Low temperature dry methane reforming over Ce, Zr and CeZr promoted Ni–Mg–Al hydrotalcite-derived catalysts
Résumé
Hydrotalcite derived catalysts promoted with Ce, Zr and CeZr showed considerable activity in dry methane reforming (DMR) at low temperatures (550°C). Direct methane decomposition resulting in the extensive formation of fishbone-type carbon nanofibers was substantially inhibited in the presence of Zr. Physicochemical characterization by means of N 2 adsorption, XRD, TPR and CO 2-TPD evidenced narrower porosity and higher surface areas for the Zr-containing catalysts, together with the presence of smaller Ni particles (around 4 nm) and CO 2 preferential adsorption in weak basic sites. Such small Ni particles are inactive towards the direct methane decomposition reaction. The ability of the Zr-containing catalysts to adsorb CO 2 on weak basic sites results in the formation of active carbonate species that are able to react with methane through the DMR route. The reverse Boudouard reaction occurs simultaneously to a certain extent in the presence of Zr-promoted catalyst, since carbon nanotube formations were visible on the catalyst surface upon its utilization.
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