Oxidative steam reforming of methane over nickel catalysts supported on Al2O3–CeO2–La2O3

Abstract

Nickel catalysts supported on Al₂O₃, Al₂O₃–CeO₂, Al₂O₃–La₂O₃, and Al₂O₃–CeO₂–La₂O₃ were synthesized via the sol–gel method in acidic solution. The influence of the chemical composition and textural properties of the catalysts on oxidative steam reforming of methane was studied. Methane, oxygen, nitrogen and steam were fed into a fixed bed reactor and tested under atmospheric pressure at 550 °C, with O/C ratio = 0.3, S/C ratio = 1.0, and WHSV = 170.8 h⁻¹. During 6 h of reaction, methane conversion and hydrogen selectivity were determined. Although lanthanide oxides are known to have excellent features, the addition of ceria or lanthana did not improve the catalytic performance of the Ni/Al₂O₃ system. Nevertheless the addition of both dopants was needed to end up with a stable catalyst. Characterization results revealed a low crystallite size (40 Å), a high fraction of accessible Ni⁰ species (73.6%), migration of nickel and ceria from the bulk to the surface during activity tests, and a very low amount of coke deposited (4.7 mg C per g catalyst) on the Ni/Al₂O₃–CeO₂–La₂O₃ catalyst that resulted in high catalytic activity.