【作者】 罗升；

【导师】 李永丹；

【作者基本信息】 天津大学 ， 工业催化， 2010， 硕士

【摘要】 Sholl等人采用原子模拟法计算出气体在碳纳米管中的传递速率要比在具有相同孔径的分子筛等微孔材料中的速率高几个数量级。由此推测,具有均一孔径的碳纳米管膜将具有高的选择性和高渗透通量。本文分别在α-Al₂O₃和石英基体上制备了碳纳米管膜,并对得到的碳纳米管膜进行了表征和研究。采用浮动催化热裂解法,以二茂铁为催化剂,乙炔为碳源在多孔α-Al₂O₃基底上制备碳纳米管膜。碳纳米管的生长受到很多因素的影响,鉴于此,本文考察了工艺条件对碳纳米管膜生长的影响。详细考察了催化剂用量、反应温度等工艺参数对碳纳米管生长情况的影响。二茂铁的用量过大,催化剂颗粒过大,起催化作用的颗粒数目相对减少,催化活性大为降低;减少二茂铁的用量,铁颗粒减少,颗粒尺寸变小,铁催化剂颗粒间的间距增大,从而陶瓷基体表面铁颗粒的分布密度降低,催化剂活性提高。温度升高,碳纳米管的生长速度加快,但催化剂失活快,碳纳米管的产量减少。分别考察了上述几个工艺参数后,得出催化剂用量为0.25 g,反应温度为750℃,反应时间为10 min,乙炔流量为100 sccm时能够制备出有一定取向性的碳纳米管阵列。得到的碳纳米管外径小于40 nm。通过dip-coating的方法在石英片上沉积了较小尺寸、均匀分布的纳米级Co/Mo双金属催化剂颗粒。石英片预处理、添加乙二醇有利于获得直径较小、分布均匀的催化剂。然后采用CVD法在石英片上制备了直径较小的碳纳米管阵列。密实均匀的催化剂能保证生长出来的碳纳米管具有足够的密度,从而彼此限制生长的方向,达到准直定向的效果。优化后的工艺条件:在300 sccm的N₂/H₂（3 vol% H₂）气氛下加热还原,反应温度为750℃,乙炔气体流量为30 sccm,反应时间为10 min。更多还原

【Abstract】 Sholl and coworkers found that the transport rates in nanotubes were magnitude of orders faster than in zeolites with comparable pore size calculated by atomic simulation method. One-dimensional pore of carbon nanotubes can improve the Selective separation of gas mixtures. Thus, we predict that carbon nanotubes film with a uniform pore size will have a high selectivity and high permeation flux. In this paper, films of carbon nanotubes were prepared on quartz and porousα-Al₂O₃ substrates, and carbon nanotube films obtained were characterized and studied.A floating catalytic pyrolysis method, with ferrocene as the precursor of catalyst and acetylene as a carbon source, was employed in the growth of CNTs on the porousα-Al₂O₃ substrate. The CNT growth is affected by many factors. In view of this, this paper examined the process conditions on the growth of carbon nanotube films. The parameters in the CNT growth process, including the amount of catalyst, temperature, were examined in details. It was found that the catalyst particles become larger with the amount of catalyst increase, leading to the substantially reduction of the catalytic activity. The amount of iron particles drastically reduced and the size become smaller with the amount of ferrocene reduction. Consequently, the space between the iron catalyst particles increases and the density of iron catalyst particles decrease. As the reaction temperature increasing, the carbon nanotube growth is accelerated. Less carbon deposited due to the quick deactivation of the catalyst. An optimum condition for the growth of the aligned carbon nanotube arrays is given as follows: the amount of catalyst is 0.25 g; reaction temperature is 750 o C; reaction time is 10 min; the flow rate of acetylene is 100 sccm. The outer diameter of carbon nanotubes prepared are smaller than 40 nm.Nano-scale Co/Mo bimetallic catalyst particles were prepared and deposited on the quartz substrate with smaller sizes and uniform distribution by dip-coating method. Hydroxylation treatment of quartz surfaces and addition of viscous agent ethylene glycol in the acetate ethanol solution is preferred to small, evenly distributed catalyst particles preparation. Then by using CVD method we prepare carbon nanotubes with smaller size on quartz. The optimum conditions are as follows: the catalysts are reduced in 300 sccm N₂/H₂ （3 vol% H₂）; the reaction temperature is 750o C; acetylene gas flow rate is 30 sccm; and reaction time is更多还原