Confined Ru Sites in a 13X Zeolite for Ultrahigh H2Production from NH3Decomposition

Catalytic NH3synthesis and decomposition offer a new promising way to store and transport renewable energy in the form of NH3from remote or offshore sites to industrial plants. To use NH3as a hydrogen carrier, it is important to understand the catalytic functionality of NH3decomposition 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–1for the NH3decomposition 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 NH3is ruptured heterolytically by the frustrated Lewis pair of Ruδ+–Oδ−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 NH3to regenerate framework Brønsted acid sites that eventually are converted to molecular hydrogen.