Bio-hydrogen production by oxidative steam reforming of biogas over nanocrystalline Ni/CeO_2 catalysts

摘要

The current energy scenario, that is characterized by some unresolved problems as pollutant emissions, increasing of energy demand and fossil fuels shortage, has led to an increased interest in the use of renewable sources to integrate and progressively replace the conventional fossil fuel based systems with renewable bio-energy units. Among different options, one of the promising renewable fuels is biogas. Simultaneously, hydrogen is envisioned as a clean energy carrier for the future. In this regards, the reforming processes of biogas into hydrogen fuel, for subsequent conversion into a useful form, are gaining research interest. This study focuses on the synthesis of nanocrystalline Ni/CeO_2 catalysts for the biogas oxy-steam-reforming (OSR) process. The solution combustion synthesis (SCS) has been studied varying the fuel (oxalyldihydrazide, urea, carbohydrazide) and the cerium precursor (cerium nitrate and ammonium cerium nitrate). The physical-chemical characterizations have shown that the morphological and redox properties of the prepared samples are strictly connected with the selection of precursors and fuel for the solution combustion mixture. Particularly, the use of urea as fuel allows to improve nickel dispersion, surface area and reducibility of the catalysts, affecting positively the OSR performances.