Promoting behavior of yttrium over nickel supported on alumina-yttria catalysts in the ethanol steam reforming reaction

The effect of different amounts of Y2O3 (5%wt, 10%wt and 15%wt) on the characteristics of nickel supported over mixed non-crystalline Al2O3Y2O3 was investigated. These materials were tested in ethanol steam reforming reaction. Prior to reaction, the materials were characterized by N2 adsorption, X-ray diffraction, temperature programmed reduction, temperature programmed desorption of ammonia (NH3-TPD), and Nuclear Magnetic Resonance. As the yttrium content in the catalytic support increased, nickel started to reduce at lower temperatures and for high yttrium loading (10%wt and 15%wt) an increase in hydrogen uptake was observed. NH3-TPD showed that yttrium presence decreased the total acidity of alumina and also lowered the strength of the acid sites. The influences of the water to ethanol molar ratio and of the weight gas hourly space velocity on the reaction were also investigated. Yttrium containing systems decrease the presence of C2 compounds in the exhaust gases and show less formation of CO. After activity test, yttrium containing catalysts seem to present less carbon deposits than the nickel supported on pure alumina catalyst.