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

Summary Ni‐Fe/Al 2 O 3 alloy catalysts obtained from Ni 3‐ x Fe x Al ( x = 0‐1.2) hydrotalcite‐like 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.