Patent ID: 12202739

DETAILED DESCRIPTION

In order to better explain the objects, technical solutions and advantages of the present disclosure, the present disclosure will be further explained with reference to specific embodiments and comparative examples, with the aim of understanding the content of the present disclosure in detail, but not limiting the present disclosure. All other embodiments obtained by those having ordinary skills in the art without paying creative work belong to the protection scope of the present disclosure. Unless otherwise specified, the experimental reagents, raw materials and instruments designed in the embodiments and comparative examples of the present disclosure are all common reagents, raw materials and instruments.

Embodiment 1

An embodiment of a manganese-doped cobaltosic tetroxide and a preparation method and application thereof of the disclosure was provided, where the method included the following steps of:(1) preparing an ammonium bicarbonate aqueous solution with a concentration of 1.3 mol/L as a base solution in a reaction vessel under a protective atmosphere and a pressure of 0.5 MPa, where a volume ratio of the base solution in the reaction vessel was 40%, a pH value was 8, and a temperature was 30° C.; and after the temperature was stable, continuously introducing nitrogen for 30 minutes under a steady pressure;(2) adding a mixed metallic solution and a precipitant into the reaction vessel at a flow rate of 2.5 L/h in a steady pressure state, mixing at a rate of 500 rpm, controlling a pH of the obtained mixed solution to decrease at a rate of 0.1 pH/h to a pH of 7.3 through a PLC system for reaction until a volume ratio of the mixed solution in the reaction vessel reaches 70% to 80%, and the mixed solution starts to concentrate and precipitate; during the concentration and precipitation period, continuously introducing the mixed metallic solution and the precipitant to steady the volume ratio of the mixed solution in the reaction vessel; and stopping the reaction when a particle size of particles obtained by concentration and precipitation reached 4.1 μm to obtain a manganese-doped cobalt carbonate particle slurry; the mixed metallic solution was a mixed aqueous solution of cobalt chloride, manganese chloride, 15-crown-5 and HL-610 nonionic surfactant, a concentration of cobalt ions in the mixed metallic solution was 2 mol/L, a mass ratio of the manganese element to the cobalt element was 0.005:1, and a mass ratio of the 15-crown-5 to the HL-610 nonionic surfactant and the manganese element was 0.02:0.02:1; and the precipitant was 3 mol/L ammonium bicarbonate aqueous solution;(3) after filtering the manganese-doped cobalt carbonate particle slurry, washing with 10 wt % ascorbic acid aqueous solution for 20 minutes, then drying and sieving to obtain a manganese-doped cobalt carbonate precursor; and(4) heating the manganese-doped cobalt carbonate precursor to 650° C. in a box furnace and sintering for 3 hours, thus obtaining the manganese-doped cobaltosic tetroxide.

Embodiment 2

An embodiment of a manganese-doped cobaltosic tetroxide and a preparation method and application thereof of the disclosure was provided, where the method included the following steps of:(1) preparing an ammonium bicarbonate aqueous solution with a concentration of 1.5 mol/L as a base solution in a reaction vessel under a protective atmosphere and a pressure of 0.3 MPa, where a volume ratio of the base solution in the reaction vessel was 45%, a pH value was 8.2, and a temperature was 32° C.; and after the temperature was stable, continuously introducing nitrogen for 20 minutes under a steady pressure;(2) adding a mixed metallic solution and a precipitant into the reaction vessel at a flow rate of 3 L/h in a steady pressure state, mixing at a rate of 520 rpm, controlling a pH of the obtained mixed solution to decrease at a rate of 0.1 pH/h to a pH of 7.4 through a PLC system for reaction until a volume ratio of the mixed solution in the reaction vessel reaches 70% to 80%, and the mixed solution starts to concentrate and precipitate; during the concentration and precipitation period, continuously introducing the mixed metallic solution and the precipitant to steady the volume ratio of the mixed solution in the reaction vessel; and stopping the reaction when a particle size of particles obtained by concentration and precipitation reached 5 μm to obtain a manganese-doped cobalt carbonate particle slurry; the mixed metallic solution was a mixed aqueous solution of cobalt nitrate, manganese nitrate, 18-crown-6 and HL-610 nonionic surfactant, a concentration of cobalt ions in the mixed metallic solution was 1.8 mol/L, a mass ratio of the manganese element to the cobalt element was 0.008:1, and a mass ratio of the 18-crown-6 to the HL-610 nonionic surfactant and the manganese element was 0.04:0.04:1; and the precipitant was 2.5 mol/L ammonium bicarbonate aqueous solution;(3) after filtering the manganese-doped cobalt carbonate particle slurry, washing with 10 wt % disodium edetate aqueous solution for 20 minutes, then drying and sieving to obtain a manganese-doped cobalt carbonate precursor; and(4) heating the manganese-doped cobalt carbonate precursor to 665° C. in a box furnace and sintering for 4 hours, thus obtaining the manganese-doped cobaltosic tetroxide.

Embodiment 3

An embodiment of a manganese-doped cobaltosic tetroxide and a preparation method and application thereof of the disclosure was provided, where the method included the following steps of:(1) preparing an ammonium bicarbonate aqueous solution with a concentration of 1.8 mol/L as a base solution in a reaction vessel under a protective atmosphere and a pressure of 0.1 MPa, where a volume ratio of the base solution in the reaction vessel was 50%, a pH value was 8.4, and a temperature was 35° C.; and after the temperature was stable, continuously introducing nitrogen for 15 minutes under a steady pressure;(2) adding a mixed metallic solution and a precipitant into the reaction vessel at a flow rate of 2 L/h in a steady pressure state, mixing at a rate of 600 rpm, controlling a pH of the obtained mixed solution to decrease at a rate of 0.1 pH/h to a pH of 7.6 through a PLC system for reaction until a volume ratio of the mixed solution in the reaction vessel reaches 70% to 80%, and the mixed solution starts to concentrate and precipitate; during the concentration and precipitation period, continuously introducing the mixed metallic solution and the precipitant to steady the volume ratio of the mixed solution in the reaction vessel; and stopping the reaction when a particle size of particles obtained by concentration and precipitation reached 5.8 μm to obtain a manganese-doped cobalt carbonate particle slurry; the mixed metallic solution was a mixed aqueous solution of cobalt sulfate, manganese sulfate, dibenzo-18-crown-6 and HL-610 nonionic surfactant, a concentration of cobalt ions in the mixed metallic solution was 1.5 mol/L, a mass ratio of the manganese element to the cobalt element was 0.012:1, and a mass ratio of the dibenzo-18-crown-6 to the HL-610 nonionic surfactant and the manganese element was 0.06:0.06:1; and the precipitant was 2 mol/L ammonium bicarbonate aqueous solution;(3) after filtering the manganese-doped cobalt carbonate particle slurry, washing with 10 wt % hydrazine hydrate solution for 20 minutes, then drying and sieving to obtain a manganese-doped cobalt carbonate precursor; and(4) heating the manganese-doped cobalt carbonate precursor to 665° C. in a box furnace and sintering for 4 hours, thus obtaining the manganese-doped cobaltosic tetroxide.

Comparative Example 1

The only difference between this comparative example and Embodiment 2 was that the preparation method of the product included the following steps of:(1) preparing an ammonium bicarbonate aqueous solution with a concentration of 1.5 mol/L as a base solution in a reaction vessel with an air atmosphere and a pressure of 0.3 MPa, where a volume ratio of the base solution in the reaction vessel was 45%, a pH value was 8.2, and a temperature was 32° C.; and after the temperature was stable, continuously introducing nitrogen for 20 minutes under a steady pressure;(2) adding a mixed metallic solution and a precipitant into the reaction vessel at a flow rate of 3 L/h in a steady pressure state, mixing at a rate of 520 rpm, controlling a pH of the obtained mixed solution to decrease at a rate of 0.1 pH/h to a pH of 7.4 through a PLC system for reaction until a volume ratio of the mixed solution in the reaction vessel reaches 70% to 80%, and the mixed solution starts to concentrate and precipitate; during the concentration and precipitation period, continuously introducing the mixed metallic solution and the precipitant to steady the volume ratio of the mixed solution in the reaction vessel; and stopping the reaction when a particle size of particles obtained by concentration and precipitation reached 5 μm to obtain a manganese-doped cobalt carbonate particle slurry; the mixed metallic solution was a mixed aqueous solution of cobalt nitrate, manganese nitrate, 18-crown-6 and HL-610 nonionic surfactant, a concentration of cobalt ions in the mixed metallic solution was 1.8 mol/L, a mass ratio of the manganese element to the cobalt element was 0.008:1, and a mass ratio of the 18-crown-6 to the HL-610 nonionic surfactant and the manganese element was 0.04:0.04:1; and the precipitant was 2.5 mol/L ammonium bicarbonate aqueous solution;(3) after filtering the manganese-doped cobalt carbonate particle slurry, washing with deionized water for 20 minutes, then drying and sieving to obtain a manganese-doped cobalt carbonate precursor; and(4) heating the manganese-doped cobalt carbonate precursor to 665° C. in a box furnace and sintering for 4 hours, thus obtaining the manganese-doped cobaltosic tetroxide.

Comparative Example 2

The only difference between this comparative example and Embodiment 2 was that the preparation method of the product included the following steps of:(1) preparing an ammonium bicarbonate aqueous solution with a concentration of 1.5 mol/L as a base solution in a reaction vessel under a protective atmosphere and a pressure of 0.3 MPa, where a volume ratio of the base solution in the reaction vessel was 45%, a pH value was 8.2, and a temperature was 32° C.; and after the temperature was stable, continuously introducing nitrogen for 20 minutes under a steady pressure;(2) adding a mixed metallic solution and a precipitant into the reaction vessel at a flow rate of 3 L/h in a steady pressure state, mixing at a rate of 520 rpm, controlling a pH of the obtained mixed solution to decrease at a rate of 0.1 pH/h to a pH of 7.4 through a PLC system for reaction until a volume ratio of the mixed solution in the reaction vessel reaches 70% to 80%, and the mixed solution starts to concentrate and precipitate; during the concentration and precipitation period, continuously introducing the mixed metallic solution and the precipitant to steady the volume ratio of the mixed solution in the reaction vessel; and stopping the reaction when a particle size of particles obtained by concentration and precipitation reached 5 μm to obtain a manganese-doped cobalt carbonate particle slurry; the mixed metallic solution was a mixed aqueous solution of cobalt nitrate and manganese nitrate, a concentration of cobalt ions in the mixed metallic solution was 1.8 mol/L, and a mass ratio of the manganese element to the cobalt element was 0.008:1; and the precipitant was 2.5 mol/L ammonium bicarbonate aqueous solution;(3) after filtering the manganese-doped cobalt carbonate particle slurry, washing with 10 wt % disodium edetate aqueous solution for 20 minutes, then drying and sieving to obtain a manganese-doped cobalt carbonate precursor; and(4) heating the manganese-doped cobalt carbonate precursor to 665° C. in a box furnace and sintering for 4 hours, thus obtaining the manganese-doped cobaltosic tetroxide.

Comparative Example 3

The only difference between this comparative example and Embodiment 1 was that the 15-crown-5 was replaced with the same amount of decyltrimethylammonium chloride.

Comparative Example 4

The only difference between this comparative example and Embodiment 1 was that the HL-610 nonionic surfactant was replaced with the same amount of triethanolamine oleate.

Comparative Example 5

The only difference between this comparative example and Embodiment 1 was that a mass ratio of the 15-crown-5 to the HL-610 nonionic surfactant was 1:2, and the total dosage of the 15-crown-5 and the HL-610 nonionic surfactant was consistent with that of Embodiment 1.

Comparative Example 6

The only difference between this comparative example and Embodiment 1 was that a mass ratio of the 15-crown-5 to the HL-610 nonionic surfactant was 2:1, and the total dosage of the 15-crown-5 and the HL-610 nonionic surfactant was consistent with that of Embodiment 1.

Comparative Example 7

The only difference between this comparative example and Embodiment 3 was that the pressure of the reaction vessel in the step (1) was 0.05 MPa.

Comparative Example 8

The only difference between this comparative example and Embodiment 1 was that the pH decreasing rate of the obtained mixed solution in the step (2) was 0.15 pH/h.

Comparative Example 9

The only difference between this comparative example and Embodiment 1 was that the pH decreasing rate of the obtained mixed solution in the step (2) was 0.05 pH/h.

Effect Example 1

In order to verify the quality of the products prepared by the preparation method of the manganese-doped cobaltosic tetroxide, the particle sizes and element contents of each product were counted, and the valence states of the manganese elements in the products were fitted by XPS analysis and counted. The results are shown in Table 1.

TABLE 1D50SpanManganese elementMn2+Mn3+Mn4+Item(μm)valuecontent (ppm)wt %wt %wt %Embodiment 13.50.6536695543.51.5Embodiment 24.50.5159804849.92.1Embodiment 35.60.4787285247.20.8Comparative4.00.57594520.42752.6Example 1Comparative5.21.05601742.754.52.8Example 2Comparative5.11.12354125.931.242.9Example 3Comparative3.61.1536825642.91.1Example 4Comparative3.50.6036603835.626.4Example 5Comparative3.60.88359453.745.40.9Example 6Comparative3.50.87364637.833.528.7Example 7Comparative3.51.2136585245.82.2Example 8Comparative3.50.53332054.742.42.9Example 9

Meanwhile, the products of each embodiment/comparative example were observed by scanning electron microscope, and the results were shown inFIGS.1to10. According to the data in Table 1 and the scanning electron microscopes, it can be seen that the manganese-doped cobaltosic tetroxide products prepared by the products in each embodiment had uniform and complete particles, high dispersibility, and no obvious crushing phenomenon. The doping amount of manganese was controllable, and the divalent manganese accounted for a relatively high proportion of manganese, which might be as high as 55 wt %. In contrast, in the method of Comparative Example 1, protective atmosphere and antioxidant solution washing were not used to ensure the stability of the bivalent manganese, and the content of the high-valence manganese in the manganese element was relatively high, so that the sintered product particles were crushed and the crystal form was incomplete. No surfactant was introduced into the product of Comparative Example 2 in the preparation process, and the dispersion of the product was poor, resulting in agglomeration. In the steps of the preparation method described in Comparative Example 3, the crown ether surfactant was replaced by other conventional surfactants, which were difficult to play a good role in metal ion complexation in the precursor synthesis process, resulting in segregation of manganese, cause uneven size and wide particle size distribution of the final sintered product. In the preparation method described in Comparative Example 4, the HL-610 nonionic surfactant was replaced with triethanolamine oleate, which could not effectively inhibit the bubble effect caused by the crown ether surfactant. In the reaction process of the reaction vessel, the liquid level fluctuated excessively and the stability was poor, resulting in the manganese-doped cobalt carbonate particles continuously generating new small crystal nuclei in the synthesis process, and the particle size of the final product was uneven. From the product performance results of Comparative Examples 5 and 6, it can be seen that when the crown ether surfactant and the nonionic surfactant were combined at the same time, too much or too little of any one of the two surfactants may lead to the deterioration of the particle growth effect of the product, and the dispersibility and size uniformity might be affected. According to the preparation method of Comparative Example 7, the constant pressure was controlled to be low, and the pressure environment weakened intermolecular Brownian motion, and at the same time, caused insufficient nitrogen, and tetravalent manganese with more components still appeared in the final product, resulting in incomplete product particles. It can also be clearly seen fromFIG.10that the product particles are damaged. The pH change rate of the preparation method described in Comparative Example 8 was too high in the reaction process of the mixed solution, which directly accelerated the agglomeration phenomenon between the crystal nuclei, resulting in uneven particle size, and a Span value of the product was too large under the same particle size. However, in the preparation method described in Comparative Example 9, the pH change rate was too low. When the liquid level in the reaction vessel reached the level of the concentrated solution, ammonium bicarbonate in the base solution was not completely consumed, and a large number of manganese ammonia complexes existed. As a clear solution generated by concentration was discharged from the reaction system, a manganese content in the final product was lower than a theoretical value.

Finally, it should be noted that the embodiments above are merely used to illustrate the technical solutions of the present disclosure, but are not intended to limit the protection scope of the present disclosure. Although the present disclosure has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present disclosure can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present disclosure.