摘要
在新型火焰反应器生产纳米TiO2的过程中使用TEM微栅在不同火焰高度位置处进行原位取样分析,得到生长过程中纳米TiO2颗粒的粒径和形态.TiO2颗粒经历了成核、生长、聚并、烧结的过程.调节反应物浓度为7.9×10-5～5.7×10-3mol/L,研究了不同反应物浓度对纳米颗粒生长过程的影响,高前驱体浓度形成较高的单体浓度,使颗粒间碰撞几率增加,从而得到粒径较大的颗粒,产物粒径17～85nm.调节CH4和O2流量,改变温度场,研究温度对颗粒生长过程的影响,在相同反应物浓度条件下,较高的温度下形成分散性好、一次粒径为63nm的颗粒,而在较低的温度下形成的颗粒一次粒径为35nm,但颈部烧结严重;增加喷嘴气流速度减小了反应停留时间,颗粒粒径从63nm减小到36nm.
During the flame synthesis of titanium dioxide （TiO2） nanoparticles by oxidation of titanium tetrachloride （TiCl4）, transmission electron microscope （TEM） grids were used to collect particle samples at different heights of the flame reactor. The particle diameters and morphology were obtained in the particle growth process. The influences of reactant concentration, reaction temperature and gas velocity on the particle growth process were studied. A TiO2 particle experienced nucleation, growth, agglomeration and sintering processes. Higher precursor concentration produced more primary particles in the early stage so that more colliding chances between particles were allowed for, which resulted in larger particles in the end. Primary particle size changed from 17 to 85 nm when the precursor concentration was adjusted from 7.9×10^-5 to 5.7×10^-3 mol/L. The reaction temperature depended on the gas flow rates of methane and oxygen. Higher reaction temperature generated mono-dispersed but large primary particles of 63 nm, while low reaction temperature caused small but seriously sintered particles of 35 nm. The increase of the gas velocity decreased the particle diameter from 63 to 36 nm due to the shortened residence time.
出处
《过程工程学报》
EI
CAS
CSCD
北大核心
2007年第5期944-951,共8页
The Chinese Journal of Process Engineering
基金
全国博士学位论文作者专项资金资助项目(编号:200245)
关键词
二氧化钛
纳米颗粒
火焰反应器
颗粒生长
titanium dioxide
nanoparticles
flame reactor
particle growth
