CN110467226B

CN110467226B - A kind of preparation method of iron-based hydrotalcite

Info

Publication number: CN110467226B
Application number: CN201810443841.8A
Authority: CN
Inventors: 李大鹏; 黄传峰; 蒋中山
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-05-10
Filing date: 2018-05-10
Publication date: 2022-02-22
Anticipated expiration: 2038-05-10
Also published as: CN110467226A

Abstract

The invention discloses a preparation method of iron-based hydrotalcite, which directly takes ferrous salt as raw material and takes the ferrous salt and Mg²⁺、Zn²⁺、Cu²⁺、Ni²⁺、Co²⁺、Ca²⁺、Mn²⁺And oxidizing the soluble salt by air or oxygen under the condition that the pH value is 5.5-10.5 to obtain the iron-based hydrotalcite. The invention has simple preparation process, mild reaction condition and Fe³⁺The raw material sources are wide and cheap, the obtained iron-based hydrotalcite has high crystallization degree and uniform crystal phase and grain size, the amount of other metals in the hydrotalcite laminate except the metal Fe in the hydrotalcite prepared by the method can be much lower than that of the hydrotalcite prepared by the traditional method, and the Fe prepared by the traditional method³⁺In the hydrotalcite-based compound, divalent metal raw materials (Ni, Co, Cu, Zn and the like) and Fe³⁺The metal molar ratio of the raw materials is generally more than 2, so that the hydrotalcite can be synthesized, and the method for synthesizing the hydrotalcite can reduce the raw material ratio to 0.1, and can be used for synthesizing the hydrotalcite doped with other positive divalent metal elements at a low molar ratio.

Description

Preparation method of iron-based hydrotalcite

Technical Field

The invention relates to a preparation method of iron-based hydrotalcite.

Background

Hydrotalcite is Layered Double Hydroxide (LDHs), and is a material with wide application value. Since the first preparation of hydrotalcite by chemical means in 1942, the development and utilization of hydrotalcite materials is of increasing interest to today's world scientists. The chemical composition is as follows: [ M ] A²⁺ _1-xM³⁺ _x(OH)₂]^x+(A^n-)_x/n·mH₂O, where M is a cation on the lamina, common cations that can enter the lamina are divalent metals: cu²⁺、Mg²⁺、Ni²⁺、Co²⁺、Fe²⁺、Zn²⁺、Ca²⁺、Mn²⁺、Pt²⁺Etc.; trivalent metal: al (Al)³⁺、Fe³⁺、Cr³⁺Etc. each of the plate layers is made of octahedra composed of multiple cations and oxygen atoms through common angle and common prismForming an ordered and uniform planar structure; a is an anion between the laminae, common anions are: OH group^-、SO₄ ^2-、CO₃ ^2-、Cl^-、NO₃ ^-And the like. After the 90 s of the last century, the structural characteristics of hydrotalcite were revealed, due to its composition M²⁺、M³⁺And the size is adjustable, and the hydrotalcite has wide application in a plurality of fields such as catalysts, catalyst carriers, flame retardants, insecticides, sewage treatment agents, electrorheological control agents, medicines, medicine carriers and the like, and has higher economic value.

The iron-based hydrotalcite is an important component, and the cheap raw material source of the iron-based hydrotalcite enables the hydrotalcite to have wide application value. At present, the iron-based hydrotalcite is generally prepared by mixing M²⁺Salt solution with Fe³⁺The salt solution is synthesized by coprecipitation method, hydrothermal synthesis method, nucleation crystallization isolation method, microwave crystallization method, etc. Patent CN 103359792A discloses a preparation method of MgFe binary hydrotalcite²⁺With Fe³⁺The MgFe binary hydrotalcite with higher Fe content is synthesized by the coprecipitation method of the two ionic salt solutions. Patent CN 103864155A discloses a preparation method of high-crystallinity iron-based hydrotalcite-like compound, which is prepared by mixing divalent metal ions with Fe³⁺Iron-based hydrotalcite with high crystallization is hydrothermally synthesized by a urea method. More patents related to hydrotalcite synthesis are all to synthesize target divalent and trivalent metal ion salt solutions by a traditional coprecipitation method, a hydrothermal synthesis method, a nucleation-crystallization isolation method and the like. The class passing Fe³⁺The hydrotalcite crystallization condition of the synthesis method using salt as raw material is harsh, and Fe³⁺The salt cost is high, and the synthesis method is complex.

Disclosure of Invention

The invention aims to provide a preparation method of iron-based hydrotalcite, which has the advantages of simple preparation process, mild conditions, wide raw material sources, high crystallization degree of the obtained hydrotalcite and uniform particle size.

Aiming at the purposes, the technical scheme adopted by the invention is as follows: mixing ferrous salt with M²⁺Soluble salt of (A), M^e+Dissolving the soluble salt in water, and stirring at 10-90 DEG CReacting for 0.5-10 hours, introducing air or oxygen into the reaction liquid in the reaction process, and adding an alkali solution to control the pH of the reaction liquid to be 5.5-10.5; after the reaction is finished, dehydrating and drying to obtain the iron-based hydrotalcite with the chemical composition of [ (M)²⁺)_1-x(Fe³⁺M^e+)_x(OH)₂]^x+[(A^n-)_x/n·mH₂O]^x-Wherein M is²⁺Is Mg²⁺、Fe²⁺、Zn²⁺、Cu²⁺、Ni² ⁺、Co²⁺、Ca²⁺、Mn²⁺More than one of (A), (B), (C), (M)^e+Is Al³⁺、Co³⁺、Cr³⁺、Ti³⁺、Mo ⁵⁺0 to 3 kinds of A^n-Is OH^-、SO₄ ^2-、NO₃ ^-、CO₃ ^2-、Cl^-1 to 3 of them, x is (Fe)³⁺+M^e+) And (M)²⁺+Fe³⁺+M^e+) Wherein x is not less than 0.2 and not more than 0.33, m is the amount of crystal water, and m is 0-10.

The preparation method of the iron-based hydrotalcite is preferably as follows: mixing ferrous salt with M²⁺Soluble salt of (A), M^e+Dissolving the soluble salt in water, stirring and reacting for 1.5-8 hours at 25-50 ℃, and introducing air or oxygen into the reaction liquid and adding an alkali solution to control the pH of the reaction liquid to be 6.0-9.0 in the reaction process.

The chemical composition of the iron-based hydrotalcite may be [ (M)²⁺Fe²⁺)_1-x(Fe³⁺M^e+)_x(OH)₂]^x+[(A^n-)_x/n·mH₂O]^x-Wherein M is²⁺Is Mg²⁺、Zn²⁺、Cu²⁺、Ni²⁺、Co²⁺、Ca²⁺、Mn²⁺1 to 3 kinds of (M)^e+Is Al³⁺、Co³⁺、Cr³⁺、Ti³⁺、Mo ⁵⁺0 to 3 kinds of A^n-Is OH^-、SO₄ ^2-、NO₃ ^-、CO₃ ^2-、Cl^-1 to 3 of them, x is (Fe)³⁺+M^e+) And (M)²⁺+Fe³⁺+M^e++Fe²⁺) Wherein x is not less than 0.2 and not more than 0.33, m is the amount of crystal water, and m is 0-10.

In the preparation method of the iron-based hydrotalcite, the ferrous salt and M^e+Total molar amount of soluble salt and M²⁺The molar ratio of the soluble salt is 1: 0.1-4.

The above alkaline solution is ammonia water, NaOH aqueous solution, KOH aqueous solution, Na₂CO₃Aqueous solution, NaHCO₃Aqueous solution, urea aqueous solution, or a mixture of two or more thereof.

M above²⁺The soluble salt of (A) is sulfate, nitrate or chloride; the ferrous salt being Fe²⁺Sulfate or chloride salts of (a); m^e+In soluble salt of (3) Al³⁺、Cr³⁺And Ti³⁺The soluble salt is sulfate, nitrate or chloride, Co³⁺And Mo⁵⁺The soluble salt of (a) is a chloride salt.

The invention has the following beneficial effects:

1. the invention takes ferrous salt as raw material to prepare Fe by process oxidation under mild condition³⁺Hydrotalcite-based compounds. The method has the advantages of simple preparation process, mild reaction conditions, wide and cheap raw material sources, and the obtained Fe³⁺The hydrotalcite-based material has high crystallization degree and uniform crystal phase and grain size.

2. The hydrotalcite prepared by the method of the invention has much lower amount of other metals on hydrotalcite laminate than the traditional method except the metal Fe³⁺In the base hydrotalcite, divalent metal raw materials (Ni, Co, Cu, Zn and the like) and Fe³⁺The hydrotalcite synthesized by the method can reduce the raw material ratio to 0.1, obviously reduce the usage amount of other divalent metal element raw materials, and can be used for synthesizing hydrotalcite doped with other divalent metal elements with low molar ratio.

Drawings

FIG. 1 is an XRD pattern of NiFe hydrotalcite prepared in examples 1 to 5.

FIG. 2 is an XRD pattern of ZnCrFe hydrotalcite, NiFeAl hydrotalcite, CuMgCaFe hydrotalcite, MgCoFe hydrotalcite, and ZnCoFeMo hydrotalcite prepared in examples 6 to 10.

FIG. 3 is an SEM photograph of the NiFe hydrotalcite prepared in example 1.

FIG. 4 is an SEM photograph of the NiFe hydrotalcite prepared in example 2.

FIG. 5 is an SEM photograph of the NiFe hydrotalcite prepared in example 3.

FIG. 6 is an SEM photograph of the NiFe hydrotalcite prepared in example 4.

FIG. 7 is an SEM photograph of the NiFe hydrotalcite prepared in example 5.

Fig. 8 is an SEM photograph of the ZnCrFe hydrotalcite prepared in example 6.

Fig. 9 is an SEM photograph of NiFeAl hydrotalcite prepared in example 7.

Fig. 10 is an SEM photograph of the cumgcfe hydrotalcite prepared in example 8.

Fig. 11 is an SEM photograph of the mgcfe hydrotalcite prepared in example 9.

Figure 12 is an SEM photograph of the ZnCoFeMo hydrotalcite prepared in example 10.

Detailed Description

The invention is further illustrated with reference to the following figures and examples, but the scope of the invention is not limited to these examples.

Example 1

2.700g of nickel sulfate hexahydrate and 0.714g of ferrous sulfate heptahydrate are added to 75mL of deionized water according to the molar ratio of Ni to Fe being 4:1, and then the solution obtained is passed through at a flow rate of 1m³And h, gradually adding 1mol/L ammonia water solution while controlling the pH of the reaction solution to be 6.8-7.3, stirring and reacting for 2 hours at 40 ℃, then performing suction filtration and drying in a constant-temperature drying oven at 150 ℃ to obtain the NiFe hydrotalcite.

Example 2

In this example, according to Ni: Fe ═ 2:1, 1.350g of nickel sulfate hexahydrate and 0.714g of ferrous sulfate heptahydrate were added to 75mL of deionized water, and other steps were the same as in example 1, thereby obtaining NiFe hydrotalcite.

Example 3

In this example, according to Ni: Fe ═ 1:1, 0.675g of nickel sulfate hexahydrate and 0.714g of ferrous sulfate heptahydrate were added to 75mL of deionized water, and other steps were the same as in example 1, thereby obtaining NiFe hydrotalcite.

Example 4

In this example, 0.338g of nickel sulfate hexahydrate and 0.714g of ferrous sulfate heptahydrate were added to 75mL of deionized water in a ratio of Ni to Fe of 0.5:1, and other steps were performed in the same manner as in example 1 to obtain NiFe hydrotalcite.

Example 5

In this example, 0.135g of nickel sulfate hexahydrate and 0.714g of ferrous sulfate heptahydrate were added to 75mL of deionized water in a ratio of Ni to Fe of 0.2:1, and other steps were performed in the same manner as in example 1 to obtain NiFe hydrotalcite.

Example 6

2g of zinc nitrate hexahydrate, 1.32g of chromium sulfate hexahydrate and 1.87g of ferrous sulfate heptahydrate were added to 67mL of deionized water in a molar ratio of Zn to Cr to Fe of 1:0.5:1, and then the resulting solution was passed through a flow of 0.5m³Air/h, and simultaneously gradually adding 0.25mol/L aqueous solution of sodium hydroxide to control the pH value of the reaction solution to be 6.5, stirring and reacting for 6 hours at 35 ℃, then carrying out suction filtration and drying in a constant-temperature drying box at 100 ℃ to obtain the ZnCrFe hydrotalcite.

Example 7

According to the molar ratio of Ni, Fe and Al being 2:1:1, 1.50g of nickel nitrate, 1.14g of ferrous sulfate heptahydrate and 1.54g of aluminum nitrate nonahydrate are added into 80mL of deionized water, and then a flow of 0.5m is introduced into the obtained solution³Air/h, and simultaneously gradually adding 0.25mol/L potassium hydroxide aqueous solution and 0.25mol/L sodium carbonate aqueous solution to control the pH of the reaction solution to be 7.0, stirring and reacting at 50 ℃ for 3 hours, and then carrying out suction filtration and drying in a constant-temperature drying oven at 100 ℃ to obtain the NiFeAl hydrotalcite.

Example 8

0.80g of copper sulfate, 0.44g of magnesium nitrate, 0.33g of calcium nitrate and 0.64g of ferrous chloride were added to 100mL of deionized water in a molar ratio of Cu to Mg to Ca to Fe to 1:0.6:0.4:1, and then the resulting solution was passed through a flow rate of 0.5m³Air/h, gradually adding 1mol/L ammonia water solution to control pH of the reaction solution to 8.0, and reacting at 25 deg.C for 3 hr with stirringAnd then carrying out suction filtration and drying in a constant-temperature drying oven at 100 ℃ to obtain CuMgCaFe hydrotalcite.

Example 9

1.48g of magnesium nitrate, 0.89g of hexaammine cobalt trichloride and 0.93g of ferrous sulfate heptahydrate were added to 100mL of deionized water in a molar ratio of Mg to Co to Fe of 3:1:1, and then the resulting solution was passed through a flow of 0.5m³Air/h, and simultaneously gradually adding 1mol/L ammonia water solution and 0.25mol/L sodium bicarbonate water solution to control the pH of the reaction solution to be 8.0, stirring and reacting at 40 ℃ for 1.5 hours, then carrying out suction filtration and drying in a constant-temperature drying oven at 100 ℃ to obtain the MgCoFe hydrotalcite.

Example 10

0.60g of zinc nitrate hexahydrate, 0.19g of cobalt sulfate heptahydrate, 0.09g of ferrous sulfate heptahydrate and 0.18g of molybdenum pentachloride were added to 80mL of deionized water in a molar ratio of Zn to Co to Fe to Mo to 3:1:0.5:1, and then the resulting solution was passed through a flow of 0.5m³Air/h, and simultaneously gradually adding 0.5mol/L ammonia water solution to control the pH value of the reaction solution to be 8.5, stirring and reacting for 8 hours at 30 ℃, then carrying out suction filtration and drying in a constant-temperature drying box at 100 ℃ to obtain the ZnCoFeMo hydrotalcite.

XRD and SEM characterization of the hydrotalcites obtained in examples 1 to 10 are shown in figures 1 to 4. From the sharp and symmetrical diffraction peaks in fig. 1 and 2, the characteristic diffraction peaks corresponding to the hydrotalcite (003), (006), (012), (015), (018), (110) and (113) crystal planes, respectively, are shown. As can be seen from FIGS. 3 to 12, the obtained hydrotalcite has uniform size of the hydrotalcite sheet layer, uniform distribution and high crystallinity.

Claims

1. a preparation method of iron-based hydrotalcite, is characterized in that: the soluble salt of ferrous salt and M ²⁺ , the soluble salt of ^Me+ are dissolved in water, 10～90 ℃ of stirring reactions 0.5～10 hours, reaction process Passing air or oxygen into the reaction solution and adding an alkaline solution to control the pH of the reaction solution to be 5.5-10.5; dehydrating and drying in a constant temperature drying oven at 100-150°C after the reaction to obtain iron-based hydrotalcite, its chemical composition is (M ²⁺ Fe ²⁺ ) _1-x (Fe ^{3+ Me} ⁺ ) _x (OH) ₂ ] ^x+ [(A ^n- ) _x/n ·mH ₂ O] ^x- , where M ²⁺ is Mg One or more of ²⁺ , Zn ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Ca ²⁺ , Mn ²⁺ , ^Me+ is Al ³⁺ , Co ³⁺ , Cr ³⁺ , Ti ³⁺ , 0 to 3 kinds of Mo ⁵⁺ , ^An- is 1 to 3 kinds of OH ^- , SO ₄ ^2- , NO ₃ ^- , CO ₃ ^2- , Cl ^- , x is (Fe ³⁺ + ^Me+ ) and ( M ²⁺ + Fe ³⁺ +M ^e+ +Fe ²⁺ ) molar ratio, 0.2≤x≤0.33, m is the amount of crystal water, m=0～10.

2. the preparation method of iron-based hydrotalcite according to claim 1, is characterized in that: the soluble salt of ferrous salt and M ²⁺ , the soluble salt of ^Me+ are dissolved in water, and 25～50 ℃ of stirring reaction 1.5～ For 8 hours, during the reaction, air or oxygen is introduced into the reaction solution and an alkali solution is added to control the pH of the reaction solution to be 6.0-9.0.

3. the preparation method of iron-based hydrotalcite according to claim 1, is characterized in that: the mol ratio of the total molar weight of the soluble salt of described ferrous salt and ^Me+ and the soluble salt of M ²⁺ is 1:0.1 ~4.

4. the preparation method of iron-based hydrotalcite according to claim 1 and 2, is characterized in that: described alkaline solution is ammonia water, NaOH aqueous solution, KOH aqueous solution, Na ₂ CO ₃ aqueous solution, NaHCO ₃ aqueous solution, urea aqueous solution in any One or more mixtures.

5. the preparation method of iron-based hydrotalcite according to claim 1, is characterized in that: the soluble salt of described M ²⁺ is sulfate, nitrate or chloride; Ferrous salt is the sulfate of Fe ²⁺ or Chloride salts; the soluble salts of Al ³⁺ , Cr ³⁺ and Ti ³⁺ among the soluble salts of Me ⁺ are sulfate, nitrate or chloride salts, and the soluble salts of Co ³⁺ and Mo ⁵⁺ are chloride salts.