Titanium oxide having a hollow structure and a method for synthesizing the same

Abstract

The application provides a titanium oxide with a hollow structure and a synthesis method thereof, and the synthesis method comprises the following steps: (1) mixing an organic titanium source, a carbon material, an alcohol solvent, ammonia water and water, and then performing separation, washing and drying to obtain a first material; (2) uniformly mixing the first material, nano iron oxide, a saccharide compound and water, performing heat treatment after removing water, and then performing separation, drying and treatment with an acid solution to obtain a second material; (3) mixing the second material, an organic amine and water, and then performing hydrothermal treatment, separation, drying and calcination to obtain the titanium oxide with the hollow structure. The application further provides the titanium oxide with the hollow structure. The titanium oxide obtained by the synthesis method has a complete crystal structure and a shell structure with a hollow shape.

Description

Technical Field

[0001] This invention belongs to the field of inorganic porous material synthesis, and relates to titanium oxide and its synthesis method. Background Technology

[0002] Titanium oxide is an excellent photocatalytic material and a current research hotspot in the field of photocatalysis. Its high catalytic efficiency, stable chemical properties, and strong redox capabilities under ultraviolet light have attracted considerable attention. It is currently widely used in photocatalytic degradation of organic pollutants, solar cells, photocatalytic water splitting for hydrogen production, and gas sensors.

[0003] CN107552030A discloses a titanium dioxide nanoparticle with a multi-defect fluorine-doped hollow burr cubic structure and its preparation method. The preparation method includes the following steps: (1) Tetrabutyl titanate is added to isopropanol and stirred in an ice bath to form solution A; (2) Ammonium fluoride is dissolved in a mixture of water and acetic acid to form solution B, with ammonium fluoride as the fluorine source; (3) Solution B is added dropwise to solution A under vigorous stirring, while maintaining an ice bath during stirring to prevent gel formation, resulting in a white emulsion C; (4) Emulsion C is transferred to a reaction vessel and hydrothermally heated at 160-190°C. 10-15h; Cool to room temperature, take the precipitate and wash it with ethanol and deionized water until the pH value is 6-7, and vacuum dry it; obtain crystal sample; (5) Disperse the crystal sample in a boric acid solution, stir it in a water bath at 50-80℃ for 2-5h to obtain TiO2 nanomaterials; (6) Disperse the TiO2 nanomaterials in anhydrous ethanol, and purge the air with an inert gas; Irradiate with ultraviolet-visible light, take out the sample and dry it at 130-160℃; Repeat step (6) 2-5 times; The product is brownish-yellow, and pure anatase phase titanium dioxide hollow cubic nanoparticles are obtained.

[0004] CN109569739A discloses a titanium dioxide-based double-layer hollow material and its application in hydrogen sulfide photocatalytic treatment. The invention includes the following steps: (1) using polystyrene nanospheres with a particle size of 180 nm as templates and tetrabutyl titanate as a precursor, calcining to prepare hollow titanium dioxide particles; (2) modifying the hollow titanium dioxide with carboxylation to prepare carboxylated titanium dioxide; (3) dispersing the carboxylated titanium dioxide in ethanol, using chromium nitrate nonahydrate as an assembly agent and trimesic acid as a crosslinking agent, performing layer-by-layer self-assembly to prepare a titanium dioxide-based double-layer hollow material.

[0005] CN108452787A discloses a highly visible light active titanium dioxide hollow microsphere, its preparation method and application. The patent includes the following steps: (1) synthesizing a titanium dioxide hollow microsphere precursor; (2) taking a certain amount of the titanium dioxide hollow microsphere precursor prepared in step (1), adding a certain amount of urea and mixing it evenly, then placing the resulting mixture in a muffle furnace and heating it to 550°C for 4 hours, and cooling it to room temperature after calcination to obtain the highly visible light active high oxygen vacancy titanium dioxide hollow microsphere.

[0006] CN107008238 discloses a method for synthesizing hollow titanium dioxide materials for the degradation of organic pollutants. The invention includes the following steps: dispersing 50-150 mg of silver chloride / titanium dioxide solid precursor in 200-480 mL of ethanol solution and mixing thoroughly; sealing the above-obtained mixed solution and irradiating it under electron beam irradiation, then washing the resulting product sequentially with ethanol and distilled water, and centrifuging repeatedly to remove unreacted ions to obtain a solid; drying the obtained solid, which is the hollow titanium dioxide material.

[0007] CN102838162A discloses a porous titanium dioxide hollow sphere, a method for its preparation and adsorption of Cr(VI). The invention includes the following steps: dissolving a titanium dioxide precursor in a certain proportion of a water-organic solvent system; subjecting the entire mixture to solvothermal treatment; and then separating the solid and liquid phases to obtain porous titanium dioxide hollow spheres.

[0008] CN103803643 discloses a monodisperse mesoporous hollow nanosphere titanium dioxide and its preparation method. This invention uses polystyrene microspheres as templates. The obtained composite microspheres can remove the PS template by high-temperature calcination. Coating the outside of the titanium dioxide with silica can prevent the titanium dioxide from agglomerating during calcination and can also prevent the microspheres from breaking during calcination. Moreover, the outermost silica layer can be removed with sodium hydroxide solution. The preparation method is simple and suitable for large-scale production. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a titanium oxide with a hollow structure and a method for synthesizing it. The titanium oxide obtained by the provided synthesis method has a complete crystal structure and a hollow shell structure.

[0010] This invention provides a method for synthesizing titanium oxide with a hollow structure, the method comprising the following steps:

[0011] (1) Under mixed conditions, organic titanium source, carbon material, alcohol solvent, ammonia and water are mixed, and then separated, washed and dried to obtain the first material;

[0012] (2) The first material obtained in step (1), nano iron oxide, carbohydrate compound and water are mixed evenly, and after removing the water, heat treatment is performed. The heat treatment product is treated with acid solution and then separated and dried to obtain the second material.

[0013] (3) The second material obtained in step (2), organic amine and water are mixed and subjected to hydrothermal treatment, and then separated, dried and calcined to obtain titanium oxide with a hollow structure.

[0014] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the organic titanium source in step (1) can be at least one of propyl titanate and butyl titanate.

[0015] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the alcohol solvent in step (1) can be one or more of ethanol, propanol, and butanol.

[0016] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the carbon material in step (1) has a particle size of 1 to 6 μm and a spherical or near-spherical shape.

[0017] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the preparation method of the carbon material in step (1) is as follows: the carbon source, formaldehyde and water are mixed evenly and then treated, and then separated, washed, dried and calcined to obtain the carbon material.

[0018] In a further preferred embodiment, the carbon source in the preparation method of the carbon material can be at least one of glucose and sucrose.

[0019] In a further preferred embodiment, in the method for preparing carbon materials, the mass ratio of carbon source, formaldehyde, and water is 1:0.2-1.5:8-50, preferably 1:0.3-1.3:10-40.

[0020] In a further preferred embodiment, in the method for preparing carbon materials, the treatment temperature after uniformly mixing carbon source, formaldehyde and water is 150-210℃, preferably 160-200℃; the treatment time is 4-22h, preferably 5-20h.

[0021] In a further preferred embodiment, the separation in the preparation method of carbon materials can be carried out by filtration, which usually includes multiple filtrations, generally 1 to 10 times.

[0022] In a further preferred embodiment, the washing method for preparing carbon materials involves water washing, typically until the filtrate is neutral.

[0023] In a further preferred embodiment, the drying conditions in the preparation method of the carbon material are as follows: drying temperature is 100-150℃, and drying time is 1-20h.

[0024] In a further preferred embodiment, in the method for preparing carbon materials, the calcination treatment is carried out in the presence of an inert atmosphere, which may be nitrogen and / or an inert gas; the calcination temperature is 700–1100℃, preferably 800–1000℃; and the calcination time is 3–9 h, preferably 4–8 h.

[0025] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the mass ratio of organic titanium source, carbon material, water, alcohol solvent, and ammonia in step (1) is 0.1-0.7:1:80-220:80-220:0.8-6, preferably 0.2-0.6:1:100-200:100-200:1-5.

[0026] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the mixing process in step (1) preferably involves first mixing carbon materials, water, alcohol solvent and ammonia water evenly, and then introducing an organic titanium source into the mixture.

[0027] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the separation in step (1) can be carried out by filtration, which typically includes 1 to 10 filtrations.

[0028] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the washing in step (1) is water washing, generally until the filtrate is neutral.

[0029] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the drying temperature in step (1) is 100-150°C and the drying time is 1-20h.

[0030] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the carbohydrate compound in step (2) can be at least one of sucrose, glucose, fructose, maltose, and lactose, preferably at least one of sucrose and glucose.

[0031] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the particle size of the nano-iron oxide particles in step (2) is 2-15 nm, preferably 5-10 nm.

[0032] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the mass ratio of the first material obtained in step (1) of step (2), the carbohydrate compound, the nano iron oxide, and the water is 1:1 to 7.5: 0.08 to 0.6: 80 to 310, preferably 1:2 to 7: 0.1 to 0.5: 100 to 300.

[0033] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the temperature for removing moisture in step (2) is 80-160°C, preferably 100-150°C; the moisture is removed until it is completely removed.

[0034] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the heat treatment in step (2) is carried out in the presence of an inert atmosphere, which can be nitrogen or / or an inert gas. The heat treatment temperature is 200–400°C, preferably 300–350°C, and the heat treatment time is 1–12 h, preferably 2–10 h.

[0035] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the mass concentration of the acid solution in step (2) is 0.5% to 5.5%, preferably 1.0% to 5.0%; the acid can be at least one of hydrochloric acid, nitric acid, and sulfuric acid.

[0036] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the mass ratio of the heat-treated product to the acid solution in step (2) is 1:80–210, preferably 1:100–200. The treatment is carried out at 10–40°C for 5–35 min, preferably 10–30 min. The purpose of treating the heat-treated product with the acid solution is to remove iron oxide from the heat-treated product, thereby leaving mesoporous channels in the carbon material, which facilitates the passage of raw materials through the carbon layer to participate in the chemical reaction during subsequent reactions.

[0037] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the separation in step (2) can be carried out by filtration, which usually includes multiple filtrations, generally 1 to 10 times.

[0038] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the drying temperature in step (2) is 100-150°C and the drying time is 1-20h.

[0039] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the organic amine in step (3) can be at least one of n-butylamine, ethylenediamine, and hexamethylenediamine.

[0040] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the mass ratio of the second material obtained in step (2) of step (3), the organic amine, and the water is 1-12:1-12:100, preferably 2-10:2-10:100.

[0041] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the hydrothermal treatment temperature in step (3) is 90-210°C, preferably 100-200°C; the treatment time is 8-21h, preferably 10-20h.

[0042] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the separation in step (3) can be carried out by filtration, which usually includes multiple filtrations, generally 1 to 10 times.

[0043] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the drying temperature in step (3) is 100-150°C and the drying time is 1-20h.

[0044] Furthermore, in the above-mentioned method for synthesizing titanium oxide with a hollow structure, the calcination in step (3) is carried out at 400-600°C for 1-10 hours. The calcination is required to be carried out in the presence of an oxygen-containing atmosphere, in which the volume content of oxygen is 20%-100%. The oxygen-containing atmosphere can be at least one of oxygen, air, or a mixture of oxygen and other inert atmospheres. The inert atmosphere can be nitrogen and / or an inert gas.

[0045] This invention provides a titanium oxide with a hollow structure, which is obtained by the above-described synthesis method.

[0046] Furthermore, in the aforementioned hollow titanium oxide, the specific surface area is 50–150 m². 2 / g.

[0047] Furthermore, in the above-mentioned hollow titanium oxide, the morphology of the hollow titanium oxide is an irregular sphere or block with a cavity in the center; the particle size is 1-6 μm; and the shell thickness is 200-1000 nm.

[0048] The hollow titanium dioxide material provided by this invention can be used as a photocatalytic material for photocatalytic degradation of organic pollutants, solar cells, photocatalytic water splitting for hydrogen production, gas sensors, and other fields.

[0049] Compared with the prior art, the hollow titanium oxide and its synthesis method provided by the present invention have the following advantages:

[0050] This invention provides a novel synthetic route for titanium dioxide with a hollow shell structure. Traditional hollow materials typically use polystyrene spheres as templates, then coat the outer surface of the polystyrene spheres with a shell material, and finally remove the polystyrene spheres, leaving a hollow titanium dioxide shell. On the one hand, the polystyrene spheres used in this process are relatively expensive, resulting in high production costs; on the other hand, titanium material cannot be completely and effectively coated on the outer surface of the polystyrene spheres, ultimately failing to form a hollow shell, leading to low production efficiency.

[0051] In the synthesis method provided by this invention, the first material prepared is a titanium-carbon core-shell material forming a titanium oxide shell. Then, a new carbon layer is further introduced onto this material to form a more complex carbon-titanium-carbon hierarchical structure. After treating this material in a hydrothermal environment, not only are the physicochemical properties of titanium oxide improved, but the mechanical strength of hollow titanium oxide is also enhanced. Because the titanium oxide shell is confined between the two carbon materials, the spatial constraint allows the titanium oxide to resist the violent impact of water during the intense hydrothermal reaction, preventing damage to the titanium oxide shell. Therefore, high-quality hollow titanium oxide with high crystallinity can be prepared. Attached Figure Description

[0052] Figure 1 This is a scanning electron microscope image of the sample obtained in Example 1.

[0053] Figure 2 This is a scanning electron microscope image of the sample obtained in Example 1.

[0054] Figure 3 Scanning electron microscope images of the sample obtained in Comparative Example 1. Detailed Implementation

[0055] The technical solutions and effects of the present invention will be further illustrated below with reference to the embodiments, but the invention is not limited to the following embodiments.

[0056] In this invention, the pore structure of the material was characterized by N2 adsorption-desorption using a physical adsorption instrument from Micron Technology (USA). Prior to measurement, the sample was vacuum-treated at 300°C for at least 4 hours. The specific surface area was calculated using the BET formula.

[0057] In this invention, the microcrystalline morphology of the material was characterized by scanning electron microscopy (SEM) using a JSM-6 301F scanning electron microscope (equipped with an Oxford EDS) from Nippon Electronics Corporation. The operating voltage was 20 kV, the working distance was 15 mm, and the resolution was 1.5 nm.

[0058] In this invention, the crystal phase structure and crystallinity of the material are characterized by X-ray diffraction. The test is performed using a Rigaku D / max2500 X-ray diffractometer with a Cu target, Kα radiation source, graphite monochromator, tube voltage of 40kV, tube current of 80mA, scanning range of 5° to 40°, step size of 0.1°, and scanning speed of 1° / min.

[0059] In this invention, all chemical reagents used in the embodiments and comparative examples are analytical chemical reagents, which can be obtained by purchasing commercially available products.

[0060] Example 1

[0061] (1) First, glucose, formaldehyde and distilled water are mixed and stirred for 1 hour, with the mass ratio of glucose, formaldehyde and water being 1:1.0:30; then the mixture is placed in a reaction vessel and treated at 166°C for 10 hours; then the solid product is washed with distilled water 4 times until neutral, dried at 130°C for 12 hours, and then treated at 810°C in a nitrogen atmosphere for 5 hours to obtain carbon material.

[0062] (2) After mixing the carbon material, water, ethanol, and ammonia obtained in step (1) evenly, tetrabutyl titanate is added dropwise, wherein the mass ratio of tetrabutyl titanate, carbon material, water, ethanol, and ammonia is 0.50:1:135:155:3.0. Then the solid product is washed four times with distilled water until neutral, and then dried at 120°C for 12 hours to obtain the first material.

[0063] (3) Mix the first material, water, nano iron oxide and sucrose, wherein the mass ratio of the first material, sucrose, nano iron oxide and water is 1:3.4:0.37:134, and then evaporate the water at 100°C; then treat it at 315°C for 5 hours in a nitrogen atmosphere; then mix it with hydrochloric acid solution (1.0wt% hydrochloric acid solution, the mass ratio of solid material and acid solution after treatment is 1:115) for 23 minutes; then filter the obtained sample 4 times, and then dry it in an oven at 110°C for 12 hours to obtain the second material.

[0064] (4) The second material, ethylenediamine and water were mixed and loaded into the reactor and treated at 126°C for 12 hours. The mass ratio of the second material, ethylenediamine and water was 3.4:3.6:100. The resulting sample was then filtered four times and dried in an oven at 110°C for 12 hours. Finally, it was calcined in air at 510°C for 7 hours. The resulting sample was numbered A1.

[0065] Figure 1 These are scanning electron microscope images of the prepared sample A1, produced by... Figure 1 It can be seen that the sample is an irregular hollow sphere. Figure 2 These are scanning electron microscope images of the prepared sample after grinding. Figure 2 It can be seen that after grinding, the sample structure was destroyed, producing spherical shell fragments.

[0066] Example 2

[0067] (1) First, glucose, formaldehyde and distilled water are mixed and stirred for 1 hour, with the mass ratio of glucose, formaldehyde and water being 1:0.4:10; then the mixture is placed in a reaction vessel and treated at 166°C for 18 hours; then the solid product is washed with distilled water 4 times until neutral, dried at 120°C for 12 hours, and then treated at 850°C in a nitrogen atmosphere for 8 hours to obtain carbon material.

[0068] (2) After mixing the carbon material, water, ethanol, and ammonia obtained in step (1) evenly, titanate is added dropwise, wherein the mass ratio of titanate, carbon material, water, ethanol, and ammonia is 0.2:1:170:200:5. Then the solid product is washed four times with distilled water until neutral, and dried at 120°C for 12 hours to obtain the first material.

[0069] (3) The first material obtained in step (2), water, nano-iron oxide and sucrose are mixed, wherein the mass ratio of the first material, sucrose, nano-iron oxide and water is 1:2.5:0.55:130. Then the water is evaporated at 100°C; then it is treated at 320°C for 3 hours in a nitrogen atmosphere; then it is mixed with hydrochloric acid solution (3.2wt% hydrochloric acid solution, the mass ratio of solid material and acid solution after treatment is 1:120) and treated for 17 minutes; then the obtained sample is filtered 4 times, and then placed in an oven to dry at 110°C for 12 hours to obtain the second material.

[0070] (4) The second material obtained in step (3), ethylenediamine and water, are mixed and loaded into a reactor and treated at 100°C for 10 hours. The mass ratio of the second material, ethylenediamine and water, is 3:3:100. The resulting sample is then filtered four times, dried in an oven at 110°C for 12 hours, and finally calcined in air at 500°C for 7 hours. The resulting sample is numbered A2.

[0071] Example 3

[0072] (1) First, glucose, formaldehyde and distilled water are mixed and stirred for 1 hour, with the mass ratio of glucose, formaldehyde and water being 1:1.2:38; then the mixture is placed in a reaction vessel and treated at 190°C for 6 hours; then the solid product is washed with distilled water 4 times until neutral, dried at 120°C for 12 hours, and then treated at 900°C in a nitrogen atmosphere for 4 hours to obtain carbon material.

[0073] (2) After mixing the carbon material, water, ethanol, and ammonia obtained in step (1) evenly, titanate is added dropwise, wherein the mass ratio of titanate, carbon material, water, ethanol, and ammonia is 0.6:1:110:120:1. Then the solid product is washed four times with distilled water until neutral, and dried at 120°C for 12 hours to obtain the first material.

[0074] (3) The first material obtained in step (2), water, nano-iron oxide and sucrose are mixed, wherein the mass ratio of the first material, sucrose, nano-iron oxide and water is 1:6:0.2:200. Then the water is evaporated at 100℃; then it is treated at 350℃ for 10h in a nitrogen atmosphere; then it is mixed with hydrochloric acid solution (3.5wt% hydrochloric acid solution, the mass ratio of solid material and acid solution after treatment is 1:185) and treated for 20min; then the obtained sample is filtered 3 times, and then placed in an oven to dry at 110℃ for 12h.

[0075] (4) The second material obtained in step (3), ethylenediamine, and water are mixed and placed in a reactor and treated at 200°C for 20 hours, wherein the mass ratio of the second material, ethylenediamine, and water is 8:9:100. The resulting sample is then filtered four times, dried in an oven at 110°C for 12 hours, and finally calcined in air at 500°C for 7 hours. The resulting sample is numbered A3.

[0076] Example 4

[0077] (1) First, glucose, formaldehyde and distilled water are mixed and stirred for 1 hour, with the mass ratio of glucose, formaldehyde and water being 1:0.95:33; then the mixture is placed in a reaction vessel and treated at 195°C for 10 hours; then the solid product is washed with distilled water 4 times until neutral, dried at 120°C for 12 hours, and then treated at 850°C in a nitrogen atmosphere for 5 hours to obtain carbon material.

[0078] (2) Mix the carbon material, water, ethanol, and ammonia obtained in step (1) evenly, and add tetrabutyl titanate dropwise. The mass ratio of tetrabutyl titanate, carbon material, water, alcohol, and ammonia is 0.40:1:138:155:4.5. Then wash the solid product with distilled water four times until neutral, and dry it at 120°C for 12 hours to obtain the first material.

[0079] (3) The first material obtained in step (2), water, nano-iron oxide particles and sucrose are mixed, wherein the mass ratio of the first material, sugar, nano-iron oxide and water is 1:2.6:0.43:169. Then the water is evaporated at 100℃; then it is treated at 330℃ for 5h in a nitrogen atmosphere; then it is mixed with hydrochloric acid (1.8t% hydrochloric acid solution, the mass ratio of solid material and acid solution after treatment is 1:173) for 20min; then the resulting sample is filtered 3 times and then placed in an oven to dry at 110℃ for 12h.

[0080] (4) The second material obtained in step (3), ethylenediamine and water are mixed and loaded into the reactor and treated at 135°C for 12 hours. The mass ratio of the second material, ethylenediamine and water is 5.8:9:100. The obtained sample is then filtered three times, dried in an oven at 110°C for 12 hours, and finally calcined in air at 500°C for 7 hours. The obtained sample is numbered A4.

[0081] Example 5

[0082] (1) First, glucose, formaldehyde and distilled water are mixed and stirred for 1 hour, with the mass ratio of glucose, formaldehyde and water being 1:1.15:25; then the mixture is placed in a reaction vessel and treated at 175°C for 13 hours; then the solid product is washed with distilled water 4 times until neutral, dried at 120°C for 12 hours, and then treated at 790°C for 5.5 hours in a nitrogen atmosphere to obtain carbon material.

[0083] (2) Mix the carbon material, water, propanol, and ammonia obtained in step (1) evenly, and add tetrabutyl titanate dropwise. The mass ratio of tetrabutyl titanate, carbon material, water, propanol, and ammonia is 0.71:1:150:155:2.5. Then wash the solid product with distilled water four times until neutral, and dry it at 120°C for 12 hours to obtain the first material.

[0084] (3) The first material obtained in step (2), water, nano-iron oxide and glucose are mixed, wherein the mass ratio of the first material, glucose, nano-iron oxide and water is 1:3.3:0.3:180. Then the water is evaporated at 100℃; then it is treated at 310℃ for 5h in a nitrogen atmosphere; then it is mixed with hydrochloric acid solution (2.2wt% hydrochloric acid solution, the mass ratio of solid material and acid solution after treatment is 1:160) and treated for 13min; then the obtained sample is filtered 3 times and then placed in an oven to dry at 110℃ for 12h.

[0085] (4) The second material obtained in step (3), ethylenediamine, and water are mixed and loaded into a reactor and treated at 121°C for 12 hours. The mass ratio of the second material, amine, and water is 7.6:7.5:100. The resulting sample is then filtered four times and placed in an oven to dry at 110°C for 12 hours. Finally, it is calcined in air at 525°C for 7 hours. The resulting sample is numbered A5.

[0086] Comparative Example 1

[0087] (1) First, glucose, formaldehyde and distilled water are mixed and stirred for 1 hour, with the mass ratio of glucose, formaldehyde and water being 1:1.0:30; then the mixture is placed in a reaction vessel and treated at 166°C for 10 hours; then the solid product is washed with distilled water 4 times until neutral, dried at 130°C for 12 hours, and then treated at 810°C in a nitrogen atmosphere for 5 hours to obtain carbon material.

[0088] (2) After mixing the carbon material, water, ethanol, and ammonia obtained in step (1) evenly, tetrabutyl titanate is added dropwise, wherein the mass ratio of tetrabutyl titanate, carbon material, water, ethanol, and ammonia is 0.50:1:135:155:3.0. Then the solid product is washed four times with distilled water until neutral, and then dried at 120°C for 12 hours to obtain the first material.

[0089] (3) The second material, ethylenediamine, and water were mixed and loaded into a reactor and treated at 126°C for 12 hours. The mass ratio of the second material, ethylenediamine, and water was 3.4:3.6:100. The resulting sample was then filtered four times, dried in an oven at 110°C for 12 hours, and finally calcined in air at 510°C for 7 hours. The resulting sample was numbered D1. Figure 3 These are scanning electron microscope images of the prepared sample (after grinding), by Figure 3It can be seen that the obtained sample has a blocky crystal morphology. No broken spherical particles were found after grinding, indicating that no hollow structure was formed.

[0090] Comparative Example 2

[0091] The experiment was essentially the same as in Example 1, except that in step (3), the acid concentration used for the acid treatment was 15 wt%, and the resulting sample was numbered D2. This method yielded too little solid product, making it impossible to obtain the target product, and the experiment failed.

[0092] Comparative Example 3

[0093] The experiment was basically the same as in Example 1, except that the acid treatment in step (3) was performed at a temperature of 115°C, and the resulting sample was numbered D3. The method yielded too little solid product, making it impossible to obtain the target product, and the experiment failed.

[0094] Comparative Example 4

[0095] The process is basically the same as in Example 1, except that the carbon material in step (1) is ordinary activated carbon material. The carbon material particles are uneven in shape and size, and the particles are irregular shapes such as strips and blocks. The particle size ranges from tens of nanometers to several micrometers, which does not meet the requirements of this invention. The resulting sample is numbered D4.

[0096] Comparative Example 5

[0097] The results were essentially the same as in Example 1, except that the hot alkaline treatment in step (4) was omitted. The resulting sample was designated D5, and its properties are shown in Table 1. Granular titanium oxide particles were obtained; no hollow structure was obtained. This indicates that the prepared hollow titanium oxide decomposed during the preparation process, thus failing to yield hollow titanium oxide.

[0098] Table 1. Physicochemical properties of samples obtained from each embodiment and comparative example.

[0099]

[0100] Note: The sample obtained in Example 1 is used as a reference in this invention, and its crystallinity is set to 100%. The relative crystallinity of all other samples is obtained by comparing it with the crystallinity of the reference.

Claims

1. A method for synthesizing titanium oxide with a hollow structure, the method comprising the following steps: (1) Under mixed conditions, organic titanium source, carbon material, alcohol solvent, ammonia and water are mixed, and then separated, washed and dried to obtain the first material; (2) The first material obtained in step (1), nano iron oxide, sugar compound and water are mixed evenly, and after removing the water, heat treatment is performed. The heat treatment product is treated with acid solution and then separated and dried to obtain the second material. (3) The second material obtained in step (2), organic amine and water are mixed and subjected to hydrothermal treatment, and then separated, dried and calcined to obtain titanium oxide with a hollow structure.

2. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The organic titanium source in step (1) is at least one of propyl titanate and butyl titanate.

3. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The alcohol solvent in step (1) is one or more of ethanol, propanol, and butanol.

4. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The carbon material in step (1) has a particle size of 1 to 6 μm and is spherical or near-spherical in shape.

5. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The preparation method of carbon material in step (1) is as follows: carbon source, formaldehyde and water are mixed evenly and then processed, and then separated, washed, dried and calcined to obtain carbon material.

6. The method for synthesizing titanium oxide with a hollow structure according to claim 5, characterized in that: The carbon source is at least one of glucose and sucrose.

7. The method for synthesizing titanium oxide with a hollow structure according to claim 5, characterized in that: The mass ratio of carbon source, formaldehyde, and water is 1:0.2-1.5:8-50, preferably 1:0.3-1.3:10-40.

8. The method for synthesizing titanium oxide with a hollow structure according to claim 5, characterized in that: The treatment temperature after uniformly mixing carbon source, formaldehyde and water is 150-210℃, preferably 160-200℃; the treatment time is 4-22h, preferably 5-20h.

9. The method for synthesizing titanium oxide with a hollow structure according to claim 5, characterized in that: The calcination process is carried out in the presence of an inert atmosphere, wherein the inert atmosphere is nitrogen and / or an inert gas, the calcination temperature is 700–1100℃, preferably 800–1000℃, and the calcination time is 3–9 h, preferably 4–8 h.

10. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The mass ratio of organic titanium source, carbon material, water, alcohol solvent and ammonia in step (1) is 0.1-0.7:1:80-220:80-220:0.8-6, preferably 0.2-0.6:1:100-200:100-200:1-5.

11. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The carbohydrate compound in step (2) is at least one of sucrose, glucose, fructose, maltose, and lactose, preferably at least one of sucrose and glucose.

12. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The particle size of the nano-iron oxide particles in step (2) is 2-15 nm, preferably 5-10 nm.

13. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: In step (2), the mass ratio of the first material obtained in step (1), the carbohydrate compound, the nano iron oxide, and the water is 1:1 to 7.5: 0.08 to 0.6: 80 to 310, preferably 1:2 to 7: 0.1 to 0.5: 100 to 300.

14. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The heat treatment in step (2) is carried out in the presence of an inert atmosphere, which is nitrogen or / or an inert gas. The heat treatment temperature is 200-400℃, preferably 300-350℃, and the heat treatment time is 1-12h, preferably 2-10h.

15. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The mass concentration of the acid solution in step (2) is 0.5% to 5.5%, preferably 1.0% to 5.0%; the acid is at least one of hydrochloric acid, nitric acid, and sulfuric acid.

16. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The organic amine in step (3) is at least one of n-butylamine, ethylenediamine, and hexamethylenediamine.

17. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The mass ratio of the second material, organic amine, and water obtained in step (2) of step (3) is 1-12:1-12:100, preferably 2-10:2-10:

100.

18. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The hydrothermal treatment temperature in step (3) is 90-210℃, preferably 100-200℃; the treatment time is 8-21h, preferably 10-20h.

19. The method for synthesizing titanium oxide with a hollow structure according to claim 1, characterized in that: The roasting in step (3) is carried out at 400-600℃ for 1-10 hours. The roasting needs to be carried out in the presence of an oxygen-containing atmosphere, in which the volume content of oxygen is 20%-100%. The oxygen-containing atmosphere is at least one of oxygen, air, or a mixture of oxygen and other inert atmospheres. The inert atmosphere is nitrogen and / or an inert gas.

20. A titanium oxide having a hollow structure, characterized in that: The hollow titanium oxide is obtained by the synthesis method described in any one of claims 1-19.

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