Influence of Cation Substitutions Based on ABO3 Perovskite Materials, Sr1–x Y x Ti1–y Ru y O3−δ, on Ammonia Dehydrogenation

In order to screen potential catalytic materials for synthesis and decomposition of ammonia, a series of ABO3 perovskite materials, Sr1–x Y x Ti1–y Ru y O3−δ (x = 0, 0.08, and 0.16; y = 0, 0.04, 0.07, 0.12, 0.17, and 0.26) were synthesized and tested for ammonia dehydrogenation. The influence of A or B site substitution on the catalytic ammonia dehydrogenation activity was determined by varying the quantity of either A or B site cation, producing Sr 1– x Y x Ti0.92Ru0.08O3−δ and Sr0.92Y0.08 Ti 1– y Ru y O3−δ, respectively. Characterizations of the as-synthesized materials using different analytical techniques indicated that a new perovskite phase of SrRuO3 was produced upon addition of large amounts of Ru (≥12 mol %), and the surface Ru0 species were formed simultaneously to ultimately yield Ru z (surface)/Sr0.92Y0.08 Ti 1– y Ru y – z O3−δ and/or Ru z – w (surface)/Sr w Ru w O3/Sr0.92–w Y0.08 Ti 1– y Ru y – z O3−δ. The newly generated surface Ru0 species at the perovskite surfaces accelerated ammonia dehydrogenation under different conditions, and Sr0.84Y0.16Ti0.92Ru0.08O3−δ exhibited a NH3 conversion of ca. 96% at 500 °C with a gas hourly space velocity (GHSV) of 10 000 mL gcat –1 h–1. In addition, Sr0.84Y0.16Ti0.92Ru0.08O3−δ further proved to be highly active and stable toward ammonia decomposition at different reaction temperatures and GHSVs for >275 h.