Hydrogen Production by Steam Gasification of Biomass Using Ni−Al Coprecipitated Catalysts Promoted with Magnesium

Ni−Al coprecipitated catalysts promoted with magnesium have been prepared using the rising and the constant pH techniques, two precipitant agents [(1) KOH and K 2 CO 3, and (2) NH 4 OH)] and different metal contents. Catalyst characterization by temperature-programmed reduction and CO 2 reforming of methane as a test reaction served to select the appropriate catalysts for use in the steam gasification of biomass. The catalysts selected were NiMgAl 2 O 5, prepared at constant pH and precipitated with KOH and K 2 CO 3; NiMgAl 4 O 8 and NiMgAl 1.24 O 3.86, both prepared at increasing pH with NH 4 OH. Biomass steam gasification experiments were carried out at 700 °C and at atmospheric pressure using different steam/biomass (S/B) and catalyst weight/biomass flow rate (W/B) ratios. From an analysis of the results obtained, the initial activity and stability of the catalysts have been studied. The NiMgAl 2 O 5 catalyst presents the best performance showing the highest initial activity and stability. This work evidences an improvement of the NiMgAl 2 O 5 catalyst with respect to the previously studied NiAl 2 O 4 catalyst.