A hollow shell double transition metal oxide and its preparation method and application

Abstract

The present invention provides a hollow shell type double transition metal oxide and a preparation method and application thereof, and relates to the technical field of inorganic nanomaterials. Specifically, a solution containing a carbon source, a transition metal chloride and a precipitant is prepared, the pH is adjusted to 9 to 12 by triethanolamine, and then a hydrothermal reaction is carried out; after the reaction is completed, a precursor is separated and the precursor is heat-treated to obtain a hollow shell type double transition metal oxide. The double transition metal oxide of the present invention has the advantages of small and uniform particle size, controllable size, and large specific surface area, presents a regular spherical shape, and has good catalytic performance; the preparation process of the present invention has the advantages of being simple and easy, low cost, environmentally friendly, and highly repeatable, and has good application prospects in the field of catalysis.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic nanomaterials, and in particular to a hollow shell type double transition metal oxide and a preparation method and application thereof. Background Art

[0002] Double transition metal oxides are spinel structure compounds formed by the combination of two transition metal elements and oxygen. They have magnetic, optical, electrical, catalytic and other properties and play an important role in data storage, biotechnology, electronics, lasers, sensors, conversion reactions, energy storage and conversion, etc. After long-term research, double transition metal oxides have made great progress in both preparation technology and application fields.

[0003] Specifically, the magnetic applications of double transition metal oxides include information technology (data storage), biotechnology (magnetic sensing), and the electronics industry (spintronic devices). Transparent or semi-transparent double transition metal oxides exhibit optical properties of electrochemiluminescence, photoluminescence, and light absorption, and have application prospects in laser devices and magneto-optical recording. The electrical properties of double transition metal oxides also extend their applications to energy storage, such as supercapacitors and metal ion batteries. Most chemically valence-changing spinel oxides exhibit redox capacitance. At the same time, double transition metal oxides are also widely used in the positive and negative electrodes of lithium-ion batteries.

[0004] At present, the mainstream preparation methods of double transition metal oxides include high temperature self-propagation method and co-precipitation method. Among them, the high temperature self-propagation method relies on the internal chemical energy of the reactants themselves for synthesis. The operation process usually includes raw material mixing, ignition reaction, propagation of combustion wave and collection of products; the advantage of this method is that it has a faster reaction speed and higher synthesis efficiency. The co-precipitation method reacts a solution containing the target metal ions with an appropriate precipitant to precipitate the metal ions in the form of precipitation, and then obtains the target product through steps such as washing, drying and calcination; the advantage of this method is that the reaction process is easy to control, the obtained product has uniform composition and good applicability. However, although the above processes can prepare double metal oxides with different morphologies and structures, they are limited by the defects of the properties of the raw materials themselves and many constraints. The synthesized double transition metal oxides have a small specific surface area and are difficult to meet the needs of low specific surface area in the fields of catalysts and electrode materials.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a method for preparing a hollow shell type double transition metal oxide, which is mainly used to solve the defect that conventional preparation processes including high temperature self-propagating method or co-precipitation method are difficult to prepare double transition metal oxide products with low specific surface area.

[0007] The second object of the present invention is to provide a hollow shell type double transition metal oxide, which has the advantages of controllable particle size and high specific surface area.

[0008] The third object of the present invention is to provide the use of the hollow shell double transition metal oxide in catalysis.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] A method for preparing a hollow shell double transition metal oxide comprises the following steps:

[0011] A solution containing a carbon source, a transition metal chloride and a precipitant is prepared, the pH value is adjusted to 9-12 by triethanolamine, and then a hydrothermal reaction is carried out; after the reaction is completed, a precursor is separated and the precursor is heat-treated to obtain a hollow shell-type double transition metal oxide.

[0012] A double transition metal oxide is prepared based on the preparation method of the hollow shell type double transition metal oxide, and the use of the double transition metal oxide in catalysis.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The present invention provides a method for preparing a double transition metal oxide with a hollow shell structure, which solves the problem that the double transition metal oxide with a hollow shell structure is difficult to prepare. The obtained double transition metal oxide has a small particle size, controllable size, large specific surface area, and good catalytic performance. At the same time, the preparation process of the present invention is simple, easy to operate, low-cost, and environmentally friendly. The batch and stable preparation of the double transition metal oxide with a hollow shell structure can be achieved only by hydrothermal method and heat treatment in air.

[0015] (2) In the preparation process provided by the present invention, a carbon source is used as a template for a hollow shell structure, and a precursor of a solid carbon sphere wrapped by a metal mixture is obtained by a precipitant and a hydrothermal reaction. Finally, the precursor is subjected to a heat treatment to eliminate the carbon, thereby obtaining a double transition metal oxide with a hollow shell structure coated on the outer layer of the carbon sphere. As a typical advantage, the particle size (D90) of the prepared double transition metal oxide hollow sphere is 500nm to 600nm, and the morphology is a regular hollow shell sphere with a large specific surface area of ​​70 to 100m 2 / g, which is beneficial to its application in the field of catalysis. DETAILED DESCRIPTION

[0016] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but those skilled in the art will appreciate that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those who do not specify the manufacturer for reagents or instruments used are conventional products that can be purchased commercially. In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be interpreted as indicating or implying relative importance.

[0017] The first aspect of the present invention is to provide a method for preparing a hollow shell type double transition metal oxide, which mainly comprises the following steps: preparing a solution comprising a carbon source, a transition metal chloride and a precipitant, adjusting the pH to 9 to 12 by triethanolamine, and then performing a hydrothermal reaction; after the reaction is completed, separating a precursor, and heat-treating the precursor to obtain a hollow shell type double transition metal oxide.

[0018] It is worth noting that, since the object prepared in the present invention is the oxide of "double transition metal", the transition metal chloride raw materials used should include two different chloride raw materials.

[0019] As a preferred embodiment, the carbon source includes at least one of glucose, galactose, fructose or sucrose.

[0020] As a preferred embodiment, the transition metal chloride includes at least two of ferric chloride, cobalt chloride or nickel chloride; it is understandable that common soluble salts include nitrates or chlorides, and generally the same salt is used for synthesis. In the preparation process of the present invention, it is empirically found that it takes longer for chlorides to generate the target product than for nitrates. Therefore, the carbon source can first be generated by a hydrothermal reaction to generate a carbon sphere template, and then the chloride reacts and attaches to the carbon sphere template, thereby better realizing the preparation concept of the hollow sphere structure of the present invention.

[0021] As a preferred embodiment, the precipitant includes at least one of sodium bicarbonate, ammonium bicarbonate or urea.

[0022] As a preferred embodiment, based on the amount of substance, the usage ratio of the two transition metal chlorides is (1.2-2.8):1, including but not limited to any one of 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or a ratio interval consisting of any two of them, and 2:1 is more preferred.

[0023] As a preferred embodiment, in terms of the amount of substance, the amount of the two transition metal chlorides and the amount ratio of the carbon source is 3: (0.25-1.5), including but not limited to any one of 3: 0.25, 3: 0.3, 3: 0.4, 3: 0.5, 3: 0.6, 3: 0.8, 3: 1, 3: 1.2, 3: 1.4, 3: 1.5 or any two of the ratio intervals. As a preferred embodiment, when the carbon source includes glucose, galactose, fructose (monosaccharides), the amount of the two transition metal chlorides and the amount ratio of the carbon source are preferably 3: (0.5-1.5), and when the carbon source includes sucrose (disaccharides), the amount of the two transition metal chlorides and the amount ratio of the carbon source are preferably 3: (0.25-0.75).

[0024] As a preferred embodiment, the ratio of the sum of the molar amounts of the transition metal oxides obtained corresponding to the two transition metal chlorides to the amount of the precipitant is 1:(5-15), including but not limited to any one of 1:5, 1:6, 1:8, 1:10, 1:12, 1:14, 1:15 or any two of the ratios.

[0025] As a preferred embodiment, the pH is adjusted to any one of 9, 9.2, 9.5, 9.8, 10, 10.2, 10.5, 10.8, 11, 11.2, 11.5, 11.8, and 12, or a numerical range consisting of any two of them. It is worth noting that when the pH is less than 9, it is not conducive to increasing the specific surface area of ​​the spherical precursor; when the pH value is greater than 12, the specific surface area of ​​the spherical precursor does not change much, but the cost increases and irregular particles appear.

[0026] As a preferred embodiment, the "preparation of a solution comprising a carbon source, a transition metal chloride and a precipitant" comprises the following steps: first adding the carbon source to deionized water for a first mixing; then adding the transition metal chloride for a second mixing; and then adding the precipitant for a third mixing.

[0027] As a more preferred embodiment, the first mixing, the second mixing and the third mixing are independently carried out by one or more methods including oscillation, stirring, ultrasound, shaking table, etc.; it is further preferred to use a combination of ultrasound and stirring, wherein the intensity of the ultrasound is 30kHz to 100kHz, and the frequency of the stirring is 200rpm to 1500rpm.

[0028] As a preferred embodiment, the hydrothermal reaction is carried out in a closed state; the temperature of the hydrothermal reaction is 110°C to 190°C, and the time of the hydrothermal reaction is 2h to 12h. By controlling the temperature and time of the hydrothermal reaction, a carbon sphere template with uniform morphology and suitable diameter can be obtained.

[0029] As an optional embodiment, the temperature of the hydrothermal reaction includes but is not limited to any one of 110, 120, 130, 140, 150, 160, 170, 180, 190 (°C) or a numerical range consisting of any two of them, and the time of the hydrothermal reaction includes but is not limited to any one of 2, 3, 4, 5, 6, 8, 10, 12 (h) or a numerical range consisting of any two of them.

[0030] As a preferred embodiment, after the reaction is completed, a solid phase is first obtained by solid-liquid separation, and then dried to obtain the precursor; as a more preferred embodiment, the drying temperature is 80°C to 120°C, and the drying time is 24h to 36h.

[0031] As a preferred embodiment, the heat treatment is carried out in an air atmosphere, the heat treatment temperature is 300° C. to 450° C., and the heat treatment time is 1 h to 6 h.

[0032] As an optional embodiment, the temperature of the heat treatment includes but is not limited to any one of 300, 320, 340, 350, 360, 380, 400, 420, 440, 450 (°C) or a numerical range consisting of any two of them, and the time of the heat treatment includes but is not limited to any one of 1, 2, 3, 4, 5, 6 (h) or a numerical range consisting of any two of them.

[0033] The second aspect of the present invention is to provide a double transition metal oxide, which is prepared based on the preparation method of the hollow shell double transition metal oxide as described in the first aspect.

[0034] The third aspect of the present invention is to provide the use of the double transition metal oxide as described in the second aspect in catalysis. It is worth noting that the use includes but is not limited to catalytic products made based on the double transition metal oxide, catalytic reaction processes using the double transition metal oxide, chemical products made by catalysis based on the double transition metal oxide, etc.; that is, no matter whether other catalysts are involved, any product or method involving the double transition metal oxide can be used as an embodiment of the present invention.

[0035] Example 1

[0036] (1) Add 50 mL of deionized water and 0.01 mol of glucose powder to a blue-capped bottle, stir and ultrasonicate for 5 min each, then add 0.02 mol of cobalt chloride hexahydrate and 0.01 mol of nickel chloride hexahydrate, stir and ultrasonicate for 30 min each, then add 0.08 mol of ammonium bicarbonate and continue ultrasonicate and stirring for 30 min each, add triethanolamine dropwise to adjust the pH of the reaction solution to 10, then heat to 130°C for hydrothermal reaction for 2 h, filter after the reaction, and dry at 80°C for 36 h to obtain the reactant precursor.

[0037] (2) The obtained reactant precursor was heat treated at 300°C for 2 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 552 nm, and specific surface area of ​​94 m 2 / g of large specific surface area double transition metal oxides.

[0038] Example 2

[0039] (1) Add 50 mL of deionized water and 0.01 mol of fructose powder to a blue-capped bottle, stir and ultrasonicate for 5 min each, then add 0.02 mol of ferric chloride hexahydrate and 0.01 mol of cobalt chloride hexahydrate, stir and ultrasonicate for 30 min each, then add 0.12 mol of urea and continue ultrasonicate and stirring for 30 min each, add triethanolamine dropwise to adjust the pH of the reaction solution to 12, then heat to 170°C for hydrothermal reaction for 3 h, filter after the reaction, and dry at 80°C for 36 h to obtain the reactant precursor.

[0040] (2) The obtained reactant precursor was heat treated at 300°C for 2 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 510 nm, and specific surface area of ​​87 m 2 / g of large specific surface area double transition metal oxides.

[0041] Example 3

[0042] (1) Add 50 mL of deionized water and 0.012 mol of galactose powder to a blue-capped bottle, stir and ultrasonicate for 5 min each, then add 0.02 mol of ferric chloride hexahydrate and 0.01 mol of cobalt chloride hexahydrate, stir and ultrasonicate for 30 min each, then add 0.08 mol of sodium bicarbonate and continue ultrasonicate and stirring for 30 min each, add triethanolamine dropwise to adjust the pH of the reaction solution to 11, then heat to 160°C for hydrothermal reaction for 3 h, filter after the reaction, and dry at 80°C for 36 h to obtain the reactant precursor.

[0043] (2) The obtained reactant precursor was heat treated at 300°C for 2 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 513 nm, and specific surface area of ​​97 m 2 / g of large specific surface area double transition metal oxides.

[0044] Example 4

[0045] (1) Add 50 mL of deionized water and 0.012 mol of glucose powder to a blue-capped bottle, stir and ultrasonicate for 5 min each, then add 0.02 mol of ferric chloride hexahydrate and 0.01 mol of cobalt chloride hexahydrate, stir and ultrasonicate for 30 min each, then add 0.08 mol of urea and continue ultrasonicate and stirring for 30 min each, add triethanolamine dropwise to adjust the pH of the reaction solution to 11, then heat to 170°C for hydrothermal reaction for 4 h, filter after the reaction, and dry at 80°C for 36 h to obtain the reactant precursor.

[0046] (2) The obtained reactant precursor was heat treated at 300°C for 2 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 570 nm, and specific surface area of ​​89 m 2 / g of large specific surface area double transition metal oxides.

[0047] Example 5

[0048] (1) Add 50 mL of deionized water and 0.005 mol of sucrose powder to a blue-capped bottle, stir and ultrasonicate for 5 min each, then add 0.02 mol of cobalt chloride hexahydrate and 0.01 mol of nickel chloride hexahydrate, stir and ultrasonicate for 30 min each, then add 0.08 mol of ammonium bicarbonate and continue ultrasonicate and stirring for 30 min each, add triethanolamine dropwise to adjust the pH of the reaction solution to 10, then heat to 130°C for hydrothermal reaction for 2 h, filter after the reaction, and dry at 80°C for 36 h to obtain the reactant precursor.

[0049] (2) The obtained reactant precursor was heat treated at 400°C for 5 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 588 nm, and specific surface area of ​​98 m 2 / g of large specific surface area double transition metal oxides.

[0050] Comparative Example 1

[0051] (1) Add 50 mL of deionized water and 0.002 mol of glucose powder to a blue-capped bottle, stir and sonicate for 5 min each, then add 0.02 mol of cobalt chloride hexahydrate and 0.01 mol of nickel chloride hexahydrate, stir and sonicate for 30 min each, then add 0.08 mol of ammonium bicarbonate and continue sonicating and stirring for 30 min each, dropwise add triethanolamine to adjust the pH of the reaction solution to 10, then heat to 130°C for hydrothermal reaction for 2 h, filter after the reaction, and dry at 80°C for 36 h to obtain a reactant precursor.

[0052] (2) The obtained reactant precursor was heat treated at 300°C for 2 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 480 nm, and specific surface area of ​​53 m 2 / g of double transition metal oxides.

[0053] Comparative Example 2

[0054] (1) Add 50 mL of deionized water, 0.02 mol of ferric chloride hexahydrate, and 0.01 mol of cobalt chloride hexahydrate to a blue-capped bottle, stir and ultrasonicate for 30 min each, then add 0.08 mol of urea and continue ultrasonicating and stirring for 30 min each, add ammonia water to adjust the pH of the reaction solution to 10, then heat to 120°C for hydrothermal reaction for 24 h, filter after the reaction, and dry at 80°C for 36 h to obtain the reactant precursor.

[0055] (2) The obtained reactant precursor was heat treated at 300°C for 2 h in an air atmosphere to obtain particles with uniform distribution, regular hollow spherical morphology, D90 particle size of 540 nm, and specific surface area of ​​39 m 2 / g of double transition metal oxides.

[0056] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a hollow shell double transition metal oxide, characterized in that: The steps include: A solution containing a carbon source, a transition metal chloride and a precipitant is prepared, the pH value is adjusted to 9-12 by triethanolamine, and then a hydrothermal reaction is carried out; after the reaction is completed, a precursor is separated and the precursor is heat-treated to obtain a hollow shell-type double transition metal oxide.

2. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The D90 particle size of the hollow shell double transition metal oxide is 500nm to 600nm, and the wall thickness of the hollow shell is 10nm to 25nm; Preferably, the specific surface area of ​​the hollow shell double transition metal oxide is 70 m 2 / g~100m 2 / g.

3. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The carbon source includes at least one of glucose, galactose, fructose or sucrose; and / or, the transition metal chloride comprises at least two of ferric chloride, cobalt chloride or nickel chloride; And / or, the precipitant includes at least one of sodium bicarbonate, ammonium bicarbonate or urea.

4. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The molar ratio of the two transition metal chlorides is (1.2-2.8):1, preferably 2:

1.

5. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The molar ratio of the transition metal chloride to the carbon source is 3:(0.25-1.5).

6. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The molar ratio of the sum of the molar amounts of the transition metal chloride corresponding to the prepared transition metal oxide to the precipitant is 1:(5-15).

7. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 110° C. to 190° C., and the time of the hydrothermal reaction is 2 h to 12 h.

8. The method for preparing the hollow shell type double transition metal oxide according to claim 1, characterized in that: The temperature of the heat treatment is 300° C. to 450° C., and the time of the heat treatment is 1 hour to 6 hours.

9. A double transition metal oxide obtained by the method for preparing a hollow shell type double transition metal oxide according to any one of claims 1 to 8.

10. Use of the double transition metal oxide according to claim 9 in catalysis.