兰州大学机构库 >物理科学与技术学院
氧化铝非晶纳米颗粒的制备与表征
Alternative TitlePreparation and characterizations of amorphous alumina nanoparticles
王甲泰
Thesis Advisor李建功
2016-06-02
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword氧化铝 非晶态 纳米颗粒 均匀沉淀法 尺寸控制 分散性
Abstract本工作以廉价硝酸铝、硫酸铝和甲酰胺作为原料,采用化学均匀沉淀法来制备非晶态氧化铝。研究了制备过程中沉淀剂加入量、硝酸铝和硫酸铝的用量对平均颗粒尺寸、尺寸分布的影响,最终制备尺寸可控、分散性良好的非晶态氧化铝纳米颗粒。同时对直接沉淀法及常用的尿素为沉淀剂的匀沉淀法进行了探索。 研究表明,采用直接沉淀法,以硝酸铝和氨水为原料,溶液环境中的pH值对前驱体的结构有重要影响。当溶液的pH值不大于7时,制备的前驱体为非晶态。如果溶液为碱性环境,制备的前驱体含有晶态的γ-AlOOH 和α-Al(OH)3。煅烧温度对最终氧化铝结构有重要影响,在700°C以下煅烧能制得非晶态氧化铝,而在700°C以上煅烧会有γ-Al2O3生成。直接沉淀法制备的非晶态氧化铝颗粒形状不规则,并且团聚严重,团聚体的尺寸不均匀。 采用化学均匀沉淀法,以尿素作为沉淀剂,以硝酸铝和硫酸铝按一定摩尔比混合作为铝源,制备氧化铝前驱体,将前驱体在700°C以下煅烧,制得非晶态氧化铝,但颗粒团聚严重,其颗粒尺寸较大。在最佳条件,即硫酸铝/硝酸铝的摩尔比为1:9,总Al3+浓度为2 mmol/L下,制备的非晶态氧化铝平均颗粒尺寸为100 nm。 以甲酰胺作为沉淀剂,采用化学均匀沉淀法,并且以硝酸铝和硫酸铝按照一定的摩尔比混合作为铝源,制备非晶态氧化铝。结果表明,甲酰胺的加入量对颗粒的尺寸分布及平均尺寸有重要影响,平均颗粒尺寸随着甲酰胺用量的增大而增大。在硫酸铝/硝酸铝的摩尔比为1:9时,当加入甲酰胺为10 mL,制备的非晶态氧化铝平均颗粒尺寸为37 nm;当加入100 mL甲酰胺时,平均颗粒尺寸为23 nm。硫酸铝/硝酸铝的摩尔比对最终非晶态氧化铝的颗粒尺寸有重要影响,非晶态氧化铝的平均颗粒尺寸随着硫酸铝/硝酸铝的摩尔比的增大而增大。在加入100 mL甲酰胺时,当硫酸铝/硝酸铝的摩尔比为1:9时制备的非晶态氧化铝的平均颗粒尺寸最小,为23 nm;当硫酸铝/硝酸铝的摩尔比为5:5时,制备的平均颗粒尺寸为70 nm。
Other AbstractIn this work, cheap aluminum nitrate, aluminum sulfate, and formamide were used as starting materials to prepare the precursors of amorphous alumina using a facile homogeneous precipitation method. The effect of the type and amount of precipitating agent, aluminum sulfate/nitrate molar ratio, and precipitation method on the average particle size, size distribution and particle morphology of amorphous alumina nanoparticles were studied. Finally, well-dispersed spherical amorphous alumina nanoparticles with a narrow size distributions and controlled particle sizes were successfully prepared. The results show that the pH of the solution in the environment has a major effect on the structure of precursor when the aluminum nitrate and ammonia were used as raw materials and the direct precipitation method was applied. When the pH value of the solution is not more than 7, the precursor prepared is amorphous. If the solution is an alkaline environment, the precursor prepared contain crystalline γ-AlOOH and α-Al(OH)3. Calcination temperature also has an important effect on the final structure of alumina. Amorphous alumina was obtained when the calcination temperature is below 700°C, and γ-Al2O3 forms when the calcination temperature is 700°C. The amorphous alumina particles prepared is irregular shape, serious agglomeration and the aggregates has broad size distribution. If urea was used as precipitant, the mixtures of aluminum sulfate and aluminum nitrate with different molar ratios were used as aluminum sources for preparing alumina precursor particles. The amorphous alumina with severe agglomeration and larger particle size were obtained when the calcination temperature is below 700°C. Under the optimal conditions, the amorphous alumina with particle size of 100 nm and severe agglomeration were obtained at an aluminum sulfate/nitrate molar ratio of 1:9 and a total concentration of Al3+ of 2 mmol/L. If formamide was used as the precipitant, the mixtures of aluminum sulfate and aluminum nitrate with different molar ratios were used as aluminum sources for preparing alumina precursor particles. The amount of formamide added clearly strongly affects the particle size distribution and average particle size of the final amorphous alumina nanoparticles. This means that the particle size of the final product can be controlled by adjusting the amount of formamide added in the reaction. The average particle size of amorphous alumina particles decreases with incr...
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Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229141
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
王甲泰. 氧化铝非晶纳米颗粒的制备与表征[D]. 兰州. 兰州大学,2016.
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