| ?-Al2O3 is one of the important adsorption and catalytic materials,and the hydrothermal/solvothermal method is one of the effective methods for preparing?-Al2O3nanomaterials.An"environmentally friendly solvent"ionic liquid is used as a templating agent to assist in the synthesis of porous?-Al2O3 materials.However,due to the disadvantages of high cost and potential toxicity,it cannot be applied on a large scale.A deep eutectic solvent,also known as an"ionic liquid analogue."Compared with ionic liquids,deep eutectic solvents not only have similar physicochemical properties and structural design,but also have the advantages of low price and easy degradation,and are known as“green solvents in the 21st century”.Based on this,in this paper,a deep eutectic solvent was used as a template?or solvent?to synthesize a precursor with a certain size and morphology,and then calcined to obtain a?-Al2O3 nanomaterial with the same apparent morphology.The effects of parameters such as hydrothermal temperature and raw material ratio on the nanostructure of precursors and the pore characteristics of?-Al2O3 were investigated in order to obtain porous?-Al2O3nanomaterials with specific morphology and uniform size.In this paper,the effects of reaction conditions on the nanostructure of precursors and the porous characteristics of?-Al2O3 were investigated by using AlCl3·6H2O and?NH4?2CO3 as raw materials in the choline chloride/glycerol system.The results show that the reaction conditions affect the apparent morphology and size of the product;one-dimensional rod or strand-like nanostructures are obtained at 120-180°C;the product size increases with increasing temperature;when the temperature rises to 200°C,two-dimensional flaky or three-dimensional flower-like nanostructures were obtained;the increase in water volume,the increase in the amount of raw materials,and add water order to the front in the system all increase the size of the product;when Al?NO3?3·9H2O is the aluminum source,the product size decreases.After the precursor was calcined at 600°C for 2 h,porous?-Al2O3 with the same morphology was obtained.In the molar ratio n?DES?:n?AlCl3?:n??NH4?2CO3?:n?H2O?=30:1:7:180,when the hydrothermal temperature is 150°C,the bundled?-Al2O3 is obtained.Large specific surface area?207.1 m2/g?and excellent pore structure have the highest adsorption efficiency for methyl orange.Choline chloride/urea and choline chloride/triethanolamine are also used in the preparation of?-Al2O3 materials.When adding water in front,Al?NO3?3·9H2O and?NH4?2CO3 were used as raw materials to synthesize precursors and?-Al2O3 materials.The results show that the reaction conditions affect the apparent morphology and size of the product;one-dimensional rod or strand-like nanostructures are obtained at 150-200°C,and the product size increases with increasing temperature;As the amount of water gradually increases,the size of the product gradually becomes uneven from increasing;the amount of the raw material increases,the product size increases.In the choline chloride/urea system,when n?DES?:n?Al?NO3?3?:n??NH4?2CO3?:n?H2O?=10:1:3:100,and the hydrothermal temperature is 150°C,the?-Al2O3 nanorods were prepared with large specific surface area?165.9 m2/g?,and the adsorption efficiency for methyl orange was higher.Compared with the other two deep eutectic solvents,the nano-?-Al2O3 and the precursor obtained in the choline chloride/urea are larger in size under certain conditions of water.In summary,by adjusting the type of deep eutectic solvent,preparation conditions,etc.,it is possible to control the synthesis of?-Al2O3 nanomaterials with a certain apparent morphology and pore structure.This work provides a theoretical basis and practical experience for the development of new methods for the preparation of?-Al2O3 nanomaterials. |
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