Effects of support and promoter on Ru catalyst activity in microwave-assisted ammonia synthesis

Microwave-assisted ammonia synthesis is a promising alternative to the energy-intensive Haber-Bosch process, specially at small- and medium-scale with renewable H-2 as resource. Here, we report that Cs promoted Ru/CeO2 catalyst exhibits considerable activity at 533 K and ambient pressure. In this work, the combined theoretical and experimental approaches are adopted to optimize the electronic and geometric structures of Ru on the catalysts. Both DFT modeling work and structural characterization show that the strong interaction between Ru and CeO2 results in the formation of highly dispersed Ru particles favoring ammonia synthesis. The higher electron donating ability of CeO2 and lower electronegativity of Cs promoter result in higher electron density on Ru reducing the N equivalent to N dissociation barrier. The work demonstrates the potential of microwave-assisted catalytic process in activating stable molecules for ammonia synthesis.

Automated summary

This study demonstrates the high activity of Cs-promoted Ru/CeO2 catalyst for ammonia synthesis at 533K and ambient pressure, achieved through optimized electronic and geometric structures. The strong interaction between Ru and CeO2 leads to the formation of highly dispersed Ru particles favorable for ammonia synthesis. CeO2's higher electron donating ability and Cs promoter's lower electronegativity result in increased electron density on Ru, reducing the N dissociation barrier.