Comparative study of Ni, Co, Cu supported on γ-alumina catalysts for hydrogen production via the glycerol steam reforming reaction

Abstract

Catalysts with active phase Ni, Co or Cu supported on γ-alumina were synthesized at constant loading (8 wt.%) and tested for the glycerol steam reforming reaction (GSR). The synthesized samples, at their calcined and/or their reduced form, were characterized by BET, ICP, XRD, DRS, NH3-TPD, CO2-TPD, TPR and SEM. The carbon deposited on their surface under reaction conditions was characterized by TEM, TPO, TGA and Raman. Catalytic performance for the glycerol steam reforming reaction was studied in order to investigate the effects of reaction temperature on: (i) glycerol total conversion, (ii) glycerol conversion to gaseous products, (iii) hydrogen selectivity and yield, (iv) selectivity of carbonaceous gaseous products, (v) selectivity of liquid products and (vi) molar ratios of H2/CO and CO/CO2 in the gaseous products' mixture. The stability of all catalysts was also investigated through time on stream experiments. It was concluded that catalytic performance, including liquid products' distribution, depends on the acid-base properties of the materials. Specifically, a drastic drop in the activity of the Ni/Al catalyst was observed, while Co/Al and Cu/Al catalysts deactivate in a slower rate, confirming that coke deposition, associated with dehydration, cracking and polymerization reactions, takes place on the catalyst's surface strong acid sites.