CN106517261B - The preparation method of magnesium-based complex metal hydroxide - Google Patents

Abstract

The invention discloses a preparation method of a magnesium-based composite metal hydroxide. The magnesium-based composite metal hydroxide includes low-priced main laminate cations, high-priced main laminate cations and interlayer anions, wherein the low-priced main laminate cations It includes at least magnesium ions; the preparation method includes steps: S1, mixing the by-product magnesium hydroxide with a purity of not less than 60% and the water-soluble salt of the first low-valent cation to obtain the first mixture; S2, mixing the first mixture with The water-soluble salts of high-valent cations are mixed and dissolved in water to obtain a second mixture; S3, reacting the second mixture at 80°C to 300°C for 4h to 100h, the reaction product is subjected to solid-liquid separation, and the obtained solid phase is washed and dried to obtain Magnesium-based composite metal hydroxide. According to the preparation method of the magnesium-based composite metal magnesium hydroxide of the present invention, the by-product magnesium hydroxide is used as a raw material, which realizes waste recycling and reduces pollution and waste.

Description

Preparation method of magnesium-based composite metal hydroxide

technical field

The invention belongs to the technical field of inorganic non-metallic functional materials, and in particular relates to a preparation method of magnesium-based composite metal hydroxide.

Background technique

my country is rich in sea lake brine and ore magnesium resources. During the development and utilization of magnesium resources, a considerable amount of magnesium hydroxide is produced by-product. Due to the low purity of the by-product magnesium hydroxide (magnesium hydroxide content is not less than 60%) and many types of impurity ions, it cannot be directly used by most enterprises. abandoned. A large amount of by-product magnesium hydroxide not only restricts further production, but also causes resource waste and unreasonable development. Therefore, it is of great significance to recycle by-product magnesium hydroxide.

Composite metal hydroxides (LDHs for short) is a layered material. LDHs are assembled by positively charged metal hydroxide laminates and negatively charged interlayer anions. The metal hydroxide laminates have Metal cations of different charges. In the existing LDHs, the metal cations are mainly divalent metal cations and trivalent metal cations, so the general structural formula of the LDHs can be expressed as: [M ⁺ M ²⁺ _1-y-0.5x-2z M ³⁺ _y M ⁴⁺ _z (OH) ₂ ](A ^n- ) _y/n ·mH ₂ O, where M ⁺ , M ²⁺ , M ³⁺ and M ⁴⁺ respectively represent a Valence metal cations, divalent metal cations, trivalent metal cations and tetravalent metal cations, A ^n- means interlayer anion, 0≤x≤0.4, 0≤y≤0.7, 0≤z≤0.5, 0≤y+0.5 x+2z≤1, where y and z cannot be 0 at the same time, and m is the amount of interlayer water molecules.

LDHs have the characteristics of adjustable host and guest element types and quantities, adjustable layer elasticity, adjustable size and shape, etc. LDHs are widely used in catalysis, energy, biosensors, adsorption, Medicine and other research fields have aroused widespread interest and great attention. The industry is highly related and permeable, and can be widely used in many fields and industries of the national economy.

The traditional preparation methods of LDHs mainly include hydrothermal method, precipitation method, in situ synthesis method, ion exchange method, roasting reduction method and so on. In the traditional preparation method of LDHs, on the one hand, it is necessary to use sodium hydroxide, ammonia water, sodium carbonate, ammonium carbonate, etc. as raw materials, and new by-products will be introduced. The LDHs still need to be washed. The traditional method will produce about 2 tons of sodium salts, ammonium salts and other by-products for every ton of LDHs produced, requiring dozens or even hundreds of times of water for washing, resulting in a large waste of water resources; On the one hand, some methods also require acid gases such as CO ₂ , which makes the operation more complicated, and the inadvertent use of gas will also bring high pressure danger.

Contents of the invention

In order to solve the problems in the above-mentioned prior art, the present invention provides a preparation method of magnesium-based composite metal hydroxide, which can use the by-product magnesium hydroxide to prepare magnesium-based composite metal hydroxide, realizing the Recycling and reuse of waste to reduce pollution and waste.

In order to achieve the above-mentioned purpose of the invention, the present invention has adopted following technical scheme:

A method for preparing a magnesium-based composite metal hydroxide, the magnesium-based composite metal hydroxide includes low-priced main laminate cations, high-priced main laminate cations, and interlayer anions, wherein the low-priced main laminate cations Including at least magnesium ions; the preparation method includes the step: S1, mixing the by-product magnesium hydroxide with the water-soluble salt of the first low-valent cation to obtain the first mixture; wherein, the hydroxide in the by-product magnesium hydroxide The mass percentage of magnesium is not less than 60%; S2, the first mixture is mixed with a water-soluble salt of a high-valent cation and dissolved in water to obtain a second mixture; S3, the second mixture is heated at 80°C to 300°C The reaction is carried out for 4h to 100h, the reaction product is separated from solid and liquid, and the obtained solid phase is washed and dried to obtain the magnesium-based composite metal hydroxide.

Further, the first low-valent cation is the same as the low-valent host laminate cation; the high-valent cation is the same as the high-valent host laminate cation.

Further, the first low-valent cation is selected from Li ⁺ , Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ and Be ²⁺ at least one; the hypervalent cation is selected from Al ³⁺ , Ni ³⁺ , Co ³⁺ , Fe ³⁺ , Mn ³⁺ , Cr ³⁺ , V ³⁺ , Ti ³⁺ , In ^{3 +} , Ga ³⁺ , Sn ⁴⁺ , Ti ⁴⁺ and Zr ⁴⁺ .

Further, the anion in the water-soluble salt of the first low-valent cation and the water-soluble salt of the high-valent cation is selected from any one of Cl ^- , SO ₄ ^2- , CO ₃ ^2- , and NO ₃ ^- .

Further, the anion in the water-soluble salt of the first low-valent cation is the same as the anion in the water-soluble salt of the high-valent cation.

Further, the ratio of the total amount of magnesium ions and first low-valent cations to the amount of water-soluble salts of high-valent cations in the first mixture is 1:2 to 6:1; the first The ratio of the amount of magnesium ions to the first low-valent cations in the mixture is 1:1-1000:1.

Further, in the step S1, it also includes: adding the hydroxide of the second low-valent cation into the first mixture.

Further, the ratio of the total substance amount of magnesium ions, the first low-valent cation, and the second low-valent cation to the substance amount of the water-soluble salt of the high-valent cation in the first mixture is 1:2 to 6: 1. The ratio of the total amount of magnesium ions and second low-valent cations to the first low-valent cations in the first mixture is 1:1-1000:1.

Further, the second low-valent cation is the same as the low-valent host laminate cation.

Further, the second low-valent cation is selected from Li ⁺ , Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ and at least one of Be ²⁺ .

The present invention rationally selects the reactants and at the same time reasonably controls the ratio between the reactants, so that finally the composite metal hydroxides (magnesium-based LDHs) including magnesium ions are mainly obtained without accompanying sodium hydroxide and sodium carbonate and other by-products; the obtained magnesium-based LDHs can be used after simple washing, which greatly reduces the use of fresh water resources such as washing water, and at the same time achieves nearly 100% atom economy, which meets the requirements of green chemistry. At the same time, magnesium-based LDHs have excellent thermal stability, flame retardancy, and anti-ultraviolet aging properties, and are important functional additives for optimizing the properties of PVC, PP, PE, EVA and other polymer materials. The preparation of magnesium-based LDHs from industrial by-product magnesium hydroxide can not only realize waste recycling and reduce costs, but also promote the development of related industrial chains and realize high-value utilization of magnesium resources.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail. This invention may, however, be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, the embodiments are provided to explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to particular intended uses.

It will be understood that although the terms "first", "second", etc. may be used herein to describe various substances, these substances should not be limited by these terms. These terms are only used to distinguish one substance from another.

The invention discloses a preparation method of a magnesium-based composite metal hydroxide. The magnesium-based composite metal hydroxide includes low-priced main laminate cations, high-priced main laminate cations and interlayer anions, wherein the low-priced main laminate The cations include at least magnesium ions.

The preparation method of magnesium-based composite metal hydroxide according to the present invention comprises the following steps:

S1. Mix the by-product magnesium hydroxide with the water-soluble salt of the first low-valent cation to obtain the first mixture.

Specifically, by-product magnesium hydroxide refers to magnesium hydroxide coarse ore in which the mass percentage of magnesium hydroxide is not less than 60%, which can be derived from by-products produced during the processing of other minerals; by-product magnesium hydroxide The purity is preferably more than 70%.

Preferably, the hydroxide of the second subvalent cation is also included in the first mixture; that is, the by-product magnesium hydroxide, the water-soluble salt of the first subvalent cation and the hydroxide of the second subvalent cation are mixed , to obtain the first mixture.

Specifically, the first low-valent cation and the second low-valent cation are the same as the low-valent host laminate cation in the magnesium-based composite metal hydroxide, wherein the first low-valent cation and the second low-valent cation are respectively represented by X ₁ , X ₂ said.

The two types of metal cations with different valence states in the pre-prepared magnesium-based composite metal hydroxide are divalent metal cations and trivalent metal cations; thus, the first low-valent cation and the second low-valent cation are selected from At least one of Li ⁺ , Mg ²⁺ , Zn ²⁺ , ^{Ca 2+} , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ and Be ²⁺ .

The anion in the water-soluble salt of the first low-valent cation is selected from any one of Cl ^- , SO ₄ ^2- , CO ₃ ^2- , and NO ₃ ^- .

When there is no hydroxide of the second low-valent cation in the first mixture, the ratio of the amount of the magnesium ion in the first mixture to the water-soluble salt of the first low-valent cation is preferably 1:1 to 1000:1 ; When there is the hydroxide of the second low-valent cation in the first mixture, then be the magnesium ion in the first mixture, the total substance amount of the hydroxide of the second low-valent cation and the water-soluble content of the first low-valent cation The ratio of the amount of salts is preferably 1:1 to 1000:1.

S2. Mixing the first mixture with a water-soluble salt of a hypervalent cation and dissolving in water to obtain a second mixture.

Specifically, the high-valent cation is the same as the high-valent host laminate cation, represented by Y; the high-valent cation is selected from Al ³⁺ , Ni ³⁺ , Co ³⁺ , Fe ³⁺ , Mn ³⁺ , Cr ³⁺ , V ³⁺ , Ti At least one of ³⁺ , In ³⁺ , Ga ³⁺ , Sn ⁴⁺ , Ti ⁴⁺ and Zr ⁴⁺ .

More specifically, when there is no hydroxide of the second low-valent cation in the first mixture, the total amount of the magnesium ion in the first mixture, the water-soluble salt of the first low-valent cation and the water-soluble salt of the high-valent cation The ratio of the amount of the salt is 1:2～6:1; when there is the hydroxide of the second low-valent cation in the first mixture, then the magnesium ion in the first mixture, the first low-valent cation The ratio of the total amount of the water-soluble salt and the hydroxide of the second low-valent cation to the amount of the water-soluble salt of the high-valent cation is 1:2˜6:1.

Preferably, the quality of the water used is controlled to be 1 to 100 times the quality of the water-soluble salt of the high-valent cation.

S3. Reacting the second mixture at 80° C. to 300° C. for 4 h to 100 h, separating the reaction product from solid and liquid, and washing and drying the obtained solid phase to obtain a magnesium-based composite metal hydroxide.

Before the reaction of the second mixture, the second mixture is preferably stirred for 0.1 h to 4 h to fully dissolve and disperse to form a uniform second mixture.

The second mixture is preferably subjected to a hydrothermal reaction at a temperature of 80°C to 250°C in a hydrothermal reaction tank.

The solid phase obtained is preferably dried at 80° C. for 12 h.

Measure the pH value of the magnesium-based composite metal hydroxide obtained, and find that it is close to neutral, that is to say, the magnesium-based composite metal hydroxide obtained according to the preparation method of the magnesium-based composite metal hydroxide in the preparation process It will not produce a large amount of alkaline by-products such as sodium carbonate and sodium hydroxide, and the reactants are basically completely reacted, and can be used without multiple washing operations, which not only saves a lot of fresh water resources such as washing water, but also utilizes a lot of by-products. Magnesium hydroxide is produced as a raw material, which reduces waste and pollution, reduces costs, and simplifies the process.

Hereinafter, the preparation method of the magnesium-based composite metal hydroxide according to the present invention will be described in detail with reference to specific examples. For the convenience of comparison of each example, each example is analyzed and compared in the form of a table. The comparative results under different experimental parameters in Examples 1-7 are shown in Table 1.

Table 1 is according to the contrast of embodiment 1-7 of the present invention under different experimental parameters

Note: In Table 1, "molar ratio" refers to the total amount of substances of magnesium ion and the water-soluble salt of the first low-valent cation in the first mixture when there is no hydroxide of the second low-valent cation in the first mixture The ratio of the amount of substance to the water-soluble salt of the high-valent cation, or when the hydroxide of the second low-valent cation exists in the first mixture, the magnesium ion, the water-soluble salt of the first low-valent cation, the second The ratio of the total amount of species of hydroxides of low-valent cations to the amount of species of water-soluble salts of high-valent cations.

Of course, the preparation method of the magnesium-based composite metal hydroxide according to the present invention is not limited to those described in the above-mentioned examples 1-7; The metal cations on the metal hydroxide laminates of the magnesium-based composite metal hydroxide are at least one of Mg ²⁺ and monovalent metal cations, trivalent metal cations, and tetravalent metal cations, and can also include other divalent metal cations Metal cations; at the same time, for metal cations of the same valence state, cations of multiple metals may also be included.

While the invention has been shown and described with reference to particular embodiments, it will be understood by those skilled in the art that changes may be made in the form and scope thereof without departing from the spirit and scope of the invention as defined by the claims and their equivalents. Various changes in details.

Claims (6)

1. A preparation method of magnesium-based composite metal hydroxide, said magnesium-based composite metal hydroxide comprising low-priced main body laminate cations, high-priced main body laminate cations and interlayer anions, wherein said low-priced main body layer Plate cations include at least magnesium ions; it is characterized in that, the preparation method comprises steps: S1. Mix the by-product magnesium hydroxide with the water-soluble salt of the first low-valent cation to obtain the first mixture; wherein, the mass percentage of magnesium hydroxide in the by-product magnesium hydroxide is not less than 60%; the The first low-valent cation is selected from Li ⁺ , Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ and Be ²⁺ At least one of, and the anion in the water-soluble salt of the first low-valent cation is the same as the anion in the water-soluble salt of the high-valent cation; S2. The first mixture is mixed with a water-soluble salt of a high-valent cation and dissolved in water to obtain a second mixture; the high-valent cation is selected from Al ³⁺ , Ni ³⁺ , Co ³⁺ , Fe ³⁺ , and Mn ³ At least one of ⁺ , Cr ³⁺ , V ³⁺ , Ti ³⁺ , In ³⁺ , Ga ³⁺ , Sn ⁴⁺ , Ti ⁴⁺ and Zr ⁴⁺ ; the water-soluble salt of the first low-valent cation and the anion in the water-soluble salt of the hypervalent cation are selected from any one of Cl ^- , SO ₄ ^2- , CO ₃ ^2- , NO ₃ ^- ; S3. Reacting the second mixture at 80° C. to 300° C. for 4 h to 100 h, separating the reaction product from solid and liquid, and washing and drying the obtained solid phase to obtain the magnesium-based composite metal hydroxide. 2. preparation method according to claim 1, is characterized in that, in the described first mixture, the ratio of the total amount of substance of magnesium ion, the first low-valent cation and the amount of substance of the water-soluble salt of described high-valent cation 1:2-6:1; the ratio of the amount of magnesium ions to the first low-valent cations in the first mixture is 1:1-1000:1. 3. The preparation method according to claim 1, characterized in that, in the step S1, further comprising: adding the hydroxide of the second low-valent cation into the first mixture. 4. preparation method according to claim 3, is characterized in that, the water-soluble salt of magnesium ion, the first low-valent cation, the total substance amount of the second low-valent cation and the described high-valent cation in the first mixture The ratio of the amount of substance is 1:2～6:1; the ratio of the total amount of substance of magnesium ion and second low-valent cation in the first mixture to the amount of substance of the first low-valent cation is 1 :1～1000:1. 5. The preparation method according to claim 3, characterized in that, the second low-valent cation is the same as the low-valent main laminate cation. 6. The preparation method according to claim 5, wherein the second low-valent cation is selected from Li ⁺ , Mg ²⁺ , Zn ^{2 +} , Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ^{2 +} , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ and Be ²⁺ .