Low-temperature preparation process of low-valence vanadium oxide

Abstract

The application provides a low-temperature preparation process of low-valence vanadium oxide, and relates to the technical field of vanadium oxide preparation.The vanadium-containing raw material is dissolved in an organic acid system, a low-valence vanadium oxide intermediate is obtained through a low-temperature hydrothermal reduction reaction, and the preparation of the low-valence vanadium oxide is realized through calcination.The application significantly reduces the reaction temperature of the hydrothermal reduction reaction by using a specific organic acid system, realizes the low-temperature preparation of the low-valence vanadium oxide, and has the advantages of simple preparation process, safety and environmental protection, small product particle size and easy realization of large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of vanadium oxide preparation technology, and in particular to a low-temperature preparation process for low-valent vanadium oxides. Background Technology

[0002] Low-valent vanadium oxides are a type of conversion reaction anode material. Compared to alloy reaction anode materials, low-valent vanadium oxides exhibit smaller volume changes, and compared to insertion reaction anode materials, they can provide higher capacity. Therefore, low-valent vanadium oxides are a highly promising alternative to graphite as an anode material. Furthermore, because low-valent vanadium oxides can significantly reduce the energy consumption in the stepwise reduction process of vanadium oxides, they are ideal high-quality raw materials for the preparation of vanadium nitride, vanadium-aluminum alloys, and metallic vanadium.

[0003] Existing methods for preparing low-valent vanadium oxides include isothermal reduction and ball milling. Isothermal reduction involves reducing V₂O₃ with hydrogen at specific temperatures (1375℃, 1400℃) to prepare VO powder. However, this method suffers from high energy consumption, significant safety risks, and large, uneven particle size of the product. Ball milling, on the other hand, involves sintering vanadium hydride and V₂O₃ together under vacuum and high temperature (1477℃) conditions for 5 hours to synthesize crude VO. y VO was then synthesized by high-energy ball milling for 4 hours using propanol as a solvent. y However, this method has problems such as complex process, high energy consumption, and high oxygen content in the product.

[0004] Chinese patent CN110747358A proposes a method for precipitating vanadium from vanadium-containing oxalic acid leaching mother liquor via hydrothermal decomposition. This patent prepares VC2O4·2H2O under hydrothermal conditions of 180-250℃, 1-5h, and 1-5MPa. However, this method suffers from harsh reaction conditions, high equipment requirements, high energy consumption, and difficulty in industrialization. Summary of the Invention

[0005] To overcome the problems of harsh reaction conditions, high equipment requirements, high temperature, high energy consumption, and difficulty in industrialization in the existing vanadium precipitation process, this invention provides a low-temperature preparation process for low-valent vanadium oxides, which significantly reduces the reaction temperature of the hydrothermal reduction reaction by utilizing an organic acid system.

[0006] The low-temperature preparation process of low-valent vanadium oxide described in this invention includes the following steps:

[0007] (1) Dissolve the vanadium-containing raw material in oxalic acid to obtain a vanadium ion acid solution;

[0008] (2) Add ascorbic acid to the vanadium ion acid solution to obtain a mixed reaction solution. Perform a hydrothermal reduction reaction at 110-165℃ for 30-120 minutes. After the reaction is completed, cool to room temperature, filter and wash to obtain the low-valent vanadium oxide intermediate VC2O4·2H2O.

[0009] (3) The low-valent vanadium oxide intermediate is calcined, and after calcination, the system is cooled to room temperature to obtain low-valent vanadium oxide VO. y .

[0010] Furthermore, in step (1), the vanadium-containing raw material is one or more of vanadium oxide, vanadate, and vanadium-containing minerals.

[0011] Furthermore, the vanadium oxide is one or more of V2O5, VO2, or V2O3.

[0012] Furthermore, the vanadate is one or both of ammonium vanadate and calcium vanadate.

[0013] Furthermore, the vanadium-containing mineral is one or more of vanadium slag, coal shale, and vanadium-containing catalysts.

[0014] Furthermore, in step (1), the vanadium ion is V 5+ V 4+ V 3+ One or more of them.

[0015] Furthermore, in step (1), the concentration of vanadium ions in the organic acid solution containing vanadium ions is 10-20 g / L, and the concentration of oxalate is 100-350 g / L.

[0016] Furthermore, in step (2), the concentration of ascorbic acid in the hydrothermal reduction reaction system is 30-100 g / L.

[0017] Preferably, in step (2), the reaction temperature of the hydrothermal reduction reaction is 140℃~160℃.

[0018] Furthermore, in step (2), the hydrothermal reduction reaction is carried out under stirring conditions.

[0019] Furthermore, in step (3), the calcination temperature is 200℃~700℃ and the calcination time is 30min~120min.

[0020] Preferably, in step (3), the calcination temperature is 400℃~500℃.

[0021] Furthermore, in step (3), the calcination process is carried out under a protective atmosphere.

[0022] Furthermore, the protective atmosphere is an inert gas or a reducing gas.

[0023] Furthermore, the inert gas is nitrogen or argon.

[0024] Furthermore, the reducing gas is hydrogen or ammonia.

[0025] Furthermore, in step (3), the calcination process is carried out under a vacuum of 0.01 to 0.6 MPa.

[0026] Furthermore, in step (3), the low-valent vanadium oxide VO y The value of y in the equation ranges from 0.1 to 1.3.

[0027] Preferably, in step (3), the value of y in the low-valent vanadium oxide VOy ranges from 0.7 to 1.1.

[0028] Preferably, in step (3), the value of y in the low-valent vanadium oxide VOy is 0.7, 1, or 1.1.

[0029] In a pure oxalic acid system, to reduce high-valence vanadium ions to V 2+ The preparation of VC2O4·2H2O requires a reaction temperature ≥180℃. However, the high reaction temperature of water also causes high pressure problems, ultimately resulting in the current low-valent vanadium oxide preparation conditions being harsh, requiring sophisticated equipment, high temperatures, high energy consumption, and making industrialization difficult.

[0030] Therefore, this invention introduces ascorbic acid, a more reducing organic acid, into the oxalic acid system, successfully designing a new organic acid system, namely, an oxalic acid-ascorbic acid mixed system. The organic acid system of this invention can achieve the reduction of high-valence vanadium ions (V2) at relatively low hydrothermal temperatures. 5+ →V 4+ →V 3+ →V 2+ A VC2O4·2H2O intermediate was successfully prepared, and then a specific calcination process was used to decompose VC2O4·2H2O into low-valence vanadium oxides, thus realizing the low-temperature preparation of low-valence vanadium oxides.

[0031] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0032] This invention utilizes a specific organic acid system to significantly reduce the reaction temperature of the hydrothermal reduction reaction, enabling the low-temperature preparation of low-valent vanadium oxides. Furthermore, the preparation process of this invention is simple to operate, safe and environmentally friendly, and produces small-particle-size products that are easy to mass-produce industrially. Attached Figure Description

[0033] The present invention will be further described below with reference to the accompanying drawings.

[0034] Figure 1 This is a phase analysis diagram of the precipitated product in Example 1 of the present invention. Detailed Implementation

[0035] The technical solution provided by the present invention will be further described below with reference to the embodiments.

[0036] Example 1

[0037] A low-temperature preparation process for low-valent vanadium oxides, comprising the following steps:

[0038] (1) Preparation of vanadium-containing solution: Dissolve 4g of oxalic acid and 0.2g of vanadium pentoxide in 20mL of deionized water, then add 1.5g of ascorbic acid, mix well to form a slurry, and add it to the reaction vessel. The reaction temperature is 140℃, the reaction time is 60min, and the stirring speed is 300r / min. After the reaction is completed, cool to room temperature, filter and wash to obtain the low-valent vanadium oxide intermediate VC2O4·2H2O.

[0039] ICP analysis revealed a precipitation rate of 99.8% for V in the solution. The phase analysis of the precipitated product is as follows: Figure 1 As shown in the figure, the main product is VC2O4·2H2O;

[0040] (2) The low-valent vanadium oxide intermediate VC2O4·2H2O was placed in a vertical tube furnace for calcination at a temperature of 600℃ for 45 min, with a hydrogen flow rate of 100 mL / min. The product was cooled to room temperature to obtain the low-valent vanadium oxide.

[0041] Through detection and calculation, the vanadium oxide is VO 0.7 .

[0042] Example 2

[0043] A low-temperature preparation process for low-valent vanadium oxides, comprising the following steps:

[0044] (1) Preparation of vanadium-containing solution: Dissolve 4g of oxalic acid and 0.2g of vanadium trioxide in 15mL of deionized water, then add 1.5g of ascorbic acid, mix well to form a slurry, and add it to the reaction vessel. The reaction temperature is 160℃, the reaction time is 45min, and the stirring speed is 300r / min. After the reaction is completed, cool to room temperature, filter and wash to obtain the low-valent vanadium oxide intermediate VC2O4·2H2O.

[0045] ICP analysis showed that the precipitation rate of V in the solution was 99.9%.

[0046] (2) The low-valent vanadium oxide intermediate VC2O4·2H2O was placed in a vertical tube furnace for calcination at a temperature of 450°C for 60 min, with a high-purity nitrogen flow rate of 400 mL / min. The product was cooled to room temperature to obtain the low-valent vanadium oxide.

[0047] Based on detection and calculation, the chemical formula of vanadium oxide is deduced to be VO. 0.9 .

[0048] Example 3

[0049] A low-temperature preparation process for low-valent vanadium oxides, comprising the following steps:

[0050] (1) Preparation of vanadium-containing solution: Dissolve 4g of oxalic acid and 0.5g of ammonium vanadate in 25mL of deionized water, then add 2.5g of ascorbic acid, mix well to form a slurry, and then add it to the reaction vessel. The reaction temperature is 155℃, the reaction time is 90min, and the stirring speed is 300r / min. After the reaction is completed, cool to room temperature, filter and wash to obtain the low-valent vanadium oxide intermediate VC2O4·2H2O.

[0051] ICP analysis showed that the precipitation rate of V in the solution was 99.4%.

[0052] (2) The low-valent vanadium oxide intermediate VC2O4·2H2O was placed in a vertical tube furnace for calcination at a temperature of 300℃ for 60 min, with a high-purity argon flow rate of 300 mL / min. After the reaction was completed, the product was cooled to room temperature to obtain the low-valent vanadium oxide.

[0053] Based on detection and calculation, the chemical formula of vanadium oxide is deduced to be VO. 1.1 .

[0054] Comparative Example 1

[0055] (1) According to the method described in patent CN110747358A, the hydrothermal reaction temperature is changed to prepare the low-valent vanadium oxide intermediate VC2O4·2H2O. The specific steps are as follows:

[0056] Add 4g of oxalic acid, 0.2g of vanadium pentoxide, and 15mL of deionized water to the reaction vessel. The reaction temperature is 140℃, the reaction time is 90min, and the stirring speed is 300r / min.

[0057] ICP analysis showed that vanadium ions did not precipitate in the solution. This comparative example demonstrates that the hydrothermal decomposition temperature of vanadium ions in a single oxalic acid system must be above 180℃.

[0058] (2) The preparation process described in this invention is used to prepare the low-valent vanadium oxide intermediate VC2O4·2H2O. The specific steps are as follows:

[0059] Add 4g of oxalic acid, 0.2g of vanadium pentoxide, 15mL of deionized water, and 1.8g of ascorbic acid to a reaction vessel. The reaction temperature is 140℃, the reaction time is 90min, and the stirring speed is 300r / min.

[0060] ICP analysis showed that the precipitation rate of V in the solution was 99.7%.

[0061] Therefore, the preparation process provided by the present invention can achieve efficient precipitation of vanadium ions under low-temperature hydrothermal conditions.

[0062] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A low-temperature preparation process for low-valent vanadium oxide, characterized in that, Includes the following steps: (1) Dissolve the vanadium-containing raw material in oxalic acid to obtain a vanadium ion acid solution; (2) Add ascorbic acid to the vanadium ion acid solution to obtain a mixed reaction solution. The mass ratio of vanadium-containing raw material to ascorbic acid in the mixed reaction solution is 2-5:15-25. The hydrothermal reduction reaction is carried out at 110℃-165℃ for 30-120 minutes. After the reaction is completed, cool to room temperature, filter and wash to obtain low-valent vanadium oxide intermediate VC2O4·2H2O. (3) The low-valent vanadium oxide intermediate is calcined, and after calcination, it is cooled to room temperature to obtain low-valent vanadium oxide VO. y , where 0.1≤y≤1.

3.

2. The low-temperature preparation process of low-valent vanadium oxide according to claim 1, characterized in that, In step (1), the vanadium ion concentration in the vanadium acid solution is 10-20 g / L, and the oxalate concentration is 100-350 g / L.

3. The low-temperature preparation process of low-valent vanadium oxide according to claim 1, characterized in that, The concentration of ascorbic acid in the mixed reaction solution in step (2) is 30-100 g / L.

4. The low-temperature preparation process of low-valent vanadium oxide according to claim 1, characterized in that, In step (3), the roasting temperature is 200℃~700℃ and the roasting time is 30min~120min.

5. The low-temperature preparation process of low-valent vanadium oxide according to claim 1, characterized in that, In step (3), the low-valent vanadium oxide VO y In the case of 0.7 ≤ y ≤ 1.

1.

6. The low-temperature preparation process of low-valent vanadium oxide according to claim 5, characterized in that, In step (3), the low-valent vanadium oxide VO y In this case, y is 0.7, 1.0, or 1.1.

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