Molybdenum-based oxide rich in oxygen-containing functional group as well as preparation method and application of molybdenum-based oxide
Patent Information
- Application Number
- CN202410875174.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-02
- Publication Date
- 2024-12-20
Smart Images
Figure CN119160942A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of inorganic non-metallic nanomaterial modification, and in particular to a molybdenum-based oxide rich in oxygen-containing functional groups, and a preparation method and application thereof. Background Art
[0002] When the molybdenum element forms ions, it can have different valence states, so it can form oxides with different valence states. Each oxide has different structures and properties. Different molybdenum-based oxides can also be obtained according to the doped impurity metal ions. Molybdenum dioxide, molybdenum trioxide and molybdenum tetraoxide are the three most widely used molybdenum oxides. They have important applications in catalysts, materials science and electronic devices. The production of molybdenum oxides generally adopts wet chemical methods. In the wet chemical production process, since molybdenum ions can exist in different valence states and can also form complex molybdate ions and heteropolyacid ions with different anions, this will cause the bonding type between molybdenum and oxygen and the stacking density of crystals to be very different in the formation of molybdenum-based oxides. It is precisely because of such rich possibilities that the existence form of molybdenum ions in the solution can be used to control the composition of its main molybdenum oxygen polyhedrons through protonation and coordination, and then obtain molybdenum-based oxides with different surface oxygen-containing functional groups, which is of great significance to the improvement of high-activity molybdenum-based catalysts and functional materials preparation technology. Summary of the invention
[0003] The purpose of the present invention is to provide a molybdenum-based oxide rich in oxygen-containing functional groups, and a preparation method and application thereof. The molybdenum-based oxide rich in oxygen-containing functional groups is prepared by using a high-purity precursor solution in combination with multi-step crystallization. Compared with commercial molybdenum oxides, the molybdenum-based oxide has richer surface functional groups, solves the problem of poor solubility of existing molybdenum-containing oxides in aqueous solutions, especially acidic aqueous solutions, improves the coordination ability of molybdenum oxide, and significantly improves its surface activity and catalytic activity compared with commercial molybdenum oxide materials.
[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0005] A method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups, characterized in that the method adopts a high-purity precursor solution and combines a multi-step crystallization process to obtain a molybdenum-based oxide rich in oxygen-containing functional groups, and the method specifically comprises the following steps:
[0006] (1) Preparation of precursor solution: adding alkali solution to molybdenum solid raw material for leaching treatment, and obtaining molybdenum-containing reaction precursor solution after impurity removal from the obtained leaching solution;
[0007] (2) adding an oxidizing ligand to the molybdenum-containing reaction precursor solution obtained in step (1) under acidic conditions to carry out a coordination reaction to obtain a high-purity precursor solution;
[0008] (3) primary crystallization: crystallizing the high-purity precursor solution obtained in step (2) at a temperature below the boiling point of the aqueous solution to obtain a primary crystal product;
[0009] (4) Secondary crystallization: the primary crystallization product is subjected to a second crystallization in a salt-free water to obtain a secondary crystallization product;
[0010] (5) Drying treatment: After the secondary crystallization product is dried, the molybdenum-based oxide rich in oxygen-containing functional groups is obtained.
[0011] Furthermore, in step (1), the molybdenum solid raw material is one or more of molybdenum roasted sand, sodium molybdate, calcium molybdate, ammonium molybdate, ammonium polymolybdate, molybdic acid, heteropolymolybdic acid and heteropolymolybdate; the alkali solution is a NaOH solution with a concentration of 20-35wt.%, and the pH value of the leaching solution is controlled to 12-13 by controlling the amount of alkali solution added, and the molybdenum concentration in the leaching solution is controlled to 80-120g / L.
[0012] Furthermore, in step (1), the impurity removal treatment is to subject the leached solution to deammoniation treatment and then to adsorption and impurity removal treatment by a weakly alkaline anion exchange resin; the pH of the solution before impurity removal is adjusted to 7-12; and the adsorption linear velocity during the adsorption and impurity removal treatment is controlled to be 1-4 m / h.
[0013] Furthermore, the coordination reaction process of step (2) is as follows: hydrochloric acid and hydrogen peroxide are added to the molybdenum-containing reaction precursor solution, and the molybdenum ions are coordinated under the dual action of proton hydrogen and peroxide to obtain a high-purity precursor solution; wherein: the mass ratio of hydrogen peroxide (calculated according to the amount of H2O2 in hydrogen peroxide) to Mo is 1:(3-5), the reaction time is 0.5-2h, and the endpoint pH is lower than 1.
[0014] Furthermore, in step (3), the reaction temperature of the primary crystallization is 30-90°C, stirring is started, and the reaction time is 1-50h.
[0015] Furthermore, in step (4), secondary crystallization refers to fully mixing the primary crystallization product obtained in step (3) with salt-free water in a mass ratio of (0.5-3):1, allowing the surface ions to further diffuse and crystallize at room temperature to obtain dried precursor crystals (secondary crystallization product).
[0016] Furthermore, in step (5), the drying temperature is 60-200° C., and the drying time is 1-3 h.
[0017] Furthermore, the deamination treatment in step (1) specifically refers to the use of a stripping tower to control the alkali-ammonium ratio (OH - / NH4 +) is 2.5-3.5, at this time the pH of the solution is > 14, and the feed rate is controlled at 3-8m 3 / h, NH4 in the solution after deammoniation + The concentration is ≤50mg / L. After deammoniation, an appropriate amount of molybdenum solid raw material is added to the solution to adjust the pH to pH=7-12.
[0018] The surface of the molybdenum-based oxide prepared by the method of the present invention is rich in oxygen-containing functional groups, and the oxygen-containing functional groups are Mo=O, O-Mo-O and HOH.
[0019] The molybdenum-based oxide has good solubility in phosphoric acid or phosphoric acid-like solution and is applied to the preparation of molybdenum-containing complexes.
[0020] The technical principles of the present invention are as follows:
[0021] The present invention first uses alkali solution to make most of the molybdenum ions in the molybdenum solid raw material enter the aqueous solution. In this process, the molybdenum ions mainly exist in the form of molybdate, and some cations with similar chemical properties to the molybdenum ions will also participate in it. Alkali metal ions and alkaline earth metal ions and similar cations will also enter the aqueous solution, and the positive and negative charges of the molybdenum ions are attracted to form a coexistence system. Therefore, to control the surface state of the final molybdenum-based oxide, it is necessary to control the coordination of the molybdenum ions in the crystallization precursor solution and the stacking and dehydration mode of the molybdenum oxygen polyhedron. In this aspect, on the basis of the above-mentioned traditional process steps, the method of impurity removal of platinum-like metal ions and peroxide coordination under acidic conditions is innovatively introduced, which not only adjusts the valence state of the molybdenum ions, but also controls the existence mode of the molybdenum oxygen polyhedron, wherein the end point of impurity removal and the coordination of peroxide with the molybdenum ion are the key, and the two are innovatively combined to obtain a molybdenum-based oxide material rich in oxygen-containing functional groups, which has a regular grain shape and abundant surface active sites, and can produce enough surface sites for the catalytic reaction, thereby improving the catalytic activity of the material as a whole.
[0022] The advantages and beneficial effects of the present invention are as follows:
[0023] 1. The present invention obtains a molybdenum-based oxide material rich in oxygen-containing functional groups through an improved preparation process, which has stronger coordination and complexing activity.
[0024] 2. The method adopted by the present invention has strong adaptability and can be applied to molybdenum-based oxide materials composed of impurity elements.
[0025] 3. The improved method adopted in the present invention has reference significance for the dissolution and purification of molybdenum-containing raw materials, is simple to operate, and has low requirements on equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 The microscopic morphology of the molybdenum-based oxide rich in oxygen-containing functional groups prepared in Example 1;
[0027] Figure 2 The infrared spectrum results of the molybdenum-based oxide rich in oxygen-containing functional groups prepared in Example 1;
[0028] Figure 3 This is the light absorption diagram of the molybdenum-based oxide prepared in Example 2. DETAILED DESCRIPTION
[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0030] In the following examples, the concentration of concentrated hydrochloric acid is 30 vol.% or more, and the concentration of hydrogen peroxide (H2O2 content) is 30 vol.% or more.
[0031] Embodiment 1:
[0032] This embodiment is the preparation of molybdenum oxide rich in oxygen-containing functional groups, which specifically includes the following steps:
[0033] (1) Preparation of precursor solution: A 30 wt.% NaOH solution was added to the crude molybdic acid solid raw material for leaching. The amount of NaOH solution was controlled to control the pH value of the leaching solution to 12-13, and the molybdenum concentration in the leaching solution was controlled to 80-120 g / L.
[0034] The obtained leaching solution is treated with impurities to obtain a molybdenum-containing reaction precursor solution, specifically: the leaching solution is first treated with deamination and then treated with adsorption and impurity removal by weakly alkaline anion exchange resin; the deamination treatment is carried out by using a stripping tower equipment (stripping deamination tower) (feed speed 5-6m 3 / h), control the alkali-ammonium ratio (OH - / NH4 + ) is about 3.0, at which time the pH of the solution is greater than 14, and the NH4 + The concentration is ≤50mg / L. After deammoniation, a small amount of molybdic acid is added to the solution to adjust the pH value to pH=12.
[0035] The solution with pH=12 obtained after deamination treatment is subjected to adsorption and impurity removal treatment by anion exchange resin, and the adsorption linear velocity is controlled to be 4m / h. The anion exchange resin is used to remove anionic impurities such as P, As, Si, W, and V in the solution.
[0036] (2) adding hydrogen peroxide to the molybdenum-containing reaction precursor solution obtained after the adsorption and impurity removal treatment in step (1) under acidic conditions to carry out coordination reaction to obtain a high-purity precursor solution; wherein the acidic condition is controlled by dripping concentrated hydrochloric acid, and the addition flow rate of concentrated hydrochloric acid is 0.2m 3 / h, the pH value of the solution is controlled at about pH=3 by adding concentrated hydrochloric acid; the mass ratio of the added hydrogen peroxide (calculated according to the amount of H2O2 in the hydrogen peroxide) to the Mo in the solution is 1:(3-5), the precipitation end point acidity is 50g / L, and the reaction time is 2h; after the reaction, concentrated hydrochloric acid is added to adjust the solution end point pH to 0.5.
[0037] (3) primary crystallization: crystallizing the high-purity precursor solution obtained in step (2) at 90° C. under stirring conditions for 20 hours to obtain a primary crystal product;
[0038] (4) Secondary crystallization: placing the primary crystallization product in a deionized water, mixing the primary crystallization product with the deionized water in a mass ratio of 1:1, and performing a second crystallization at room temperature to obtain a secondary crystallization product;
[0039] (5) Drying treatment: The secondary crystallized product is dried at 100° C. for 2 h to obtain the molybdenum-based oxide rich in oxygen-containing functional groups.
[0040] Embodiment 2:
[0041] This embodiment is the preparation of molybdenum oxide rich in oxygen-containing functional groups, which specifically includes the following steps:
[0042] (1) Preparation of precursor solution: A 30 wt.% sodium hydroxide solution was added to the molybdenum roasted sand solid raw material for leaching treatment, and the amount of NaOH solution was controlled to control the pH value of the leaching solution to 12-13, and the molybdenum concentration in the leaching solution was controlled to 80-120 g / L.
[0043] The obtained leaching solution is treated with impurities to obtain a molybdenum-containing reaction precursor solution, specifically: the leaching solution is first treated with deamination and then treated with adsorption and impurity removal by weakly alkaline anion exchange resin; the deamination treatment is carried out by using a stripping tower equipment (stripping deamination tower) (feed speed 5-6m 3 / h), control the alkali-ammonium ratio (OH - / NH4 + ) is about 3.0, at which time the pH of the solution is greater than 14, and the NH4 + The concentration is ≤50mg / L. After deammoniation, a small amount of molybdenum roasted sand is added to the solution to adjust the pH value to pH=12.
[0044] The solution with pH=12 obtained after deamination treatment is subjected to adsorption and impurity removal treatment by anion exchange resin, and the adsorption linear velocity is controlled to be 3m / h. The anion exchange resin is used to remove anionic impurities such as P, As, Si, W, and V in the solution.
[0045] (2) adding hydrogen peroxide to the molybdenum-containing reaction precursor solution obtained after the adsorption and impurity removal treatment in step (1) under acidic conditions to carry out coordination reaction to obtain a high-purity precursor solution; wherein the acidic condition is controlled by dripping concentrated hydrochloric acid, and the addition flow rate of concentrated hydrochloric acid is 0.2m 3 / h, the pH value of the solution is controlled at about pH=3 by adding concentrated hydrochloric acid; the mass ratio of the added hydrogen peroxide (calculated according to the amount of HO2 in the hydrogen peroxide) to the Mo in the solution is 1:(3-5), the precipitation end point acidity is 28g / L, the reaction time is 0.5h, and concentrated hydrochloric acid is added after the reaction to adjust the solution end point pH to 0.5.
[0046] (3) primary crystallization: crystallizing the high-purity precursor solution obtained in step (2) at 85° C. under stirring conditions for 20 hours to obtain a primary crystal product;
[0047] (4) Secondary crystallization: placing the primary crystallization product in a deionized water, mixing the primary crystallization product with the deionized water in a mass ratio of 1:1.2, and performing a second crystallization at room temperature to obtain a secondary crystallization product;
[0048] (5) Drying treatment: The secondary crystallization product is dried at 95° C. for 2 h to obtain the molybdenum-based oxide rich in oxygen-containing functional groups.
[0049] Figure 1 This is the microscopic morphology of the molybdenum-based oxide prepared in Example 1. It can be seen that the molybdenum-based oxide is a columnar structure with good surface crystallization.
[0050] Figure 2 This is the infrared spectrum of the molybdenum-based oxide prepared in Example 1. It can be seen that compared with commercial molybdenum oxide, the functional group peak intensity of the material in Example 1 is significantly enhanced, and the oxygen-containing functional groups are Mo=O, O-Mo-O and HOH.
[0051] Figure 3 is the light absorption diagram of the molybdenum-based oxide prepared in Example 2, Figure 3 It can be seen that the material ( Figure 3 Sample 1) has stronger light absorption properties in the ultraviolet band than commercial molybdenum oxide.
[0052] After testing, the molybdenum-based oxides prepared in Examples 1-2 have the same microscopic morphology, infrared spectral characteristics and light absorption characteristics.
[0053] Embodiment 3:
[0054] The molybdenum-based oxide obtained in Example 1 was mixed with concentrated phosphoric acid (concentration 85 wt.% or more) in a molar ratio of 1:3 (the concentrated phosphoric acid was calculated based on the H3PO4 contained therein), and heated to 80°C to dissolve it for 25 minutes.
[0055] Comparative Example 1:
[0056] Commercial analytical grade molybdenum trioxide and concentrated phosphoric acid (concentration 85 wt.% or more) were mixed in a molar ratio of 1:3 (the concentrated phosphoric acid was calculated based on the H3PO4 contained therein), and heated to 80°C to dissolve them for 40 minutes.
[0057] The above embodiments are for reference only. The preparation methods of controlling the crystal form of molybdenum-based oxides and molybdenum-based oxide-like crystal forms that are similar to or extended from the concept of this patent are all within the scope of protection of this patent.
Claims
1. A method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups, characterized in that: The method is to use a high-purity precursor solution and combine it with a multi-step crystallization process to obtain a molybdenum-based oxide rich in oxygen-containing functional groups. The method specifically includes the following steps: (1) Preparation of precursor solution: adding alkali solution to molybdenum solid raw material for leaching treatment, and obtaining molybdenum-containing reaction precursor solution after impurity removal from the obtained leaching solution; (2) adding an oxidizing ligand to the molybdenum-containing reaction precursor solution obtained in step (1) under acidic conditions to carry out a coordination reaction to obtain a high-purity precursor solution; (3) primary crystallization: crystallizing the high-purity precursor solution obtained in step (2) at a temperature below the boiling point of the aqueous solution to obtain a primary crystal product; (4) Secondary crystallization: the primary crystallization product is subjected to a second crystallization in a salt-free water to obtain a secondary crystallization product; (5) Drying treatment: After the secondary crystallization product is dried, the molybdenum-based oxide rich in oxygen-containing functional groups is obtained.
2. The method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups according to claim 1, characterized in that: In step (1), the molybdenum solid raw material is one or more of molybdenum roasted sand, sodium molybdate, calcium molybdate, ammonium molybdate, ammonium polymolybdate, molybdic acid, heteropolymolybdic acid and heteropolymolybdate; the alkali solution is a NaOH solution with a concentration of 20-35wt.%, and the pH value of the leaching solution is controlled to 12-13 by controlling the amount of alkali solution added, and the molybdenum concentration in the leaching solution is controlled to 80-120g / L.
3. The method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups according to claim 1, characterized in that: In step (1), the impurity removal treatment is to subject the leached solution to deammoniation treatment and then to adsorption and impurity removal treatment by a weakly basic anion exchange resin; The pH of the solution before impurity removal is adjusted to 7-12; the adsorption linear speed during adsorption impurity removal treatment is controlled at 1-4m / h.
4. The method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups according to claim 1, characterized in that: The coordination reaction process of step (2) is as follows: hydrochloric acid and hydrogen peroxide are added to the molybdenum-containing reaction precursor solution, and the molybdenum ions are coordinated under the dual action of proton hydrogen and peroxide to obtain a high-purity precursor solution; wherein: the mass ratio of hydrogen peroxide (calculated according to the amount of H2O2 in hydrogen peroxide) to Mo is 1:(3-5), the reaction time is 0.5-2h, and the end point pH is lower than 1.
5. The method for preparing the molybdenum-based oxide rich in oxygen-containing functional groups according to claim 1, characterized in that: In step (3), the reaction temperature of the primary crystallization is 30-90° C., stirring is started, and the reaction time is 1-50 h.
6. The method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups according to claim 1, characterized in that: In step (4), secondary crystallization refers to fully mixing the primary crystallization product obtained in step (3) with salt-free water in a mass ratio of (0.5-3):1, allowing the surface ions to further diffuse and crystallize at room temperature to obtain dried precursor crystals (secondary crystallization product).
7. The method for preparing a molybdenum-based oxide rich in oxygen-containing functional groups according to claim 1, characterized in that: In step (5), the drying temperature is 60-200° C. and the drying time is 1-3 h.
8. The method for preparing the molybdenum-based oxide rich in oxygen-containing functional groups according to claim 3, characterized in that: The deamination treatment in step (1) specifically refers to the use of a stripping tower to control the alkali-ammonium ratio (OH – / NH4 + ) is 2.5-3.5, at this time the pH of the solution is > 14, and the feed rate is controlled at 3-8m 3 / h, NH4 in the solution after deammoniation + The concentration is ≤50mg / L, and the solution after deammoniation is adjusted to pH=7-12 using molybdenum solid raw material.
9. A molybdenum-based oxide rich in oxygen-containing functional groups prepared by the method according to any one of claims 1 to 8, characterized in that: The surface of the molybdenum-based oxide is rich in oxygen-containing functional groups, and the oxygen-containing functional groups are Mo=O, O-Mo-O and HOH.
10. The use of the molybdenum-based oxide rich in oxygen-containing functional groups according to claim 9, characterized in that: The molybdenum-based oxide has good solubility in phosphoric acid or phosphoric acid-like solution and is applied to the preparation of molybdenum-containing complexes.