CN1796283A - Method and technique for preparing Nano type sol of polyaluminium chloride in high purity - Google Patents

Abstract

The invention relates to a preparation method and process of high-purity nano-type polyaluminum chloride sol. Activated aluminum hydroxide and industrial hydrochloric acid are used as raw materials, and a two-stage reverse dissolution process is adopted to prepare a polyaluminum chloride solution with a degree of alkalinity greater than 50%, and then use high-purity calcium aluminate as an alkalizing agent to adjust the alkalinity of the solution to more than 70%. The process can realize the complete dissolution of aluminum hydroxide raw materials under normal pressure and relatively low temperature, and the product has high purity, and the sum of the morphological content of Keggin structure nano-Al ₁₃ and Al ₃₀ in the prepared polyaluminum chloride sol is greater than 70%. The degree of oxidation is 70-85%, and the total aluminum concentration is 10-19% (calculated as Al ₂ O ₃ ). The products are widely used as raw materials for modern fine chemical adhesives, neutral paper sizing agents, intermediates or additives for modern pharmaceuticals and cosmetics, coupling agents and catalysts for chemical production, and flocculants for water treatment. It has more potential application value in the fields of inorganic nanocomposite materials and inorganic membrane materials that have emerged in recent years.

Description

A kind of preparation method and technology of high-purity nano-type polyaluminum chloride sol

technical field

The present invention relates to the preparation method and technology of inorganic polymer polyaluminum chloride sol, especially the preparation of a kind of high-purity nano-type polyaluminum chloride sol with high degree of alkalization and high morphological content of nano Keggin structure Al ₁₃ and Al ₃₀ The method and process, and the products are widely used as raw materials for fine chemical adhesives, neutral papermaking sizing agents, intermediates or additives for pharmaceuticals and cosmetics, coupling agents and catalysts for chemical production, and flocculants for water treatment. In addition, it has more potential application value in the fields of inorganic nanocomposite materials and inorganic membrane materials that have emerged in recent years.

Background technique

Polyaluminum chloride sol is a sol product obtained by hydrolysis and polymerization of high-concentration aluminum chloride solution (>2mol/L) under artificial forced hydrolysis reaction conditions. High-concentration, high-purity polyaluminum chloride sol has been widely used in recent years as raw materials for fine chemical adhesives, neutral paper-making sizing agents, pharmaceutical and cosmetic intermediates or additives, coupling agents and catalyst raw materials in chemical production processes , and water treatment flocculants. In particular, high-purity nano-polyaluminum chloride sol has potential application value in the fields of inorganic nanocomposite materials and inorganic membrane materials that have emerged in recent years.

In the 20th century, limited by the precision of nuclear magnetic resonance spectrometer resolution ( ²⁷ Al NMR), it was impossible to decipher the sol form in high-concentration polyaluminum solutions. It has always been believed that the hydrolytic polymerization form of Al ₁₃ with Keggin structure is the advantage in polyaluminum chloride solutions. Morphology, ignoring the importance of the shape of the sol formed by the aggregation of Al ₁₃ , thus limiting the application range of high-concentration aluminum sol products.

At the beginning of the 21st century, with the rapid development of modern industry, high-concentration polyaluminum chloride solution has been used more and more in the fields of modern fine chemicals, papermaking, medicine, composite materials, and inorganic membranes. At the same time, with the improvement of the resolution accuracy of the nuclear magnetic resonance spectrometer, the study confirmed that the Al ₃₀ form and its aggregation form are the dominant forms in the high-concentration polymerized aluminum solution, which is the result of further polymerization and transformation of the Al ₁₃ form of the Keggin structure under high temperature conditions. . The form of Al ₃₀ has 18 positive charges, and the unit particle size is about 2.0nm. It has higher charge neutralization ability and morphological stability than Al ₁₃ , and its content directly affects the performance of the product. Therefore, high-concentration, high-purity, and high- _Al30- form polymerized aluminum sol products are the ideal goals pursued by the production process of high-purity nano-sized polymerized aluminum sol.

The main factors affecting the content of nano-morphological Al ₁₃ and Al ₃₀ in the polymerized aluminum solution are alkalization degree, preparation temperature, alkali addition rate, etc. The optimum alkalization degree is about 75%, and the lower the preparation temperature, the more conducive to preventing Al ₁₃ and Al ₃₀ are transformed into high-polymerization forms, and adding alkali at a slow rate is beneficial to the formation of Al ₁₃ and Al ₃₀ , but too slow alkali addition rate will reduce equipment capacity and increase production costs.

At present, high-purity polyaluminum chloride sol is mainly prepared by refluxing metal aluminum with hydrochloric acid or aluminum trichloride solution for a long time at high temperature (USP3535268, USP3340205). However, due to uncontrollable reaction rate and long heating time in this production method, the The prepared polyaluminum chloride sol has high polymer content, low nano-morphology Al ₁₃ and Al ₃₀ content, and high production cost by using high-purity aluminum as raw material. Chinese patent CN1101622A reports that Al ₂ O ₃ ·H ₂ O is used as raw material to prepare polymeric aluminum sol through acidolysis and peptization of a mixture of inorganic acid, organic acid or inorganic acid and strong acidic cation exchange resin, but this preparation method The reaction time is long, and the aluminum particle size distribution of the prepared product is uneven, and the particle size distribution range is 10-350nm. Chinese patent CN1445167A reports that alumina or aluminum hydroxide or boehmite is used as aluminum source to react with hydrochloric acid or aluminum trichloride solution under high temperature and high pressure to prepare aluminum sol, but this preparation needs to be reacted under high pressure and the reaction conditions are harsh.

In addition, in the production field of high-purity polyaluminum chloride flocculants, industrial aluminum hydroxide gel is generally prepared by one-step acid-dissolving method. In order to ensure the dissolution rate of aluminum hydroxide and the alkalinity of the product, the reaction must be carried out in a high-pressure reactor. The reaction temperature is above 150°C, the reaction pressure is above 0.3MPa, and the reaction time is long, which generally takes 6-8 hours to complete. The reaction conditions are harsh, and the alkalinity of the product can only reach 45-55%. Al ₁₃ and Al The content of ₃₀ is only 20-30%.

Chinese patent CN1508292, CN1177653 have reported adopting aluminum trichloride to be electrolytic solution respectively, and aluminum plate is anode, and iron plate is cathode, and the aqueous solution of polyaluminum chloride is prepared by low-voltage, high-current electrolytic reaction, and the _Al13 content of product can reach 70 % or more, but this production method needs to consume anodic aluminum plates, the product cost is high, and it is only suitable for small-scale production applications.

The present invention proposes a high-purity nano-polymeric aluminum chloride sol preparation method and process to solve the above problems. It adopts a two-stage reverse stripping process of activated aluminum hydroxide, which can realize aluminum hydroxide under normal pressure and low temperature. High dissolution rate, and high alkalinity of the solution, avoiding the defects of the conventional hot pressure melting process, which leads to the conversion of nano-morphologies such as Al ₁₃ and Al ₃₀ to high-polymeric forms due to long heating time at high temperature. At the same time, high-purity aluminum acid is used Calcium is used as an alkalizing agent to adjust the degree of alkalinization, which meets the requirements of slow alkali addition and can effectively prevent the formation of aluminum hydroxide gel.

Contents of the invention

The purpose of the present invention is mainly to provide a preparation method and process of high-purity nano-polymer aluminum chloride sol with high alkalinity, high content of nano-morphology Al ₁₃ and Al ₃₀ , and mild preparation conditions.

The main technical content of the present invention is: under normal pressure conditions, using activated aluminum hydroxide and industrial hydrochloric acid as raw materials, adopting a two-stage reverse dissolution method to prepare a polyaluminum chloride solution with a degree of alkalinity greater than 50%, and then using high-purity aluminum Calcium acid is used as an alkalizing agent, and the alkalization degree of the solution is adjusted to more than 70%, so as to obtain a high-purity polyaluminum chloride sol with high concentration, high alkalization degree, and high Al ₁₃ and Al ₃₀ content.

All the reaction processes of the invention are carried out under normal pressure, the reaction equipment is simple and the cost is low.

The active aluminum hydroxide used in the present invention is amorphous aluminum hydroxide, which has better acid solubility than crystalline aluminum hydroxide prepared by seed separation method.

The mass concentration of the industrial hydrochloric acid used in the present invention is 15-35%.

The molar ratio of active aluminum hydroxide and hydrochloric acid in the two-stage acid-dissolving process of the present invention is 1:1.4-2.0.

The two-stage reverse stripping method described in the present invention refers to the low alkalization degree prepared in the first-stage acid-dissolving kettle and the second-stage acid-dissolving kettle by using activated aluminum hydroxide as an alkalizing agent according to the difference in acid solubility of activated aluminum hydroxide. The polyaluminum chloride solution is reacted to increase the alkalinity of the solution to over 50%, and the unreacted aluminum hydroxide is filtered and returned to the second-stage acid-dissolving kettle as a raw material to react with high-concentration hydrochloric acid.

The total dissolution rate of the two stages of aluminum hydroxide of the present invention is 100%.

The stripping temperature of the active aluminum hydroxide described in the present invention is 85-100° C., and the alkali-adjusting temperature of calcium aluminate is 80-90° C.

The high-purity calcium aluminate used in the present invention is obtained by roasting the mixture of calcium carbonate and aluminum hydroxide at about 1300-1500°C, the particle size of calcium aluminate is 30-80 mesh, and the molar ratio of calcium carbonate and aluminum hydroxide It is 1:1.0～3.0.

The dissolution time of the first and second stages of the active aluminum hydroxide of the present invention is 2-3 hours, and the alkali-adjustment time of the calcium aluminate is 1-2 hours.

The quality of the high-purity calcium aluminate (CaO·nAl ₂ O ₃ ) needed for adjusting the degree of alkalization in the present invention can be estimated according to the following formula:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 56</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 102</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 6</span>}\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}}$

Among them, B ₁ and B ₂ are the alkalinity of the solution before and after alkali adjustment respectively, C is the molar number of Al ³⁺ in the solution, n is the molar ratio of Al ₂ O ₃ and CaO in calcium aluminate, and η is the molar ratio of calcium aluminate Dissolution rate.

In the polyaluminum chloride sol prepared by the present invention, the sum of the contents of nano-morphology Al ₁₃ and Al ₃₀ is greater than 70%, the alkalization degree is 70-85%, and the total aluminum concentration is 10-19% (calculated as Al ₂ O ₃ ).

Description of drawings

Accompanying drawing 1 is the production process schematic diagram of polyaluminum chloride sol of the present invention. In the figure: 1a is the second-stage acid-dissolving kettle, 1b is the first-stage acid-dissolving kettle, 1c is the alkali-adjusting kettle, 2a, 2b, and 2c are all reflux condensers, 3a, 3b are filter tanks, and 4a is low alkalization polymerized chlorine Aluminum storage tank, 4b is the high alkalization polyaluminum chloride storage tank.

Accompanying drawing 2 is the ²⁷ AlNMR spectrogram of the prepared polyaluminum chloride sol.

In the figure: the peaks at 80ppm, 4ppm (broad peak) and 0ppm represent the resonance peaks of internal standard sodium aluminate, dimer and aluminum monomer (Al _m ) respectively; 62.5ppm and 70ppm (broad peak) represent Al The resonance peaks of alumina tetrahedron in ₁₃ and Al ₃₀ , the broad peak at 10-12ppm represents the resonance peak of alumina octahedron in Al ₁₃ , Al ₃₀ and other forms.

Detailed ways

The specific implementation of the present invention will be described below in conjunction with an example of the production method of the nano-type polyaluminum chloride sol of the present invention.

Example 1:

Add 225L of hydrochloric acid with a concentration of 31% into the second-stage acid-dissolving kettle 1a, and at the same time add 78kg of aluminum hydroxide returned from the filter tank 3a, stir and heat up to 95°C, and react for 2 hours; after the reaction, put the reactants into the first-stage acid-dissolving kettle 1b Add 115kg of active aluminum hydroxide, stir and heat up to 95°C for 1hr, add 445kg of water to adjust the total aluminum concentration of the solution, continue stirring and reacting for 1hr at 95°C, cool down after the reaction, filter in the filter tank 3a, and return the filter residue to the second Section continues to carry out acid-dissolution reaction, makes filtrate 818kg, puts into low alkalization degree polyaluminum chloride storage tank 4a, and total aluminum concentration is 9.2%, and alkalization degree is 51.8%; 818kg low alkalization degree polyaluminium chloride Pump into the alkali adjustment kettle 1c, add 64kg of high-purity calcium aluminate, stir and heat up to 90°C for 1.5hr to cool, put it in the filter tank 3b for filtration, return the filter residue to the next batch of alkali adjustment to continue to use, and obtain 868kg of filtrate, total aluminum The concentration is 13.0%, the degree of alkalization is 75.1%, and it is put into the storage tank 4b of polyaluminum chloride with high alkalization degree; the product is analyzed by ²⁷ AlNMR, and the content of Al ₁₃ is 22.6%, the content of Al ₃₀ is 50.6%, and the content of Al ₁₃ and Al The sum of the ₃₀ contents is 73.2%.

Example 2:

Add 365L of hydrochloric acid with a concentration of 20% into the second-stage acid-dissolving kettle 1a, and at the same time add 78kg of aluminum hydroxide returned from the filter tank 3a, stir and heat up to 95°C, and react for 2.5hr; after the reaction is completed, put the reactants into the first-stage acid-dissolving kettle In 1b, add 115kg of active aluminum hydroxide, stir and heat up to 90°C for 1.5hr, add 330kg of water to adjust the solution to the required total aluminum concentration, continue stirring and reacting at 90°C for 1hr, cool down after the reaction, and filter in the filter tank 3a , the filter residue returns to the second section to continue the acid-dissolving reaction, and 843kg of filtrate is obtained, which is put into the low alkalization polyaluminum chloride storage tank 4a, the total aluminum concentration is 8.6%, and the alkalization is 52.6%; the 843kg low alkalization Pump the polyaluminum chloride into the base adjustment kettle 1c, add 75.7kg of high-purity calcium aluminate, stir and heat up to 80°C for 2 hours, cool, put it in the filter tank 3b for filtration, and return the filter residue to the next batch of base adjustment to continue to use to obtain the filtrate 900kg, the total aluminum concentration is 12.7%, and the degree of alkalization is 78.0%, and puts into the polyaluminum chloride storage tank 4b with high alkalization degree; the product is analyzed by ²⁷ AlNMR, and the content of Al ₁₃ is 25.4%, and the content of Al ₃₀ is 46.3%, The sum of Al ₁₃ and Al ₃₀ contents is 71.7%.

Claims (9)

1, a kind of preparation method of Nano type sol of polyaluminium chloride in high purity and technology, it is characterized in that: under condition of normal pressure, adopt active aluminium hydroxide and technical hydrochloric acid to make raw material, adopt two sections reverse stripping methods to prepare basicity greater than 50% polymeric aluminum chlorides solution, adopt high-purity calcium aluminate to make basifier then, the regulator solution basicity makes Nano type sol of polyaluminium chloride in high purity.

2, Nano type sol of polyaluminium chloride in high purity according to claim 1 is characterized in that: nano shape Al in the polymerize aluminum chloride ₁₃And Al ₃₀The content sum greater than 70%, basicity is 70～85%, total aluminium concentration is 10～19% (with Al ₂O ₃Meter).

3, active aluminium hydroxide raw material according to claim 1 is characterized in that: used aluminium hydroxide is amorphousness aluminium hydroxide.

4, technical hydrochloric acid according to claim 1 is characterized in that: its mass concentration is 15～35%.

5, the production technique of polymerize aluminum chloride according to claim 1 is characterized in that: the mole proportioning of two sections molten process active aluminium hydroxides of reverse acid and hydrochloric acid is 1: 1.4～2.0.

6, two sections reverse stripping methods according to claim 1, it is characterized in that: adopt active aluminium hydroxide to make basifier, the polymeric aluminum chlorides solution reaction of the low basicity that in one section molten still of acid, prepares with two sections molten stills of acid, improve the solution basicity, unreacted aluminium hydroxide returns two sections molten stills of acid after filtering and makes raw material, continues reaction with concentrated hydrochloric acid.

7, the production technique of sol of polyaluminium chloride according to claim 1, it is characterized in that: the stripping temperature of active aluminium hydroxide is 85～100 ℃, one, two section dissolution time of active aluminium hydroxide is 2～3hr, and total solubility rate that active aluminium hydroxide is two sections is 100%.

8, the production technique of sol of polyaluminium chloride according to claim 1 is characterized in that: it is 80～90 ℃ that calcium aluminate is transferred the alkali temperature, and it is 1～2hr that calcium aluminate is transferred the alkali time.

9, high-purity calcium aluminate according to claim 1, it is characterized in that: high-purity calcium aluminate is that solugastril makes 1300～1500 ℃ of left and right sides roastings, the granularity of calcium aluminate is 30～80 orders, and wherein the mole proportioning of lime carbonate and aluminium hydroxide is 1: 1.0～3.0.

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