Catalytic methane decomposition to hydrogen and carbon over hydrotalcite‐derivative composition‐uniform and sintering‐resistant Ni‐Fe / Al ₂ O ₃ alloy catalysts

Abstract

Ni-Fe/Al 2 O 3 alloy catalysts obtained from Ni 3-x Fe x Al (x = 0-1.2) hydrotalcitelike compounds are tested in CH 4 decomposition at 600 C to produce H 2 and carbon. By calcination at 500 C, nickel-iron-aluminum hydrotalcite is decomposed into Ni(Fe,Al)O solid solution; upon reduction at 800 C, Ni-Fe alloy with uniform composition and the average size of 9.4 to 10.3 nm is formed.The Ni-Fe/Al 2 O 3 alloy catalysts exhibit higher catalytic life and carbon yield than the Ni 3 Al counterpart, with the optimal alloy composition being Ni: Fe = 4:1. Carbon nanotubes are produced on all catalysts, and the average carbon diameter is decreased to a certain degree by Ni-Fe alloying. XRD indicates that Ni-Fe alloy is less sintered than Ni metal under the reaction atmosphere, which may account for the decrease in the carbon diameter. This study provides a way for the preparation of a uniform Ni-Fe alloy catalyst and its sintering resistance is helpful for controlling the carbon morphology.