Preparation method of flaky cerium carbonate

Abstract

The invention discloses a preparation method of flaky cerium carbonate, and belongs to the technical field of rare earth compound preparation. Comprising the following steps: adding a rare earth cerium salt solution, an ammonium bicarbonate solution and a monocarboxylic substance solution into pure water in a parallel flow manner, carrying out a mixed reaction, controlling the pH value of a reaction endpoint, and carrying out solid-liquid separation to obtain the flaky cerium carbonate. According to the invention, by utilizing the complexing ability of a monocarboxylic substance and rare earth ions, the nucleation and growth regulation of the cerium carbonate crystallization process and the controllable synthesis of the cerium carbonate morphology are realized; the preparation method is simple and easy to implement and low in cost, and the obtained product has a flaky morphology and can be applied to the fields of shielding materials, flame-retardant materials and the like.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth compound preparation, in particular to a method for preparing flaky cerium carbonate. Background Art

[0002] As "industrial catalysts", rare earth elements are widely used in electronics, petrochemicals, metallurgy, environmental protection and other fields. Rare earths can be used to produce fluorescent materials, polishing materials, permanent magnetic materials, catalytic materials, optical fiber materials, etc., and the physicochemical properties such as the morphology and structure of rare earth ions determine the performance of the materials. With the development of science and technology, people have put forward higher requirements for special performance materials. Therefore, the controllable synthesis of inorganic materials with special morphology and size is becoming increasingly urgent.

[0003] CN110104671A discloses a method for inducing crystallization of flaky cerium carbonate. The method comprises: preparing a cerium salt solution with a concentration of 0.02-0.5 mol / L and a pH value of 3.5-5.0; adding needle-shaped cerium carbonate crystals as seeds to the cerium salt solution and performing ultrasonic dispersion; then dripping a precipitant solution, stirring continuously during the process, and continuing to stir after the dripping until all amorphous cerium carbonate is transformed into crystals, filtering, washing and drying the precipitate in turn to obtain a flaky cerium carbonate crystal product. The reaction product obtained by the inventive method is in a flaky morphology, and has the advantages of fast sedimentation speed, small precipitation volume, and easy filtration. However, the method also has the disadvantages of low concentration of cerium salt solution and great difficulty in subsequent wastewater treatment.

[0004] CN103539194B discloses a method for preparing flaky cerium carbonate. The method is: first, a portion of the ammonium bicarbonate solution is added to the reactor, and then the trivalent cerium ion solution and the ammonium bicarbonate solution are added to the reactor at a slow speed. After reacting for about 5 minutes, the flow rate of the trivalent cerium ion solution and the ammonium bicarbonate solution is increased according to their volume ratio to ensure that the trivalent cerium ions and the ammonium bicarbonate solution flow out at the same time; finally, the cerium carbonate is obtained by suction filtration and drying. This method and the present invention are both for preparing flaky cerium carbonate, but the method has a low raw material concentration, a complex operating process, and a large amount of subsequent wastewater treatment.

[0005] CN112126977B discloses a method for preparing high-purity flaky single crystals and flaky dense aggregated cerium carbonate. The method comprises: adding triammonium citrate in advance to regulate the crystallization process when precipitating cerium with ammonium (bi) carbonate. The required molar ratio of ammonium bicarbonate to cerium ions is R ac The molar ratio of ammonium carbonate to cerium ions is 5-8. ac The ratio of the cerium carbonate to the cerium carbonate is 2.5-4, the amount of triammonium citrate added is ≥ 0.1%, and the aging crystallization time is ≥ 0.1%. The method is the same as the present invention for preparing flaky cerium carbonate, but the method requires a longer aging time, while the present invention does not require aging. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing flaky cerium carbonate to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is a method for preparing flaky cerium carbonate, comprising the following steps: adding a rare earth cerium salt solution, an ammonium bicarbonate solution and a monobasic carboxyl substance solution into pure water in parallel for mixed reaction, controlling the pH value at the reaction end point to be acidic, and obtaining the flaky cerium carbonate through solid-liquid separation.

[0009] The second technical solution of the present invention is the flaky cerium carbonate prepared by the preparation method.

[0010] Based on the above technical solution, the present invention has the following technical effects:

[0011] The invention utilizes the complexing ability of monocarboxyl substances and rare earth ions to achieve nucleation and growth regulation of the cerium carbonate crystallization process and controllable synthesis of the cerium carbonate morphology; the preparation method is simple and easy, with low cost; the obtained product has a flaky morphology and can be applied to the fields of shielding materials, flame retardant materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 This is a SEM image of the cerium carbonate obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0015] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0016] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0017] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0018] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0019] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0020] The embodiment of the present invention provides a method for preparing flaky cerium carbonate, comprising the following steps: adding a rare earth cerium salt solution, an ammonium bicarbonate solution and a monobasic carboxyl substance solution into pure water in parallel for mixed reaction, controlling the pH value at the reaction end point to be acidic, and obtaining the flaky cerium carbonate through solid-liquid separation.

[0021] In some specific embodiments, the rare earth cerium salt is selected from at least one of cerium chloride, cerium nitrate and cerium sulfate; the concentration of the rare earth cerium salt solution is 10 to 330 g / L, preferably 250 to 300 g / L, calculated as REO.

[0022] In some specific embodiments, the molar concentration of the ammonium bicarbonate solution is 1.0 to 3.3 mol / L, preferably 2.5 to 3.0 mol / L. Increasing the molar concentration of the ammonium bicarbonate solution is conducive to reducing the water used for preparing the ammonium bicarbonate, thereby reducing the amount of wastewater to be treated.

[0023] In some specific embodiments, the monocarboxyl substance is selected from at least one of monocarboxylic acid or monocarboxylate; in terms of REO, the mass of the monocarboxyl substance is 1% to 10%, preferably 1% to 6%, and more preferably 2% to 5% of the mass of the rare earth cerium salt. After the addition of acetic acid, a coating layer is formed on the surface of the crystal, which reduces the interfacial energy between the solid-liquid interface, so that the crystal exhibits anisotropy when nucleating and growing at different interfaces, thereby causing the cerium carbonate crystal to develop into a lamellar structure.

[0024] In some specific embodiments, the Ce in the rare earth cerium salt solution is 3+ CO3 with ammonium bicarbonate solution 2- The molar ratio is 1:(2.5~3.8).

[0025] In some specific embodiments, the temperature of the mixed reaction is 20-80° C., preferably 35-45° C. The appropriate temperature ensures the diffusion rate of the solute molecules during the crystallization process, thereby affecting the crystal morphology of the product.

[0026] In some specific embodiments, the reaction endpoint pH is controlled to be 6.2-6.7.

[0027] In some specific embodiments, the solid-liquid separation method is vacuum filtration. During solid-liquid separation, the solid product is washed with deionized water in an amount 3-6 times the mass of the solid.

[0028] Controlling the above parameters within the scope of the present invention is conducive to the anisotropy of the crystals during nucleation and growth at different interfaces, thereby causing the cerium carbonate crystals to develop into a lamellar structure.

[0029] The embodiment of the present invention also provides flaky cerium carbonate prepared by the preparation method.

[0030] In the present invention, REO represents a rare earth oxide.

[0031] Example 1

[0032] At 45°C, 2 g of acetic acid (analytical grade) was added to 140 mL of 280 g / L cerium chloride solution, and then added dropwise to a reactor containing 200 mL of pure water as the base liquid in parallel with 300 mL of 2.5 mol / L ammonium bicarbonate solution. The mixture was mixed and reacted, and the reaction end point pH was 6.7.

[0033] The precipitated product was vacuum filtered and rinsed with deionized water 6 times the solid mass. The SEM image of the obtained cerium carbonate is shown in Figure 1 Scanning electron microscope (SEM) image: The test was carried out using a ZEISS Sigma 500 scanning electron microscope.

[0034] Example 2

[0035] At 20°C, 2 g of formic acid (analytical grade) was added to 140 mL of 280 g / L cerium nitrate solution, and then added dropwise to a reactor containing 200 mL of pure water as the base liquid in parallel with 250 mL of 3.0 mol / L ammonium bicarbonate solution, and mixed for reaction. The reaction end point pH was 6.7.

[0036] The precipitated product was vacuum filtered and rinsed with deionized water 6 times the solid mass, and the obtained cerium carbonate had a flaky morphology.

[0037] Example 3

[0038] At 45°C, 0.8 g of propionic acid (analytical grade) was added to 140 mL of 280 g / L cerium chloride solution, and then added dropwise to a reactor containing 200 mL of pure water as the base liquid in parallel with 300 mL of 2.5 mol / L ammonium bicarbonate solution, and mixed for reaction. The reaction end point pH was 6.7.

[0039] The precipitated product was vacuum filtered and rinsed with deionized water 6 times the solid mass, and the obtained cerium carbonate had a flaky morphology.

[0040] Example 4

[0041] At 60°C, 2 g of acetic acid (analytical grade) was added to 140 mL of 280 g / L cerium chloride solution, and then added dropwise to a reactor containing 200 mL of pure water as the base liquid in parallel with 300 mL of 2.5 mol / L ammonium bicarbonate solution, and mixed for reaction. The reaction end point pH was 6.7.

[0042] The precipitated product was vacuum filtered and rinsed with deionized water 6 times the solid mass, and the obtained cerium carbonate had a flaky morphology.

[0043] Example 5

[0044] At 45°C, 0.8 g of acetic acid (analytical grade) was added to 140 mL of 280 g / L cerium chloride solution, and then added dropwise to a reactor containing 200 mL of pure water as the base liquid in parallel with 250 mL of 3.0 mol / L ammonium bicarbonate solution, and mixed to react. The reaction end point pH was 6.7.

[0045] The precipitated product was vacuum filtered and rinsed with deionized water 6 times the solid mass, and the obtained cerium carbonate had a flaky morphology.

[0046] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technical users in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing flaky cerium carbonate, characterized in that: The following steps are involved: A rare earth cerium salt solution, an ammonium bicarbonate solution and a monobasic carboxyl substance solution are added into pure water in parallel for mixed reaction, the pH value at the reaction end point is controlled to be acidic, and the flaky cerium carbonate is obtained by solid-liquid separation.

2. The preparation method according to claim 1, characterized in that: The rare earth cerium salt is selected from at least one of cerium chloride, cerium nitrate and cerium sulfate; the concentration of the rare earth cerium salt solution is 10-330 g / L in terms of REO.

3. The preparation method according to claim 1, characterized in that: The molar concentration of the ammonium bicarbonate solution is 1.0 to 3.3 mol / L.

4. The preparation method according to claim 1, characterized in that: The monocarboxyl substance is selected from at least one of monocarboxylic acid and monocarboxylate; the mass of the monocarboxyl substance is 1% to 10% of the mass of the rare earth cerium salt in terms of REO.

5. The preparation method according to claim 1, characterized in that: The Ce in the rare earth cerium salt solution 3+ CO3 with ammonium bicarbonate solution 2- The molar ratio is 1:(2.5~3.8).

6. The preparation method according to claim 1, characterized in that: The temperature of the mixed reaction is 20-80°C.

7. The preparation method according to claim 1, characterized in that: The reaction endpoint pH value was controlled to be 6.2-6.

7.

8. The flaky cerium carbonate prepared by the preparation method according to any one of claims 1 to 7.

Images