Alumina nanowires / rods, methods of making and applications thereof

Abstract

The application relates to the technical field of aluminum oxide, in particular to an aluminum oxide nanowire / nanorod as well as a preparation method and application thereof. The length-diameter ratio of the aluminum oxide nanowire / nanorod is greater than or equal to 10, and the specific surface area is greater than or equal to 200 m 2 / g. The content of five-coordinated Al 3+ defect sites in the aluminum oxide nanowire / nanorod is greater than or equal to 1.95 mmol / g, and the proportion is greater than or equal to 10%. The aluminum oxide nanowire / nanorod provided by the application has a high density of unsaturated coordination aluminum species (five-coordinated Al 3+ ), and can be widely applied to the fields of petroleum chemical industry and fine chemical industry, in particular, to the fields of catalyst carrier, gas-liquid adsorption, solid-phase filler and sewage treatment agent.

Description

Technical Field

[0001] This invention relates to the field of alumina technology, specifically to an alumina nanowire / rod, its preparation method, and its application. Background Technology

[0002] Currently, it is estimated that 85% of the global chemical industry involves catalytic processes, particularly heterogeneous catalysis, a diverse and highly interdisciplinary field that combines materials and surface science, physics, analytical and theoretical chemistry, and chemical engineering. It is a crucial aspect of the entire catalytic process. Catalysts are the core of industrial catalytic processes, and catalyst supports are one of the key factors influencing catalyst activity. Common supports currently include metal oxides, metal-organic frameworks (MOFs), molecular sieves, carbon materials, and novel materials. By rationally designing the support structure, such as introducing vacancies, doping, and lattice defects, catalytic performance can be effectively improved. For example, Zhang et al. found that small-crystal ZrO2 catalysts have a high exposure ratio of defect sites such as edges, corners, and steps. Under the same treatment conditions, they are more likely to generate high concentrations of active Zr species, resulting in higher alkane activation capabilities (Nature Communications, 2018, 9, 3794). Therefore, developing catalyst materials with specific morphologies is a hot research direction for improving the efficiency of industrial processes.

[0003] One-dimensional nanomaterials, such as nanorods or nanowires, have attracted widespread attention for constructing nanoscale optoelectronic, optical, and chemical sensors. One-dimensional metal oxide materials retain a high specific surface area, exhibit better thermal stability, and possess excellent adsorption capabilities for specific chemical or biological molecules. One-dimensional nanomaterials have been widely used in the fabrication of solid-state devices, such as field-effect transistors, inverters, light-emitting diodes, sensors, and even simple memory.

[0004] Alumina is a typical acidic support, widely used in catalysis research and industrial applications. Changes in the physicochemical properties of alumina affect its interaction with metals, thus influencing the interaction between reactants and products. In recent years, with the development of preparation techniques, nanostructured alumina has attracted widespread attention due to its rich microstructures and high catalytic performance. As a support, alumina can provide catalysts with high thermal and hydrothermal stability, and its different pore sizes and various specific structural exposure surfaces also provide a powerful site for the modification and alteration of active metal species. Recent studies have found that alumina with an unsaturated coordination structure (five-coordinate Al)... 3+ γ-alumina with defect sites has a significant impact on the dispersion of metals and can improve the interaction between metals and supports (Nanoscale, 2015, 7, 13313-13344). Based on this, we developed Al with high specific surface area and high five-coordinate...3+ Al2O3 nanowires with high defect site content are of great significance for the design of efficient industrial catalysts and the development of efficient and energy-saving chemical processes.

[0005] Currently, alumina nanowires / rods can be prepared using specialized methods, controlled preparation parameters, and the addition of template agents. For example, CN111848140A and CN103991889A prepared alumina nanowires / rods via freeze-drying and ball milling, respectively; CN103449491A and CN110512310A introduced emulsifiers or additives during alumina preparation to achieve alumina nanowire preparation; CN109467110A, CN114394612A, CN102557092A, and CN101880049A prepared nanorod / wire alumina materials by introducing template agents such as graphene and monosaccharides, but the template agents need to be removed during the preparation process; CN101885501A used metallic Cu as a catalyst to complete the growth of alumina nanowires.

[0006] However, research on the preparation of alumina nanowires / rods using simple and efficient methods is still limited, especially on the efficient and simple acquisition of nanowires / rods with high five-coordinate Al content. 3+ No method has yet been reported for preparing alumina nanowires / rods with defect sites that simultaneously possess high aspect ratio and high specific surface area. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned technical problems and provide an alumina nanowire / rod, its preparation method, and its application. This alumina nanowire / rod possesses excellent aspect ratio and specific surface area, as well as a high content and high proportion of five-coordinated Al. 3+ Defect sites; at the same time, this method simplifies the process flow and facilitates industrial production.

[0008] The first aspect of this invention provides alumina nanowires / rods, wherein the alumina nanowires / rods have an aspect ratio ≥10 and a specific surface area ≥200m². 2 / g; Five-coordinated Al in the alumina nanowires / rods 3+ The content of defective sites is ≥1.95mmol / g, accounting for ≥10%.

[0009] In this invention, unless otherwise specified, the alumina nanowires / rods include alumina nanowires and alumina nanorods.

[0010] In this invention, the coordination of alumina includes tetracoordination, pentacoordination, and hexacoordination, namely Al(VI), Al(V), and Al(IV). Al(VI) and Al(IV) are fully coordinated, meaning that all Al atoms are occupied by O atoms. Al(V) is special; in this case, the Al atom lacks one O coordination site, meaning that the Al atom has unpaired electrons. Therefore, Al(V) can adsorb metals and participate in chemical reactions. This is why alumina with a high content and high proportion of Al(V) is required for preparation.

[0011] Preferably, the surface of the alumina nanowires / rods has a convex structure.

[0012] Preferably, in 27 In the solid-state NMR spectrum of Al, the alumina nanowires / rods have characteristic peaks with chemical shifts of 7ppm±10%, 40ppm±10%, and 77ppm±10%.

[0013] A second aspect of this invention provides a method for preparing alumina nanowires / rods, the method comprising:

[0014] (1) Aluminum source, alkaline compound, optional biomimetic inducer, regulator and solvent are mixed and aged to obtain an aged product containing alumina precursor seed crystals.

[0015] (2) The aging product is subjected to solvothermal treatment to obtain a solid-liquid mixture;

[0016] (3) The solid-liquid mixture is subjected to solid-liquid separation, and the resulting alumina precursor is dried and calcined in sequence to obtain alumina nanowires / rods;

[0017] The conditions for the solvothermal treatment include: a temperature of 80-200℃ and a time of 4-72h.

[0018] The third aspect of this invention provides an alumina nanowire / rod provided in the first aspect, or an alumina nanowire / rod prepared by the preparation method provided in the second aspect, for use in catalyst supports, gas-liquid adsorption, solid-phase fillers, and wastewater treatment agents.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The alumina nanowires / rods provided by the present invention effectively enhance the five-coordinated Al under the premise of having excellent aspect ratio and high specific surface area. 3+ The content and proportion of defect sites; preferably, the alumina nanowires / rods also have a convex structure, so that the alumina nanowires / rods have specific structural characteristics;

[0021] (2) The preparation method provided by this invention directly uses aging and solvothermal treatment on a mixture containing an aluminum source to regulate the density of specific sites on the alumina surface, specifically by regulating unsaturated coordinated aluminum species (five-coordinate Al). 3+ The density of defect sites; this preparation method uses alkaline compounds and regulators, assisted by direct aging and solvothermal treatment, to regulate the unsaturated coordinated aluminum species on the alumina surface;

[0022] (3) The preparation method provided by the present invention also utilizes natural biological drying agents as biomimetic inducers to form nanowire materials / rods with convex structures; at the same time, the preparation method does not require the addition of template agents, catalysts or emulsifiers, which simplifies the process and facilitates industrial production.

[0023] (4) The alumina nanowires / rods provided by this invention have a high number of unsaturated coordinated aluminum species (five-coordinate Al). 3+ With its high density, it can be widely used in petrochemical and fine chemical industries, especially in catalyst carriers, gas-liquid adsorption, solid fillers and wastewater treatment agents. Attached Figure Description

[0024] Figure 1 Here is a SEM image of the alumina nanowires S1 prepared in Example 1;

[0025] Figure 2 The image shows the XRD pattern of the alumina nanowires S1 prepared in Example 1.

[0026] Figure 3 The N2 adsorption-desorption curve of the alumina nanowires S1 prepared in Example 1 is shown.

[0027] Figure 4 The alumina nanowires S1 prepared in Example 1 27 Al solid-state nuclear magnetic resonance spectrum;

[0028] Figure 5 Here is a SEM image of the alumina nanowires S2 prepared in Example 2;

[0029] Figure 6 SEM image of alumina DS1 prepared in Comparative Example 1;

[0030] Figure 7 For the commercial alumina DS3 in Comparative Example 3 27 Nuclear magnetic resonance spectrum of Al solid. Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] The first aspect of this invention provides alumina nanowires / rods, wherein the alumina nanowires / rods have an aspect ratio ≥10 and a specific surface area ≥200m². 2 / g; the five-coordinated Al in the alumina nanowires 3+ The content of defective sites is ≥1.95mmol / g, accounting for ≥10%.

[0033] The inventors of this application have discovered that the surface structure of alumina is complex, and its microstructure enables diverse applications in the fine chemical industry. However, the density of specific structures can limit its application in particular fields. Therefore, by controlling the density of specific sites on the alumina surface, especially by controlling the unsaturated coordinated aluminum species (five-coordinate Al), this method can be applied to alumina. 3+ The density of defect sites effectively improves the five-coordinated Al content while ensuring that alumina nanowires have excellent aspect ratio and high specific surface area. 3+ The content of defect sites makes the five-coordinated Al in alumina nanowires... 3+ The content of defective sites is ≥1.95mmol / g, accounting for ≥10%.

[0034] In a preferred embodiment, during the preparation of alumina nanowires / rods, a natural biological desiccant with a superhydrophobic structure is added as a biomimetic inducer, such as the nanosheet structure on canna leaves or the nanowires on the surface of ramie leaves. By utilizing the special surface structure of natural organisms, a specific structure can be effectively induced for alumina nanowires / rods to form, that is, a convex structure with a spherical shape is formed on the surface of alumina nanowires / rods.

[0035] In this invention, unless otherwise specified, five-coordinated Al 3+ The content of defect sites is based on 27 The calculation is performed using the NMR spectrum of Al solid-state aluminum. Specifically, the aluminum species in the alumina material are classified into three types: those with chemical shifts around 7, 40, and 77 ppm, belonging to Al(VI), Al(V), and Al(IV) structures, respectively. The molar fraction of unsaturated coordinated aluminum species (Al(V)) is determined based on the ratio of their peak areas. Based on the above molar fraction, multiplying the molar fraction of Al(V) by twice the number of moles of alumina in 1g of alumina nanowires / rods yields the molar content of Al(V): x(Al(V)) × 2 × 0.0098, where 0.0098 represents the number of moles of Al₂O₃ in 1g. The number of moles of alumina is the sum of the moles of aluminum species Al(VI), Al(V), and Al(IV).

[0036] In some embodiments of the present invention, preferably, the aspect ratio of the alumina nanowires / rods is 10-1000, for example, 10, 20, 50, 80, 100, 200, 300, 500, 1000, and any value within the range of any two values, preferably 10-300; the specific surface area is 200-500 m². 2 / g, for example, 200m 2 / g、220m 2 / g、250m 2 / g、280m 2 / g、300m 2 / g、500m 2 / g, and any value within the range of any two values, preferably 200-300m 2 / g. In this invention, the specific surface area parameter was measured using a fully automated isothermal adsorption analyzer.

[0037] In one specific embodiment of the present invention, when the aspect ratio is 10, the nano-alumina has a rod-like structure, that is, alumina nanorods; when the aspect ratio is greater than 10, the nano-alumina has a linear structure, that is, alumina nanowires.

[0038] In some embodiments of the present invention, preferably, the alumina nanowires / rods contain five-coordinated Al. 3+ The defect site content is 1.95-5.9 mmol / g, for example, 2 mmol / g, 2.5 mmol / g, 3 mmol / g, 3.5 mmol / g, 4 mmol / g, 4.5 mmol / g, 5 mmol / g, 5.5 mmol / g, 5.9 mmol / g, or any value within any range of two such values, preferably 2.9-4.9 mmol / g; the percentage is 10-30%, for example, 10%, 15%, 18%, 20%, 22%, 25%, 30%, or any value within any range of two such values, preferably 15-25%. In this invention, alumina nanowires / rods that meet the above ranges are more conducive to improving the adsorption activity and catalytic activity of unsaturated coordinated aluminum species.

[0039] In some embodiments of the present invention, preferably, the length of the alumina nanowires / rods is 10nm-500μm, more preferably 100nm-300μm.

[0040] In this invention, the alumina nanowires / rods have a mesoporous structure. Preferably, the pore volume of the alumina nanowires / rods is 0.1-5 cm³. 3 / g, preferably 0.2-3cm 3 / g; the average pore size is 5-100nm, preferably 10-60nm. In this invention, the average pore size parameter and pore volume parameter are both measured using a fully automatic isothermal adsorption instrument and calculated using the BJH model.

[0041] In some embodiments of the present invention, preferably, such as Figure 1 As shown, the surface of the alumina nanowires / rods has a convex structure.

[0042] In some embodiments of the present invention, more preferably, the diameter of the convex structure is 1-100 nm, more preferably 1-60 nm; the coverage of the convex structure is ≤30%, more preferably 5-30%. In the present invention, coverage refers to the proportion of the convex structure on the surface of the alumina nanowire / rod.

[0043] In some embodiments of the present invention, preferably, the alumina nanowires / rods have an amorphous crystalline phase structure. In this invention, the crystal phase parameters are obtained using X-ray powder diffraction analysis; the microstructure parameters are measured using scanning electron microscopy.

[0044] In some embodiments of the present invention, preferably, in 27 In the solid-state NMR spectrum of Al, the alumina nanowires / rods have characteristic peaks with chemical shifts of 7ppm±10%, 40ppm±10%, and 77ppm±10%, which are attributed to aluminum species structures of Al(VI), Al(V), and Al(IV), respectively.

[0045] A second aspect of this invention provides a method for preparing alumina nanowires / rods, the method comprising:

[0046] (1) Aluminum source, alkaline compound, optional biomimetic inducer, regulator and solvent are mixed and aged to obtain an aged product containing alumina precursor seed crystals.

[0047] (2) The aging product is subjected to solvothermal treatment to obtain a solid-liquid mixture;

[0048] (3) The solid-liquid mixture is subjected to solid-liquid separation, and the resulting alumina precursor is dried and calcined in sequence to obtain alumina nanowires / rods;

[0049] The conditions for the solvothermal treatment include: a temperature of 80-200℃ and a time of 4-72h.

[0050] In the preparation method provided by this invention, an alkaline compound (preferably urea) is used as a precipitant. Through slow hydrolysis in solvothermal treatment, an alkali is formed to promote the formation of alumina. The crystallization rate of the aluminum precursor is controlled by combining the conditions of solvothermal treatment and the amount of alkaline compound, thereby realizing the formation of nanowire / rod-shaped alumina. At the same time, a regulator is added, which can be specifically adsorbed during solvothermal treatment (crystallization process), thereby guiding the formation of alumina and forming a specific nanowire / rod morphology.

[0051] In some embodiments of the present invention, preferably, in step (1), the molar ratio of the alkaline compound to the aluminum source (calculated as Al) is 4-100:1, for example, 4:1, 5:1, 8:1, 10:1, 15:1, 20:1, 30:1, 50:1, 100:1, and any value within the range of any two values, preferably 4-20:1. In the present invention, when the molar ratio is lower than 4:1, the amount of alkaline compound is too small, which is not conducive to alumina precipitation; when the molar ratio is higher than 100:1, the amount of alkaline compound is too large, the precipitation rate during crystallization is too high, which is not conducive to the formation of nano-morphological alumina.

[0052] In some embodiments of the present invention, preferably, in step (1), the mass ratio of the aluminum source, alkaline compound, biomimetic inducer and regulator is 1-20:1-35:0-0.5:0.001-1, more preferably 2-10:3-10:0.001-0.1:0.01-1.

[0053] In some embodiments of the present invention, preferably, the ratio of the aluminum source in g to the solvent in mL is 1-20:35-200, more preferably 2-10:60-90.

[0054] In this invention, the ratio of the amount of aluminum source, alkaline compound, biomimetic inducer, regulator and solvent used can satisfy the above-mentioned limitations.

[0055] In this invention, the mixing conditions have a wide range of selection, as long as the above components are mixed. Preferably, the mixing conditions include: a temperature of 0-50°C, more preferably 20-35°C; a rotation speed of 0-1000 rpm, more preferably 200-500 rpm; and a time of 0.5-5 h, more preferably 0.5-2 h.

[0056] In this invention, a wide range of types of aluminum source can be selected. Preferably, the aluminum source is a soluble aluminum salt, including but not limited to aluminum nitrate, aluminum chloride, aluminum acetylacetonate, aluminum acetate, etc.

[0057] In this invention, a wide range of types of alkaline compounds can be selected. Preferably, the alkaline compound is selected from inorganic bases and / or organic bases, more preferably from at least one of ammonia, urea, sodium hydroxide, and tetrapropylammonium hydroxide, and more preferably from urea.

[0058] In one specific embodiment of the present invention, the concentration of ammonia water is 25 wt%, and the concentration of tetrapropylammonium hydroxide solution is 25 wt%.

[0059] In this invention, a wide range of types of biomimetic inducers can be selected. Preferably, the biomimetic inducer is selected from natural biological drying preparations, and the natural organisms are selected from at least one of watermelon rind, lotus leaf, rice leaf, and ramie leaf.

[0060] In one specific embodiment of the present invention, when the biomimetic inducer is selected from two natural desiccant preparations, and the natural organism is selected from two of watermelon rind, lotus leaf, rice leaf and ramie leaf, the present invention does not limit the mass ratio of the two natural desiccant preparations.

[0061] In this invention, a natural biological desiccant with a superhydrophobic structure is added as a biomimetic inducer, such as the nanosheet structure on canna leaves or the nanowires on the surface of ramie leaves. By utilizing the special surface structure of natural organisms, alumina nanowires / rods can be effectively induced to form a specific structure, that is, to form a convex structure with a spherical shape on the alumina nanowires / rods.

[0062] In this invention, a wide range of types of regulators can be selected. Preferably, the regulator is selected from ammonium compounds, and more preferably from at least one of ammonium carbonate, ammonium bicarbonate, ammonium sulfate, and ammonium oxalate.

[0063] In this invention, a wide range of solvents can be selected. Preferably, the solvent is selected from at least one of water, methanol, ethanol, toluene, N,N-dimethylformamide, etc.; more preferably, the solvent is water.

[0064] In this invention, step (1), the aging process, aims to convert aluminum ions in the mixture into alumina precursor seed crystals. Preferably, the aging conditions include: a temperature of 0-100°C, more preferably 30-80°C; and a time of 0.5-24 h, more preferably 0.5-5 h.

[0065] In this invention, solvothermal treatment aims to further grow alumina precursor crystals through a dissolution-crystallization process in a hydrothermal environment. By controlling the solvothermal conditions, a product with a specific morphology can be obtained. Without solvothermal treatment, the crystals cannot participate in the dissolution-crystallization process and cannot form a specific morphology.

[0066] In some embodiments of the present invention, more preferably, the conditions for the solvothermal treatment include 100-150°C and a time of 12-48 hours.

[0067] In some embodiments of the present invention, the drying is intended to remove residual solvent from the alumina precursor. Preferably, in step (3), the drying conditions include: a temperature of 80-150°C, more preferably 90-110°C; and a time of 5-72 h, more preferably 12-24 h.

[0068] In this invention, a wide range of drying methods can be selected. Preferably, the drying methods include, but are not limited to, spray drying, forced-air drying, vacuum drying, etc.

[0069] In some embodiments of the present invention, preferably, in step (3), the calcination conditions include: a temperature of 300-1000℃, preferably 400-600℃; and a time of 1-8h, preferably 3-5h. In the present invention, the calcination is carried out in a muffle furnace or a tube furnace, and the calcination atmosphere is a non-reducing gas, preferably at least one of air, nitrogen, and argon.

[0070] In some embodiments of the present invention, preferably, the method further includes: filtering and washing the alumina precursor sequentially before drying.

[0071] In this invention, the filtration and washing are intended to remove residual alkaline compounds and regulators from the alumina precursor. Preferably, the filtration apparatus includes, but is not limited to, water pumps, diaphragm pumps, and diffusion pumps.

[0072] In some embodiments of the present invention, preferably, the washing process includes: contacting the filtered product with a washing liquid and washing it. The washing liquid used for washing has a wide range of choices; preferably, the washing liquid is selected from water and / or C1-C5 monohydric alcohols, including but not limited to methanol, ethanol, 1-pentanol, etc.

[0073] The third aspect of this invention provides an alumina nanowire / rod provided in the first aspect, or an alumina nanowire / rod prepared by the method provided in the second aspect, for use in catalyst supports, gas-liquid adsorption, solid-phase fillers, and wastewater treatment agents.

[0074] In this invention, the high specific surface area and high five-coordinate Al are beneficial for adsorbing more substances in the adsorption reaction; as a catalyst support, it can load more and more metals more stably; as a catalyst, the presence of unsaturated coordinated Al can provide more reaction sites for the reaction and improve the reaction efficiency.

[0075] According to a particularly preferred embodiment of the present invention, an alumina nanowire / rod is provided, wherein the alumina nanowire / rod has an aspect ratio of 10-300 and a specific surface area of ​​200-300 μm². 2 / g; Five-coordinated Al in the alumina nanowires / rods 3 + The content of defect sites is 1.95-5.9 mmol / g, accounting for 10-30%;

[0076] The alumina nanowires / rods mentioned above are prepared by the following methods: (1) mixing an aluminum source, an alkaline compound, a selective biomimetic inducer, a regulator and a solvent, aging the mixture to obtain an aged product containing alumina precursor seeds; (2) subjecting the aged product to solvothermal treatment to obtain a solid-liquid mixture; (3) separating the solid-liquid mixture into solid and liquid components, and drying and calcining the obtained alumina precursors in sequence to obtain alumina nanowires / rods.

[0077] The conditions for the solvothermal treatment include: a temperature of 80-200℃; a time of 4-72h; a molar ratio of the alkaline compound to the aluminum source (calculated as Al) of 4-100:1; and the inducing agent is selected from natural biological drying agents, wherein the natural biological agent is selected from at least one of watermelon rind, lotus leaf, rice leaf and ramie leaf.

[0078] The present invention will be described in detail below through embodiments.

[0079] The physical properties of the products obtained in Examples 1-15 and Comparative Examples 1-4 are listed in Table 1.

[0080] Example 1

[0081] (1) 4.5g of aluminum source (aluminum nitrate nonahydrate), 6.5g of alkaline compound (urea), 0.1g of biomimetic inducer (dried watermelon rind and dried lotus leaf in a mass ratio of 1:1), 0.05g of regulator (ammonium carbonate) and 60mL of solvent (water) were mixed (temperature 10℃, rotation speed 600rpm, time 5h). The mixture was aged at 30℃ for 4h to obtain an aged product containing alumina precursor crystal seeds.

[0082] The molar ratio of the above-mentioned alkaline compound to the above-mentioned aluminum source (calculated as Al) is 9:1;

[0083] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 120 °C for 48 h to obtain a solid-liquid mixture.

[0084] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with isopropanol. The washed product was dried in a blower oven at 120°C for 8 hours and then calcined in a muffle furnace at 550°C for 4 hours to obtain alumina nanowires S1.

[0085] The SEM image of the alumina nanowire S1 is shown below. Figure 1 As shown, by Figure 1 It can be seen that the alumina nanowire S1 exhibits a nanowire structure and has a convex structure.

[0086] The XRD pattern of the alumina nanowire S1 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the alumina nanowire S1 exhibits an amorphous crystalline structure.

[0087] The N2 adsorption-desorption curves of the aforementioned alumina nanowires S1 are shown in the figure below. Figure 3 As shown, by Figure 3 It is known that the alumina nanowire S1 has a mesoporous structure, and the formation of the mesoporous structure is presumably due to the stacked mesopores formed by the stacking of nanowire materials.

[0088] Among them, the above-mentioned alumina nanowires S1 27 The nuclear magnetic resonance spectrum of Al solid is as follows: Figure 4 As shown, by Figure 4 It can be seen that the characteristic peaks with chemical shifts at 7, 40, and 77 ppm belong to Al(VI), Al(V), and Al(IV) structures, respectively. Calculations show that the five-coordinated Al in the alumina nanowire S1... 3+ The proportion of defective sites reached 12%, with a specific content of 2.35 mmol / g.

[0089] Example 2

[0090] (1) Mix 4.5g of aluminum source (aluminum nitrate nonahydrate), 6.5g of alkaline compound (urea), 0.01g of regulator (ammonium carbonate) and 60mL of solvent (water) (temperature 30℃, rotation speed 500rpm, time 2h), and age the mixture at 30℃ for 4h to obtain an aged product containing alumina precursor crystals.

[0091] The molar ratio of the above-mentioned alkaline compound to the above-mentioned aluminum source (calculated as Al) is 9:1;

[0092] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 100 °C for 48 h to obtain a solid-liquid mixture.

[0093] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower oven at 110°C for 12 hours and then calcined in a muffle furnace at 550°C for 4 hours to obtain alumina nanowires S2.

[0094] The SEM image of the alumina nanowire S2 is shown below. Figure 5 As shown, by Figure 5 It can be seen that the alumina nanowire S2 exhibits a nanowire structure and has an excellent aspect ratio.

[0095] Among them, the XRD pattern of the above-mentioned alumina nanowire S2 is similar to... Figure 2 Similarly; the N2 adsorption-desorption curves of the alumina nanowires S2 described above are similar to... Figure 3 Similarly; the above-mentioned alumina nanowires S2 27 Al solid NMR spectrum and Figure 4 similar.

[0096] Example 3

[0097] (1) 4.5g of aluminum source (aluminum nitrate nonahydrate), 6.5g of alkaline compound (urea), 0.01g of biomimetic inducer (dried lotus leaf), 0.01g of regulator (ammonium bicarbonate) and 60mL of solvent (water) were mixed (temperature 0℃, rotation speed 1000rpm, time 2h). The mixture was aged at 30℃ for 4h to obtain an aged product containing alumina precursor crystal seeds.

[0098] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 9:1;

[0099] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 80 °C for 48 h to obtain a solid-liquid mixture.

[0100] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with 1-pentanol. The washed product was dried in a blower oven at 100°C for 12 hours and then calcined in a muffle furnace at 400°C for 6 hours to obtain alumina nanowires S3.

[0101] Example 4

[0102] (1) 5g of aluminum source (aluminum chloride), 12.5g of alkaline compound (ammonia water with a concentration of 25wt%), 0.03g of biomimetic inducer (dried rice leaves), 0.02g of regulator (ammonium oxalate) and 35mL of solvent (methanol) were mixed (temperature 20℃, rotation speed 600rpm, time 4h). The mixture was aged at 20℃ for 4h to obtain an aged product containing alumina precursor crystals.

[0103] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 4.9:1;

[0104] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 140 °C for 48 h to obtain a solid-liquid mixture.

[0105] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with 1-pentanol. The washed product was dried in a blower oven at 100°C for 12 hours and then calcined in a muffle furnace at 600°C for 2 hours to obtain alumina nanowires S4.

[0106] Example 5

[0107] (1) 3g of aluminum source (aluminum acetylacetonate), 22g of alkaline compound (NaOH), 0.001g of biomimetic inducer (dried ramie leaf), 0.5g of regulator (ammonium sulfate) and 100mL of solvent (toluene) were mixed (temperature 15℃, rotation speed 800rpm, time 3h), and the resulting mixture was aged at 50℃ for 5h to obtain an aged product containing alumina precursor crystals;

[0108] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 59.5:1;

[0109] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 200 °C for 12 h to obtain a solid-liquid mixture.

[0110] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower oven at 80°C for 30 hours and then calcined in a muffle furnace at 800°C for 3 hours to obtain alumina nanowires S5.

[0111] Example 6

[0112] (1) 5g of aluminum source (aluminum acetate), 100g of alkaline compound (25wt% tetrapropylammonium hydroxide solution), 0.007g of biomimetic inducer (dried watermelon rind), 0.8g of regulator (ammonium carbonate) and 95mL of solvent (ethanol) were mixed (temperature 5℃, rotation speed 500rpm, time 2h). The mixture was aged at 80℃ for 2h to obtain an aged product containing alumina precursor seeds.

[0113] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 5:1;

[0114] (2) The above-mentioned aging product was transferred to a 300 mL hydrothermal reactor and subjected to solvothermal treatment at 100 °C for 48 h to obtain a solid-liquid mixture.

[0115] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower oven at 100°C for 20 hours and then calcined in a muffle furnace at 500°C for 5 hours to obtain alumina nanowires S6.

[0116] Example 7

[0117] (1) 10g of aluminum source (aluminum nitrate), 40g of alkaline compound (ammonia water with a concentration of 25wt%), 0.06g of biomimetic inducer (dried rice leaves and dried lotus leaves with a mass ratio of 1:1), 0.01g of regulator (ammonium bicarbonate) and 100mL of solvent (methanol) were mixed (temperature 0℃, rotation speed 600rpm, time 4h), and the mixture was aged at 60℃ for 5h to obtain an aged product containing alumina precursor crystal seeds;

[0118] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 22:1;

[0119] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 80 °C for 72 h to obtain a solid-liquid mixture.

[0120] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower drying oven at 120°C for 10 hours and then calcined in a muffle furnace at 600°C for 2 hours under static air to obtain alumina nanowires S7.

[0121] Example 8

[0122] (1) 7.5g of aluminum source (aluminum chloride), 32.5g of alkaline compound (ammonia water with a concentration of 25wt%), 0.01g of biomimetic inducer (dried ramie leaves and dried lotus leaves with a mass ratio of 1:1), 0.05g of regulator (ammonium sulfate) and 90mL of solvent (water) were mixed (temperature 45℃, rotation speed 800rpm, time 2h). The mixture was aged at 30℃ for 3h to obtain an aged product containing alumina precursor crystals.

[0123] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 8.5:1;

[0124] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 200 °C for 12 h to obtain a solid-liquid mixture.

[0125] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower oven at 150°C for 5 hours and then calcined in a muffle furnace at 600°C for 2 hours to obtain alumina nanowires S8.

[0126] Example 9

[0127] (1) 4g of aluminum source (aluminum chloride), 10g of alkaline compound (ammonia water with a concentration of 25wt%), 0.07g of biomimetic inducer (dried watermelon rind and dried rice leaves with a mass ratio of 1:1), 0.1g of regulator (ammonium bicarbonate) and 95mL of solvent (toluene) were mixed (temperature 50℃, rotation speed 800rpm, time 3h). The mixture was aged at 50℃ for 5h to obtain an aged product containing alumina precursor crystals.

[0128] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 4.9:1;

[0129] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 150 °C for 24 h to obtain a solid-liquid mixture.

[0130] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower drying oven at 110°C for 20 hours and then calcined in a muffle furnace at 400°C under static air for 4 hours to obtain alumina nanowires S9.

[0131] Example 10

[0132] (1) Mix 5g of aluminum source (aluminum acetylacetonate), 15g of alkaline compound (NaOH), 0.005g of biomimetic inducer (dried watermelon rind), 0.1g of regulator (ammonium bicarbonate) and 100mL of solvent (methanol) (temperature 30℃, rotation speed 600rpm, time 2h), and age the mixture at 60℃ for 12h to obtain an aged product containing alumina precursor crystals;

[0133] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 24.3:1;

[0134] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 120 °C for 12 h to obtain a solid-liquid mixture.

[0135] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower drying oven at 80°C for 24 hours and calcined in a muffle furnace at 550°C for 4 hours to obtain alumina nanowires S10.

[0136] Example 11

[0137] (1) 2g of aluminum source (aluminum acetylacetonate), 40g of alkaline compound (ammonia water with a concentration of 25wt%), 0.02g of biomimetic inducer (dried watermelon rind), 0.02g of regulator (ammonium bicarbonate) and 60mL of solvent (water) were mixed (temperature 30℃, rotation speed 900rpm, time 0.5h). The mixture was aged at 30℃ for 24h to obtain an aged product containing alumina precursor crystal seeds.

[0138] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 95.4:1;

[0139] (2) The above-mentioned aging product was transferred to a 200 mL hydrothermal reactor and subjected to solvothermal treatment at 160 °C for 72 h to obtain a solid-liquid mixture.

[0140] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with ethanol. The washed product was dried in a blower oven at 60°C for 30 hours and then calcined in a muffle furnace at 400°C for 6 hours to obtain alumina nanowires S11.

[0141] Example 12

[0142] (1) 5g of aluminum source (aluminum acetate), 95g of alkaline compound (25wt% tetrapropylammonium hydroxide), 0.1g of biomimetic inducer (dried watermelon rind), 0.2g of regulator (ammonium sulfate) and 100mL of solvent (N,N-dimethylformamide) were mixed (temperature 50℃, rotation speed 900rpm, time 0.5h). The mixture was aged at 40℃ for 6h to obtain an aged product containing alumina precursor seeds.

[0143] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 4.8:1;

[0144] (2) The above-mentioned aging product was transferred to a 300 mL hydrothermal reactor and subjected to solvothermal treatment at 150 °C for 60 h to obtain a solid-liquid mixture.

[0145] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with isopropanol. The washed product was dried in a blower oven at 150°C for 10 hours and then calcined in a muffle furnace at 550°C for 6 hours to obtain alumina nanowires S12.

[0146] Example 13

[0147] (1) 5g of aluminum source (aluminum acetate), 125g of alkaline compound (25wt% tetrapropylammonium hydroxide), 0.09g of biomimetic inducer (dried watermelon rind), 0.02g of regulator (ammonium sulfate) and 70mL of solvent (methanol) were mixed (temperature 0℃, rotation speed 500rpm, time 3h). The mixture was aged at 30℃ for 12h to obtain an aged product containing alumina precursor seeds.

[0148] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 6.3:1;

[0149] (2) The above-mentioned aging product was transferred to a 300 mL hydrothermal reactor and subjected to solvothermal treatment at 200 °C for 48 h to obtain a solid-liquid mixture.

[0150] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with isopropanol. The washed product was dried in a blower oven at 120°C for 6 hours and then calcined in a muffle furnace at 550°C for 4 hours to obtain alumina nanowires S13.

[0151] Example 14

[0152] (1) 4.5g aluminum source (aluminum nitrate), 5.5g alkaline compound (NaOH), 0.002g biomimetic inducer (dried watermelon rind), 0.05g regulator (ammonium oxalate) and 50mL solvent (water) were mixed (temperature 10℃, rotation speed 700rpm, time 1h). The mixture was aged at 30℃ for 12h to obtain an aged product containing alumina precursor crystals.

[0153] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 11.5:1;

[0154] (2) The above-mentioned aging product was transferred to a 100 mL hydrothermal reactor and subjected to solvothermal treatment at 100 °C for 60 h to obtain a solid-liquid mixture.

[0155] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The resulting alumina precursor was sequentially filtered and washed with isopropanol. The washed product was dried in a blower drying oven at 100°C for 9 hours and then calcined in a muffle furnace at 500°C for 6 hours to obtain alumina nanowires S14.

[0156] Example 15

[0157] (1) 4.5g of aluminum source (aluminum nitrate), 45g of alkaline compound (ammonia water with a concentration of 25wt%), 0.05g of biomimetic inducer (dried watermelon rind), 0.02g of regulator (ammonium carbonate) and 200mL of solvent (water) were mixed (temperature 10℃, rotation speed 700rpm, time 1h). The mixture was aged at 30℃ for 8h to obtain an aged product containing alumina precursor crystal seeds.

[0158] The molar ratio of the above-mentioned alkaline compound to the aluminum source (calculated as Al) is 55.2:1;

[0159] (2) The above-mentioned aging product was transferred to a 300 mL hydrothermal reactor and subjected to solvothermal treatment at 200 °C for 12 h to obtain a solid-liquid mixture.

[0160] (3) The above solid-liquid mixture was subjected to solid-liquid separation. The alumina precursor was then filtered and washed with isopropanol. The washed product was dried in a blower oven at 60°C for 15 hours and then calcined in a muffle furnace at 450°C for 8 hours to obtain alumina nanowires S15.

[0161] Comparative Example 1

[0162] The method is the same as in Example 2, except that...

[0163] In step (1), the amount of alkaline compound (urea) was replaced with 2.2g, the amount of regulator (ammonium carbonate) was replaced with 0.1g, the molar ratio of the alkaline compound to the aluminum source (calculated as Al) was 3.1:1, and the other conditions were the same, to obtain alumina DS1.

[0164] The SEM image of the aforementioned alumina DS1 is shown below. Figure 6 As shown, by Figure 6 It can be seen that alumina DS1 does not have a nanowire structure and is a bulk alumina structure.

[0165] Comparative Example 2

[0166] The method is the same as in Example 2, except that...

[0167] In step (2), the temperature of the solvent heat treatment is replaced with 60°C, which is the same as the conditions, to obtain alumina DS2.

[0168] Comparative Example 3

[0169] Commercial alumina (Sinopharm Chemical Reagent Co., Ltd., CAS No.: 1344-28-1, Batch No.: 20170401) was used as alumina DS3.

[0170] Among them, the above-mentioned alumina DS3 27 The nuclear magnetic resonance spectrum of Al solid is as follows: Figure 7As shown, by Figure 7 It can be seen that the chemical shift has no characteristic peak at 40 ppm, indicating that the above-mentioned alumina DS3 does not have five-coordinated Al. 3+ That is, the Al(V) structure.

[0171] Comparative Example 4

[0172] The method is the same as in Example 1, except that...

[0173] In step (2), the above-mentioned aging product is directly heated at 100°C for 48 hours, with the other conditions remaining the same, to obtain alumina DS4.

[0174] Table 1

[0175]

[0176]

[0177] Continued from Table 1

[0178]

[0179] As shown in Table 1, compared with Comparative Examples 1-4, the alumina nanowires prepared by the method provided in this invention in Examples 1-15 have high aspect ratio and high specific surface area, as well as high content and high proportion of five-coordinated Al. 3+ Defect position.

[0180] Meanwhile, compared to Example 2, the alumina nanowires prepared in Examples 1 and 3-15 not only have nanowire-like structures but also convex structures due to the addition of biomimetic inducers, and the diameter of the convex structure is 3-55 nm with a coverage of 5-28%.

[0181] Test case

[0182] The alumina nanowires prepared in Examples 1-2 and the commercial alumina of Comparative Example 3 were used as supports for loading gallium (Ga) species. Due to the high specific surface area and abundant five-coordinated Al in the alumina nanowires, Ga species were successfully loaded. 3+ The structure can effectively anchor Ga species.

[0183] The preparation method includes mixing 0.0227 g gallium nitrate, 0.6 g of the above-mentioned support, and 10 mL of water, stirring at 25 °C for 4 h, and drying at 110 °C for 24 h; the dried sample is then calcined in air at 550 °C for 5 h to obtain Ga-based alumina nanowire catalysts Ga / Al2O3-NW-1, Ga-based alumina nanowire catalysts Ga / Al2O3-NW-2, and Ga-based commercial alumina catalysts Ga / Al2O3-Comm, respectively.

[0184] The catalysts prepared above were used in the oxygen-free dehydrogenation reaction of propane. The specific reaction conditions were: feed ratio C3H8:N2 = 2:3, propane gas velocity 8 mL / min, nitrogen gas velocity 12 mL / min, catalyst dosage 50 mg, heating rate 10 °C / min, and reaction temperature 600 °C. The test results are shown in Table 2.

[0185] Table 2

[0186] catalyst Propane conversion rate, % Propylene selectivity, % Example 1 Ga / Al203-NW-1 9.4 89.7 Example 2 <![CDATA[Ga / Al2O3-NW-2]]> 10 84.6 Comparative Example 3 <![CDATA[Ga / Al2O3-Comm]]> 5.6 56.0

[0187] As shown in Table 2, compared with Comparative Example 3, the catalyst prepared by using the alumina nanowires provided by this invention as a support has a higher propane conversion rate and propylene selectivity in the propane oxygen-free dehydrogenation reaction.

[0188] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An alumina nanowire / rod, characterized in that, The alumina nanowires / rods have an aspect ratio of 10-1000 and a specific surface area of ​​200-500 m². 2 / g; Five-coordinated Al in the alumina nanowires / rods 3+ The content of defective sites ranges from 1.95 to 5.9 mmol / g, accounting for 10-30%; The alumina nanowires / rods have an amorphous crystalline structure. The alumina nanowires / rods are prepared by the following methods: (1) mixing an aluminum source, an alkaline compound, a regulator and a solvent, aging the mixture to obtain an aged product containing alumina precursor seeds; (2) subjecting the aged product to solvothermal treatment to obtain a solid-liquid mixture; (3) separating the solid-liquid mixture, drying and calcining the obtained alumina precursor in sequence to obtain the alumina nanowires / rods. The conditions for the solvothermal treatment include: a temperature of 80-200℃ and a time of 4-72 hours. The molar ratio of the alkaline compound to the aluminum source (calculated as Al) is 4-100:1; The regulator is selected from ammonium compounds.

2. The alumina nanowires / rods according to claim 1, wherein, The alumina nanowires / rods have an aspect ratio of 10-300 and a specific surface area of ​​200-300 m². 2 / g; And / or, the five-coordinated Al in the alumina nanowires / rods 3+ The content of defect sites is 2.9-4.9 mmol / g; accounting for 15-25%.

3. The alumina nanowires / rods according to claim 1, wherein, The length of the alumina nanowires / rods is 10 nm-500 μm; And / or, the pore volume of the alumina nanowires / rods is 0.1-5 cm³ / g; the average pore size is 5-100 nm.

4. The alumina nanowires / rods according to claim 3, wherein, The length of the alumina nanowires / rods is 100nm-300μm; And / or, the pore volume of the alumina nanowires / rods is 0.2-3 cm³ / g; the average pore size is 10-60 nm.

5. The alumina nanowires / rods according to claim 1, wherein, The surface of the alumina nanowires / rods has a convex structure; The diameter of the convex structure is 1-100 nm; The coverage of the convex structure is 5-30%.

6. The alumina nanowires / rods according to claim 5, wherein, The diameter of the convex structure is 1-60 nm; the coverage of the convex structure is 5-30%.

7. The alumina nanowires / rods according to any one of claims 1-6, wherein, exist 27 In the solid-state NMR spectrum of Al, the alumina nanowires / rods have characteristic peaks with chemical shifts of 7ppm±10%, 40ppm±10%, and 77ppm±10%.

8. A method for preparing alumina nanowires / rods, characterized in that, The preparation method includes: (1) Aluminum source, alkaline compound, regulator and solvent are mixed and aged to obtain aged product containing alumina precursor seed crystals; (2) The aging product is subjected to solvothermal treatment to obtain a solid-liquid mixture; (3) The solid-liquid mixture is subjected to solid-liquid separation, and the resulting alumina precursor is dried and calcined in sequence to obtain alumina nanowires / rods; The conditions for the solvothermal treatment include: a temperature of 80-200℃ and a time of 4-72h. The molar ratio of the alkaline compound to the aluminum source (calculated as Al) is 4-100:1; The regulator is selected from ammonium compounds.

9. The preparation method according to claim 8, wherein, In step (1), the mixture further includes a biomimetic inducer, and the mass ratio of the aluminum source, alkaline compound, biomimetic inducer and regulator is 1-20:1-35:0-0.5:0.001-1; And / or, the ratio of the aluminum source in g to the solvent in mL is 1-20:35-200; And / or, the aging conditions include: a temperature of 0-100°C; The time is 0.5-24 hours.

10. The preparation method according to claim 9, wherein, In step (1), The molar ratio of the alkaline compound to the aluminum source (calculated as Al) is 4-20:1; And / or, the mass ratio of the aluminum source, alkaline compound, biomimetic inducer and regulator is 2-10:3-10:0.001-0.1:0.01-1; And / or, the ratio of the aluminum source in g to the solvent in mL is 2-10:60-90; And / or, the aging conditions include: a temperature of 30-80°C; The time is 0.5-5 hours.

11. The preparation method according to claim 9, wherein, In step (1), The alkaline compound is selected from inorganic bases and / or organic bases; And / or, the biomimetic inducer is selected from natural biological drying agents, and the natural organism is selected from at least one of watermelon rind, lotus leaf, rice leaf and ramie leaf.

12. The preparation method according to claim 11, wherein, In step (1), The alkaline compound is selected from at least one of ammonia, urea, sodium hydroxide, and tetrapropylammonium hydroxide; And / or, the regulator is selected from at least one of ammonium carbonate, ammonium bicarbonate, ammonium sulfate, and ammonium oxalate.

13. The preparation method according to any one of claims 8-12, wherein, In step (2), the conditions for the solvent heat treatment include: a temperature of 100-150℃ and a time of 12-48h; And / or, in step (3), the drying conditions include: a temperature of 80-150°C; and a time of 5-72 hours; And / or, the calcination conditions include: a temperature of 300-1000℃; and a time of 1-8 hours; And / or, the calcination is carried out in a non-reducing gas.

14. The preparation method according to claim 13, wherein, In step (3), The drying conditions include: a temperature of 90-110℃ and a time of 12-24 hours; And / or, the calcination conditions include: a temperature of 400-600℃; and a time of 3-5h.

15. The alumina nanowires / rods according to any one of claims 1-7, or the alumina nanowires / rods prepared by the preparation method according to any one of claims 8-14, are used in catalyst supports, gas-liquid adsorption, solid phase fillers and wastewater treatment agents.

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