Co-production of hydrogen and carbon nanotubes by catalytic cracking of waste cooking oil model compound over Ni-Cu/Al-KCC-1.

Ni-Cu/Al-KCC-1 catalysts with different metal contents were prepared using fibrous nano-silica (Al-KCC-1) as a support. Field emission scanning electron microscopy observations showed that the spherical particle morphology and fibrous structure of the Al-KCC-1 were not changed after metal loading. Transmission electron microscopy images demonstrated that the introduction of copper improved the dispersion of the nickel, while X-ray diffraction and hydrogen temperature-programmed reduction confirmed the formation of a Ni-Cu alloy. The N2-Brunauer-Emmett-Teller specific surface areas of the catalysts were in the range of 269-378 m2/g and the average pore diameters were 7.988-12.078 nm. These Ni-Cu/Al-KCC-1 catalysts were used to promote the cracking of waste cooking oil model compound (WCOMC) to produce H2 and carbon nanotubes (CNTs), and the 10 wt% Ni-5 wt% Cu/Al-KCC-1 exhibited the highest catalytic activity. At a WCOMC flow rate of 0.04 mL/min and 750 °C, the instantaneous volume fraction of H2 reached 49.8 vol% and the content of H2 in the gaseous product was close to 71.4 vol%.