取样时间和碳源气体流量对火焰法催化裂解乙烯制备碳纳米管的影响

Effect of Sampling Time and Carbon Source Gas Flow Rate on the Carbon Nanotubes Synthesized from C_2H_4 by Flame Method

采用火焰法,并使用Fe/Mo/Al2O3型载体催化剂,催化裂解乙烯制备了碳纳米管,并对取样时间和乙烯气体流量进行了实验探究。结果表明:取样温度保持1000℃,He和H2气体流量保持为经验配比He∶H2=2∶3时,取样时间越长,生成的碳纳米管数量也越多,而取样时间达到7 min时,碳纳米管的数量已经基本稳定;乙烯气体流量为0.2 L/min时,生成的碳纳米管在质量和数量上都达到较佳,乙烯流量偏低或者偏高都不利于碳纳米管的生成;实验中制备的碳纳米管以双壁或者少壁的多壁碳纳米管为主,没有单壁碳纳米管生成。

Carbon nanotubes（ CNTs） were synthesized by catalytic pyrolysis of C2H4 using flame method with carrier catalyst of Fe / Mo / Al2O3. The sampling time and the gas flow rate of C2H4 were both studied. The experimental results show that： with the sampling temperature being 1000 ℃,He and H2 gas flow ratio being the experiential ratio of 2 ∶ 3,carbon nanotubes increase in size and number as the sampling time is prolonged. The number of carbon nanotubes is basically stable when the sampling time reached 7 min. When the gas flow rate of C2H4 reached 0. 2 L / min,carbon nanotubes achieve better both in quality and quantity. Too low or too high of the gas flow rate would both impede the formation of carbon nanotubes. Most of the carbon nanotubes synthesized in the experiment were double-walled or less-walled of the multi-walled carbon nanotubes. Single-walled carbon nanotubes are not synthesized.