Effect Of Iron Based Catalysts On Synthesis Of Carbon Nanotubes By Pyrolysis Flame Method

On the basis of the research experience on the synthesis of carbon nanotubes by pyrolysis flame method,this paper has made a more detailed and in-depth study on the iron based catalysts.The influence of the change of hydrogen on the catalytic effect of the iron based catalysts was studied to find the most suitable gas environment for the iron based catalysts.Then the iron ratio in the iron based catalysts was changed and the influence of iron based catalysts on the synthesis of carbon nanotubes under different iron content was studied.Then,a new type of polymetallic catalyst was prepared.By comparing with the former,the effect of Ni on the catalytic effect of the catalyst is also discussed.Finally,the catalytic effect of iron,cobalt and nickel based catalysts was compared and analyzed in this paper.Experimental research and analysis showed that:(1)When the flow rate of hydrogen is 0.35L/min,the catalytic effect of the iron based catalyst is the best in the experiment of pyrolysis flame method.In this case,the production and quality of carbon nanotubes can reach a good level.If the flow rate of hydrogen is smaller,the production of carbon nanotubes will be reduced.If the flow rate of hydrogen is too large,the quality of the carbon tube will be worse.(2)In this paper,Fe-Mo/Al2O3 was used as a catalyst for the experiment.When the ratio of Fe:Mo:Al is 1.5:0.17:16,the mass and production of multi walled carbon nano tubes can be maintained at a higher level.This condition is suitable for mass production of multi walled carbon nanotubes.The content of iron is too high or too low,which is not conducive to the formation of carbon nanotubes.In this experiment,an appropriate amount of Ni was added to the Fe-Mo/Al2O3 catalyst to form a Fe/Ni-Mo/Al2O3 multi metal catalyst.After Ni was added,the activity of the iron based catalyst was improved,and the orientation of the carbon tube was enhanced.When the ratio of Fe:Ni:Mo:Al is 1:0.5:0.17:16,the production of carbon nanotubes is higher and the directivity is better.(4)Iron based catalysts are more suitable for the synthesis of carbon nanotubes by flame method.