Catalytic partial oxidation of methane to synthesis gas over

The partial oxidation of methane to syngas was studied in this work over Ni-containing ceria catalysts with nickel content of 5, 10 and 20 at. % at atmospheric pressure. All catalysts, in the as prepared state, showed similar activity and CO selectivity at T 550C. Catalyst pre-reduction was not required. Reaction mixtures were dilute, containing 3 mol % CH4 and 1.5 mol% O2. Methane conversion and CO selectivity approached their respective thermodynamic equilibrium values above 550C. The H2/CO ratio was equal to 2 at T> 600C. In the range 0.54–0.04 g s/cm3 (STP), contact time effects were absent in partial oxidation of methane over the 5 at. % Ni–Ce(La)Ox catalyst. The phase composition, nickel dispersion and carbon deposition on the catalysts were investigated by various characterization techniques, including XRD, STEM/EDS, XPS and TPO analyses. The 5 at. % Ni–Ce(La)Ox catalyst, comprising highly dispersed nickel oxide in ceria, showed excellent resistance to carbon deposition and stable performance during 100 h-on-stream at 650C. On the other hand, high-content (>10 at.%) nickel in ceria, comprising both dispersed nickel and bulk nickel oxide particles, was unstable even after a much shorter time-on-stream; carbon deposition was clearly the cause of this performance instability. © 2001 Elsevier Science B.V. All rights reserved