A supported black phosphorus catalyst and its preparation method and application

Abstract

The present invention discloses a supported black phosphorus catalyst, a preparation method thereof and an application thereof, relating to the technical field of black phosphorus catalysts. In the present invention, a traditional Sn 24 P 19.3 I8 ternary complex is supported by a catalyst carrier, and then a supported black phosphorus catalyst is prepared after high-temperature heat treatment. The supported black phosphorus catalyst prepared by the present invention not only maintains high catalytic activity, but also is convenient for recycling and reuse, and can be applied to the continuous production of black phosphorus.

Description

Technical Field

[0001] The invention belongs to the technical field of black phosphorus catalysts, and specifically relates to a supported black phosphorus catalyst and a preparation method and application thereof. Background Art

[0002] Black phosphorus is a high-value-added fine phosphorus chemical product and a two-dimensional material similar to graphene. It has broad application prospects in the fields of sensing, energy storage, catalysis, flame retardancy and medicine. Among the many methods for preparing black phosphorus that have been developed, such as high pressure method, mercury catalysis method, bismuth melting method, mechanical ball milling method, chemical vapor deposition method, molten salt method and mineralization method, the mineralization method is the hottest topic among researchers and is also the most promising method for the continuous preparation of black phosphorus.

[0003] The mineralization method for preparing black phosphorus was first developed by Lang et al. (Inorganic Chemistry, 2007, 46(10): 4028-4035) in 2007. They used gold, tin powder and tin tetraiodide as mineralizers, mixed them with raw red phosphorus in a certain mass ratio, put them into a quartz ampoule and sealed them in a vacuum, and prepared black phosphorus crystals under low pressure and 600°C. In order to solve the problem of high cost of mineralizers containing precious metal gold, Nilges et al. (Journal of Crystal Growth, 2014, 405: 6-10) optimized it, using tin and tin tetraiodide as mineralizers, mixing them with red phosphorus raw materials and sealing them in a vacuum, heating them to 650°C, then cooling them to 500°C, keeping them warm for a certain period of time and then cooling them to room temperature. The obtained black phosphorus crystals are of higher purity and larger size. Chen et al. (CrystEngComm, 2017, 19(47):7207-7212) prepared Sn by mixing tin, tin tetraiodide and red phosphorus in a molar ratio of 15:12:1 into a sealed silicon tube and keeping it at 500°C for 5 days. 24 P 19.3 I8 ternary complex, mixed with red phosphorus and heated to prepare black phosphorus crystals, and confirmed Sn 24 P 19.3 The I8 ternary complex is the only nucleating agent in the growth process of black phosphorus and also the catalyst for the preparation of black phosphorus. 24 P 19.3 I8 ternary complex (hereinafter referred to as PISn) is a highly efficient catalyst for the preparation of black phosphorus. Using PISn catalyst, black phosphorus with high purity and good crystal shape can be prepared under relatively mild and easy-to-control conditions.

[0004] At present, PISn catalyst powder will be mixed with red phosphorus raw materials or even covered by red phosphorus powder. The powder itself is stacked, so that it cannot expose more active sites, resulting in low activity. In addition, the catalyst powder is mixed with red phosphorus raw materials or contacted and mixed with liquid by-products such as white phosphorus during the reaction, making it difficult to recycle and reuse. On the other hand, the powdered catalyst cannot meet the requirements of the catalytic bed in the continuous preparation of black phosphorus, which is not conducive to the continuous preparation of black phosphorus. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a supported black phosphorus catalyst, which is Sn 24 P 19.3 The I8 ternary complex (i.e., powdered black phosphorus catalyst) is loaded in a catalyst carrier, thereby obtaining a structured catalyst product. The loaded black phosphorus catalyst of the present invention is heated to react with red phosphorus, has high catalytic activity, and is easy to recycle and reuse after the reaction is completed, thus overcoming the disadvantages of using powdered catalysts.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A method for preparing a supported black phosphorus catalyst comprises the following steps:

[0008] (1) Preparation of PISn powder

[0009] First, prepare Sn 24 P 19.3 I8 ternary complex, which is prepared by referring to the method disclosed in the paper "Facile and Efficient Preparation of High-Purity Black Phosphorus Based on a Vapor-Solid-Vapor Phase Growth Mechanism" (Industrial & Engineering Chemistry Research, 2022, 61 (35): 13032-13039.), specifically, Sn 24 P 19.3 The molar mass ratio of each element in the I8 ternary complex is tin, tin tetraiodide and red phosphorus. The mixture is placed in a quartz tube and sealed in a vacuum. The sealed quartz tube is heated. The specific heating procedure is to first heat it to 550°C, keep it for 30 minutes, then cool it to 500°C after 225 minutes and keep it for 30 minutes; then heat it to 550°C and repeat the above heat treatment for 6 times. After cooling, Sn 24 P 19.3 I8 ternary complex.

[0010] Then Sn 24P 19.3 The I8 ternary complex (i.e., PISn) is ground and sieved to obtain PISn powder for later use;

[0011] (2) Preparation of PISn catalyst slurry

[0012] The PISn powder is mixed with triethanolamine, polyvinyl alcohol, polyethylene glycol and deionized water and then ball-milled, polypropylene glycol and ammonium bicarbonate are added in sequence during the ball-milling process, and the PISn catalyst slurry is obtained after uniform ball-milling, wherein the mass ratio of the PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol, deionized water, polypropylene glycol and ammonium bicarbonate in the PISn catalyst slurry is 50-70:1:3-8:3-8:20-40:0.2:3-8;

[0013] (3) Immersion drying treatment

[0014] The catalyst carrier is immersed in the PISn catalyst slurry for 1 to 5 minutes, taken out, drained and dried, and the above immersion and drying are repeated three times;

[0015] (4) Heat treatment

[0016] The catalyst after the impregnation and drying treatment in step (3) is heated to 300-600° C. in an inert atmosphere or vacuum for 30-300 minutes, and then cooled to room temperature to obtain supported black phosphorus.

[0017] Preferably, the particle size of the PISn powder in step (1) is not greater than 0.15 mm (100 mesh).

[0018] Preferably, the catalyst carrier is any one of a nickel foam carrier, an alumina foam ceramic carrier or a cordierite honeycomb ceramic carrier.

[0019] Preferably, the drying temperature in step (3) is 50 to 90° C., and the drying time is 5 to 30 minutes.

[0020] Preferably, the heating rate of the heating treatment in step (4) is 5 to 10°C / min.

[0021] Preferably, the cooling rate in step (4) is 50 to 80° C. / min / min.

[0022] The present invention also provides a supported black phosphorus catalyst, which is prepared by the above method. Triethanolamine is used as a dispersant, polyvinyl alcohol is used as a binder, polyethylene glycol is used as a plasticizer, polypropylene glycol is used as a defoaming agent, and ammonium bicarbonate is used as a pore-forming agent. The PISn loading amount in the supported black phosphorus catalyst of the present invention is 0.2 to 0.6 mg / mm 3 .

[0023] The present invention also provides an application of a supported black phosphorus catalyst, specifically, adding the supported black phosphorus catalyst of the present invention to red phosphorus, and subjecting the catalyst to sealed heating treatment to prepare black phosphorus, wherein the added amount of the supported black phosphorus catalyst accounts for 25-50% of the mass of the red phosphorus. Preferably, the sealed heating temperature is 535° C., and the heating time is 5 hours.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention prepares PISn powder into a supported catalyst, solves the problem of powder catalyst stacking and mixing with red phosphorus raw materials to cover active sites, and improves catalytic activity.

[0026] The present invention can not only improve the catalytic activity of the catalyst, but also the supported black phosphorus catalyst of the present invention is easy to separate from the raw materials and by-products, can be reused, and is suitable for the continuous preparation of black phosphorus. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a physical picture of the supported black phosphorus catalyst prepared in Example 1;

[0028] Figure 2 The XRD pattern of the supported black phosphorus catalyst prepared in Example 1;

[0029] Figure 3 This is a physical picture of black phosphorus obtained by reacting the supported black phosphorus catalyst of Example 1 with red phosphorus;

[0030] Figure 4 This is a SEM image of black phosphorus obtained by reacting the supported black phosphorus catalyst in Example 1 with red phosphorus;

[0031] Figure 5 The XRD pattern of black phosphorus obtained by reacting the supported black phosphorus catalyst in Example 1 with red phosphorus;

[0032] Figure 6 is a Raman graph of black phosphorus obtained by reacting the supported black phosphorus catalyst of Example 1 with red phosphorus;

[0033] Figure 7 This is an EDS spectrum of black phosphorus obtained by reacting the supported black phosphorus catalyst in Example 1 with red phosphorus;

[0034] Figure 8 This is a physical picture of the supported black phosphorus catalyst prepared in Example 2;

[0035] Fig. 9 This is a physical picture of the supported black phosphorus catalyst prepared in Example 3;

[0036] Fig.10 This is a physical picture of the powder catalyst prepared in Comparative Example 1;

[0037] Fig.11 This is a physical picture of the flaky self-forming catalyst prepared in Comparative Example 2. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments.

[0039] Example 1

[0040] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0041] (1) Weigh Sn 24 P 19.3 The I8 ternary complex is ground and passed through a 100-mesh sieve to obtain PISn powder for later use;

[0042] (2) PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol and deionized water are weighed in sequence, and placed in a ball mill containing zirconium balls, and the ball mill is placed in a horizontal ball mill for ball milling. After ball milling for 22 hours, polypropylene glycol is added dropwise to the ball mill, and the ball milling is continued for 2 hours, and then ammonium bicarbonate is added and stirred evenly to obtain a PISn catalyst slurry; wherein the mass ratio of PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol, deionized water, polypropylene glycol and ammonium bicarbonate in the PISn catalyst slurry is 50:1:4:4:35:0.2:5.8;

[0043] (3) Place the nickel foam catalyst carrier (10*10 mm cylinder, 40 ppi pore size) into the above PISn catalyst slurry and immerse for 1 min, then take it out and drain it, and place it in a 50°C oven to dry for 5 min. Repeat this step three times;

[0044] (4) The foamed nickel catalyst carrier loaded with the PISn catalyst slurry was heated using a tubular furnace with a preset heating and cooling program. The specific procedure was as follows: at room temperature, the temperature was raised to 460°C at a rate of 5°C / min and kept at that temperature for 180 min. Nitrogen was introduced during the heating treatment to remove volatile organic matter. Then the temperature was cooled at a rate of 80°C / min. After cooling to room temperature, the supported black phosphorus catalyst was obtained.

[0045] The physical image and XRD spectrum of the supported black phosphorus catalyst prepared by the present invention are as follows: Figure 1 and Figure 2 As shown; by comparing the XRD pattern with the PISn standard card, the characteristic peaks correspond one to one without offset, and no other obvious impurity peaks are found, indicating that the prepared high-density nickel foam structured PISn catalyst has high purity and good crystallinity.

[0046] In order to verify the catalytic activity of the high-density nickel foam structured PISn catalyst, we heated the catalyst together with red phosphorus to react and prepare black phosphorus. The preparation process of black phosphorus is as follows:

[0047] 400 mg of the above-mentioned supported black phosphorus catalyst was added to 800 mg of red phosphorus, placed in a quartz tube and vacuum-sealed, heated to 535° C. for 5 h, and after cooling, the tube was opened to obtain black phosphorus, and the supported black phosphorus catalyst was recovered.

[0048] Figure 3 This is a photo of the prepared black phosphorus. Figure 4 To obtain the SEM image of black phosphorus, the layered structure of black phosphorus can be seen, and the obtained samples were characterized by XRD and Raman, such as Figure 5 and Figure 6 As shown, Figure 5 It can be seen that the sample has three diffraction peaks at 16.58°, 34.21°, and 52.19°, which are consistent with the characteristic peaks of black phosphorus reported in previous literature, and the characteristic peaks are very sharp, indicating that its crystallization is better than orthorhombic black phosphorus. In addition to the characteristic peaks of black phosphorus, no peaks of other substances are found, indicating that the prepared black phosphorus has a high purity (purity 99.99%). Raman spectra of black phosphorus are taken, and Figure 6 We can see the Raman characteristic peaks of black phosphorus, which are A and B caused by the out-of-plane vibration mode. g 1 Peak (360.43cm -1 ) and A caused by in-plane vibration 2 g Peak (465.90cm -1 ), B 2g Peak (437.45cm -1 ). This once again proves that black phosphorus was prepared using a supported black phosphorus catalyst. In addition to the Raman characteristic peaks of black phosphorus, no peaks of other substances appeared, which once again shows that the obtained black phosphorus has no impurities.

[0049] The yield of black phosphorus prepared by using the supported black phosphorus catalyst of the present invention is 98.8%.

[0050] Example 2

[0051] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0052] (1) Weigh Sn 24 P 19.3 The I8 ternary complex is ground and passed through a 100-mesh sieve to obtain PISn powder for later use;

[0053] (2) PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol and deionized water are weighed in sequence, and placed in a ball mill containing zirconium balls, and the ball mill is placed in a horizontal ball mill for ball milling. After ball milling for 22 hours, polypropylene glycol is added dropwise to the ball mill, and the ball milling is continued for 2 hours, and then ammonium bicarbonate is added and stirred evenly to obtain a PISn catalyst slurry; wherein the mass ratio of PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol, deionized water, polypropylene glycol and ammonium bicarbonate in the PISn catalyst slurry is 63.8:1:2:2:28:0.2:3;

[0054] (3) The alumina foam ceramic catalyst carrier (10*10 mm cylinder, 40 ppi pore size) was immersed in the above PISn catalyst slurry for 1 min, then taken out and drained, and then placed in an oven at 50° C. to dry for 5 min.

[0055] Repeat this step three times;

[0056] (4) The foamed nickel catalyst carrier loaded with the PISn catalyst slurry was heated using a tubular furnace with a preset heating and cooling program. The specific procedure was as follows: at room temperature, the temperature was raised to 360°C at a rate of 5°C / min and kept at that temperature for 180 min. Nitrogen was introduced during the heating treatment to remove volatile organic matter. Then the temperature was cooled at a rate of 50°C / min. After cooling to room temperature, the supported black phosphorus catalyst was obtained.

[0057] The supported black phosphorus catalyst was used to prepare black phosphorus according to the method of Example 1, wherein the yield of black phosphorus was 98.3%.

[0058] Example 3

[0059] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0060] (1) Weigh Sn 24 P 19.3 The I8 ternary complex is ground and passed through a 100-mesh sieve to obtain PISn powder for later use;

[0061] (2) PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol and deionized water are weighed in sequence, and placed in a ball mill containing zirconium balls, and the ball mill is placed in a horizontal ball mill for ball milling. After ball milling for 22 hours, polypropylene glycol is added dropwise to the ball mill, and the ball milling is continued for 2 hours, and then ammonium bicarbonate is added and stirred evenly to obtain a PISn catalyst slurry; wherein the mass ratio of PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol, deionized water, polypropylene glycol and ammonium bicarbonate in the PISn catalyst slurry is 70:1:2:2:22:0.2:2.8;

[0062] (3) The cordierite honeycomb ceramic catalyst carrier (10*10 mm cylinder, 1 mm pore size) was immersed in the above PISn catalyst slurry for 1 min, taken out and drained, and then placed in an oven at 50° C. to dry for 5 min.

[0063] Repeat this step three times;

[0064] (4) The foamed nickel catalyst carrier loaded with the PISn catalyst slurry was heated using a tubular furnace with a preset heating and cooling program. The specific procedure was as follows: at room temperature, the temperature was raised to 460°C at a rate of 5°C / min and kept at that temperature for 60 min. Nitrogen was introduced during the heating treatment to remove volatile organic matter. Then the temperature was cooled at a rate of 80°C / min. After cooling to room temperature, the supported black phosphorus catalyst was obtained.

[0065] The supported black phosphorus catalyst was used to prepare black phosphorus according to the method of Example 1, wherein the yield of black phosphorus was 97.7%.

[0066] Comparative Example 1

[0067] A powdered black phosphorus catalyst, namely the PISn powder prepared in step (1) of Example 1.

[0068] The PISn powder was reacted with red phosphorus according to the above-mentioned method for preparing black phosphorus, wherein the yield of black phosphorus was 90%.

[0069] Comparative Example 2

[0070] A method for preparing a sheet-like self-forming black phosphorus catalyst, the specific steps are as follows:

[0071] (1) Pour the PISn powder prepared in Example 1 into a tableting mold and apply a pressure of 12 MPa using a hydraulic tableting machine to press the powder into a catalyst tablet prototype;

[0072] (2) The obtained self-forming catalyst prototype is placed in a quartz tube and heated according to the method of step (4) of Example 1. After cooling to room temperature, a self-forming black phosphorus catalyst is obtained.

[0073] The sheet-like self-forming catalyst was used to prepare black phosphorus according to the method of Example 1, wherein the yield of black phosphorus was 91.3%. The sheet-like self-forming black phosphorus catalyst had low mechanical strength and was brittle and easily broken.

[0074] Comparative Example 3

[0075] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0076] The supported catalyst was prepared according to the method of Example 1, except that the dispersant triethanolamine was not added to the slurry. The prepared catalyst slurry could not form a stable suspension as in Example 1, and a large amount of catalyst powder particles were deposited at the bottom. The catalyst loading was less than 0.1 mg / mm 3 .

[0077] Comparative Example 4

[0078] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0079] The supported catalyst was prepared according to the method of Example 1, except that the binder polyvinyl alcohol was not added to the slurry. The prepared catalyst slurry could not form a viscous liquid, had an extremely low viscosity, and could hardly be loaded on the catalyst carrier. The catalyst loading was less than 0.01 mg / mm 3 .

[0080] Comparative Example 5

[0081] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0082] The supported catalyst was prepared according to the method of Example 1, except that the plasticizer polyethylene glycol was not added to the slurry. The prepared catalyst slurry could not form a compact and smooth catalyst layer as in Example 1 when loaded. The catalyst layer was in the form of loose and dispersed particles that were easily dropped. The catalyst loading was less than 0.2 mg / mm 3 .

[0083] Comparative Example 6

[0084] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0085] The supported catalyst was prepared according to the method of Example 1, with the only difference being that the defoaming agent polypropylene glycol was not added to the slurry. The prepared catalyst slurry contained many tiny bubbles, which would clog the pores of the carrier during loading, preventing excess catalyst slurry from flowing out and failing to form a supported catalyst with a porous structure. During the reaction, the gas phase could not pass through the pores inside the catalyst for reaction and transportation.

[0086] Comparative Example 7

[0087] A method for preparing a supported black phosphorus catalyst, the specific steps are as follows:

[0088] The supported catalyst was prepared according to the method of Example 1, with the only difference being that the pore-forming agent ammonium bicarbonate was not added to the slurry. After loading, the catalyst slurry prepared in Example 1 was heated to decompose the ammonium bicarbonate into carbon dioxide and ammonia to escape, thereby achieving the effect of creating fine pores inside the catalyst layer, thereby increasing the specific surface area of ​​the catalyst layer and improving the catalytic activity. When ammonium bicarbonate is not added, fine pores cannot be formed inside the catalyst layer, the specific surface area is relatively small, and the catalytic activity is relatively low. The supported black phosphorus catalyst was used to prepare black phosphorus according to the method of Example 1, wherein the yield of black phosphorus was 95.4%.

[0089] It should be noted that the above are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and other variations are possible. All variations directly or indirectly derived from the disclosure of the present invention by those skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for preparing a supported black phosphorus catalyst, characterized in that: The following steps are involved: (1) Preparation of PISn powder Sn 24 P 19.3 The I8 ternary complex is ground and sieved to obtain PISn powder for later use; (2) Preparation of PISn catalyst slurry The PISn powder is mixed with triethanolamine, polyvinyl alcohol, polyethylene glycol and deionized water and then ball-milled, polypropylene glycol and ammonium bicarbonate are added in sequence during the ball-milling process, and the PISn catalyst slurry is obtained after uniform ball-milling, wherein the mass ratio of the PISn powder, triethanolamine, polyvinyl alcohol, polyethylene glycol, deionized water, polypropylene glycol and ammonium bicarbonate in the PISn catalyst slurry is 50-70:1:3-8:3-8:20-40:0.2:3-8; (3) Dipping and drying treatment The catalyst carrier is placed in the PISn catalyst slurry and immersed for 1 to 5 minutes, taken out and dried after draining, and the above immersion and drying are repeated three times; the catalyst carrier is any one of a nickel foam carrier, an alumina foam ceramic carrier or a cordierite honeycomb ceramic carrier; (4) Heating treatment The catalyst after the impregnation and drying treatment in step (3) is heated to 300-600°C in an inert atmosphere or vacuum for 30-300 min, and then cooled to room temperature to obtain a supported black phosphorus catalyst; the PISn loading in the supported black phosphorus catalyst is 0.2-0.6 mg / mm 3 .

2. The method for preparing a supported black phosphorus catalyst according to claim 1, characterized in that: The particle size of the PISn powder in step (1) is not greater than 0.15 mm.

3. The method for preparing a supported black phosphorus catalyst according to claim 1, characterized in that: In step (3), the drying temperature is 50-90°C and the drying time is 5-30 minutes.

4. The method for preparing a supported black phosphorus catalyst according to claim 1, characterized in that: The heating rate of the heating treatment in step (4) is 5-10°C / min.

5. The method for preparing a supported black phosphorus catalyst according to claim 1, characterized in that: The cooling rate in step (4) is 50-80°C / min.

6. A supported black phosphorus catalyst, characterized in that: Prepared by the method according to any one of claims 1 to 5.

7. The use of the supported black phosphorus catalyst according to claim 6, characterized in that: The supported black phosphorus catalyst is added to red phosphorus, and the mixture is sealed and heated to prepare black phosphorus. The added amount of the supported black phosphorus catalyst accounts for 25-50% of the mass of the red phosphorus.

8. The use according to claim 7, characterized in that: The sealing heating temperature is 535° C. and the heating time is 5 h.

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