Preparation method of trifluoro vanadium oxide

Abstract

The invention discloses a preparation method of trifluoro vanadium oxide, and belongs to the technical field of fine chemical engineering. The method comprises the following steps: uniformly mixing vanadium pentoxide powder with a gamma-Cr2O3 catalyst, putting the mixture into a reactor, maintaining the temperature in the reactor within the range of 120-150 DEG C, introducing fluorine-containing gas into the reactor for gas-solid reaction, performing magnetic separation on solids obtained by the gas-solid reaction to obtain a trifluorovanadium oxide product, and condensing tail gas obtained by the gas-solid reaction to recover a vanadium pentafluoride product; the method is simple in reaction process, safe in technological operation, high in product purity and high in conversion rate.

Description

Technical Field

[0001] The invention relates to a method for preparing trifluoro vanadium oxide, in particular to a method for preparing trifluoro vanadium oxide with high purity and high conversion rate, belonging to the technical field of fine chemical industry. Background Art

[0002] Vanadium trifluoride (VOF3) is a white crystal at room temperature. Trifluoroacetic acid and CH2Cl2 may be the only solvents that can dissolve it without reacting. Therefore, most reactions of vanadium trifluoride are carried out in these two solvents. In many cases, adding some ethyl acetate can greatly increase the solubility of the reagent in the above two solvents.

[0003] VOF3 is mainly used in organic synthesis for intramolecular or intermolecular oxidative coupling reactions of phenol or phenol ether compounds. Since the preparation and storage of VOF3 are difficult, and its price and reaction system are expensive, it is often used in the synthesis of important natural products.

[0004] At present, there are two main research methods for the preparation of VOF3:

[0005] (1) Using dry oxygen and vanadium trifluoride powder for thermal reaction, VOF3 can be generated. The reaction equation is as follows:

[0006] 2VF3+O2→2VOF3;

[0007] (2) ClF3 reacts with VOCl3 to generate VOF3. The reaction equation is as follows:

[0008] ClF3+VOCl3→VOF3;

[0009] The first method is oxidation method, the reaction product is single, but the raw material VF3 has poor stability and is easy to combine with water to form other products. The consumption of raw materials will reduce the generation rate of VOF3. The second method is difficult to synthesize the raw materials themselves, and will produce harmful gases such as Cl2, making the synthesis difficult. Summary of the invention

[0010] In view of the defects of the prior art, the object of the present invention is to provide a method for preparing trifluorovanadium oxide, which has mild reaction conditions and a high yield of trifluorovanadium oxide with a purity of more than 99%.

[0011] In order to achieve the above technical objectives, the present invention provides a method for preparing trifluorovanadium oxide, which comprises the following steps: uniformly mixing vanadium pentoxide powder and a γ-Cr2O3 catalyst, placing the mixture in a reactor, maintaining the temperature in the reactor within the range of 120 to 150°C, introducing a fluorine-containing gas into the reactor for a gas-solid reaction, separating the solid obtained by the gas-solid reaction by magnetic separation to obtain a trifluorovanadium oxide product, and recovering the vanadium pentafluoride product by condensing the tail gas obtained by the gas-solid reaction.

[0012] The key to the technical solution of the present invention is that a γ-Cr2O3 catalyst is introduced into the fluorination reaction process of vanadium pentoxide, which can not only reduce the temperature of the fluorination reaction, such as reacting at a temperature below 150°C, but also increase the yield of trifluorovanadium oxide, the yield of which can reach 45% (calculated by mass of V). At the same time, it is easy to separate from the trifluorovanadium oxide product by magnetic separation, thereby facilitating the acquisition of high-purity trifluorovanadium oxide, such as a purity of more than 99%.

[0013] As a preferred solution, the mass of the γ-Cr2O3 catalyst is 1-10% of the mass of the vanadium pentoxide powder. If the content of the γ-Cr2O3 catalyst is too little, the reaction will be insufficient. If the amount of the γ-Cr2O3 catalyst added is too much, the catalyst utilization rate will be low and the material will be wasted. The mass of the γ-Cr2O3 catalyst is further preferably 2-5% of the mass of the vanadium pentoxide powder.

[0014] As a preferred solution, the fluorine-containing gas comprises fluorine gas and carrier gas, wherein the mass percentage of fluorine gas is 20-40%. As a more preferred solution, the carrier gas comprises at least one of nitrogen gas and argon gas.

[0015] As a preferred solution, the conditions of the gas-solid reaction are: the temperature is controlled at 120-150°C, the reaction time is 1-3 hours, the flow rate of the fluorine-containing gas is 30-200 mL / min, and the reaction pressure is controlled at above 0.1 MPa. The preferred reaction conditions are conducive to improving the conversion rate of vanadium pentoxide. The reaction temperature has an impact on the conversion rate. If the temperature is not reached, the reaction is incomplete, resulting in a low conversion rate.

[0016] The preparation method of trifluorovanadium oxide provided by the present invention has the following specific process:

[0017] Step 1: Mix the raw materials. Mix fluorine gas and nitrogen in proportion and put them into the mixed gas bottle. Add a quantitative catalyst γ-Cr2O3 to the V2O5 powder and mix them evenly.

[0018] Step 2: Reactor pretreatment. Control the flow rate of mixed gas entering the reactor, place a nickel-based material tray containing mixed raw materials in the reactor, slowly introduce nitrogen into the reactor, remove the internal air, and increase the temperature to 120°C, and dry until the moisture content is below 10ppm.

[0019] Step 3: Reaction to generate crude products. Keep the reactor temperature at 120-150°C, pass the fluorine-nitrogen mixed gas in the mixed gas bottle into the reactor, and the fluorine gas and V2O5 react in the reactor to generate crude vanadium oxyfluoride and vanadium pentafluoride products; the reaction equation is as follows:

[0020] V2O5+4F2→VOF3+VF5+2O2

[0021] The gas-solid reaction temperature is controlled at 120-150° C., the reaction time is 1-3 hours, the gas feed flow rate is 30-200 mL / min, and the reaction pressure is controlled above 0.1 MPa.

[0022] Step 4: Product collection: The γ-Cr2O3 and VOF3 powder in the tray are separated by strong magnetic separation to obtain a VOF3 solid product with a purity of more than 99%.

[0023] Step 5: Tail gas collection: The exhausted hot tail gas is passed into a condenser, the temperature of the condenser is controlled at room temperature, and vanadium pentafluoride is collected.

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

[0025] 1) The present invention can synthesize trifluorovanadium oxide at a low temperature of 120-150° C. with low energy consumption.

[0026] 2) The conversion rate of the vanadium pentoxide raw material of the present invention is relatively high.

[0027] 3) The present invention can obtain VOF3 products with a purity higher than 99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flow chart of the preparation process of trifluorovanadium oxide. DETAILED DESCRIPTION

[0029] The following specific examples are intended to further illustrate the present invention rather than to limit the scope of protection of the claims.

[0030] Example 1

[0031] The mass ratio of fluorine gas in the mixed gas is 20%, and the rest of the gas is nitrogen. Take 250g of vanadium pentoxide, add 10g of γ-Cr2O3 powder, mix well and place on a tray, slowly introduce nitrogen, raise the temperature to 120°C, and dry until the moisture content is below 10ppm. Keep the reactor temperature at 120°C, pass the fluorine-nitrogen mixed gas in the mixed gas bottle into the reactor, the reaction time is 3 hours, and the reaction pressure is controlled at 0.1MPa. The γ-Cr2O3 and VOF3 powder in the tray are separated by strong magnetism to obtain a VOF3 solid product with a purity of more than 99%, and the VOF3 yield is 45.3% (calculated by vanadium mass). The reactor is followed by a condenser to collect vanadium pentafluoride.

[0032] Example 2

[0033] The mass ratio of fluorine gas in the obtained mixed gas is 20%, and the rest of the gas is nitrogen. Take 250g of vanadium pentoxide, add 8g of γ-Cr2O3 powder, mix well and place on a tray, slowly introduce nitrogen, raise the temperature to 120°C, and dry until the moisture content is less than 10ppm. Keep the reactor temperature at 135°C, pass the fluorine-nitrogen mixture in the mixed gas bottle into the reactor, the reaction time is 2 hours, and the reaction pressure is controlled at 0.1MPa. The γ-Cr2O3 and VOF3 powder in the tray are separated by strong magnetism to obtain a VOF3 solid product with a purity of more than 99%, and the VOF3 yield is 45.6% (calculated by vanadium mass). A condenser is connected to the reactor to collect vanadium pentafluoride.

[0034] Example 3

[0035] The mass ratio of fluorine gas in the obtained mixed gas is 20%, and the rest of the gas is nitrogen. Take 250g of vanadium pentoxide, add 5g of γ-Cr2O3 powder, mix well and place on a tray, slowly introduce nitrogen, raise the temperature to 120°C, and dry until the moisture content is less than 10ppm. Keep the reactor temperature at 150°C, pass the fluorine-nitrogen mixture in the mixed gas bottle into the reactor, the reaction time is 1 hour, and the reaction pressure is controlled at 0.1MPa. The γ-Cr2O3 and VOF3 powder in the tray are separated by strong magnetism to obtain a VOF3 solid product with a purity of more than 99%. The VOF3 yield is 45.1% (calculated by vanadium mass). A condenser is connected to the reactor to collect vanadium pentafluoride.

[0036] Comparative Example 1

[0037] The ratio of fluorine gas in the obtained mixed gas is 20%, and the rest of the gas is nitrogen. Take 250g of vanadium pentoxide, without adding γ-Cr2O3 powder, evenly place it on a tray, slowly pass nitrogen, raise the temperature to 120°C, and dry until the moisture content is less than 10ppm. Keep the reactor temperature at 150°C, pass the fluorine-nitrogen mixture in the mixed gas bottle into the reactor, the reaction time is 2 hours, and the reaction pressure is controlled at 0.1MPa. Take the VOF3 powder in the tray and obtain a VOF3 solid product with a purity of only 93%, and the VOF3 conversion rate is only 37.2% (calculated by vanadium mass). Connect a condenser to the reactor to collect vanadium pentafluoride.

Claims

1. A method for preparing trifluorovanadium oxide, characterized in that: After the vanadium pentoxide powder and the γ-Cr2O3 catalyst are uniformly mixed, they are placed in a reactor, the temperature in the reactor is maintained in the range of 120-150°C, and a fluorine-containing gas is introduced into the reactor for gas-solid reaction. The solid obtained by the gas-solid reaction is separated by magnetic separation to obtain a trifluorovanadium oxide product, and the tail gas obtained by the gas-solid reaction is condensed to recover the vanadium pentafluoride product.

2. The method for preparing trifluorovanadium oxide according to claim 1, characterized in that: The mass of the γ-Cr2O3 catalyst is 1-10% of the mass of the vanadium pentoxide powder.

3. The method for preparing trifluorovanadium oxide according to claim 1, characterized in that: The fluorine-containing gas comprises fluorine gas and carrier gas, wherein the mass percentage content of the fluorine gas is 20-40%.

4. The method for preparing trifluorovanadium oxide according to claim 3, characterized in that: The carrier gas includes at least one of nitrogen and argon.

5. The method for preparing trifluorovanadium oxide according to any one of claims 1 to 4, characterized in that: The conditions of the gas-solid reaction are: the temperature is controlled at 120-150° C., the reaction time is 1-3 hours, the flow rate of the fluorine-containing gas is 30-200 mL / min, and the reaction pressure is controlled at above 0.1 MPa.

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