A method for preparing MgV2O4

Abstract

The present invention discloses a preparation method of MgV2O4. The preparation method includes: (1) drying V2O5; (2) uniformly mixing Mg powder, an additive with the dried V2O5 to obtain a mixture; (3) compacting the mixture obtained in step (2); (4) placing the blank in a reaction vessel, heating it to 600 °C at a heating rate of 15 K / min and then stopping heating to initiate a self-propagating reaction; (5) pickling and drying the reacted material to obtain MgV2O4. Compared with the existing preparation methods, the present invention has the prominent characteristics of simple process, short cycle and energy saving, which is conducive to large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium vanadate preparation, and in particular to a preparation method of MgV2O4. Background Art

[0002] MgV2O4 is an ideal material for studying magnetic frustration and has good visible light catalytic performance. At present, the preparation methods of MgV2O4 mainly include two types: pyrometallurgy and hydrometallurgy. Mamiya H et al. used V2O3 and MgO as raw materials, proportioned them according to a molar ratio of 1:1, and heated them in a flowing atmosphere of 10% H2 and 90% Ar to 1353K and kept them warm for 40h to obtain the product. Tang W et al. added NH4VO3 and magnesium acetate to ethylene glycol, stirred for 3h, then transferred them to an autoclave, kept them at 453K for 36h, washed the obtained product with absolute ethanol and then dried it in vacuum for 12h, and finally kept the collected product in an N2 atmosphere at 873K for 2h to obtain MgV2O4 powder. Patent CN103898602A prepared MgV2O4 by a two-step solid-phase sintering method. First, magnesium carbonate or basic magnesium carbonate and vanadium pentoxide were used as raw materials, and MgV2O6 was prepared by a solid-phase sintering method. Secondly, MgV2O6 was reduced in hydrogen or a reducing atmosphere to obtain MgV2O4. Patent CN112093821A mixed a magnesium source, metavanadate and polyol, then carried out a microwave solvothermal reaction, and finally calcined the solid to obtain MgV2O4.

[0003] At present, the methods for preparing MgV2O4 all require a long time and a large amount of energy provided from the outside, which will inevitably become a technical bottleneck hindering the large-scale application of MgV2O4-containing materials in the future. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a preparation method of MgV2O4. This preparation method utilizes the characteristics of fast self-propagating reaction speed and high instantaneous temperature, uses metallic Mg to reduce V2O5 to in-situ synthesize MgV2O4, and then pickles to remove the excess MgO.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] A preparation method of MgV2O4 mainly includes the following steps:

[0007] (1) Dry V2O5.

[0008] (2) Uniformly mix Mg powder, an additive and the dried V2O5 to obtain a mixture.

[0009] (3) Press the mixture obtained in step (2) into a blank.

[0010] (4) Place the blank in the reaction vessel, heat it up to 600 °C at a heating rate of 15 K / min, then stop heating to initiate the self-propagating reaction;

[0011] (5) Pickle and dry the material obtained from the reaction to obtain MgV2O4.

[0012] As a preferred solution, in step (1), place V2O5 in a blast drying oven and dry it at a temperature of 120 - 150 °C for 10 - 24 h.

[0013] As a preferred solution, in step (2), the molar ratio of V2O5 to Mg is 1:2.

[0014] As a preferred solution, in step (2), the additive is a mixture of KClO3 and Mg, the molar ratio of KClO3 to Mg is 1:3, and the addition amount of the additive is 2 - 5% of the total mass of V2O5 and Mg powder;

[0015] As a preferred solution, in step (3), the pressure during pressing into a blank is 10 - 50 MPa, and the blank is a cylinder or a cube.

[0016] As a preferred solution, in step (4), the reaction vessel is filled with Ar gas, and the pressure of the Ar gas is 1 - 10 MPa.

[0017] As a preferred solution, in step (4), the ignition method is overall heating ignition, and the reaction time is 1 - 60 s.

[0018] As a preferred solution, in step (5), the concentration of the hydrochloric acid solution used for pickling is 0.1 - 4 mol / L, the pickling temperature is 30 - 60 °C, and the pickling time is 0.5 - 2 h.

[0019] As a preferred solution, in step (5), the drying temperature is 20 - 50 °C, and the time is 0.1 - 5 h.

[0020] The present invention uses Mg to reduce V2O5 to obtain V2O3 and MgO, and V2O3 and MgO generate MgV2O4 at high temperatures. In order to increase the temperature of the system, a KClO3 - Mg mixture with a high heat release is selected as the additive. The overall heating ignition method not only increases the internal energy of the system but also makes the reaction more uniform. After pickling to remove the excess MgO and KCl, pure MgV2O4 is obtained. During the self-propagating reaction, Mg is prone to volatilization and loss, and the volatilized Mg is likely to adhere to places such as the furnace door and recrystallize, causing danger. Therefore, an inert gas with a pressure of 1 - 10 Mpa is filled in the reaction kettle, which not only increases the boiling point of Mg but also inhibits the volatilization of Mg.

[0021] The reactions involved include:

[0022] V2O5 + 2Mg = V2O3 + 2MgO;

[0023] KClO3 + 3Mg = 3MgO + KCl;

[0024] V2O3 + MgO = MgV2O4;

[0025] MgO + H + = Mg 2+ + H2O;

[0026] KCl = K + + Cl - 。

[0027] The present invention selects the KClO3-Mg mixture as an additive, and the function of the additive is to increase the heat release of the system and promote the combination of V2O3 and MgO to form MgV2O4.

[0028] Compared with the existing technologies, the features and beneficial effects of the present invention are as follows:

[0029] 1), The production cycle of the preparation method of the present invention is short. The self-propagating reaction can be completed in only a few seconds, and pickling and drying can also be completed within dozens of hours, which is greatly shortened compared with other preparation methods.

[0030] 2), The preparation method of the present invention saves energy consumption. The self-propagating reaction only requires a small amount of energy to initiate the reaction, and pickling only requires a solution slightly higher than room temperature.

[0031] 3), The preparation method of the present invention has a short process flow, the equipment involved is simple, the maintenance cost is low, and it is easy to industrialize production.

[0032] The following further specifically describes the present invention in detail with reference to the accompanying drawings of the embodiments and specific embodiments. Description of the Drawings

[0033] Figure 1 is the process flow chart of the preparation of the present invention.

[0034] Figure 2 is the XRD pattern of the product prepared in Example 1 of the present invention.

[0035] Figure 3 is the SEM image of the product prepared in Example 1 of the present invention. Detailed Embodiments

[0036] The present invention discloses a preparation method of MgV2O4. Please refer to Figure 1 , and this preparation method mainly includes the following steps:

[0037] (1), Place V2O5 in a forced-air drying oven and dry it at a temperature of 120 - 150 °C for 10 - 24 h;

[0038] (2), Uniformly mix the dried V2O5 with Mg powder and an additive to obtain a mixture; among them, the molar ratio of V2O5 to Mg is 1:2, and the addition amount of the additive is 2 - 5% of the total mass of V2O5 and Mg powder; the additive is a mixture of KClO3 and Mg, and the molar ratio of KClO3 to Mg is 1:3;

[0039] (3), Press the mixture obtained in step (2) into a blank at a pressure of 10 - 50 MPa. The blank is a cylinder or a cube;

[0040] (4), Place the blank in a reaction vessel. The reaction vessel is filled with Ar gas, and the pressure of the Ar gas is 1 - 10 MPa. Heat it at a heating rate of 15 K / min to 600 °C and then stop heating to initiate a self-propagating reaction. The ignition method is overall heating ignition, and the reaction time is 1 - 60 s;

[0041] (5), Pickle and dry the material obtained from the reaction to obtain MgV2O4; among them, the concentration of the hydrochloric acid solution used for pickling is 0.1 - 4 mol / L, the pickling temperature is 30 - 60 °C, and the pickling time is 0.5 - 2 h. The drying temperature is 20 - 50 °C, and the time is 0.1 - 5 h.

[0042] It should be noted that the V2O5 used in the embodiments of the present invention is of analytical purity, Mg and hydrochloric acid are both industrial-grade products, the particle size of Mg is less than 0.5 mm, and the argon gas used is 99.99% high-purity argon gas.

[0043] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0044] Example 1

[0045] A preparation method of MgV2O4 mainly includes the following steps:

[0046] (1) Place V2O5 in a forced-air drying oven and dry it at a temperature of 130 °C for 12 h;

[0047] (2) Uniformly mix V2O5, Mg, and an additive according to a mass ratio of 182 g:48 g:7 g, and then place it in a vacuum ball mill. The material-to-ball ratio is 10:2, the rotation speed is 150 r / min, and the time is 35 min;

[0048] (3) Cold-press the mixture obtained in step (2) into a shape. The pressure is 20 MPa, the diameter of the blank is 100 mm, and the height is 40 mm;

[0049] (4) Place the blank in the reaction vessel. The argon pressure in the reaction vessel is 5 MPa. Heat it at a heating rate of 15 K / min until 600 °C and then stop heating to initiate the self-propagating reaction;

[0050] (5) Pickle and dry the cooled product to obtain MgV2O4. The concentration of the hydrochloric acid solution used for pickling is 0.2 mol / L, with an excess of 5%. The pickling temperature is 30 °C, and the pickling time is 0.5 h. The drying temperature is 45 °C, and the drying time is 5 h.

[0051] Figure 2 The XRD pattern of the MgV2O4 prepared in this example is shown. As can be seen from the figure, no diffraction peaks of other impurities are found on the XRD pattern, indicating that pure MgV2O4 can be obtained by the preparation method of the present invention.

[0052] Figure 3 The SEM image of the MgV2O4 prepared in this example is shown. As can be seen from the figure, after high-temperature sintering, the product is a dense block.

[0053] Example 2

[0054] The difference between Example 2 and Example 1 is only that in step (5), the concentration of the hydrochloric acid solution used for pickling is 2 mol / L, with an excess of 5%. The pickling temperature is 30 °C, the pickling time is 20 min, the drying temperature is 45 °C, and the drying time is 5 h.

[0055] Example 3

[0056] The difference between Example 3 and Example 1 is only that V2O5, Mg, and the additive are uniformly mixed in a mass ratio of 182 g: 48 g: 10 g.

[0057] In this specification, the various examples are described in a progressive manner. The key point of each example is to illustrate the differences from other examples. For the same or similar parts among the various examples, reference can be made to each other.

[0058] The above has introduced in detail a preparation method of a kind of MgV2O4 provided by the present invention. Specific examples are used in this article to elaborate on the principle and specific implementation manner of the present invention. The above examples are only used to help understand the method and core idea of the present invention. It should be pointed out that for those of ordinary skill in the art, any simple modification, equivalent change, and modification made to the above examples based on the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A method for preparing MgV2O4, characterized in that, It mainly includes the following steps: (1) Dry V2O5; (2) Uniformly mix Mg powder, additives and the dried V2O5 to obtain a mixture; (3) Press the mixture obtained in step (2) into a blank; (4) Place the blank in a reaction vessel, heat it up to 600 °C at a heating rate of 15 K / min and then stop heating to initiate a self-propagating reaction; (5) Pickle and dry the material obtained from the reaction to obtain MgV2O4; Among them, in step (2), the molar ratio of V2O5 to Mg powder is 1:2; the additive is a mixture of KClO3 and Mg, and the molar ratio of KClO3 to Mg in the additive is 1:

3. The addition amount of the additive is 2-5% of the total mass of V2O5 and Mg powder; In step (4), the reaction vessel is filled with Ar gas, and the pressure of the Ar gas is 1-10 MPa; the ignition method is overall heating ignition, and the reaction time is 1-60 s.

2. The preparation method of MgV2O4 according to claim 1, wherein In step (1), place V2O5 in a forced-air drying oven and dry it at a temperature of 120-150 °C for 10-24 h.

3. A method for preparing MgV2O4 according to claim 1, characterized in that, In step (3), the pressure during pressing into a blank is 10-50 MPa, and the blank is a cylinder or a cube.

4. The preparation method of MgV2O4 according to claim 1, characterized in that, In step (5), the concentration of the hydrochloric acid solution used for pickling is 0.1-4 mol / L, the pickling temperature is 30-60 °C, and the pickling time is 0.5-2 h.

5. The preparation method of MgV2O4 according to claim 1, characterized in that, In step (5), the drying temperature is 20-50 °C and the time is 0.1-5 h.

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