Three-dimensional ordered macroporous Ru-substituted BaZrO3 perovskites: active catalysts for ammonia synthesis under mild conditions†
Three-dimensional ordered macroporous (3DOM) BaZr(1−x)RuxO3 perovskites were prepared by a PMMA-templating strategy and applied for ammonia synthesis for the first time. The 3DOM BaZr(1−x)RuxO3 catalysts have a periodic macroporous structure and Ru species are dispersed in the well-arranged pores. The 3DOM BaZr0.95Ru0.05O3 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.