Effect of Ce/Zr ratio in CeZr-CoRh catalysts on the hydrogen production by glycerol steam reforming

Abstract

The H2 production by glycerol steam reforming has been studied using fluorite-type mixed oxides of CZCoRh. The effect of the Ce/Zr ratio on the catalytic properties and its influence on the catalytic behavior are discussed. The catalysts were characterized before and after catalytic test by XRD, Raman spectroscopy, BET surface area, HRTEM, H2-TPR and TPD-TPO. The results show that an increase of the cerium amount enhances both the stability and the selectivity toward H2 and CO2. This is related to the improvement of the reducibility and re-oxidation properties, oxygen storage capacity and metal support interaction. The activity results demonstrate that selective H2 production is related to the capacity of the catalysts to activate H2O under reaction conditions. This step ensures the steam reforming of the by-products to H2. The progressive loss of this capacity reduces the H2 production, decreasing the steam reforming ability and the glycerol decomposition becomes predominant. In this last case the production of CO, CH4 and C2H4 is promoted along with the formation of condensable products as hydroxyacetone, acetaldehyde and acrolein.