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The ability of NaCl-type binary transition metal nitrides (incorporating La, Ce, Y, Zr or Hf) to act as catalytic supports facilitating ammonia decomposition was examined. The effect of nitrogen vacancies formed on nitrides can be understood in terms of the ionic radii of the metal cations. A clear correlation between the N2 desorption temperature and catalytic activity was found. [ABSTRACT FROM AUTHOR]

Nickel is a promising candidate as an alternative to ruthenium for an ammonia decomposition catalyst. However, the performance of Ni‐based catalysts for ammonia decomposition is still not sufficient to achieve a good hydrogen production rate under low‐temperature because the weak nitrogen affinity of Ni reduces the frequency of the ammonia decomposition reaction. Here, it is reported that Ni supported on barium titanium oxynitride (Ni/h‐BaTiO3−xNy) with a hexagonal structure acts as a highly active and water‐durable catalyst for ammonia decomposition. The operation temperature is reduced by over 140 °C when N3− ions are substituted onto the O2− sites of the BaTiO3 lattice, and the Ni/h‐BaTiO3−xNy catalyst significantly outperforms conventional oxide‐supported Ni catalysts for ammonia decomposition. Furthermore, the activity of Ni/h‐BaTiO3−xNy remains unchanged after exposure to water. The 15NH3 decomposition reaction and Fourier transform‐infrared spectroscopy (FT‐IR) measurements reveal that lattice nitrogen vacancy sites on h‐BaTiO3−xNy function as the active sites for ammonia decomposition. The ammonia decomposition activity of Ni/h‐BaTiO3−xNy is also higher than that of the Ni/h‐BaTiO3−xHy oxyhydride catalyst, making a contrast to the activity trend in ammonia synthesis. [ABSTRACT FROM AUTHOR]

Oxidation reaction of a gas-phase aluminum atom by a molecular oxygen was studied by a crossed-beam condition at 12.4 kJ/mol of collision energy. A (1+1) resonance-enhanced multiphoton ionization (REMPI) via the D(2)Σ(+)-X(2)Σ(+) transition of AlO was applied to ionize the product. The REMPI spectrum was analyzed to determine rotational state distributions for v = 0-2 of AlO. For several vib-rotational states of AlO, state selected angular and kinetic energy distributions were determined by a time-sliced ion imaging technique for the first time. Kinetic energy distributions were well represented by that taken into account initial energy spreads of collision energy and the population of the spin-orbit levels of the counter product O((3)P(J)) determined previously. All angular distributions showed forward and backward peaks, and the forward peaks were more pronounced than the backward one for the states of low internal energy. The backward peak intensity became comparable to the forward one for the states of high internal energy. These results and the rotational state distributions suggested that the reaction proceeds via an intermediate which has a lifetime comparable to or shorter than its rotational period.