Study on the Effect of Reduction Temperature on the Catalytic Activity of Fe-Mo/Al2O3 Catalyst and the Microstructure of Carbon Nanotubes

It is usually necessary to first perform temperature reduction treatment to enable the catalyst to exert its catalytic activity in the subsequent process of preparing carbon nanotubes by chemical vapor deposition. In this experiment, Fe-Mo/Al2O3 catalyst was prepared based on microreactor, and the effect of reduction temperature on the microstructure of the catalyst and the morphology of carbon nanotubes was investigated. The results show that the reduction temperature has a significant effect on the microstructure of the catalyst, which in turn affects its catalytic activity and the yield and quality of carbon nanotubes. Moderately reducing the reduction temperature during the catalyst reduction process is beneficial to increase the catalytic activity of the catalyst. However, although its sintering degree could be weakened when the catalyst was reduced at an excessively low temperature of 350 °C, its catalytic efficiency was greatly reduced and the degree of defects of the catalyzed carbon nanotubes was increased. When the catalysts calcined at 450 °C and reduced at 600 °C, the catalysts show excellent catalytic activity, and catalytic efficiency can reach 74.76%. In addition, the reduction temperature also has a certain effect on carbon nanotubes. As the reduction temperature increases, the span of carbon nanotubes is relatively concentrated, but the specific gravity of the thicker outer diameter gradually increases. As for the defect degree of carbon nanotubes, the carbon nanotubes M600-600 is better and the defects are fewer when the reduction temperature is reduced from 670 °C to 600 °C.