Confined Ru Sites in a 13X Zeolite for Ultrahigh H 2 Production from NH 3 Decomposition

Catalytic NH synthesis and decomposition offer a new promising way to store and transport renewable energy in the form of NH from remote or offshore sites to industrial plants. To use NH as a hydrogen carrier, it is important to understand the catalytic functionality of NH decomposition reactions at an atomic level. Here, we report for the first time that Ru species confined in a 13X zeolite cavity display the highest specific catalytic activity of over 4000 h for the NH decomposition with a lower activation barrier, compared to most reported catalytic materials in the literature. Mechanistic and modeling studies clearly indicate that the N-H bond of NH is ruptured heterolytically by the frustrated Lewis pair of Ru -O in the zeolite identified by synchrotron X-rays and neutron powder diffraction with Rietveld refinement as well as other characterization techniques including solid-state nuclear magnetic resonance spectroscopy, in situ diffuse reflectance infrared transform spectroscopy, and temperature-programmed analysis. This contrasts with the homolytic cleavage of N-H displayed by metal nanoparticles. Our work reveals the unprecedented unique behavior of cooperative frustrated Lewis pairs created by the metal species on the internal zeolite surface, resulting in a dynamic hydrogen shuttling from NH to regenerate framework Brønsted acid sites that eventually are converted to molecular hydrogen.