Carbon nanotubes (CNTs) produced by catalytic reforming of the waste plastic syngas is a high value-added by-product of hydrogen production. Catalysts play an important role in the growth of carbon nanotubes. The influences of Ni/ZSM-5 catalyst, Ni–Mn/ZSM-5 catalyst and temperature were performed in a lab-scale tubular reactor. The catalysts and product carbon were analyzed by different characterization methods, including temperature-programed reduction/oxidation, X-ray diffractometer, scanning electron microscope, transmission electron microscope, X-ray energy spectrometer. The results showed that in the presence of Ni–Mn/ZSM-5 catalyst with the addition of catalytic promoter Mn, 650 °C was the optimum temperature during the operating temperature range of 600 °C~800 °C for the rate of carbon production and hydrogen production, and the carbon production was the highest, which was 2.95gCNTs/gCatalyst (wherein the Multi-walled carbon nanotubes (MWCNTs) were main product), and compared with the monometallic Ni/ZSM-5 catalyst, the Ni–Mn/ZSM-5 catalyst with Mn addition increased the H2 content in the syngas from 14 Vol.% to 39 Vol.%. The highest carbon nanotubes proportion of 95.81% to total carbon deposition was obtained under the conditions of 750 °C. The introduction of catalytic promoter Mn transforms the growth mode of carbon nanotubes from top growth mode to bottom growth mode, and obtains carbon nanotubes with more regular structure. It suggested that Ni–Mn/ZSM-5 catalyst had the potential for high quality carbon nanotubes and H2-riched gas production 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.
Oxygen-steam gasification of biomass catalyzed by modified iron-rich red mud extract is firstly performed in our work. During the impregnation of the modified red mud extract (MRME), the pore structure characteristics and thermal behavior of the maize straw changed significantly. The influence of MRME on syngas quality, gas yield, and thermal efficiency were performed in a lab-scale gasification reactor. The results showed that higher temperature, sufficient MRME addition, appropriate equivalent ratio (ER) and a small amount of steam all promoted syngas quality and energy conversion. For maximum economic efficiency, the optimal rate of MRME addition is 30% weight ratio to maize straw. The optimal level of ER was found to be 0.23, and the maximum energy conversion ratio was 82.4% at 800 °C with optimal levels of MRME addition and ER. Compared with the raw maize straw gasification at the same operating condition, the content of H2 increased from 17.32% to 33.77%, and CO raised from 22.89% to 35.11%. It seems that the red mud extract catalyst has the potential for using as an economic efficiency industrially catalyst for high quality and H2-riched syngas production from biomass gasification.
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