Hydrogen production on alumina-supported platinum catalysts

Abstract

Hydrogen production is commercially performed by methane steam reforming over alumina-supported nickel catalysts, which deactivate by coke requiring improved catalysts. Aiming to find alternative catalysts for the reaction, the properties of Pt/Al2O3-MgO catalysts were studied in this work. It was found that small amounts of magnesium (Al/Mg (molar)=5) enter into alumina lattice and produce magnesium aluminate on the surface. For higher amounts (Al/Mg=2) only magnesium aluminate is produced. For even higher contents (Al/Mg=0.2) aluminum enters into magnesia lattice, producing magnesia and magnesium aluminate on the surface. The specific surface area, acidity and platinum dispersion changed with magnesium amount, the aluminum-richest catalyst (Al/Mg=5) showing the highest values. Consequently, the activity and selectivity of the catalysts change in methane steam reforming and in water gas shift reaction, different values of products yield and H2/CO being obtained. The sample with Al/Mg=5 is the most promising catalyst to produce hydrogen.