A process for the preparation of solid vanadyl sulfate

Abstract

The application discloses a method for preparing vanadyl sulfate solid, comprising the following steps: (1) mixing V2O5 with concentrated sulfuric acid in a reactor; (2) introducing a reducing gas into the reactor, and obtaining a vanadyl sulfate solution after the reaction is completed; (3) adding a trace amount of reducing agent into the vanadyl sulfate solution, uniformly stirring, and then obtaining vanadyl sulfate crystals through post-treatment; and (4) drying the vanadyl sulfate crystals to obtain vanadyl sulfate solid. The method for preparing vanadyl sulfate solid can increase the drying temperature of vanadyl sulfate to 60-95 DEG C by introducing a trace amount of reducing agent into the vanadyl sulfate solution, so that the drying temperature is increased and the drying time is reduced, and meanwhile, the intermediate state of vanadium pentoxide is ensured not to be oxidized at a high drying temperature. The method is simple in process, improves the production efficiency of vanadyl sulfate solid, increases the yield of vanadyl sulfate solid, and guarantees the stability and quality of the product.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and specifically to a method for preparing vanadium oxysulfate solid. Background Technology

[0002] VOSO4 has wide applications in coating materials, denitrification catalysts, biomaterials, and vanadium redox flow batteries, with a promising market prospect. VOSO4 is typically sold in solid form. Current VOSO4 production processes use high-purity V₂O₅ as raw material, SO₂, oxalic acid, sodium sulfite, and sulfuric acid as reducing agents, and sulfuric acid solution as a solvent to prepare a vanadium oxysulfate solution. This solution is then subjected to vacuum distillation to obtain a high-concentration saturated vanadium oxysulfate solution. The saturated VOSO4 solution is dried at 35°C for 24 hours to obtain solid VOSO4. However, due to strict requirements from buyers regarding the pentavalent vanadium content in solid VOSO4, the existing preparation methods suffer from the following main problems.

[0003] Drying a saturated VOSO4 solution at 35°C for 24 hours is considered excessively long. However, increasing the drying temperature of the saturated vanadium oxysulfate solution, for example, to 60°C, leads to the formation of an intermediate product converting tetravalent vanadium to pentavalent vanadium. This alters the water of crystallization content of vanadium oxysulfate, reducing its stability and causing the product to fail to meet customer requirements. It also severely impacts production efficiency, resulting in low yields. Furthermore, solid VOSO4 often cannot be sold immediately after production. During storage, tetravalent vanadium is oxidized to pentavalent vanadium by air, leading to substandard product quality and unsaleable goods.

[0004] Patent application number 201910791690.X discloses a method for preparing solid vanadium oxysulfate. This invention utilizes a vanadium-containing solution obtained from vanadium slag in steelmaking converters through roasting and leaching. The method involves targeted iron removal, vanadium valence conversion, solvent extraction for purification, and back-extraction with mixed acids to obtain a high-purity vanadium oxysulfate solution. Solid vanadium oxysulfate is then obtained through direct negative pressure distillation and crystallization. However, this process does not address technical solutions for improving the stability of solid vanadium oxysulfate.

[0005] Patent application number 202110038827.1 discloses a method for purifying vanadium oxysulfate through melt crystallization. This patent first heats low-purity vanadium oxysulfate raw material to a molten state, then performs primary crystallization and primary filtration to obtain crude vanadium oxysulfate crystals and crystallization residue. The crude vanadium oxysulfate crystals are then purified by sweating and centrifugation filtration to obtain high-purity vanadium oxysulfate and sweating residue. Finally, the crystallization residue and sweating residue are collected and cooled to obtain crude vanadium oxysulfate byproduct. The purpose of this patent is to purify low-purity vanadium oxysulfate; however, it does not address technical solutions for increasing yield or improving the stability of vanadium oxysulfate.

[0006] The aforementioned problems in existing technologies severely limit the production efficiency of VOSO4, reduce its output, and consequently restrict its sales. Cost reduction and efficiency improvement encompass multiple aspects, among which improving production efficiency is crucial. From the laboratory to pilot production and then to industrialization, chemical products consistently face the challenge of improving production efficiency, increasing output, and ensuring product quality; therefore, solving these problems is essential. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing vanadium oxysulfate solid, which can increase the drying temperature of vanadium oxysulfate to 60-95°C, thereby achieving the goal of increasing the drying temperature and reducing the drying time, while also ensuring that vanadium oxysulfate is not oxidized to the pentavalent vanadium intermediate state at the higher drying temperature.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing vanadium oxysulfate solid, comprising the following steps:

[0010] (1) Mix V2O5 with concentrated sulfuric acid in a reactor;

[0011] (2) A reducing gas is introduced into the reactor, and after the reaction is complete, a vanadium oxysulfate solution is obtained;

[0012] (3) Add a small amount of reducing agent to the vanadium oxysulfate solution, stir evenly, and then obtain vanadium oxysulfate crystals through post-treatment;

[0013] (4) Dry the vanadium oxysulfate crystals to obtain vanadium oxysulfate solid.

[0014] According to one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, in step (1), the purity of V2O5 is 99.999%, the mass fraction of concentrated sulfuric acid is ≥90%, and the mass ratio of V2O5 to concentrated sulfuric acid is 1:(0.6-1.0).

[0015] According to one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, in step (2), reducing gas sulfur dioxide is introduced from the bottom of the reactor.

[0016] According to one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, the reaction process in step (2) further includes a step of measuring the temperature and pressure inside the reactor to determine whether the reaction is complete.

[0017] In one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, in step (3), the trace reducing agent added is one of V2(SO4)3, oxalic acid, V2O3, and sodium sulfite.

[0018] In one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, the molar ratios of V2(SO4)3 and V2O3 to vanadium oxysulfate are 1:2000-4000, and the molar ratios of oxalic acid and sodium sulfite to vanadium oxysulfate are 1:4000-8000, respectively.

[0019] In one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, in step (3), the mixture is stirred for 2-4 hours.

[0020] According to one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, in step (3), the post-treatment includes a vacuum distillation step, after which vanadium oxysulfate slurry is obtained with a solid-liquid ratio of 0.5-0.9 and a vacuum distillation time of 2-4 hours.

[0021] According to one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, the post-treatment further includes a crystallization and filtration step, wherein the crystallization time is 2-4 hours and the filtration is performed through a plate and frame filter.

[0022] According to one embodiment of the method for preparing vanadium oxysulfate solid according to the present invention, in step (4), drying is carried out in an oven at a temperature of 60-95°C for a time of 4-12 hours.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0024] The method for preparing vanadium oxysulfate solid of the present invention introduces a trace amount of reducing agent, such as one of V2(SO4)3, oxalic acid, V2O3, and sodium sulfite, into the vanadium oxysulfate solution. This can increase the drying temperature of vanadium oxysulfate to 60-95°C, thereby achieving the goal of increasing the drying temperature and reducing the drying time while ensuring that vanadium oxysulfate is not oxidized to the intermediate state of pentavalent vanadium at the higher drying temperature.

[0025] In addition, it can ensure that vanadium oxysulfate solid is not oxidized to the pentavalent vanadium intermediate state during the storage period before sale, thereby improving the stability of vanadium oxysulfate solid and extending its shelf life.

[0026] The method of this invention is simple and improves the production efficiency of vanadium oxysulfate solid, shortening the production cycle from 42 hours to 30 hours. This method also increases the yield of vanadium oxysulfate solid from 17 tons / month to 24 tons / month, ensuring product stability and quality. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of the method for preparing vanadium oxysulfate solid according to the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0030] like Figure 1 As shown, the present invention provides a method for preparing vanadium oxysulfate solid, comprising the following steps:

[0031] (1) Mix V2O5 with concentrated sulfuric acid in a reactor;

[0032] (2) A reducing gas is introduced into the reactor, and after the reaction is complete, a vanadium oxysulfate solution is obtained;

[0033] (3) Add a small amount of reducing agent to the vanadium oxysulfate solution, stir evenly, and then obtain vanadium oxysulfate crystals through post-treatment;

[0034] (4) Dry the vanadium oxysulfate crystals to obtain vanadium oxysulfate solid.

[0035] In a preferred embodiment, in step (1), the purity of V2O5 is 99.999%, the mass fraction of concentrated sulfuric acid is ≥90%, and the mass ratio of V2O5 to concentrated sulfuric acid is 1:(0.6-1.0).

[0036] In a preferred embodiment, in step (2), reducing gas sulfur dioxide is introduced from the bottom of the reactor, which can be a reaction vessel. Since the reaction to prepare vanadium oxysulfate is exothermic, the temperature inside the reaction vessel first rises, then stabilizes, and finally begins to decrease after the reaction is complete. Simultaneously, because the solubility of sulfur dioxide gas in the liquid decreases after the reaction is complete, it remains gaseous inside the reaction vessel. When the pressure inside the reaction vessel begins to rise, it indicates that the reaction is complete. Therefore, a temperature measuring device and a pressure measuring device can be installed on the reaction vessel. By measuring the temperature and pressure inside the reaction vessel and observing the temperature and pressure changes, it is possible to effectively determine whether the reaction is complete.

[0037] In a preferred embodiment, the trace reducing agent added in step (3) is one of V2(SO4)3, oxalic acid, V2O3, and sodium sulfite. Those skilled in the art should understand that the molar number of vanadium oxysulfate produced can be calculated using the mass of added V2O5. Therefore, the molar ratio of the added reducing agent to vanadium oxysulfate can be calculated according to the number of electrons provided by different reducing agents. For a single molecule providing one reducing electron, the trace reducing agent is added at a molar ratio of 1:4000-8000; for a single molecule providing two reducing electrons, the trace reducing agent is added at a molar ratio of 1:2000-4000. In a preferred embodiment, the molar ratios of V2(SO4)3 and V2O3 to vanadium oxysulfate are 1:2000-4000, and the molar ratios of oxalic acid and sodium sulfite to vanadium oxysulfate are 1:4000-8000.

[0038] In a preferred embodiment, in step (3), stirring is performed for 2-4 hours. The post-treatment includes a vacuum distillation step, after which vanadium oxysulfate slurry is obtained with a solid-liquid ratio of 0.5-0.9, and the vacuum distillation time is 2-4 hours. The post-treatment also includes a crystallization and filtration step, where crystallization takes 2-4 hours and is performed using a plate and frame filter.

[0039] In a preferred embodiment, in step (4), drying is carried out in an oven at a temperature of 60-95°C for 4-12 hours.

[0040] The following specific examples illustrate the method for preparing vanadium oxysulfate solid according to the present invention.

[0041] Example 1

[0042] 300 kg of vanadium pentoxide with a purity of 99.999% was mixed with 200 kg of concentrated sulfuric acid with a mass fraction of 98% in a reaction vessel to obtain a slurry. Sulfur dioxide gas was introduced from the bottom of the reaction vessel, and after the reaction was complete, a vanadium oxysulfate solution was obtained. 520 g of solid V2(SO4)3 was added to the reaction vessel, stirred for 2 h, and then distilled under reduced pressure for 3 h. When the solid-liquid ratio was 0.76, solid-liquid separation was performed using a plate and frame filter. After crystallization for 2 h, vanadium oxysulfate containing trace amounts of trivalent vanadium was obtained. The solid was then placed in an oven and dried at 80 °C for 5 h to obtain solid vanadium oxysulfate.

[0043] Example 2

[0044] 300 kg of vanadium pentoxide with a purity of 99.999% was mixed with 230 kg of concentrated sulfuric acid with a mass fraction of 97% in a reaction vessel to obtain a slurry. Sulfur dioxide gas was introduced from the bottom of the reaction vessel, and after the reaction was complete, a vanadium oxysulfate solution was obtained. 210 g of solid V₂O₃ was added to the reaction vessel, stirred for 2 h, and then distilled under reduced pressure for 3 h. When the solid-liquid ratio was 0.8, solid-liquid separation was performed using a plate and frame filter. After crystallization for 2.5 h, vanadium oxysulfate containing trace amounts of trivalent vanadium was obtained. The solid was then placed in an oven and dried at 90 °C for 4 h to obtain solid vanadium oxysulfate.

[0045] Example 3

[0046] 300 kg of vanadium pentoxide with a purity of 99.999% was mixed with 200 kg of concentrated sulfuric acid with a mass fraction of 98% in a reaction vessel to obtain a slurry. Sulfur dioxide gas was introduced from the bottom of the reaction vessel, and after the reaction was complete, a vanadium oxysulfate solution was obtained. 150 g of solid oxalic acid was added to the reaction vessel, stirred for 3 h, and then distilled under reduced pressure for 3 h. When the solid-liquid ratio was 0.9, solid-liquid separation was performed using a plate and frame filter. After crystallization for 2 h, vanadium oxysulfate containing trace amounts of trivalent vanadium was obtained. The solid was then placed in an oven and dried at 85 °C for 5 h to obtain solid vanadium oxysulfate.

[0047] Example 4

[0048] 300 kg of vanadium pentoxide with a purity of 99.999% and 300 kg of concentrated sulfuric acid with a mass fraction of 98% were mixed in a reaction vessel to obtain a slurry. Sulfur dioxide gas was introduced from the bottom of the reaction vessel, and after the reaction was complete, a vanadium oxysulfate solution was obtained. 110 g of sodium sulfite solid was added to the reaction vessel, stirred for 3 h, and then distilled under reduced pressure for 3 h. When the solid-liquid ratio was 0.5, solid-liquid separation was performed using a plate and frame filter. After crystallization for 3 h, vanadium oxysulfate containing trace amounts of trivalent vanadium was obtained. The solid was then placed in an oven and dried at 60 °C for 12 h to obtain solid vanadium oxysulfate.

[0049] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0050] It should be noted that the components or steps in the above embodiments can be interchanged, substituted, added, or deleted. Therefore, the combinations formed by these reasonable permutations and transformations should also fall within the protection scope of this invention, and the protection scope of this invention should not be limited to the above embodiments.

[0051] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing vanadium oxysulfate solid, characterized in that, Includes the following steps: (1) Mix V2O5 with concentrated sulfuric acid in a reactor; (2) A reducing gas is introduced into the reactor, and after the reaction is complete, a vanadium oxysulfate solution is obtained; (3) Add a small amount of reducing agent to the vanadium oxysulfate solution, stir evenly, and then obtain vanadium oxysulfate crystals through post-treatment; (4) Dry the vanadium oxysulfate crystals to obtain vanadium oxysulfate solid; In step (1), the purity of V2O5 is 99.999%, the mass fraction of concentrated sulfuric acid is ≥90%, and the mass ratio of V2O5 to concentrated sulfuric acid is 1:(0.6-1.0). In step (3), the added trace reducing agent is one of V2(SO4)3, oxalic acid, V2O3, and sodium sulfite; The molar ratio of V2(SO4)3 or V2O3 to vanadium oxysulfate is 1:2000-4000, and the molar ratio of oxalic acid or sodium sulfite to vanadium oxysulfate is 1:4000-8000. In step (4), drying is carried out in an oven at a temperature of 60-95℃.

2. The method according to claim 1, characterized in that, In step (2), sulfur dioxide, a reducing gas, is introduced from the bottom of the reactor.

3. The method according to claim 2, characterized in that, In the reaction process of step (2), the step of measuring the temperature and pressure inside the reactor is also included to determine whether the reaction is complete.

4. The method according to claim 1, characterized in that, In step (3), stir for 2-4 hours.

5. The method according to claim 1, characterized in that, In step (3), the post-processing includes a vacuum distillation step, after which vanadium oxysulfate slurry is obtained with a solid-liquid ratio of 0.5-0.9 and a vacuum distillation time of 2-4 hours.

6. The method according to claim 5, characterized in that, The post-processing also includes a crystallization and filtration step, with a crystallization time of 2-4 hours, followed by filtration through a plate and frame filter.

7. The method according to claim 1, characterized in that, In step (4), the drying time is 4h-12h.

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