Kinetics of hydrogen adsorption and mobility on Ru nanoparticles supported on alumina: effects on the catalytic mechanism of ammonia synthesis
(2016) Journal of Catalysis — Vol. 344, p. 16-28 (2016)
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- Relevant findings on hydrogen adsorption and mobility are provided in this work to elucidate the mechanism of low-temperature ammonia synthesis, catalyzed by polydispersed Ru nanoparticles supported on alumina. H/D isotopic exchange technique, complemented by DRIFTS analysis, was applied to study the kinetics of hydrogen adsorption/desorption on metallic Ru and hydrogen diffusivity on alumina, for catalysts presenting different size distributions of Ru nanoparticles. H atoms adsorbed on large Ru nanoparticles present higher mobility and they migrate on alumina via exchange with OH groups. A broad size distribution of Ru nanoparticles leads to synergy in the rate of ammonia synthesis, and also in hydrogen mobility. The mechanism of catalytic cooperation involves transfer of H atoms from large to small nanoparticles, where the reaction rate is promoted. Considering dynamic catalytic processes in the formulation of kinetic models is crucial for a more accurate description of processes and the development of large-scale processes.
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Fernandez, C., Bion, N., Gaigneaux, E., Duprez, D., & Ruiz, P. (2016). Kinetics of hydrogen adsorption and mobility on Ru nanoparticles supported on alumina: effects on the catalytic mechanism of ammonia synthesis. Journal of Catalysis, 344, 16-28. https://doi.org/10.1016/j.jcat.2016.09.013 (Original work published 2016)