Preparation method of vanadium nitride

Abstract

The invention provides a preparation method of vanadium nitride, and belongs to the technical field of material synthesis. The method comprises the following steps: S1, pretreating a vanadium-containing compound to obtain vanadium-containing compound powder; s2, the vanadium-containing compound powder and a carbonaceous reducing agent are mixed and pressurized, and a mixed raw material is obtained; s3, calcining the mixed raw material in protective gas to obtain vanadium nitride; according to the method, the production process is simplified, and the production cost is reduced. The ammonium polyvanadate is a superior product of vanadium pentoxide and vanadium trioxide, compared with vanadium pentoxide and vanadium trioxide adopted in a mainstream process, the method for preparing the vanadium nitride by taking the ammonium polyvanadate as a raw material has the advantages that a calcination process is omitted, the processing temperature is lower, and compared with the prior art that the production temperature is 1400-1500 DEG C, the production energy consumption is large, the production cost is low, and the like. The production temperature of the method is only 1000-1200 DEG C, and the production energy consumption is lower.

Description

Technical Field

[0001] The present invention belongs to the technical field of material synthesis, and particularly relates to a method for preparing vanadium nitride. Background Art

[0002] Vanadium nitride (VN), as a typical transition metal nitride, is an important industrial raw material. It has very high thermochemical stability and strong mechanical properties. When used in cutting tools and structural materials, it can improve the creep strength of steel, enhance the toughness and plasticity of steel, and at the same time improve the thermal strength and short-term creep resistance of steel. In addition, vanadium nitride has high catalytic activity, high selectivity, good stability and anti-poisoning performance. Its catalytic behavior is similar to that of Pt, Pb and Rh, and it is a substitute for these precious and rare metals. It can be applied to fields such as electronic materials, high-temperature coating materials and supercapacitor materials.

[0003] At present, there are various methods for preparing vanadium nitride, including: pusher kiln method, microwave-assisted method, vacuum carbothermal reduction method, high-temperature carbothermal reduction nitridation method, etc. The main production method in industry is the pusher kiln method. In the pusher kiln method, the graphite crucible is continuously conveyed into the kiln body through a track. Workers only need to put the graphite crucible on the track and wait for the processing to be completed, and finally recycle the finished product. However, in this method, when the graphite crucible is processed inside the kiln body, high temperature and long time are required to achieve the goal.

[0004] This method needs to maintain the temperature at 1400 - 1500 °C during the preparation of vanadium nitride. The high temperature leads to large production energy consumption and large consumption of consumables. Therefore, a method is needed to optimize the production of vanadium nitride. Summary of the Invention

[0005] One technical problem to be solved by the present invention is: the problem of large production energy consumption and large consumption of consumables in the existing vanadium nitride preparation method.

[0006] To solve the above technical problem, an embodiment of the present invention provides a method for preparing vanadium nitride, which includes the following steps: S1. Pretreat the vanadium-containing compound to obtain vanadium-containing compound powder; S2. Mix and pressurize the vanadium-containing compound powder with a carbonaceous reducing agent to obtain a mixed raw material; S3. Calcinate the mixed raw material in a protective gas to obtain vanadium nitride.

[0007] In some embodiments, in the aforementioned method for preparing vanadium nitride, the pretreatment in S1 includes the following steps: S11. Dissolve the vanadium-containing compound in distilled water and perform water bath heating to obtain a vanadium-containing compound solution; S12. Filter the vanadium-containing compound solution multiple times and then dry it to obtain vanadium-containing compound powder.

[0008] In some embodiments, for the aforementioned method for preparing vanadium nitride, the mass ratio of the vanadium-containing compound to distilled water in S11 is 1:8 to 12.

[0009] In some embodiments, for the aforementioned method for preparing vanadium nitride, the temperature of water bath heating in S11 is 70 to 90 °C, the time of water bath heating is 50 to 70 min, the drying temperature in S12 is 90 to 110 °C, and the drying time is 120 to 180 min.

[0010] In some embodiments, for the aforementioned method for preparing vanadium nitride, the calcination process in S3 includes the following steps: S31. Preheating stage: Heat at a heating rate of 3 to 7 °C / min to 580 to 620 °C, keep warm for 50 to 70 min, and simultaneously introduce a protective gas at a rate of 450 to 550 ml / min; S32. Calcination stage: Heat from 580 to 620 °C to 1000 to 1200 °C at a heating rate of 3 to 7 °C / min, keep warm for 150 to 210 min, and simultaneously introduce a protective gas at a rate of 450 to 550 ml / min; S33. Cooling stage: Cool to 150 to 250 °C.

[0011] In some embodiments, for the aforementioned method for preparing vanadium nitride, the vanadium-containing compound in S1 is ammonium metavanadate.

[0012] In some embodiments, for the aforementioned method for preparing vanadium nitride, the carbonaceous reducing agent in S2 is dicyandiamide or a mixture of dicyandiamide and graphite powder.

[0013] In some embodiments, for the aforementioned method for preparing vanadium nitride, the molar ratio of the vanadium-containing compound powder to the carbonaceous reducing agent in S2 is 1 to 1.2:1; Wherein, the molar ratio is the molar ratio of oxygen in the vanadium-containing compound powder to carbon in the carbonaceous reducing agent.

[0014] In some embodiments, for the aforementioned method for preparing vanadium nitride, the pressure of pressurization in S2 is 2 to 4 MPa.

[0015] In some embodiments, for the aforementioned method for preparing vanadium nitride, the protective gas is nitrogen to increase the nitrogen element content in vanadium nitride.

[0016] Through the above technical solutions, the method for preparing vanadium nitride provided by the present invention has the following beneficial effects: The production process is simplified and the production cost is reduced. Ammonium metavanadate is the superior product of vanadium pentoxide and vanadium trioxide. In the present invention, ammonium metavanadate is used as the raw material to prepare vanadium nitride. Compared with the mainstream process that uses vanadium pentoxide and vanadium trioxide, the calcination process is omitted, and the processing temperature is lower. Compared with the production temperature of 1400-1500°C in the prior art, which results in high production energy consumption, the production temperature of this method only needs 1000-1200°C, and the production energy consumption is lower. Moreover, this method can modify only the processing method without destroying the original production line, thereby improving the overall production efficiency.

[0017] In addition, the ammonia gas generated by the decomposition of ammonium metavanadate at high temperature can be used as part of the nitrogen source, which plays a certain role in nitriding and reducing the material. The pores generated by the escape of the generated ammonia gas are conducive to the infiltration of nitrogen gas, making the internal reaction more uniform and improving the quality of the product. By mixing ammonium metavanadate and dicyandiamide and then performing pressure treatment, the utilization of nitrogen element can be greatly improved, and the nitrogen content and the stability of the nitrogen content of the product can also be improved.

[0018] Finally, by performing pretreatment on the vanadium-containing compound through dissolution and filtration, etc., the ammonium sulfate and sodium carbonate residues in the preparation process of ammonium metavanadate can be removed, and the sulfur content and sodium content in the finished vanadium nitride can be reduced to ensure the quality of the processing raw materials. At the same time, dicyandiamide, as a carbonaceous reducing agent, not only has excellent reducing ability, but also can release ammonia gas at 80°C, and generates intense heat when heated to near the melting point. The released heat can be used as a supplement to the heat source to accelerate the reduction reaction. On the other hand, the channels formed by the release of ammonia gas can also be used as the channels of the nitrogen source to make the nitrogen source supplement be reused twice, further increasing the nitrogen element content of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the flow chart of the preparation method of vanadium nitride provided by the present invention; Figure 2 is the flow chart of the preparation method of vanadium nitride provided in Example 1 of the present invention; Figure 3 is the electron microscope image of vanadium nitride in Example 1 of the present invention; Figure 4 is the XRD pattern of vanadium nitride in Example 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] As Figure 1 shown, this embodiment provides a preparation method of vanadium nitride, including the following steps: S1. Dissolve the vanadium-containing compound with distilled water and perform water bath heating at a temperature of 70-90°C for 50-70 min to obtain a vanadium-containing compound solution. After filtering the vanadium-containing compound solution multiple times, perform drying at a temperature of 90-110°C for 120-180 min to obtain a vanadium-containing compound powder; Among them, the mass ratio of the vanadium-containing compound to distilled water is 1:8 to 12, the vanadium-containing compound is ammonium polyvanadate, and the carbonaceous reducing agent is dicyandiamide or a mixture of dicyandiamide and graphite powder; S2. Mix the vanadium-containing compound powder and the carbonaceous reducing agent at a molar ratio of 1 to 1.2:1 and press them under a pressure of 2 to 4 MPa to obtain a mixed raw material; S3. Calcinate the mixed raw material in nitrogen. First, preheat it and heat it at a heating rate of 3 to 7 °C / min to 580 to 620 °C, keep it warm for 50 to 70 min, and simultaneously introduce the protective gas nitrogen at a rate of 450 to 550 ml / min; then carry out calcination and heat it from 580 to 620 °C to 800 to 1000 °C at a heating rate of 3 to 7 °C / min, keep it warm for 150 to 210 min, and simultaneously introduce nitrogen at a rate of 450 to 550 ml / min; finally, carry out cooling and cool it to 150 to 250 °C to obtain vanadium nitride.

[0021] The present invention will be described in detail below in conjunction with embodiments.

[0022] Example 1: As Figure 2 shown, this example provides a method for preparing vanadium nitride, including the following steps: S1. Dissolve 1.794 g of ammonium polyvanadate in 18 ml of water, heat it in a water bath at 80 °C and stir it with a magnetic rotor for 1 hour to dissolve the residual sodium carbonate and ammonium sulfate in the production of ammonium polyvanadate to obtain an ammonium polyvanadate solution; filter the ammonium polyvanadate solution, dissolve and filter the obtained filtrate with 18 ml of water again, repeat 3 times to remove impurities as much as possible, and put the obtained ammonium polyvanadate powder into an oven and dry it at 100 °C for 2 hours.

[0023] S2. Take 2.016 g of dicyandiamide and mix it evenly with the dried ammonium polyvanadate powder in a mortar, put it into a mold, press it at a pressure of 3 MPa for 3 minutes to form, and obtain an ammonium polyvanadate-dicyandiamide mixed raw material.

[0024] S3. Place the ammonium polyvanadate-dicyandiamide mixed raw material in a crucible, put it into a tube furnace, fill it with nitrogen at a flow rate of 500 ml / min, heat it at a rate of 5 °C / min to 600 °C, keep it warm for 1 hour, then heat it to 1000 °C, keep it warm for 4 hours, and cool it to 200 °C with the furnace to obtain a vanadium nitride product.

[0025] In this embodiment, during the heat preservation stage at 600°C, it can prevent the melting and decomposition of ammonium metavanadate from hindering the reduction effect. Meanwhile, during the heat preservation stage at 600 - 1000°C, reduction and nitridation occur simultaneously, and the generated CO gas can be carried away by the introduced nitrogen. During the reaction process, the nitrogen flow rate is 200 - 500 ml / min, which can not only meet the kinetic conditions of the reduction reaction but also prevent the excessive nitrogen from causing a decrease in the reaction temperature and waste of nitrogen.

[0026] In addition, since vanadium nitride has a face - centered cubic structure and can have unlimited solid solubility, the molar ratio of ammonium metavanadate - dicyandiamide in this embodiment can not only make the reduction reaction proceed fully but also ensure the nitrogen content of the product. Compared with the mainstream process, this embodiment greatly reduces the synthesis temperature while still having a high nitrogen content, and the grain size of the product reaches the nanometer level.

[0027] Example 2: The preparation method of vanadium nitride provided in this embodiment includes the following steps: S1. Dissolve 2.388 g of ammonium metavanadate in 24 ml of water, heat it in a water bath at 80°C and stir it with a magnetic rotor for 1 hour to dissolve the residual sodium carbonate and ammonium sulfate in the production of ammonium metavanadate, obtaining an ammonium metavanadate solution; filter the ammonium metavanadate solution, dissolve the obtained filtrate in 24 ml of water and filter again, repeat 3 times to remove impurities as much as possible, and put the obtained ammonium metavanadate powder into an oven and dry it at 100°C for 2 hours.

[0028] S2. Take 2.630 g of dicyandiamide and mix it evenly with the dried ammonium metavanadate powder in a mortar, put it into a mold, press it at a pressure of 6 MPa for 3 minutes to form, obtaining an ammonium metavanadate - dicyandiamide mixed raw material.

[0029] S3. Place the ammonium metavanadate - dicyandiamide mixed raw material in a crucible, put it into a tube furnace, fill nitrogen at a flow rate of 500 ml / min, heat it at a rate of 5°C / min to 600°C, keep it warm for 1 hour, then heat it to 1000°C and keep it warm for 4 hours, and cool it in the furnace to 200°C to obtain vanadium nitride products.

[0030] As Figure 4 shown, it is the XRD pattern of vanadium nitride in Example 2.

[0031] Example 3: The preparation method of vanadium nitride provided in this embodiment includes the following steps: S1. Dissolve 2.985 g of ammonium metavanadate in 30 ml of water, heat it in a water bath at 80 °C and stir it with a magnetic rotor for 1 hour to dissolve the residual sodium carbonate and ammonium sulfate in the production of ammonium metavanadate, obtaining an ammonium metavanadate solution; filter the ammonium metavanadate solution, dissolve and filter the obtained filtrate with 30 ml of water again, repeat 3 times to remove impurities as much as possible, and put the obtained ammonium metavanadate powder into an oven and dry it at 100 °C for 3 hours.

[0032] S2. Take 3.360 g of dicyandiamide and mix it well with the dried ammonium metavanadate powder in a mortar, put it into a mold, press it at a pressure of 3 MPa for 3 minutes to form, obtaining an ammonium metavanadate-dicyandiamide mixed raw material.

[0033] S3. Place the ammonium metavanadate-dicyandiamide mixed raw material in a crucible, put it into a tube furnace, fill it with nitrogen at a flow rate of 500 ml / min, heat it up at a rate of 5 °C / min to 600 °C, keep it warm for 1 hour, then heat it up to 1100 °C and keep it warm for 4 hours, and cool it down to 200 °C with the furnace to obtain a vanadium nitride product.

[0034] The component tables of each element in Examples 1 - 3 are shown in Table 1 below. Table 1: Comparison table of element components of Examples 1 - 3, national standard VN19 and national standard VN16

[0035] Among them, the component contents of each element are within the national standard values. Therefore, this preparation method is more convenient to operate and has lower actual energy consumption while ensuring the quality of the finished product. A high-quality vanadium nitride finished product can be obtained only at a lower synthesis temperature, and the content of nitrogen element in it can also be guaranteed.

[0036] Example 4: The preparation method of vanadium nitride provided in this example includes the following steps: S1. Dissolve 2.985 g of ammonium metavanadate in 30 ml of water, heat it in a water bath at 80 °C and stir it with a magnetic rotor for 1 hour to dissolve the residual sodium carbonate and ammonium sulfate in the production of ammonium metavanadate, obtaining an ammonium metavanadate solution; filter the ammonium metavanadate solution, dissolve and filter the obtained filtrate with 30 ml of water again, repeat 3 times to remove impurities as much as possible, and put the obtained ammonium metavanadate powder into an oven and dry it at 100 °C for 3 hours.

[0037] S2. Take 3.024 g of dicyandiamide, 0.096 g of graphite and mix them well with the dried ammonium metavanadate powder in a mortar, put it into a mold, press it at a pressure of 9 MPa for 3 minutes to form, obtaining an ammonium metavanadate-dicyandiamide-graphite mixed raw material.

[0038] S3. Place the ammonium metavanadate-dicyandiamide-graphite mixed raw material in a crucible, put it into a tube furnace, fill it with nitrogen at a flow rate of 500 ml / min, heat it up at a rate of 5 °C / min to 600 °C, keep it warm for 1 hour, then heat it up to 1000 °C, keep it warm for 4 hours, and cool it down to 200 °C with the furnace to obtain a vanadium nitride product.

[0039] Example 5: The preparation method of vanadium nitride provided in this example includes the following steps: S1. Dissolve 2.985 g of ammonium metavanadate in 30 ml of water, heat it in a water bath at 80 °C and stir it with a magnetic rotor for 1 hour to dissolve the residual sodium carbonate and ammonium sulfate in the production of ammonium metavanadate to obtain an ammonium metavanadate solution; filter the ammonium metavanadate solution, dissolve and filter the obtained filtrate with 30 ml of water again, repeat 3 times to remove impurities as much as possible, and put the obtained ammonium metavanadate powder into an oven and dry it at 100 °C for 3 hours.

[0040] S2. Take 2.688 g of dicyandiamide and 0.192 g of graphite powder and mix them evenly with the dried ammonium metavanadate powder in a mortar, put them into a mold, press them at a pressure of 3 MPa for 3 minutes to form, and obtain an ammonium metavanadate-dicyandiamide mixed raw material.

[0041] S3. Place the ammonium metavanadate-dicyandiamide mixed raw material in a crucible, put it into a tube furnace, fill it with nitrogen at a flow rate of 500 ml / min, heat it up at a rate of 5 °C / min to 600 °C, keep it warm for 1 hour, then heat it up to 1100 °C, keep it warm for 3 hours, and cool it down to 200 °C with the furnace to obtain a vanadium nitride product.

[0042] The content clarified in the above examples should be understood that these examples are only used to illustrate the present invention more clearly, rather than to limit the scope of the present invention. Modifications of various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the appended claims of this application.

Claims

1. A preparation method of vanadium nitride, characterized in that, It includes the following steps: S1. Obtain vanadium-containing compound powder after pretreatment of the vanadium-containing compound; S2. Mix and pressurize the vanadium-containing compound powder with a carbonaceous reducing agent to obtain a mixed raw material; S3. Calcinate the mixed raw material in a protective gas to obtain vanadium nitride.

2. The preparation method of vanadium nitride according to claim 1, characterized in that, The pretreatment in S1 includes the following steps: S11. Dissolve the vanadium-containing compound in distilled water and perform water bath heating to obtain a vanadium-containing compound solution; S12. Filter the vanadium-containing compound solution multiple times and then dry it to obtain vanadium-containing compound powder.

3. The preparation method of vanadium nitride according to claim 2, wherein In S11, the mass ratio of the vanadium-containing compound to distilled water is 1:8 - 12.

4. The preparation method of vanadium nitride according to claim 2, wherein In S11, the temperature of water bath heating is 70 - 90°C, and the time of water bath heating is 50 - 70 min. In S12, the drying temperature is 90 - 110°C, and the drying time is 120 - 180 min.

5. The preparation method of vanadium nitride according to claim 1, wherein: The calcination process in S3 includes the following steps: S31. Preheating stage: Heat at a heating rate of 3 - 7°C / min to 580 - 620°C, keep warm for 50 - 70 min, and simultaneously introduce the protective gas at a rate of 450 - 550 ml / min; S32. Calcination stage: Heat from 580 - 620°C to 1000 - 1200°C at a heating rate of 3 - 7°C / min, keep warm for 150 - 210 min, and simultaneously introduce the protective gas at a rate of 450 - 550 ml / min; S33. Cooling stage: Cool to 150 - 250°C.

6. The preparation method of vanadium nitride according to claim 1, characterized in that The vanadium-containing compound in S1 is ammonium polyvanadate.

7. A method for preparing vanadium nitride according to claim 1, characterized in that, The carbonaceous reducing agent in S2 is dicyandiamide or a mixture of dicyandiamide and graphite powder.

8. A method for preparing vanadium nitride according to claim 1, characterized in that, In S2, the molar ratio of the vanadium-containing compound powder to the carbonaceous reducing agent is 1 - 1.2:1; Among them, the molar ratio is the molar ratio of oxygen in the vanadium-containing compound powder to carbon in the carbonaceous reducing agent.

9. The preparation method of vanadium nitride according to claim 1, characterized in that, The pressure for pressurization in S2 is 2 - 4 MPa.

10. A method for preparing vanadium nitride according to claim 1, characterized in that, The protective gas in S3 is nitrogen to increase the nitrogen element content in the vanadium nitride.

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