Three-dimensional ordered macroporous Ru-substituted BaZrO3 perovskites: active catalysts for ammonia synthesis under mild conditions

Abstract

Three-dimensional ordered macroporous (3DOM) BaZr_(1−x)Ru_xO₃ perovskites were prepared by a PMMA-templating strategy and applied for ammonia synthesis for the first time. The 3DOM BaZr_(1−x)Ru_xO₃ catalysts have a periodic macroporous structure and Ru species are dispersed in the well-arranged pores. The 3DOM BaZr_0.95Ru_0.05O₃ catalyst shows effective ammonia synthesis under mild conditions. As proved by XAFS analysis, the active sites are surface Ru⁰ clusters. It was demonstrated that 3DOM BaZrO₃ is superior to S–G BaZrO₃ that was prepared by a sol–gel method in ammonia synthesis at low temperature. This phenomenon is attributed to the small crystalline size and the well-arranged macroporous structure of the former.