Catalytic Synthesis of Carbon Nanotubes by Ni/ZSM-5 Catalyst from Waste Plastic Syngas

Carbon nanotubes (CNTs) have been proved to be a high-value by-product of hydrogen production which could be obtained through catalytic reforming from waste plastic syngas. Catalyst plays an important role in the growth of carbon nanotubes. The influences of Ni/ZSM-5 catalyst and temperature were performed in a lab-scale tubular reactor. The catalyst and produced carbon were analyzed by different characterization methods. X-ray diffraction, X-ray energy dispersive spectrometer, scanning electron microscopy and transmission electron microscopy. The results showed that in the presence of catalyst, 600 °C is considered the optimal temperature during the operating temperature range of 400 °C~800 °C for carbon yield and hydrogen production rate, the highest carbon yield of 4.83 g/gcatalyst (among which the MWCNTs were the main products) and hydrogen production rate of 0.0199 L/min were obtained. Higher catalytic temperature led to higher average diameter of carbon nanotubes, which increased from 39.5 nm to 55.3 nm. The highest carbon nanotubes proportion of 98.08% to total carbon deposition was obtained under the conditions of 800 °C. It suggested that Ni/ZSM-5 catalyst has the potential for high quality carbon nanotubes and H2-riched gas production from waste plastic syngas.