CN103288108A - Method for preparing hydrotalcite compound using brucite - Google Patents

Abstract

The invention relates to the technical field of preparation of hydrotalcite compounds, in particular to a method for preparing hydrotalcite compounds by using brucite as a magnesium source. The treatment process is to feed brucite, aluminum source, alkali source and water in a certain proportion, and also choose to add a certain amount of other divalent and trivalent metal hydroxides, oxides or salts according to requirements. Within the temperature range, react in a hydrothermal reactor for 1-20 hours, and finally wash, filter and dry to obtain hydrotalcite compounds. The method provided by the invention adopts cheap brucite as a raw material, and all the raw materials do not need to be pretreated, and are directly added at the same time without any sequence, and the target product is synthesized in one step. The invention simplifies the production process, greatly reduces the production cost of hydrotalcite compounds, and provides the possibility for large-scale industrial production of cheap hydrotalcite compounds.

Description

A kind of method adopting brucite to prepare hydrotalcite compound

technical field

The invention relates to the technical field of preparation of hydrotalcite compounds, in particular to a method for preparing hydrotalcite compounds by using brucite as a magnesium source.

Background technique

Hydrotalcite-like compounds (LDHs) are a class of anionic layered compounds with broad application prospects, mainly including hydrotalcite (HT), hydrotalcite-like (HTLC for short) and their intercalation chemical product pillared hydrotalcite (Pillared LDH ). Its chemical composition can be expressed as [MⅡ _1-x MⅢ _x (OH) ₂ ] _x + (A ^n- ) _x/n mH ₂ O , where MⅡ is Mg ²⁺ , Ni ²⁺ , Co ²⁺ , Zn ^{2 +} , Cu ²⁺ and other divalent metal cations; MⅢ is Al ³⁺ , Cr ³⁺ , Fe ³⁺ , Sc ³⁺ and other trivalent metal cations; ^{An -} is an anion, such as CO ₃ ^2- , NO ₃ ^- , Cl ^- , OH ^- , SO ₄ ^2- , PO ₄ ^3- , C ₆ H ₄ (COO) ₂ ^2- and other inorganic and organic ions and complex ions. The typical molecular formula of hydrotalcite is Mg ₆ A _l2 (OH) ₁₆ CO ₃ 4H ₂ O, which has a regular octahedral structure similar to brucite [Mg(OH) ₂ ]. Adjacent octahedrons form unit layers by sharing edges , the Mg ²⁺ located on the layer can be isomorphically substituted by Al ³⁺ with similar radius within a certain range, leading to the accumulation of positive charges on the hydroxyl layer, and these skeleton positive charges are balanced by the anion CO ₃ ^2- located in the interlayer, making The entire structure is electrically neutral. Between the layers, some water molecules exist in a crystalline state, which can be removed without destroying the layer-column structure. The special chemical structure and crystal structure endow hydrotalcite with a series of excellent properties, such as the controllability of the chemical composition of the laminates, the exchangeability of interlayer anions, the controllability of the grain size distribution, etc., making it widely used in In the fields of rubber, plastics and catalysis, other metal ions can be properly introduced on the basis of magnesium aluminum hydrotalcite to improve its corresponding performance according to the application requirements.

At present, most of the hydrotalcite compounds are synthesized by the co-precipitation method, and the selected magnesium and aluminum sources are soluble salts. This method has many by-products, low production efficiency, and high cost; some people use magnesium oxide and aluminum hydroxide as raw materials. One-step hydrothermal synthesis of magnesium aluminum hydrotalcite, the magnesia used in this method is active magnesia, the price is on the high side; also some people choose brucite as magnesium source, adopt mechanical method to synthesize magnesium aluminum hydrotalcite, this method requires that the raw materials must be Pretreatment, that is, firstly, the magnesium and aluminum source materials should be mixed and ground, and then the ground mixed material should be hydrothermally crystallized. This method has the disadvantages of long process flow and many parameters to be controlled. production is difficult.

Contents of the invention

Aiming at the deficiencies of the prior art, the object of the present invention is to provide a method for hydrothermally synthesizing hydrotalcite-like compounds using brucite as a magnesium source. All raw materials do not need to be pretreated, and are directly added at the same time, without order, and can be synthesized in one step. target product. The method simplifies the hydrotalcite production process, shortens the production period and significantly reduces the production cost.

The method for preparing hydrotalcite compounds using brucite as magnesium source of the present invention comprises the following steps: feeding brucite, aluminum source, alkali source and water in a certain ratio, wherein Mg ²⁺ /Al ³⁺ moles The ratio is 1-6:1, and other divalent and trivalent metal hydroxides, oxides or salts with a molar ratio of 0.01-0.5 times that of Al ³⁺ can also be selectively added as needed, at a temperature of 100-250°C Within the range, react in a hydrothermal reactor for 1-20 hours, and finally wash, filter and dry to obtain hydrotalcite compounds.

According to a further feature of the preparation method of the present invention, the magnesium source is brucite.

According to a further feature of the preparation method of the present invention, the aluminum source is selected from: gibbsite, aluminum hydroxide, aluminum oxide, sodium aluminate, sodium metaaluminate, aluminum nitrate, aluminum sulfate, chloride at least one of aluminum.

According to a further feature of the preparation method of the present invention, the other divalent and trivalent metal ions are Ca ²⁺ , Zn ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Ni ²⁺ , Ni ³⁺ , Cu ²⁺ , Mn ³⁺ , Cr ³⁺ , Cd ²⁺ , Ti ³⁺ , La ³⁺ , Ce ³⁺ , Pr ³⁺ , Nd ³⁺ , Pm ³⁺ , Sm ³⁺ , Eu ³⁺ , at least one of Gd ³⁺ .

According to a further feature of the preparation method of the present invention, the alkali source is at least one of sodium hydroxide, potassium hydroxide, ammonia water, urea, and the corresponding ammonium salt, sodium salt, and potassium salt whose anion is ^An- , or compounds that can react to generate sodium hydroxide, potassium hydroxide, and ammonia water during the synthesis process.

According to a further feature of the preparation method of the present invention, ^the anion ^An- is CO ₃ ^2- , HCO ₃ ^- , SO ₄ ^2- , HSO ₄ - , SO ₃ ^2- , NO ₃ ^- , PO ₄ ^{3 -} , HPO ₄ ^2- , H ₂ PO ₄ ^- , HPO ₃ ^2- , H ₂ PO ₂ ^- , BO ₃ ^3- , HB ₄ O ₇ - , B ₄ O ₇ ^2- , B _{5 O 8} ^{- ,} BO ₃ At least one of ^3- , P ₂ W ₁₈ O ₆₀ ^6- , Mo ₇ O ₂₄ ^6- , and P ₂ Mo ₁₈ O ₆₀ ^6- .

According to a further feature of the preparation method of the present invention, the method is a hydrothermal synthesis method, the reaction temperature is 100-250°C, and the reaction time is 1-20 hours. All materials do not need to be pretreated, and are directly added at the same time, without sequence According to the order, the target product can be synthesized in one step.

The method for synthesizing hydrotalcite compounds in one step using brucite as the magnesium source of the present invention has the advantages of: using brucite as the magnesium source greatly reduces production costs; adopting the hydrothermal synthesis method, all raw materials do not need to be pretreated , directly added at the same time, in no particular order, to synthesize the target product in one step. The method provided by the invention significantly reduces the production cost of the hydrotalcite, simplifies the production process, shortens the production period, and provides the possibility for large-scale industrial production of cheap hydrotalcite compounds.

Description of drawings

FIG. 1 is an X-ray diffraction (XRD) pattern of the hydrotalcite synthesized in Example 1.

Fig. 2 is the infrared spectrum (FTIR) figure of the hydrotalcite synthesized in Example 1.

3 is a scanning electron microscope (SEM) image of the hydrotalcite synthesized in Example 1.

Detailed ways

The present invention will be described and illustrated in more detail below in conjunction with specific implementation examples.

The brucite that adopts in the embodiment of the present invention is produced in Yingkou, Liaoning, and its chemical composition is as shown in table 1:

Table 1: Chemical composition list of brucite

Element MgO CaO SiO _{2 Fe2O3 _} content(%) 65 1.2 1.0 0.2

Those skilled in the art know that the content of brucite from different places of origin is usually between 60-69%, which can meet the requirements of the technology of the present invention. Therefore, brucite of any product can also be used. To implement the technical scheme of the present invention.

Example 1

Weigh 2.48g brucite, 3.28g sodium metaaluminate, 4.42g sodium carbonate and a certain amount of water in a hydrothermal reaction kettle, stir well, keep the temperature at 120°C for 16h, after cooling, suction filter, wash, 90°C Dry for 12 hours to obtain magnesium aluminum hydrotalcite.

The determination of the product obtained in the preparation of embodiment 1. As shown in the XRD pattern of Figure 1, the diffraction peaks of the product are consistent with those of the card JCPDS22-700, and no other heterogeneous diffraction peaks appear, indicating that the synthesized product is magnesium aluminum hydrotalcite with uniform structure and high crystallinity. As shown in the FTIR diagram of Figure 2, there are hydroxyl ^groups and CO ₃ ^2- in the product, the vibrational absorption peak of hydroxyl is at the wave number of 3454 cm ^-1 , and the vibrational absorption peak of CO ₃ ^2- at the wave number of 1369 cm -1 is 451 cm ^-1 It is the characteristic absorption peak of hydrotalcite skeleton vibration. As shown in the SEM image of Figure 3, the synthesized hydrotalcite is flake-like. According to the above determination results, it has been successfully synthesized magnesium aluminum hydrotalcite.

Example 2

Weigh 5.54g of brucite, 5.63g of aluminum nitrate, 0.84g of sodium bicarbonate, 4ml of ammonia water, put a certain amount of water in a hydrothermal reaction kettle, stir well, keep the temperature at 200°C for 1 hour, suction filter and wash after cooling, Dry at 90°C for 12 hours to obtain magnesium aluminum hydrotalcite.

Example 3

Weigh 3.69g brucite, 1.02g alumina, 0.99g zinc hydroxide, 0.90g urea, 1.12g potassium hydroxide and put a certain amount of water in a hydrothermal reaction kettle, stir well, keep the temperature at 180°C for 4h, and cool After suction filtration, washing, and drying at 90°C for 12 hours, magnesium-aluminum-zinc hydrotalcite is obtained.

Example 4

Weigh 7.38g of brucite, 2.37g of aluminum hydroxide, 0.05g of lanthanum oxide, 3.18g of sodium carbonate, 0.4g of sodium hydroxide and a certain amount of water in a hydrothermal reaction kettle, stir well, and keep the temperature at 110°C for 24h , cooled, filtered, washed, and dried at 90°C for 12 hours to obtain magnesium-aluminum-zinc hydrotalcite.

Example 5

Weigh 2.46g brucite, 2.67g aluminum chloride, 1.15g ammonium dihydrogen phosphate, 0.8g sodium hydroxide and a certain amount of water in a hydrothermal reaction kettle, stir well, keep the temperature at 250°C for 12h, after cooling Suction filtration, washing, and drying at 90°C for 12 hours to obtain magnesium aluminum hydrotalcite with interlayer anion as phosphate.

Example 6

Weigh 3.69g of brucite, 3.42g of aluminum sulfate, 5.96g of K ₆ Mo ₇ O ₂₄ , 1.5ml of 28% potassium hydroxide and a certain amount of water, add them into the reaction kettle, stir well, and place at 160°C Constant temperature for 6 hours, after cooling, filter with suction, wash, and dry at 90°C for 12 hours to obtain Mo ₇ O ₂₄ ^6- pillared hydrotalcite.

The above-mentioned embodiments are only used to illustrate the content of the present invention, and do not include the entire scope of the technical solutions of the present invention. Those skilled in the art should know that the special chemical structure and crystal structure of hydrotalcite endow it with a series of excellent properties, such as the controllability of the chemical composition of the laminates and the exchangeability of anions between layers. As long as the metal cation has an appropriate ionic radius and charge number, that is, MⅡ and MⅢ, which are not much different from the ionic radius of Mg ²⁺ , can be accommodated in octahedral coordination centers formed by OH ^- close packing, forming stable magnesium hydroxide-like A series of binary, ternary and even quaternary LDHs can be synthesized by combining different metal cations. Other divalent and trivalent metal ions described in the present invention can be selected from Ca ²⁺ , Zn ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Ni ²⁺ , Ni ³⁺ , Cu ²⁺ , Mn ³⁺ , Cr ³⁺ , Cd ²⁺ , Ti ³⁺ , La ³⁺ , Ce ³⁺ , Pr ³⁺ , Nd ³⁺ , Pm ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ At least one; using the interlayer anion exchangeability of hydrotalcite, LDHs of interlayer anion A ^n- can be formed in different ion solution atmospheres, and the anion A ^n- can be selected from: CO ₃ ^2- , HCO ₃ ^- , SO ₄ ^2- , HSO ₄ ^- , SO ₃ ^2- , HSO ₃ ^- , NO ₃ ^- , PO ₄ ^3- , HPO ₄ ^2- , H ₂ PO ₄ ^- , HPO ₃ ^2- , H ₂ PO ₂ ^- , BO ₃ ^3- , HB ₄ O ₇ ^- , B ₄ O ₇ ^2- , B ₅ O ₈ ^- , P ₂ W ₁₈ O ₆₀ ^6- , Mo ₇ O ₂₄ ^6- or P ₂ Mo ₁₈ O ₆₀ ^6- at least one of .

Claims (6)

1. method that adopts brucite to prepare hydrotalcite-based compound is characterized in that may further comprise the steps:

, brucite, aluminium source, alkali source and water made up by a certain percentage feed intake as the magnesium source with brucite, wherein Mg ²⁺/ Al ³⁺Mol ratio is 1-6:1, and in 100-250 ℃ of temperature range, reaction is 1-20 hour in hydrothermal reaction kettle, finally by washing, filtration, drying, namely obtains hydrotalcite-based compound.

2. preparation method according to claim 1 is characterized in that: when combination feeds intake, can add Al ³⁺Mole number 0.01-0.5 doubly except aluminium, magnesium other two, oxyhydroxide, oxide compound or the salt of trivalent metal.

3. preparation method according to claim 1 is characterized in that, described aluminium source is to be selected from: gibbsite, aluminium hydroxide, aluminum oxide, sodium aluminate, sodium metaaluminate, aluminum nitrate, Tai-Ace S 150 or aluminum chloride.

4. preparation method according to claim 1 is characterized in that, described except aluminium, magnesium other two, trivalent metal ion is to be selected from: Ca ²⁺, Zn ²⁺, Fe ²⁺, Fe ³⁺, Co ²⁺, Co ³⁺, Ni ²⁺, Ni ³⁺, Cu ²⁺, Mn ³⁺, Cr ³⁺, Cd ²⁺, Ti ³⁺, La ³⁺, Ce ³⁺, Pr ³⁺, Nd ³⁺, Pm ³⁺, Sm ³⁺, Eu ³⁺Or Gd ³⁺

5. preparation method according to claim 1 is characterized in that, described alkali source is to be selected from: sodium hydroxide, potassium hydroxide, ammoniacal liquor, urea, or negatively charged ion is A ^N-Corresponding sodium salt, sylvite, ammonium salt perhaps can react the compound that generates sodium hydroxide, potassium hydroxide, ammoniacal liquor in building-up process.

6. preparation method according to claim 5 is characterized in that, described negatively charged ion is to be selected from: CO ₃ ^2-, HCO ₃ ^-, SO ₄ ^2-, HSO ₄ ^-, SO ₃ ^2-, HSO ₃ ^-, NO ₃ ^-, PO ₄ ^3-, HPO ₄ ^2-, H ₂PO ₄ ^-, HPO ₃ ^2-, H ₂PO ₂ ^-, BO ₃ ^3-, HB ₄O ₇ ^-, B ₄O ₇ ^2-, B ₅O ₈ ^-, P ₂W ₁₈O ₆₀ ^6-, Mo ₇O ₂₄ ^6-Or P ₂Mo ₁₈O ₆₀ ^6-

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