Synthesis of carbon nanotubes by thermo catalytic decomposition of methane over Cu and Zn promoted Ni/MCM-22 catalyst

Abstract

The production of carbon nanotubes (CNTs) and pure hydrogen by the thermo catalytic decomposition of methane using a nano-size Ni-Cu-Zn/MCM-22 catalyst was investigated. The effect of Cu and Zn promoters was investigated by varying the amounts of Cu and Zn from 5 to 15wt% on a 50%Ni/MCM-22 catalyst prepared by wet impregnation. The performance of these catalysts was investigated in a fixed bed tubular reactor. The catalyst 50%Ni-10%Cu-10%Zn/MCM-22 resulted highest yield of hydrogen, and bamboo-shaped CNTs compared to other catalysts. The morphology of the carbon product strongly depended on reaction temperature, the amount of copper and zinc loading, flow rate and the partial pressure of methane. At higher reaction temperatures (>750°C) methane conversion and the yield of CNTs decreased due to sintering of the Ni particles. The experimental conditions for optimizing the carbon yield were also investigated and the most favorable conditions were observed at 750°C and at a methane partial pressure of 0.25atm. The aim of this study was to investigate the influence of reaction conditions on the morphology and formation of bamboo-shaped carbon filaments on a metal nanoparticle-based catalyst at moderate temperature.