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Coke-Resistant Rh and Ni Catalysts Supported on g-Al2O3 and CeO2 for Biogas Oxidative Steam Reforming
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1  University of Salerno

Abstract:

The depletion of fossil fuels and the growing concerns related to the environmental impact of their processing has progressively switched the interest towards the utilisation of biomass-derived materials for a large variety of processes. Among them, biogas, which is a CH4-rich gas deriving from anaerobic digestion of biomass, has acquired a lot of interest as feedstock for reforming processes. The main issue in employing biogas is related to the carbon deposition and metal sintering, which are both responsible for the deactivation of the catalyst. In this work, bimetallic and monometallic Rh and Ni based formulation were supported on alumina and ceria with the aim of evaluating their activity and stability in biogas oxidative steam reforming. Rh/Al2O3 sample showed the highest activity towards the reaction and Rh addition to Ni/Al2O3 formulation enhances its catalytic performances; nevertheless, this induced a remarkably higher coke deposition in the 24-hours stability test. For this reason, ceria was selected as support for further investigations. The initial activity of the CeO2-supported catalysts was found to be close to the Al2O3-supported catalyst. Then, 50-hours stability tests were performed and a reduction in the activity was observed. Nevertheless, TPO analysis demonstrated that no coke was present on the catalyst surface, thanks to ceria oxygen mobility properties. The deactivation was in fact ascribable to the sintering of the active species, which have a worse dispersion on ceria rather than on alumina because of the lower SSA of the support.

Keywords: biogas oxidative reforming; coke resistance; metal sintering; Rh and Ni catalysts; stability
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