排序方式: 共有52条查询结果,搜索用时 15 毫秒
51.
由TiCl4/HCl配制的含钛柱化剂与粘土进行阳离子交换后得到大孔钛层柱粘土(Ti-PILC),详细研究了各种合成条件,诸如Ti(Ⅳ)及HCl浓度,柱化剂老化时间,粘土初始浓度,交换温度及配料比等对层柱粘土的大孔及比表面积的影响.优化条件合成的Ti-PILC存在两种晶面间距(d001),其中之一(2.56nm)对应大孔结构.Ti-PILC比表面积为328m2/g,500℃焙烧后d001保持2.32nm,650℃焙烧后比表面积仍达301.4m2/g.Ti-PILC的大孔结构主要取决于交换时混合液中Ti(Ⅳ)和HCl浓度,并与柱化剂老化时间、交换温度等因素有关;与原柱化剂中Ti(Ⅳ)和HCl浓度无关.混合液中CHCl提高,Ti-PILC的比表面积下降;当CHCl增至70mmol/L时,产物中大晶面间距消失,仅留下小晶面间距(~1.4nm).随着混合液中CTiCl4的提高,Ti-PILC的比表面积先上升而后下降。当CTiCl4增至146mmol/L时,产物也仅有小晶面间距(1.4nm). 相似文献
52.
A one-step method for continuous large-scale synthesis of well-defined hollow titania spheres was established by feeding titanium tetrachloride mixed with ethanol vapor to a facile diffusion flame. A mixture of TiCl4 and C2H5OH vapor was transported at 100 m/s into a flame reactor and condensed into mesoscale droplets due to Joule–Thomson cooling and the entrainment of cool gases into the expanding high-speed jet. Hollow crystalline TiO2 spheres with good thermal stability were formed after the hydrolysis of TiCl4 in the H2/air flame at about 1500 °C. Structural characterization indicates that the hollow spheres, with uniform diameter of 300 nm and shell thickness of 35 nm, consist of 20–30 nm TiO2 nanocrystallites. A formation mechanism of the hollow spheres was proposed, involving the competition between chemical reaction and diffusion during the flame process. The present study provides a new pathway for continuous and large-scale engineering of hollow nanomaterials. 相似文献