Unravelling discharge and surface mechanisms in plasma assisted ammonia reactions
Current studies on ammonia synthesis by means of atmospheric pressure plasmas respond to the urgent need of developing less environmentally aggressive processes than the conventional Haber–Bosch catalytic reaction. Herein, we systematically study the plasma synthesis of ammonia and the much less inv...
| Autores: | , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/223173 |
| Acceso en línea: | http://hdl.handle.net/10261/223173 |
| Access Level: | acceso abierto |
| Palabra clave: | Packed-bed plasma reactors Ammonia synthesis Hydrogen production Atmospheric pressure plasma Energy efficiency Inefficient plasma processes Ferroelectric materials |
| Sumario: | Current studies on ammonia synthesis by means of atmospheric pressure plasmas respond to the urgent need of developing less environmentally aggressive processes than the conventional Haber–Bosch catalytic reaction. Herein, we systematically study the plasma synthesis of ammonia and the much less investigated reverse reaction (decomposition of ammonia into nitrogen and hydrogen). Besides analyzing the efficiency of both processes in a packed-bed plasma reactor, we apply an isotope-exchange approach (using D2 instead of H2) to study the reaction mechanisms. Isotope labeling has been rarely applied to investigate atmospheric plasma reactions, and we demonstrate that this methodology may provide unique information about intermediate reactions that, consuming energy and diminishing the process efficiency, do not effectively contribute to the overall synthesis/decomposition of ammonia. In addition, the same methodology has demonstrated the active participation of the interelectrode material surface in the plasma-activated synthesis/decomposition of ammonia. These results about the involvement of surface reactions in packed-bed plasma processes, complemented with data obtained by optical emission spectroscopy analysis of the plasma phase, have evidenced the occurrence of inefficient intermediate reaction mechanisms that limit the efficiency and shown that the rate-limiting step for the ammonia synthesis and decomposition reactions are the formation of NH* species in the plasma phase and the electron impact dissociation of the molecule, respectively. |
|---|