Hydrogen generation from hydrous hydrazine over Ni/CeO2 catalysts prepared by solution combustion synthesis

Hydrous hydrazine is a promising hydrogen carrier for fuel cell vehicles owing to its high hydrogen content (8.0 wt% for N2H4.H2O), low cost and stable liquid state at ambient temperature. The development of cost effective catalysts with high activity and 100% selectivity for hydrogen generation under mild conditions, however, is a significant challenge for its practical use. In this work, a series of Ni/CeO2 catalysts were prepared by solution combustion synthesis (SCS), varying the SCS parameters in terms of ratio of precursor oxidizers (nickel nitrate and ammonium cerium nitrate), fuel-to-oxidizer ratio (0.5-3) and fuel type (hydrous hydrazine and glycine). These parameters influence the combustion behavior and, in turn, the physicochemical properties of catalysts such as crystallinity, Ni particle size, surface area and pore size as well as formation of Ni-O-Ce solid solution. The reaction mechanism for the SCS process is discussed. The tailored 6 wt% Ni/CeO2 catalyst synthesized with fuel-to-oxidizer ratio 2 and hydrous hydrazine fuel, exhibited 100% selectivity for hydrogen generation and good activity with a TOF value 34.0 h-1 at 50 degrees C, which is the highest catalytic performance among all prior reported catalysts containing Ni alone.