Influence of fe, Cr and V doping on the methane cracking performance of hydrotalcite-derived NiAl catalysts

Abstract

Methane cracking is an efficient and clean method of producing hydrogen. Currently, designing high-performance methane cracking catalysts has become a research hotspot. In this paper, Ni_2·7Fe_0·3Al, Ni_2·7Cr_0·3Al and Ni_2·7V_0·3Al catalysts were obtained by reducing hydrotalcite precursors, and the effects of Fe, Cr and V doping on the methane cracking performance of hydrotalcite-derived NiAl catalysts were investigated. Comparative studies showed that the doping of V and Cr significantly improved the catalytic performance. Especially, the presence of Cr increased the specific surface area of the catalysts, promoted the reduction of Ni species and inhibited the sintering of metals during the reaction, exhibiting optimal catalytic performance. The Ni_2·7Cr_0·3Al catalyst was stabilized with 75% hydrogen yield over 250 min at 650 °C. In addition, Ni₃Al catalysts start reacting with methane at 300 °C, while Ni_2·7Cr_0·3Al catalyst showed a higher onset temperature than Ni₃Al catalyst. There was an induction period between 300 °C and 400 °C, and the H₂ yield increased linearly with the temperature after 400 °C. The doping of V and Cr significantly altered the morphology of the deposited carbon, allowing carbon nanotubes to replace carbon particles as the main product.