On-line intermittent growth of carbon nanotubes in a self-made tapered fluidized bed reactor at different inlet distances

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The effect of the gas inlet distance on the quality and yield of carbon nanotubes (CNTs) is studied through the on-line intermittent method via a previous self-made tapered fluidized bed reactor (TFBR). The CNTs are catalytically grown on the Fe-Co-Mo/Al2O3 and Fe/Mo/Vermiculite catalyst at different inlet distances (DIDs), which clarify the effect of inlet distance and explore the optimum location. The whole process of CNTs growth in the TFBR without a distributor is explored. The effects of DIDs on catalyst flow and CNTs growth are discussed as well. Additionally, the morphology, quantity and quality of multi-walled carbon nanotubes (MWCNTs) are systematically characterized by using scanning electron microscopes (SEM), Brunauer Emment Teller (BET) and Raman Spectra. The results show that the CNTs prepared at 50 mm from the bottom of the cone have lower ash content and defect, and higher quality compared to other locations. That is, the airflow from 1/2–3/4 of the cone bottom could improve the catalytic performance of the catalyst, which results in the CNTs prepared have an excellent structure and high-efficiency carbon conversion rate.