Preparation and characterization of Ru/MgO-Al2O3 catalysts for methane steam reforming

The preparation and characterization of aluminum and magnesium oxides-supported ruthenium were described in this work, aiming to compare different supports to methane steam reforming catalysts for producing hydrogen. Gama-alumina-supported ruthenium and periclase-supported ruthenium were produced. The addition of small amounts of magnesium to alumina-supported ruthenium in the range of Mg/Al (molar)= 0.2-0.5 did not change the gama-alumina structure while high amounts (Mg/Al (molar) = 5) led to the production of periclase. Magnesium caused a decrease of specific surface area of alumina-supported ruthenium catalysts and this effect increased with the amount of the metal in solids. Magnesium also decreased the acidity of alumina-supported ruthenium and generated electron deficient ruthenium species. besides increasing their interaction with the support. The addition of magnesium increased the ruthenium dispersion but did not increase the methane conversion, suggesting that it negatively changed the electron properties of ruthenium towards methane conversion. However, it avoided deactivation during reaction and changed the activity for the water gas shift reaction, allowing tailoring the hydrogen to carbon monoxide molar ratio, The catalysts showed activity close or higher than a commercial sample, indicating that they are promising for the reaction, with the advantage that it can be tailored for several applications. (C) 2009 Elsevier B.V. All rights reserved.