Ni‐based Catalysts for Hydrogen Production from Ammonia Decomposition: Effect of Dopants and Urine Application

An enhancement of catalytic activities for ammonia decomposition was achieved using partial doping of Sr, Y, Zr, or Ce in Al 2 O 3 frameworks. Improvements of the catalytic properties, including Ni dispersion, acidic sites, and basic sites have been studied. In this study, the Ni/doped Al 2 O 3 catalysts exhibit a great improvement of Ni dispersion, which results in higher catalytic activities, relative to Ni/undoped Al 2 O 3 . Among the studied catalysts, Ni/Ce‐doped Al 2 O 3 exhibits the highest NH 3 conversion, and Ni/Y‐doped Al 2 O 3 exhibits the best catalytic stability. The results of N 2 formation from NH 3 ‐TPRx imply that the recombination of nitrogen in the NH 3 decomposition mechanism could be the rate‐determining step in this study. Decomposition of NH 3 from urine was further evaluated over active Ni/Ce‐doped Al 2 O 3 . The catalyst can produce H 2 in the range of 169‐188 μmol⋅min ‐1 ⋅g cat ‐1 with 72.1% NH 3 conversion. The role of dopants in the Al 2 O 3 frameworks for the catalytic activities was also discussed, to understand the NH 3 decomposition mechanism.