Partial oxidation of methane to syngas with air by lattice oxygen transfer over ZrO 2-modified Ce–Fe mixed oxides

Abstract

Catalytic performance of Ce–Fe mixed oxides promoted with ZrO 2 was investigated for methane partial oxidation to syngas via gas–solid reactions. The results showed that moderate amounts of ZrO 2 could strongly enhance the interaction between iron and cerium oxides via increasing the oxygen vacancy concentration and improving the dispersion of free Fe 2O 3, which improved the activity of Ce–Fe material for methane partial oxidation. However, heavy loading of ZrO 2 would lead to a phase segregation of CeO 2 and Fe 2O 3 from the Ce–Fe solid solution, resulting in a decrease in syngas selectivity. Among the tested samples, Ce–Fe–Zr (0.05) sample showed the best catalytic performance (with both high methane conversion and syngas selectivity). Despite severe sintering, the Ce–Fe–Zr (0.05) oxides presented high catalytic stability during the repetitive redox process (methane reduction/air re-oxidation) for the continuous production of syngas. This property should be attributed to the increased oxygen vacancy concentration on the mixed oxides after cycling, which could improve the lattice oxygen mobility, counteracting the native effect of material sintering on the catalytic activity for methane partial oxidation.