Vanadium electrolyte production method and vanadium electrolyte thereof

Abstract

The invention relates to a vanadium electrolyte production method in the technical field of vanadium battery production. The vanadium electrolyte production method comprises the following steps that S1, vanadium titano-magnetite waste residues are subjected to sulfuric acid leaching and ion exchange purification, and vanadium liquid is obtained; s2, biomass charcoal modification: adding 5-7% by mass of carbon nanotubes (CNTs) into straw charcoal, carrying out microwave treatment in nitrogen to form hierarchical porous activated carbon, dipping in 0.1-0.3 M Mn (NO3) 2 and 0.1-0.3 M Fe (NO3) 3 solutions, drying, and calcining to obtain a composite reduction carrier; s3, pulse ozone is introduced into the vanadium liquid to react for 30-60 min at the temperature of 60-70 DEG C, SO2 gas is introduced to react for 2-3 h at the temperature of 50-60 DEG C, a composite reduction carrier is added, micro-current (0.1-0.3 A / m < 2 >) is applied, and a reaction is conducted for 1.5-2 h at the normal temperature; and S4, adding an MIL-101 (Cr)-sulfonated-carboxymethyl double-modified chitosan composite stabilizer (0.1 wt%), and carrying out membrane concentration to obtain the vanadium electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of vanadium battery production, and particularly relates to a production method of vanadium electrolyte and the vanadium electrolyte thereof. Background Art

[0002] Vanadium electrolyte is the core material of vanadium redox flow battery, and its composition directly affects the battery performance. The main ionic composition is that vanadium ions exist in multiple valence states (the positive electrode is +4 / +5 valence, and the negative electrode is +2 / +3 valence), and charge and discharge are realized through redox reactions. Sulfate ions act as supporting electrolytes to provide a stable ionic conduction environment, and hydrogen ions adjust the pH value of the electrolyte to optimize the reaction activity.

[0003] Currently, the industrial preparation technologies of vanadium electrolyte are mainly divided into three categories: The chemical reduction method uses reducing agents such as oxalic acid to reduce V2O5 to VOSO4. This production method is environmentally friendly (only producing CO2) and has low cost, but it is necessary to pre-activate V2O5 and the reaction time is relatively long; The electrolysis method can directly obtain active electrolyte by electrolyzing and controlling the valence state of vanadium ions (such as preparing a mixed solution of trivalent / tetravalent), but the energy consumption is relatively high and precise control of electrolysis conditions is required; The high-temperature calcination method involves high-temperature reaction of vanadium oxides to form soluble compounds and then dissolving them in sulfuric acid, which is suitable for areas rich in vanadium-bearing stone coal resources, but the process is complex and the equipment requirements are high. In summary, the problems existing in the production methods of the prior art are no longer applicable to production. Therefore, there is an urgent need to provide a production method that can improve the reduction efficiency and the energy density of vanadium electrolyte. Summary of the Invention

[0004] The present invention aims to provide a production method of vanadium electrolyte and the vanadium electrolyte thereof, so as to provide a production method that can improve the reduction efficiency and the energy density of vanadium electrolyte.

[0005] To solve the above problems, the present invention provides the following technical solutions:

[0006] A production method of vanadium electrolyte, comprising the following steps: S1. The vanadium-titanium magnetite waste residue is leached with sulfuric acid and purified by ion exchange to obtain vanadium solution; S2. Biomass carbon modification: Carbon nanotubes (CNTs) (mass ratio 5-7%) are added to straw carbon, and microwave treatment is carried out in nitrogen to form hierarchical pore activated carbon, which is impregnated with 0.1-0.3M Mn(NO3)2 and 0.1-0.3M Fe(NO3)3 solutions, and then dried and calcined to obtain a composite reduction carrier; S3. Pulse ozone is introduced into the vanadium solution and reacted at 60-70°C for 30-60 min, then SO2 gas is introduced and reacted at 50-60°C for 2-3 hours, and the composite reduction carrier is added, and a microcurrent (0.1-0.3A / m 2 ) is applied, and the reaction is carried out at room temperature for 1.5-2 hours; S4. MIL-101(Cr)@sulfonated-carboxymethyl double-modified chitosan composite stabilizer (0.1wt%) is added, and the vanadium electrolyte is obtained by membrane concentration.

[0007] In some embodiments, the vanadium-titanium magnetite smelting waste residue is mixed with concentrated sulfuric acid (concentration 50%) at a solid-liquid ratio of 1:2 to 3, and a leaching solution is obtained at 90 to 120 °C; sodium thiosulfate is added to the leaching solution and stirred in an acidic environment, and a vanadium solution is obtained by filtering with a positively charged nanofiltration membrane under a pressure of 0.5 to 0.7 MPa. Sodium thiosulfate reduces Fe under acidic conditions 3+ , avoiding its competitive adsorption with vanadium; the positively charged nanofiltration membrane selectively retains impurity cations (such as Al 3+ , Ca 2+ ) by electrostatic repulsion, and the purity of the vanadium solution reaches 99.5%. The combined use of sodium thiosulfate and the nanofiltration membrane solves the problem of interference from multiple metal ions in traditional leaching solutions.

[0008] In some embodiments, the microwave treatment is intermittent irradiation 3 to 5 times at a power of 800 to 1000 W, 10 min each time. Intermittent irradiation avoids the collapse of the pore structure caused by local overheating, and at the same time promotes the uniform composite of CNTs and straw carbon to form through-hole hierarchical pores (micropores + mesopores) with a pore size distribution of 0.5 to 10 nm, and the adsorption capacity is increased by 40%.

[0009] In some embodiments, the microcurrent intensity is 0.2 A / m 2 , and the SO2 partial pressure is regulated stepwise from 0.1 MPa to 0.05 MPa. The initial high-pressure SO2 quickly starts the reduction reaction, and the low pressure in the later stage avoids excessive consumption; the microcurrent provides a continuous electron source, the reaction time is shortened by 30%, and the energy consumption is reduced by 20%.

[0010] In some embodiments, the MIL-101(Cr) crystal size of the composite stabilizer is 50 ± 5 nm. The nanoscale MOF has a high specific surface area and abundant pores, and can efficiently adsorb impurity ions; size control avoids agglomeration and the stability is increased by 25%.

[0011] In some embodiments, the hierarchical pore activated carbon is permeated in a 0.2 M Mn(NO3)2 solution under -0.1 MPa, and is calcined by programmed temperature rise (pre-oxidation at 300 °C for 1 h + nitrogen-confined pyrolysis at 600 °C for 2 h) to generate a composite reduction carrier with a size of 5 to 8 nm. Negative pressure permeation evenly fills Mn(NO3)2 into the pores of the activated carbon; pre-oxidation forms a Mn-O skeleton, and nitrogen-confined pyrolysis generates 5 to 8 nm Mn-Fe oxide particles, and the catalytic activity is increased by 50%.

[0012] In some embodiments, the composite ratio of MIL-101(Cr) and sulfonated-carboxymethyl double-modified chitosan in the composite stabilizer is 1:2 to 1:4. Chitosan provides a flexible network to coat the MOF. After the ratio is optimized, it has both rigid adsorption and flexible impact resistance, and the electrolyte circulation life is extended to more than 2000 times.

[0013] In some embodiments, microwave treatment introduces an argon / CO2 mixed atmosphere (volume ratio 1:1). CO2 reacts with carbon at high temperature to form micropores, and argon inhibits excessive oxidation, with the pore volume reaching 1.2 cm 3 / g, which is 30% higher than that in a single atmosphere.

[0014] The working principle and beneficial effects of the present invention:

[0015] Vanadium-titanium magnetite waste residue is purified by sulfuric acid leaching and ion exchange to achieve efficient extraction of vanadium. Compared with the conventional acid leaching process, a positively charged nanofiltration membrane can selectively adsorb high-valence vanadium ions to improve purity; in the modification of biomass carbon, straw carbon is added with carbon nanotubes (CNTs) and multi-stage porous activated carbon is formed by microwave treatment, significantly increasing the specific surface area (>1500 m 2 / g) and conductivity; after impregnation with Mn(NO3)2 and Fe(NO3)3 and calcination, a Mn-Fe oxide composite reduction carrier is generated, which has both catalytic activity and structural stability, solving the problems of easy agglomeration and few active sites of traditional catalysts. Pulsed ozone (60 - 70 °C) reacts with SO2 in stages, combined with a microcurrent (0.1 - 0.3 A / m 2 ), to achieve the directional reduction of vanadium ions (V 5+ →V 3+ ). Pulsed ozone can avoid overoxidation, the microcurrent promotes electron transfer, and the stepwise regulation of SO2 partial pressure further optimizes the reduction kinetics, with the vanadium conversion rate >98%; the MIL-101(Cr)@sulfonated-carboxymethyl double-modified chitosan composite stabilizer adsorbs free impurities and inhibits the disproportionation of vanadium ions through the synergistic effect of metal-organic framework (MOF) and chitosan, improving the electrolyte stability by more than 30%.

[0016] This application realizes the efficient and green preparation of vanadium electrolyte through multi-step collaborative innovation (resource utilization of waste residue, design of composite carrier, staged reaction control) and precise parameter regulation (microwave intermittent treatment, stepwise regulation of partial pressure, crystal size control), with high purity (>99.5%), high stability (2000 cycles), and low cost (biomass carbon replaces commercial carrier). Specific embodiments

[0017] The following is a further detailed description through specific embodiments:

[0018] Example: A method for producing vanadium electrolyte, comprising the following steps:

[0019] S1. Mix vanadium-titanium magnetite smelting waste residue with concentrated sulfuric acid (concentration 50%) at a solid-liquid ratio of 1:2 to obtain a leaching solution at 100 °C; add sodium thiosulfate to the leaching solution and stir and react in an acidic environment, and filter with a positively charged nanofiltration membrane at a pressure of 0.6 MPa to obtain vanadium solution;

[0020] S2. Biomass carbon modification: Carbon nanotubes (CNTs) (mass ratio 6%) are added to straw carbon (particle size 100 mesh), and microwave treatment is carried out in nitrogen to form hierarchical porous activated carbon. The microwave treatment is intermittent irradiation 4 times at a power of 900 W, 10 min each time; impregnate with a mixed solution of 0.2 M Mn(NO3)2 and 0.2 Fe(NO3)3, dry and then calcine to obtain a composite reduction carrier;

[0021] S3. Pulse ozone is introduced into the vanadium solution and reacted at 65 °C for 45 min, SO2 gas is introduced and reacted at 55 °C for 2.53 h, the composite reduction carrier is added, and a microcurrent (0.2 A / m 2 ) is applied, and the reaction is carried out at room temperature for 1.7 h. The SO2 partial pressure is regulated stepwise according to 0.1 MPa → 0.05 MPa;

[0022] S4. Add MIL-101(Cr)@sulfonated-carboxymethyl double-modified chitosan composite stabilizer (0.1 wt%), and obtain vanadium electrolyte through membrane concentration. The composite ratio of MIL-101(Cr) and sulfonated-carboxymethyl double-modified chitosan in the composite stabilizer is 1:3, and the crystal size of MIL-101(Cr) is 50 ± 5 nm.

[0023] Synthesis route of MIL-101(Cr): Dissolve Cr(NO3)3·9H2O (1.2 g) and H2BDC (0.4 g) in 50 mL of deionized water, and add 0.2 mL of HF as a mineralizing agent. Transfer to a high-pressure reaction kettle and carry out hydrothermal reaction at 150 °C for 8 h. After cooling, centrifuge to separate the product, wash it with deionized water and ethanol 3 times in sequence, and vacuum dry at 60 °C for 12 h to obtain blue powdery MIL-101(Cr). By adjusting the reaction time (shortened to 6 h) and temperature (130 °C), control the crystal size to be 50 ± 5 nm.

[0024] Sulfonated-carboxymethyl double-modified chitosan: Disperse chitosan (2 g) in 20 mL of concentrated sulfuric acid, slowly add chlorosulfonic acid (5 mL) under ice bath, and stir and react at 50 °C for 4 h. After the reaction, neutralize with NaOH solution to neutrality, dialyze and purify (cut-off molecular weight 3.5 kDa), and freeze-dry to obtain sulfonated chitosan; dissolve sulfonated chitosan (1 g) in 50 mL of deionized water, add sodium chloroacetate (3 g) and NaOH (1 g), and react at 60 °C for 6 h, dialyze to remove unreacted reagents, and freeze-dry to obtain sulfonated-carboxymethyl double-modified chitosan.

[0025] MIL-101(Cr)@Sulfonated-carboxymethyl double-modified chitosan composite stabilizer: Disperse MIL-101(Cr) (100 mg) and sulfonated-carboxymethyl double-modified chitosan (200 - 400 mg, with a mass ratio of 1:2 - 1:4) in 50 mL of deionized water. Ultrasonic treatment (power 300 W, 30 minutes) is carried out to ensure uniform dispersion. Add glutaraldehyde (0.5 wt%) as a cross-linking agent, stir at room temperature for 12 hours, centrifuge to collect the product, wash it 3 times with deionized water, and freeze-dry to obtain the composite stabilizer powder.

[0026] Control group 1: In step S2, use conventional activated carbon (unmodified) to replace the biomass carbon composite support.

[0027] Control group 2: In step S3, adopt continuous ozone treatment (non-pulsed) and a constant SO2 partial pressure (0.1 MPa).

[0028] Control 3: In step S4, use unmodified chitosan to replace the composite stabilizer.

[0029] Blank group: Blank 1: Omit the composite reduction support in step S2. Blank 2: Omit the composite stabilizer in step S4.

[0030] Purity of vanadium solution: Determine the impurity contents of Al 3+ , Fe 3+ etc. by ICP-OES; Vanadium conversion rate: Determine the conversion rate of V 5 + →V 3+ by UV-Vis spectrophotometry; Electrolyte stability: Test the stability of oxidation-reduction peaks by cyclic voltammetry (CV), and perform cyclic life tests (1C charge and discharge, cutoff capacity decays to 80%); Energy consumption: Record the energy consumption (kWh / kg product) of each step to obtain the following data:

[0031] Table 1 Comparison of vanadium solution purity and conversion rate

[0032] Group Purity of vanadium solution (%) Conversion rate of V5+→V3+ (%) Experimental group 99.6 98.5 Control group 1 97.2 85.3 Control group 2 98.1 91.7 Blank 1 95.8 72.4 Blank 2 97.2 88.2

[0033] Table 2

[0034] Group Cycle life (times) Energy consumption (kWh / kg) Experimental group 2200 12.5 Control 1 1500 15.8 Control 2 1800 14.5 Control 3 900 14.2 Blank 1 400 16.3 Blank 2 500 13.0

[0035] Table 3

[0036] Experimental group Vanadium recovery rate (%) Impurity content (ppm) Electrolyte stability (precipitation rate % in 30 days) Conductivity (S / cm) Example 98.5 120 1.2 0.85 Control group 1 87.3 450 8.7 0.62 Control group 2 91.4 280 3.5 0.73 Control group 3 93.2 210 5.8 0.68 Blank 1 65.8 780 15.6 0.41 Blank 2 96.0 150 12.4 0.52

[0037] In the examples, the purity (99.6%) and conversion rate (98.5%) of vanadium liquid were significantly higher than those of all control groups and the blank group, indicating that the synergistic effects of pulsed ozone treatment, stepped regulation of SO2 partial pressure, and composite stabilizers effectively improved the reaction efficiency and product quality. The cycle life (2200 times) and conductivity (0.85 S / cm) were the highest, verifying the key role of the biomass carbon composite support and MIL-101(Cr)@double-modified chitosan stabilizer in the long-term stability of the electrolyte. Composite reduction support (S2): Compared with unmodified activated carbon (control group 1), its hierarchical pore structure and metal loading significantly improved the adsorption capacity and reduction efficiency, with the vanadium recovery rate increased by 11.2% and impurities reduced by 73%. Pulsed ozone and partial pressure regulation (S3): Avoided the peroxidation problem caused by continuous ozone. Combining with microcurrent reduction, the conversion rate of V3+ was increased by 6.8% compared with control group 2 (constant partial pressure). Composite stabilizer (S4): The synergistic complexation of sulfonic acid / carboxymethyl groups and MIL-101(Cr) inhibited the precipitation of vanadium ions, and the precipitation rate in 30 days was only 1.2%, much lower than that of control group 3 with unmodified chitosan (5.8%). The energy consumption of the experimental group was the lowest (12.5 kWh / kg), attributed to the optimized reaction conditions and efficient support that shortened the treatment time. The blank group had incomplete reactions or a sudden drop in stability due to the lack of key components (such as composite reduction support, stabilizer), verifying the necessity of each step.

[0038] Through the innovative design of hierarchical pore activated carbon support, pulsed ozone reduction, and composite stabilizers, this method realizes the efficient preparation of high-purity vanadium electrolyte, with both low energy consumption and long cycle life, providing a reliable solution for the industrial production of vanadium liquid.

Claims

1. A production method of vanadium electrolyte, characterized in that, It includes the following steps: S1. The vanadium-titanium magnetite waste residue is leached with sulfuric acid and purified by ion exchange to obtain vanadium solution; S2. Biomass carbon modification: Carbon nanotubes (CNTs) (mass ratio 5-7%) are added to the straw carbon, and it is treated by microwave in nitrogen to form hierarchical porous activated carbon, impregnated with 0.1-0.3 M Mn(NO3)2 and 0.1-0.3 M Fe(NO3)3 solutions, and the composite reduction carrier is obtained by drying and calcination; S3. Pulse ozone is introduced into the vanadium solution and reacted at 60-70 °C for 30-60 min, SO2 gas is introduced and reacted at 50-60 °C for 2-3 hours, the composite reduction carrier is added, and a microcurrent (0.1-0.3 A / m 2 ) is applied, and the reaction is carried out at room temperature for 1.5-2 hours; S4. MIL-101(Cr)@sulfonated-carboxymethyl double-modified chitosan composite stabilizer (0.1 wt%) is added, and the vanadium electrolyte is obtained by membrane concentration.

2. The production method of vanadium electrolyte according to claim 1, characterized in that: Mix the vanadium-titanium magnetite smelting slag with concentrated sulfuric acid (concentration 50%) at a solid-liquid ratio of 1:2 to 3, and obtain a leaching solution at 90 to 120 °C; add sodium thiosulfate to the leaching solution and stir and react in an acidic environment, and filter with a positively charged nanofiltration membrane at a pressure of 0.5 to 0.7 MPa to obtain a vanadium solution.

3. The method for producing vanadium electrolyte according to claim 2, wherein: The microwave treatment is intermittent irradiation 3 to 5 times at a power of 800 to 1000 W, 10 min each time.

4. The production method of vanadium electrolyte according to claim 3, characterized in that: The micro-current intensity is 0.2 A / m 2 , and the partial pressure of SO2 is regulated step by step from 0.1 MPa to 0.05 MPa.

5. The method for producing vanadium electrolyte according to claim 4, wherein: The crystal size of MIL-101(Cr) in the composite stabilizer is 50 ± 5 nm.

6. The production method of the vanadium electrolyte according to claim 5, characterized in that: Perform osmosis on the hierarchical porous activated carbon in 0.2 M Mn(NO3)2 solution under -0.1 MPa, and generate a composite reduction carrier with a size of 5 to 8 nm through programmed temperature calcination (pre-oxidation at 300 °C for 1 h + nitrogen-confined pyrolysis at 600 °C for 2 h).

7. The method for producing vanadium electrolyte according to claim 6, characterized in that: The composite ratio of MIL-101(Cr) and sulfonated-carboxymethyl double-modified chitosan in the composite stabilizer is 1:2 to 1:

4.

8. The production method of the vanadium electrolyte according to claim 7, characterized in that: The microwave treatment introduces an argon / CO2 mixed atmosphere (volume ratio 1:1).

9. A vanadium electrolyte produced by the production method according to any one of claims 1 to 8.