Methane Combustion Over Ni/CexZr1–xO2 Catalysts: Impact of Ceria/Zirconia Ratio

Abstract A series of Ce x Zr 1–x O 2 (x=1, 0.83, 0.17, 0) supports and 2 wt.% Ni/Ce x Zr 1–x O 2 catalysts were synthesized and evaluated for CH 4 oxidation. The Ce x Zr 1–x O 2 supports showed moderate activity (T 50 =519‐638 °C) with CO by‐product formation. Nickel incorporation onto Ce x Zr 1–x O 2 lowered the T 50 to 438–477 °C and eliminated the formation of CO. The results indicated that moderate Zr doping improved the support oxygen storage capacity (OSC) and reducibility of the catalyst at low temperatures (H 2 ‐TPR) leading to an enhanced CH 4 combustion turnover frequency: Ni/ZrO 2 <Ni/Ce 0.17 Zr 0.83 O 2 <Ni/CeO 2 <Ni/Ce 0.83 Zr 0.17 O 2 . The apparent activation energies of Ni/Ce x Zr 1–x O 2 catalysts (87‐92 kJ/mol) were much lower than the ones of Ce x Zr 1–x O 2 supports and Ni/quartz sand (111‐120 kJ/mol) indicating that CH 4 oxidation is facilitated when Ni is deposited on Ce x Zr 1–x O 2 . Moreover, stability tests with H 2 O and CO 2 showed that Zr doping can improve the catalyst stability, while H 2 O had a stronger reversible inhibition effect than CO 2 for CH 4 combustion.