Method for preparing high-yield black phosphorus by using P-Fe-Sn alloy catalyst prepared based on ferrophosphorus slag

Abstract

The invention relates to a method for preparing high-yield black phosphorus by using a P-Fe-Sn alloy catalyst based on ferrophosphorus slag, which comprises the following steps: carrying out pickling soaking, reduction heat treatment and purification on ferrophosphorus slag to obtain a Fe-P intermediate, and carrying out melt alloying on the Fe-P intermediate and elemental tin according to a reasonable ratio to obtain the P-Fe-Sn alloy catalyst; red phosphorus is used as a phosphorus source, and under the action of the catalyst, reaction is carried out for 6-24 hours at 400-600 DEG C in an inert atmosphere through a gas-phase transmission method, so that oriented growth of black phosphorus is realized. The phosphorus iron slag is used as a raw material to prepare the efficient catalyst, the phosphorus iron slag is converted into a P-Fe-Sn alloy catalyst with higher value by utilizing the unique chemical thermal stability of iron phosphide and combining with the characteristic of preparing black phosphorus through catalysis of Sn, and the use proportion of the catalyst Sn is reduced; the prepared P-Fe-Sn alloy catalyst has excellent catalytic activity, and high-yield synthesis of black phosphorus can be realized. The black phosphorus prepared by the method is good in quality, high in crystallinity and low in equipment requirement, is suitable for large-scale production, and can provide technical support for industrial application of the black phosphorus.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new material black phosphorus preparation, and particularly relates to a method for preparing P-Fe-Sn alloy catalyst based on phosphorus-iron slag for high-yield black phosphorus preparation. BACKGROUND

[0002] Black phosphorus (BP) as a new two-dimensional semiconductor material, exhibits unique advantages in the fields of optoelectronic devices, energy storage and catalysis. However, its industrial application is still limited by the high price of catalyst raw materials and the high cost and low yield of preparation technology. The current mainstream preparation methods include: 1. High pressure conversion method: taking red phosphorus as raw material, directly converting under high temperature (> 200℃) and high pressure (> 1 GPa) conditions, but the equipment requirement is high, the energy consumption is large, and the product yield is low (usually < 50%).

[0003] 2. Mechanical ball milling method: using the high energy of the ball mill to prepare black phosphorus under the disordered impact of the ball milling medium, but the ball milling time is long and the temperature and pressure parameters are difficult to control, and the prepared black phosphorus has poor crystal type and is difficult to be applied to the large-scale preparation of black phosphorus.

[0004] 3. Catalyst assisted method: using Au / Sn, Bi and other metal catalysts to reduce the reaction pressure, but there are still the following problems: ① the cost of catalyst is high (such as gold-based catalyst), and complex pretreatment is required; ② the yield of Sn and other elemental metal catalysts under high temperature conditions can reach more than 90%, but based on the industrialization of large-scale preparation, the single use amount is high and the thermal stability is poor during the reaction process, which leads to serious catalyst deactivation, low recycling stability and low raw material utilization rate, which significantly increases the preparation cost; ③ waste is not further utilized: the traditional process does not solve the resource problem of phosphorus chemical by-products (such as phosphorus-iron slag).

[0005] Iron phosphate slag, a major solid waste product in the production of yellow phosphorus, is rich in Fe, P, and trace metal elements (such as Sn and Ca). Currently, it is mostly used in low-value-added building materials and refractory materials, and its high-value-added utilization technology has not yet been mastered. Secondly, the iron phosphate compounds, such as ferric phosphate, which are the most abundant component of iron phosphate slag, exhibit good chemical stability and demonstrate good catalytic activity in electrocatalytic hydrogen production. While the literature "Understanding the growth of black phosphorus crystals" indicates that using metal elements to replace part of the Sn catalyst to synthesize a binary Fe-Sn catalyst can achieve a black phosphorus production yield of over 80%, it does not study the recycling stability of the alloy catalyst or the high-yield black phosphorus crystal preparation of Sn-containing ternary alloy catalysts. Therefore, utilizing this material and combining it with a small amount of elemental tin to convert it into a high-efficiency catalyst for multiple uses can significantly reduce the cost of black phosphorus production and achieve solid waste resource recycling, aligning with the principles of green chemistry. Therefore, developing a method for preparing a high-efficiency P-Fe-Sn alloy catalyst based on iron phosphate slag as a raw material and achieving high-yield black phosphorus production has significant scientific and industrial value. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a high-efficiency P-Fe-Sn alloy catalyst based on ferrophosphorus slag as raw material for high-yield black phosphorus production. This invention aims to solve the following problems existing in current black phosphorus scale-up technologies: 1. Reliance on precious metal catalysts (such as Au) for black phosphorus production leads to high production costs; 2. High-yield black phosphorus production using existing catalysts such as tin sources is costly due to high raw material preparation costs, severe catalyst deactivation after use, poor recycling stability, and high energy consumption, making large-scale industrialization difficult; 3. Black phosphorus prepared using catalysts such as lead and bismuth has low crystal yield and causes severe environmental pollution, making high-yield material recycling difficult; 4. The industrial byproduct ferrophosphorus slag is not utilized at high value, resulting in a large environmental burden.

[0007] To achieve the above objectives, the present invention employs the following technical solution: The method for preparing high-efficiency P-Fe-Sn alloy catalysts for high-yield black phosphorus preparation based on phosphate iron slag includes the following steps: (1) pre-treating phosphate iron slag to obtain Fe-P matrix material; (2) melting alloying Fe-P matrix material with elemental tin in a certain proportion to obtain P-Fe-Sn alloy catalyst; (3) sealing red phosphorus, P-Fe-Sn alloy catalyst and iodine in a certain proportion in a reactor, and reacting by gas phase transport method to obtain black phosphorus crystals.

[0008] The above are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solution conditions.

[0009] In the above scheme, the phosphorus iron slag is any one or a combination of two of the industrial phosphorus iron slags such as phosphorus iron slag for producing yellow phosphorus and electrolytic phosphorus iron slag.

[0010] In the above scheme, the mass ratio of the Fe-P matrix material to the tin source is (5:1) to (1:1).

[0011] Preferably, the elemental tin is tin powder or tin ingot.

[0012] Preferably, the melting temperature of the alloy is 1350~1500℃.

[0013] Preferably, the melting time is 1 to 4 hours.

[0014] Red phosphorus was sealed in a reactor with the obtained P-Fe-Sn alloy and iodine, and reacted by gas-phase transport. Black phosphorus product was collected in the nucleation zone.

[0015] The gas-phase transport reaction process includes the following: red phosphorus, P-Fe-Sn alloy and iodine are sealed in a reactor, and a high-temperature reaction is carried out in the raw material zone. The material is rapidly transported to the nucleation end for low-temperature growth by the gas-phase transport agent iodine, and finally black phosphorus product is obtained by gradual deposition and crystallization.

[0016] The mass ratio of red phosphorus to P-Fe-Sn alloy catalyst and iodine is (5:1:0.2) to (15:1:0.6); the reaction temperature in the raw material zone is 535-600 ℃, the growth temperature in the nucleation zone is 470-530 ℃, and the reaction time is 6-24 h.

[0017] The reaction temperature in the raw material zone is at least 10°C higher than the reaction temperature in the nucleation zone. The total reaction time in the raw material zone and the nucleation zone is 6-24 hours, and can be any value within this time range.

[0018] During the preparation of black phosphorus, 0.1wt-1.0wt% of graphene is added as a nucleation aid.

[0019] In the above scheme, the atomic percentages of P, Fe and Sn in the P-Fe-Sn alloy catalyst composition are (40~60):(30~50):(5~20).

[0020] This application provides a method for high-yield black phosphorus preparation using a highly efficient P-Fe-Sn alloy based on ferrophosphorus slag and Sn. The method involves synthesizing a highly efficient P-Fe-Sn alloy catalyst using a specific ratio of Fe-P matrix material and Sn; then, through a specific heat treatment procedure and by mixing red phosphorus, the P-Fe-Sn alloy catalyst, and iodine in a suitable ratio, reacting under vacuum conditions to ultimately obtain black phosphorus crystals. This method is highly efficient and effectively reduces energy consumption. Furthermore, compared to other preparation methods, this method has lower requirements for related equipment, significantly reducing the overall preparation difficulty and cost.

[0021] In the method of this application, the P-Fe-Sn alloy catalyst can be recycled three or more times after preparation. Furthermore, only red phosphorus and iodine need to be added in subsequent preparation processes to achieve the preparation of black phosphorus crystals at 500 °C, further reducing the production cost of black phosphorus. The method of this invention reduces the safety hazards caused by phosphorus volatilization, has a simple process route, and can achieve large-scale industrial production, thereby promoting the application and development of black phosphorus.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Compared with traditional catalyst Sn with low thermal stability, the present invention uses a method to prepare P-Fe-Sn alloy catalyst based on ferrophosphorus slag for high-yield black phosphorus preparation. By alloying trace amounts of Sn with ferrophosphorus compounds in ferrophosphorus slag, the P-Fe-Sn alloy catalyst prepared by this method is highly efficient and significantly reduces the amount of Sn catalyst used, thus significantly reducing the cost of black phosphorus crystal preparation.

[0023] (2) The high catalytic activity of this catalyst can be used to prepare black phosphorus crystals with high yield.

[0024] (3) The high stability of the catalyst can be used to recycle the catalyst multiple times to prepare black phosphorus, which can further reduce the cost of black phosphorus crystal preparation.

[0025] The black phosphorus prepared using the technical solution of this invention has a purity greater than 90.0% and a yield greater than 90%. After 2-5 cycles of preparation, the black phosphorus purity is greater than 90.0% and the yield is greater than 60%. SEM analysis revealed that the particle size range of the black phosphorus flake structure is 1 μm-100 μm, more preferably 20 μm-90 μm, more preferably 30 μm-80 μm, and more preferably 60 μm-80 μm. Attached Figure Description

[0026] Figure 1 This is a photograph of the final black phosphorus product obtained by the method of preparing P-Fe-Sn alloy catalyst based on phosphorus iron slag in Example 1 of the present invention for preparing black phosphorus.

[0027] Figure 2 The image shows the XRD pattern of black phosphorus obtained in Example 1 of this invention.

[0028] Figure 3 This is a SEM image of the black phosphorus obtained in Example 1.

[0029] Figure 4 This is a photograph of the black phosphorus prepared in Comparative Example 2.3. Detailed Implementation

[0030] To better understand the specific content of this invention, the following specific examples will be used to illustrate the invention in detail, but the scope of protection of this invention is not limited to the following content; The main components of the ferrophosphorus slag produced from the yellow phosphorus electric furnace in the following embodiments are: (1) iron-based compounds (core components, 30-70wt%); (2) phosphorus components (10-30wt%); (3) silicates (5-20wt%); (4) other impurities (1-10wt%). This invention mainly utilizes ferrophosphorus compounds such as iron phosphide in ferrophosphorus slag, including but not limited to the direct use of synthetic ferrophosphorus compounds.

[0031] In another embodiment, Sn could not well demonstrate the recycling stability of Sn catalyst in the scale-up preparation of black phosphorus during the small-scale test (black phosphorus crystal preparation experiment within 10 g). However, the present invention is based on industrial-scale (10 kg and above) production to carry out industrial-scale preparation experiments of black phosphorus.

[0032] Example 1 Preparation of P-Fe-Sn alloy catalyst 1. Pretreatment of ferrophosphorus slag: The phosphorus-iron slag from the yellow phosphorus electric furnace was initially screened to obtain high-quality phosphorus-iron slag lumps. These lumps were then ground to a particle size of 100-200 mesh and leached with 4 mol / L hydrochloric acid at 70℃ for 4 h. After filtration, a leachate containing Fe and P was obtained. Then, the reducing agent NaBH4 was added to the leachate, and reduction precipitation was carried out at 60-80℃ to obtain Fe-P matrix material.

[0033] 2. Preparation of P-Fe-Sn alloy catalyst: Fe-P matrix material and metallic tin powder are mixed at a certain mass ratio of 10:1; Under an inert gas protective atmosphere, the P-Fe-Sn ternary alloy catalyst was obtained by melting reaction at a high temperature of 1400℃ for 4 h. After complete melting, the catalyst was naturally cooled, crushed and sieved.

[0034] 3. High-yield black phosphorus preparation: Weigh 20 kg of red phosphorus, 2 kg of P-Fe-Sn alloy catalyst and 1 kg of iodine and mix them evenly in a stainless steel metal reactor according to the mass ratio. Inert gas is introduced into the reactor and high-purity nitrogen (flow rate 75 mL / min) is introduced for protection and sealing. Under an inert gas atmosphere, the temperature was increased at a rate of 10℃ / min. The raw material zone was heated to 540℃ in 1 hour, and the nucleation zone was heated to 480℃ in 1 hour. The reaction was maintained at this temperature for 8 hours. In this process, the raw material zone undergoes a high-temperature reaction, and the material is rapidly transported to the nucleation zone by the gas-phase transport agent iodine for low-temperature nucleation and growth. The black phosphorus product is gradually deposited and crystallized. Finally, after cooling to room temperature, 18.389 kg of black phosphorus was obtained in the nucleation growth zone.

[0035] pass Figure 2 XRD qualitative analysis showed that the purity of black phosphorus reached 99.89%, and the initial black phosphorus yield was 91.945%. Figure 3 SEM images show that the particle size of the D50 black phosphorus plaque structure ranges from 60 μm to 80 μm.

[0036] Table 1 shows the XRF element content of black phosphorus measured in Example 1.

[0037] Example 2 The catalyst from Example 1 was recovered and mixed uniformly with 20 kg of red phosphorus powder, 2 kg of P-Fe-Sn alloy catalyst, and 1 kg of iodine according to the specified ratio. High-purity nitrogen gas (flow rate 75 mL / min) was introduced, and the mixture was placed in a stainless steel metal reactor and sealed. The temperature was increased at a rate of 10 °C / min. The raw material zone was heated to 540 °C in 1 hour, and the nucleation zone was heated to 480 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, 13.96 kg of black phosphorus was obtained.

[0038] Example 3 The catalyst from Example 2 was recovered and mixed uniformly with 20 kg of red phosphorus powder, 2 kg of catalyst, and 1 kg of iodine according to the specified ratio. High-purity nitrogen gas (flow rate 75 mL / min) was introduced, and the mixture was placed in a stainless steel metal reactor and sealed. The temperature was increased at a rate of 10 °C / min. The raw material zone was heated to 540 °C in 1 hour, and the nucleation zone was heated to 480 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, 12.568 kg of black phosphorus was obtained.

[0039] Table 1. Recycling stability of the catalysts prepared in Examples 1-3 for black phosphorus production.

[0040] The results of Examples 1-3 show that the black phosphorus crystal yield can still reach 69.84% when the catalyst of Example 1 is used to prepare black phosphorus again; the black phosphorus crystal yield can still reach 62.98% when the catalyst of Example 2 is used to prepare black phosphorus again. This indicates that the P-Fe-Sn alloy catalyst has high catalytic activity and good intrinsic catalytic stability. After three experiments, the yield of black phosphorus prepared by catalysis can still reach more than 60%, and the purity of black phosphorus is more than 90%, which shows good recycling stability.

[0041] Example 4 The difference from Example 1 is that the amount of Sn is further reduced, and the catalyst component is P. x Fe y-7 Sn Z-3 ; 15.183 kg of black phosphorus was obtained in the nucleation zone, with a yield of 75.915%, indicating that further reducing the Sn content would reduce the catalytic effect of the catalyst. The purity of the black phosphorus was 98.9%.

[0042] Example 5 The difference from Example 1 is that electrolytic iron phosphate slag containing 5wt% Sn was used as raw material, and 0.5wt% graphene was added as a nucleation aid; 18.113 kg of black phosphorus was obtained in the nucleation zone, indicating that the P-Fe-Sn ternary alloy catalyst prepared by electrolytic iron phosphate slag can also be used to prepare high-yield black phosphorus crystals. The black phosphorus yield obtained can reach 90.565% and the crystal quality is good, with a black phosphorus purity of 99.6%.

[0043] Comparative Example 1.1 Using only Sn as a catalyst, 2 kg of 600-mesh elemental tin powder catalyst, 20 kg of red phosphorus powder, and 1 kg of iodine were weighed and mixed evenly. High-purity nitrogen gas (flow rate 75 mL / min) was introduced, and the mixture was placed in a stainless steel metal reactor and sealed. The temperature was increased at a rate of 10 °C / min. The temperature at the raw material end was increased to 540 °C in 1 hour, and the temperature at the nucleation end was increased to 480 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, 19.23 kg of black phosphorus with a purity of 99.3% was obtained.

[0044] Comparative Example 1.2 The catalyst used in Comparative Example 2.1 was recovered and mixed uniformly with 2 kg of catalyst, 20 kg of red phosphorus powder, and 1 kg of iodine. High-purity nitrogen gas (flow rate 75 mL / min) was introduced, and the mixture was placed in a stainless steel metal reactor and sealed. The temperature was increased at a rate of 10 °C / min. The raw material zone was heated to 540 °C in 1 hour, and the nucleation zone was heated to 480 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, only 5.792 kg of black phosphorus was obtained, with a purity of 91.6%.

[0045] Comparative Example 1.3 The catalyst used in Comparative Example 2.2 was recovered and mixed uniformly with 2 kg of catalyst, 20 kg of red phosphorus powder, and 1 kg of iodine. High-purity nitrogen gas (flow rate 75 mL / min) was introduced, and the mixture was placed in a stainless steel metal reactor and sealed. The temperature was increased at a rate of 10 °C / min. The nucleation end was heated to 480 °C in 1 hour, and the raw material end was heated to 540 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, 2.816 kg of product was obtained, with a black phosphorus purity of 90.1%.

[0046] Table 2. Recycling stability of the catalysts prepared in Comparative Examples 1.1-1.3 for black phosphorus production.

[0047] As shown in Table 2, the black phosphorus yield of catalyst Sn can reach 96.15% when used for the first time, but after the first recycling, the black phosphorus yield is only 28.96%, and after the second recycling, the black phosphorus crystal preparation yield decreases to 14.08%. The results show that the low recycling stability of the catalyst is not conducive to the industrial-scale preparation of black phosphorus.

[0048] Comparative Example 2 The difference from Example 1 is that the amount of material taken is 6 kg of pretreated Fe-P matrix material and 1.2 kg of pure tin powder = 5:1, which are placed in a corundum crucible for uniform mixing.

[0049] A mixture of P-Fe matrix material and Sn was used as a catalyst. 2 kg of the catalyst was weighed and mixed evenly with 20 kg of red phosphorus powder. High-purity nitrogen gas (flow rate 75 mL / min) was introduced, and the mixture was placed in a quartz tube reactor and sealed. The temperature was increased at a rate of 10 °C / min. The raw material zone was heated to 540 °C in 1 hour, and the nucleation zone was heated to 480 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, 6 kg of black phosphorus with a purity of 98.4% was obtained.

[0050] Comparative Example 3 The difference from Example 1 is that P-Fe matrix material was used directly as catalyst. 2 kg of catalyst was weighed and mixed evenly with 20 kg of red phosphorus powder. High-purity nitrogen gas (flow rate 50 mL / min) was introduced, and the mixture was placed in a quartz tube reactor and sealed. The temperature was increased at a rate of 10 °C / min. The raw material zone was heated to 540 °C in 1 hour, and the nucleation zone was heated to 480 °C in 1 hour. The reaction was maintained at this temperature for 8 hours. After natural cooling, no black phosphorus product was obtained.

[0051] Figure 1 The image shows the actual black phosphorus crystals obtained in Example 1. As can be seen from the image, the crystals are of high quality, with almost no unreacted red phosphorus particles or impurities adhering to the surface.

[0052] Figure 2 The X-ray diffraction pattern of the black phosphorus crystals obtained in Example 1 above shows that the sample mainly exhibits the typical characteristic peaks of black phosphorus, and there are low impurity peaks. This indicates that the method of the present invention can prepare a good black phosphorus crystal with high purity.

[0053] Figure 3 The image shows a SEM image of the black phosphorus prepared in Example 1. It can be clearly observed from the image that the black phosphorus is stacked together in a sheet-like structure, which also indicates that the prepared black phosphorus crystals have high quality.

[0054] Figure 4 The image shows a physical picture of the black phosphorus prepared in Comparative Example 2.3. The corresponding black phosphorus crystal preparation yield indicates that the stability of black phosphorus preparation by recycling using elemental Sn as a catalyst during industrial scale-up is significantly reduced, decreasing from over 90% initially to below 10% after multiple uses.

Claims

1. A method for preparing a P-Fe-Sn alloy catalyst based on phosphorus iron slag, characterized by, The method comprises the following steps: (1) grinding the phosphorus-iron slag and reacting with an acid solution, filtering the leaching solution containing Fe and P after pickling, and obtaining the Fe-P matrix material after further reduction and heat treatment; (2) uniformly mixing the Fe-P matrix material obtained in step (1) with elemental tin according to the mass ratio, and carrying out melt alloying under inert atmosphere, and obtaining the P-Fe-Sn ternary alloy catalyst after natural cooling.

2. The method of claim 1, wherein, The acid solution in step (1) is one or two of hydrochloric acid, sulfuric acid or nitric acid, the concentration is 1-6 mol / L, and the reaction temperature is 50-90℃.

3. The method of claim 1, wherein, The reducing agent used in the reduction process in step (1) is NaBH4, and the heat treatment temperature is 600-800℃.

4. The method of claim 1, wherein, The mass ratio of the Fe-P matrix material to elemental tin in the melt alloying in step (2) is (5:1)-(1:1).

5. The method of claim 1, wherein, The temperature of the melt alloying in step (2) is 1350-1500℃, and the holding time is 1-4 h.

6. A method for preparing black phosphorus, further comprising the method according to any one of claims 1-5 to prepare the P-Fe-Sn alloy catalyst, and the atomic percentage of P, Fe and Sn in the P-Fe-Sn alloy catalyst is (40-60):(30-50):(5-20).

7. The method of claim 6, wherein, The red phosphorus, P-Fe-Sn alloy and iodine are sealed in a reactor, high-temperature reaction is carried out in the raw material zone, the gas-phase transport agent iodine makes the material quickly transport to the nucleation zone for low-temperature growth, and finally the black phosphorus product is obtained by gradual deposition crystallization.

8. The method of claim 7, wherein, The mass ratio of the red phosphorus to the P-Fe-Sn alloy catalyst and iodine is (5:1:0.2)-(15:1:0.6), the high-temperature reaction temperature of the raw material zone is 535-600℃, the low-temperature growth temperature of the nucleation zone is 470-530℃, and the reaction time is 6-24 h.

9. The method of claim 7, wherein, 0.1wt-1.0wt% graphene is further added as a nucleation aid in the preparation process of the black phosphorus.

10. The method according to any one of claims 6-9, characterized in that, The purity of the black phosphorus prepared by the method is greater than 99.8%, the yield of the black phosphorus is more than 90%, and the particle size range of the flaky structure of the D50 black phosphorus is 10-100 μm.

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