SYNTHESIS METHOD OF COBALT HYDROXIDE AND COBALT HYDROXIDE

Abstract

The present disclosure belongs to the technical field of metal oxide materials, and discloses a synthesis method of cobalt hydroxide and cobalt hydroxide. The synthesis method includes: (1) stirring and heating ammonium citrate, introducing a protective gas, adding a cobalt salt and a mixed alkali liquor to allow a reaction, and adjusting a pH to obtain a cobalt hydroxide slurry; and (2) subjecting the cobalt hydroxide slurry to alkali-leaching, filtering, and slurrying a resulting filter residue; and washing a resulting slurry with a detergent, and drying the resulting slurry to obtain the cobalt hydroxide. In the present disclosure, ammonium citrate is used as a base solution, and a cobalt solution and a mixed alkali liquor are added to synthesize a cobalt hydroxide slurry in one step under a protective atmosphere.

Claims

1. A synthesis method of cobalt hydroxide, the cobalt hydroxide having a specific surface area (SSA) of 44 cm.sup.2/g to 65 cm.sup.2/g, wherein the synthesis method comprises the following steps: (1) stirring and heating ammonium citrate, introducing a protective gas, adding a cobalt salt and a mixed alkali liquor to allow a reaction, and adjusting a pH to obtain a cobalt hydroxide slurry; and (2) subjecting the cobalt hydroxide slurry to alkali-leaching, filtering to obtain a filter residue, and slurrying the filter residue; and washing a resulting slurry with a detergent, and drying to obtain the cobalt hydroxide; in step (1), the mixed alkali liquor comprises a sodium hydroxide solution, hydrazine hydrate, and ammonia water; in step (2), the detergent is a citric acid solution.

2. The synthesis method according to claim 1, wherein in step (1), the ammonium citrate is prepared into a 0.8 g/L to 1.5 g/L ammonium citrate solution in advance.

3. The synthesis method according to claim 1, wherein in step (1), the protective gas is nitrogen.

4. The synthesis method according to claim 1, wherein in step (1), the cobalt salt comprises one selected from the group consisting of cobalt sulfate and cobalt chloride.

5. The synthesis method according to claim 4, wherein the cobalt salt is prepared into a cobalt salt solution in advance; and a dispersant is added to the cobalt salt solution, and the dispersant is ammonium citrate.

6. The synthesis method according to claim 1, wherein a volume of the ammonia water accounts for 10% to 12% of a total volume of the mixed alkali liquor.

7. The synthesis method according to claim 1, wherein in step (2), the alkali-leaching is conducted at 45 C. to 55 C. for 1 h to 2 h with a sodium hydroxide solution.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a scanning electron microscopy (SEM) image of the cobalt hydroxide prepared in Example 1 of the present disclosure;

[0038] FIG. 2 is an SEM image of the cobalt hydroxide prepared in Example 2 of the present disclosure;

[0039] FIG. 3 is an SEM image of the cobalt hydroxide prepared in Comparative Example 1 of the present disclosure;

[0040] FIG. 4 is an SEM image of the cobalt hydroxide prepared in Comparative Example 2 of the present disclosure; and

[0041] FIG. 5 shows X-ray diffractometry (XRD) patterns of the cobalt hydroxide prepared in Examples 1 and 2 and Comparative Examples 1 and 2.

DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES

[0042] The concepts and technical effects of the present disclosure are clearly and completely described below in conjunction with examples, so as to allow the objectives, features and effects of the present disclosure to be fully understood. Apparently, the described examples are merely some rather than all of the examples of the present disclosure. All other examples obtained by those skilled in the art based on the examples of the present disclosure without creative efforts should fall within the protection scope of the present disclosure.

Example 1

[0043] A synthesis method of cobalt hydroxide was provided in this example, including the following steps: [0044] (1) A 2 mol/L cobalt sulfate solution was prepared, and then a dispersant (ammonium citrate) with a concentration of 0.5 mol/L was added to obtain a cobalt solution; and 10 mol/L liquid caustic soda was prepared, and then hydrazine hydrate with a volume fraction of 0.5% and ammonia water with a mass fraction of 10% were added to the liquid caustic soda to obtain a mixed alkali liquor, where a volume of the ammonia water accounted for 10% of a total volume of the mixed alkali liquor. [0045] (2) 1 L of a 1 g/L ammonium citrate solution and 10 L of 15 g/L ammonia water were added as a base solution to a 100 L reactor, and then pure water was added to adjust a pH to 11; nitrogen was introduced as a protective gas, and the base solution was heated to 40 C. and stirred at a stirring frequency of 30 Hz; the cobalt salt solution (cobalt sulfate solution and ammonium citrate) and the mixed alkali liquor (liquid caustic soda, ammonia water, and hydrazine hydrate) were concurrently fed into the reactor, during which a pH was controlled at 12; and when a volume of a reaction solution was about 80% of a volume of the reactor, the feeding was stopped, and the reaction solution was further stirred for 2 h to obtain a cobalt hydroxide slurry. [0046] (3) The cobalt hydroxide slurry was spin-dried in a centrifuge and then transferred back to the reactor, and then 50 L of a 1 mol/L sodium hydroxide solution was added to soak the cobalt hydroxide slurry for 1 h at 55 C.; the cobalt hydroxide slurry was filtered out, spin-dried, and transferred back to the reactor, then the reactor (100 L) was filled up with pure water, and a reactor body was heated to 50 C.; and a resulting mixture was stirred for 1 h at a stirring rate of 30 hz to obtain a cobalt hydroxide slurry. [0047] (4) The cobalt hydroxide slurry was centrifuged in a centrifuge, washed with water (including 1 g/L citric acid monohydrate) at a water consumption of 50 L/Kg, and then dried in an oven at 90 C. to obtain a pink cobalt hydroxide powder with uniform morphology and large SSA.

[0048] FIG. 1 is an SEM image of the cobalt hydroxide prepared in Example 1, and it can be seen from FIG. 1 that the cobalt hydroxide prepared in Example 1 has prominent morphological consistency and no obvious agglomeration.

[0049] Table 1 shows indexes of dried cobalt hydroxide

TABLE-US-00001 Co S Na D50 BET 62.45 0.013% 0.004% 1.6 m 61 cm.sup.2/g

[0050] It can be known from Table 1 that the cobalt hydroxide prepared in Example 1 has a very low sulfur content and a large SSA.

Example 2

[0051] A synthesis method of cobalt hydroxide was provided in this example, including the following steps: [0052] (1) A 1 mol/L cobalt sulfate solution was prepared, and then a dispersant (ammonium citrate) with a concentration of 0.1 mol/L was added to obtain a cobalt solution; and 15 mol/L liquid caustic soda was prepared, and then hydrazine hydrate with a volume fraction of 1% and ammonia water with a mass fraction of 15% were added to the liquid caustic soda to obtain a mixed alkali liquor, where a volume of the ammonia water accounted for 10% of a total volume of the mixed alkali liquor. [0053] (2) 1 L of a 1 g/L ammonium citrate solution and 10 L of 15 g/L ammonia water were added as a base solution to a 100 L reactor, nitrogen was introduced as a protective gas, and the base solution was heated to 60 C. and stirred at a stirring frequency of 30 Hz; the cobalt salt solution (cobalt sulfate solution and ammonium citrate) and the mixed alkali liquor (liquid caustic soda, ammonia water, and hydrazine hydrate) were concurrently fed into the reactor, during which a pH was controlled at 10; and when a volume of a reaction solution was about 80% of a volume of the reactor, the feeding was stopped, and the reaction solution was further stirred for 2 h to obtain a cobalt hydroxide slurry. [0054] (3) The cobalt hydroxide slurry was spin-dried in a centrifuge and then transferred back to the reactor, and then a 2 mol/L sodium hydroxide solution was added to soak the cobalt hydroxide slurry for 1 h at 55 C.; the cobalt hydroxide slurry was filtered out, spin-dried, and transferred back to the reactor, then the reactor was filled up with pure water, and a reactor body was heated to 50 C.; and a resulting mixture was stirred for 1 h at a stirring rate of 30 hz to obtain a cobalt hydroxide slurry. [0055] (4) The cobalt hydroxide slurry was centrifuged in a centrifuge, washed with water (including 0.1 g/L citric acid monohydrate) at a water consumption of 20 L/Kg, and then dried in an oven at 90 C. to obtain a pink cobalt hydroxide powder with uniform morphology and large SSA.

[0056] FIG. 2 is an SEM image of the cobalt hydroxide prepared in Example 2, and it can be seen from FIG. 2 that the cobalt hydroxide prepared in Example 2 has uniform morphology and structure and no obvious agglomeration.

[0057] Table 2 shows indexes of dried cobalt hydroxide

TABLE-US-00002 Co S Na D50 BET 63.50 0.024% 0.005% 3.1 m 44 cm.sup.2/g

[0058] It can be known from Table 2 that the cobalt hydroxide prepared in Example 2 has a very low sulfur content and a large SSA.

Comparative Example 1

[0059] A synthesis method of cobalt hydroxide was provided in this comparative example, including the following steps:

[0060] This comparative example was different from Example 1 in that no dispersant was added to the cobalt salt solution (cobalt sulfate solution and ammonium citrate) and the base solution (that is, no dispersant was added to the cobalt salt, and no ammonium citrate was added as a base solution). Obtained cobalt hydroxide had a large particle size and poor morphological uniformity.

[0061] FIG. 3 is an SEM image of the cobalt hydroxide prepared in Comparative Example 1, and it can be seen from FIG. 3 that the cobalt hydroxide prepared in Comparative Example 1 has agglomerates with different sizes.

[0062] Table 3 shows indexes of dried cobalt hydroxide.

TABLE-US-00003 TABLE 3 Co S Na D50 BET 62.75 0.030% 0.006% 6.1 m 11 cm.sup.2/g

[0063] It can be known from Table 3 that the cobalt hydroxide prepared in Comparative Example 1 has a large particle size and a small SSA.

Comparative Example 2

[0064] A synthesis method of cobalt hydroxide was provided in this comparative example, including the following steps:

[0065] This comparative example was different from Example 1 in that no detergent (citric acid monohydrate) was added to washing water.

[0066] FIG. 4 is an SEM image of the cobalt hydroxide prepared in Comparative Example 2, and it can be seen from FIG. 4 that the prepared cobalt hydroxide has irregular morphology and obvious agglomeration, that is, the dried cobalt hydroxide has many agglomerates and is partly oxidized.

Comparative Example 3

[0067] A synthesis method of cobalt hydroxide was provided in this comparative example, including the following steps:

[0068] This comparative example was different from Example 1 in that step (3) was as follows: the cobalt hydroxide slurry was spin-dried in a centrifuge and then transferred back to the reactor, then the reactor was filled up with pure water, and a reactor body was heated to 50 C.; and a resulting mixture was stirred for 1 h at a stirring rate of 30 hz to obtain a cobalt hydroxide slurry.

[0069] Table 4 shows indexes of dried cobalt hydroxide.

TABLE-US-00004 TABLE 4 Co S Na D50 BET 62.1 0.110% 0.003% 2.2 m 50 cm.sup.2/g

[0070] It can be seen from Table 4 that, according to ICP test, the dried cobalt hydroxide obtained in Comparative Example 3 has an S content of 1,100 ppm.

[0071] FIG. 5 shows XRD patterns of the cobalt hydroxide prepared in Examples 1 and 2 and Comparative Examples 1 and 2, and it can be seen from FIG. 5 that a diffraction peak of cobalt oxyhydroxide appears at about 10.50 in the XRD pattern of Comparative Example 2 at 2, indicating that there is cobalt oxyhydroxide in the cobalt hydroxide. Cobalt oxyhydroxide is an impurity, and the presence of cobalt oxyhydroxide indicates that the cobalt hydroxide has been oxidized, resulting in a reduced yield.

[0072] The present disclosure is described in detail with reference to the accompanying drawings and examples, but the present disclosure is not limited to the above examples. Within the scope of knowledge possessed by those of ordinary skill in the technical field, various changes can also be made without departing from the purpose of the present disclosure. In addition, the examples in the present disclosure or features in the examples may be combined with each other in a non-conflicting situation.