Effect of the active metals on the selective H2 production in glycerol steam reforming

The production of hydrogen by glycerol steam reforming was studied using CeZr(Co, CoRh) catalysts. The effect of Co and Rh presence on the properties of the mixed oxides and the effect on the catalytic behavior were considered. The catalysts were characterized before and after testing by XRD, Raman, TPR, H2-TPD, TPD-TPO and HRTEM. It was observed that the presence of Co allowed the selective H2 production related with the presence of a metallic phase at the beginning of the reaction. The presence of Rh favored even more the H2 production and also increased the stability of the catalyst. For CeZrCoRh, the presence of both metals enhanced the catalyst reduction capacity, a characteristic that significantly improved the catalytic behavior for glycerol steam reforming. The selective H2 production was related to the capacity of the catalyst to activate H2O under the reaction conditions. The progressive loss of this capacity decreases the production of H2, and glycerol decomposition is actually favored over glycerol steam reforming. According to the initial distribution of products, and its evolution with time on stream, two main reaction pathways were proposed.

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► The presence of both Co anf Rh enhances the catalyst reduction capacity.
► Selective H2 production related to the catalyst's capacity to activate water under the reaction conditions.
► Thermal decomposition of glycerol is superimposed with its steam reforming.