide, stir for 30min. Then add 0.945g platinum nitrate and 1.721g cerium nitrate, continue stirring for 30min. Then put it in a crystallization kettle, crystallize at 180℃ for 72h, and roast at 540℃ for 4h to obtain the core.
[0060] Then take 5g of the core and 10g of silica sol, mix them, stir at 80℃ until dry. After grinding, place them on a tray in a crystallization kettle, add tetrapropylammonium hydroxide under the tray as a template. Crystallize at 180℃ for 72h, and calcine at 540℃ for 8h. Catalyst B is obtained.
[0061] Example 3
[0062] Take 300g water and 69g tetrapropylammonium bromide, mix them, stir at 70℃, add 215.76g ethyl orthosilicate and 23.64g tetrabutyl titanate, stir for 60min. Then add 14.8g tetraammine platinum nitrate and 23.2g cerium isopropoxide, continue stirring for 15min. Then place in a crystallization kettle, crystallize at 160℃ for 48h, and calcine at 540℃ for 4h to obtain the inner core.
[0063] Then take 5g of the core and 15g of silica sol, mix them, stir at 80℃ until dry. After grinding, place them on a tray in a crystallization kettle, add n-butylamine as a template under the tray. Crystallize at 180℃ for 72h, and calcine at 500℃ for 6h. Catalyst C is obtained.
[0064] Comparative Example 1 (Traditional Catalyst)
[0065] A commercially available platinum mesh catalyst was purchased from Shin-Etsu Co., Ltd. of Japan and was recorded as catalyst D.
[0066] Comparative Example 2 (without adding cerium)
[0067] Take 300g water and 60g tetrapropylammonium hydroxide, mix them, stir at 80℃, add 3.54g white carbon black and 4.73g titanium dioxide, stir for 30min. Then add 0.0945g platinum nitrate, continue stirring for 30min. Then place in a crystallization kettle, crystallize at 180℃ for 72h, and roast at 540℃ for 4h to obtain the core.
[0068] Then take 5g of the core and 10g of silica sol, mix them, stir at 80℃ until dry. After grinding, place them on a tray in a crystallization kettle, add tetrapropylammonium hydroxide under the tray as a template agent. Crystallize at 180℃ for 72h, and calcine at 450℃ for 4h to obtain catalyst E.
[0069] Comparative Example 3 (without housing)
[0070] Take 300g water and 69g tetrapropylammonium bromide, mix them, stir at 60℃, add 53.94g ethyl orthosilicate and 11.82g tetrabutyl titanate and stir for 30min. Then add 0.369g tetraammine platinum nitrate and 0.39g cerium isopropoxide and continue stirring for 30min. Then put it in a crystallization kettle, crystallize at 160℃ for 48h, and calcine at 540℃ for 4h to obtain the core. It is recorded as catalyst F
[0071] The performance characterization results of the catalysts prepared in each embodiment and comparative example are shown in Table 1, wherein the evaluation of the yield of hydrocyanic acid was carried out according to the following process: Specifically, the evaluation was carried out using a fixed bed reactor, the reaction temperature was 600°C, the space velocity was 1500h -1 , the feed ratio of methane: ammonia: air is 1:1.1:24.
[0072] Table 1 Evaluation data of each catalyst
[0073]
[0074]
[0075] The comparison between catalyst D and A shows that cerium plays an important role in the yield of hydrocyanic acid in this reaction. Catalyst E shows that the traditional platinum mesh catalyst has poor effect at a low temperature of 600℃.
[0076] Catalyst F shows that the presence of the shell is beneficial to improving the yield of hydrocyanic acid.
Claims
1. A platinum-cerium bimetallic catalyst, It is characterized in that The platinum-cerium bimetallic catalyst is an MFI-type catalyst with a core-shell structure, wherein the core is PtCe@TS-1 and the outer shell is S-1. The platinum element accounts for 0.1-6% of the total mass of the catalyst, and the cerium element accounts for 0.1-5% of the total mass of the catalyst.
2. The preparation method of the platinum-cerium bimetallic catalyst according to claim 1, It is characterized in that The following steps are involved: (1) Preparation of the catalyst core PtCe@TS-1 by hydrothermal synthesis; (2) The catalyst core is mixed with silica sol, and the surface silicon source is crystallized into S-1 at high temperature using template vapor in a crystallization kettle, thereby finally obtaining the platinum-cerium bimetallic catalyst.
3. The preparation method according to claim 2, It is characterized in that The TS-1 described in step (1) is a titanium silicalite molecular sieve having an MFI structure.
4. The preparation method according to claim 2 or 3, It is characterized in that In step (1), the catalyst core PtCe@TS-1 is prepared by the hydrothermal synthesis method as follows: a titanium source, a silicon source, a template, a platinum salt, and a cerium salt are added to a reactor and stirred, and then placed in a crystallization kettle for crystallization to obtain a catalyst core.
5. The preparation method according to claim 4, It is characterized in that The titanium source is selected from at least one of titanium dioxide, tetrabutyl titanate, tetraethyl titanate, and titanium isopropoxide; and / or The silicon source is selected from one or more of methyl orthosilicate, ethyl orthosilicate, tetrabutyl silicate, nano-scale silica sol, and white carbon black; and / or The template agent is selected from one or more of n-butylamine, triethylamine, ammonia water, hexamethylenediamine, tetrapropylammonium hydroxide and tetrapropylammonium bromide; and / or The platinum salt is selected from at least any one of tetraammine platinum nitrate, platinum acetylacetonate, platinum nitrate, platinum sulfate, and platinum chloride; and / or The cerium salt is selected from one or more of cerium nitrate, cerium isopropoxide and cerium sulfate.
6. The preparation method according to claim 5, It is characterized in that The molar ratio of the silicon source to the template is 0.2-5:1, and the molar ratio of the titanium source to the template is 0.01-0.5:1; and / or The amount of the platinum salt added is 0.2-8% of the mass of silicon in the silicon source, calculated on the mass of the platinum element; and / or Calculated by the mass of cerium element, the added amount of the cerium salt is 0.2-6% of the mass of silicon in the silicon source.
7. The preparation method according to claim 6, It is characterized in that First, the template is prepared into a 10-50% aqueous solution, and a titanium source and a silicon source are added in a 60-90°C water bath under stirring; after the addition is completed, stirring is continued for 20-60 minutes; then platinum salt and cerium salt are added, and stirring is continued for 10-30 minutes; the solution is placed in a crystallization kettle and crystallized at 150-200°C for 24-72 hours; after the crystallization is completed, the solution is dried and calcined at 400-600°C for 4-6 hours to obtain PtCe@TS-1.
8. According to the preparation method described in claim 2, It is characterized in that The mass ratio of the catalyst core to the silica sol in step (2) is 1:2-5; Preferably, step (2) is: a) mixing the catalyst core with silica sol, drying them in a water bath at 50-80° C. while stirring until they are dry, and then grinding them into fine powder for later use; b) Take a crystallization kettle, which is equipped with a tray, and the bottom of the kettle is filled with a template solution. The tray supports the fine powder of step a) above the template liquid surface, and then crystallizes at 120-180° C. for 24-72 hours, and then calcines at 450-540° C. for 4-8 hours to obtain a catalyst.
9. Use of the platinum-cerium bimetallic catalyst according to claim 1 or the platinum-cerium bimetallic catalyst prepared by the preparation method according to any one of claims 2 to 8 in the methane process for preparing hydrocyanic acid; Preferably, a fixed bed reactor is used for evaluation, the reaction temperature is 600°C, and the space velocity is 1500h -1 , the feed ratio of methane: ammonia: air is 1:1.1:
24.
10. The use according to claim 9, It is characterized in that When the platinum-cerium bimetallic catalyst is used in the reaction of preparing hydrocyanic acid from methane, the yield of hydrocyanic acid is greater than 60%.