Synthesis of alumina-supported Co 2 P catalysts under methane dry reforming feed gas conditions

Unlike the conventional H2-reduction route, which involves energy-intensive reduction, mandatory passivation, and an additional pre-reduction step before use, our in situ synthesis route directly generates alumina-supported cobalt phosphide catalysts from a methane dry-reforming feed gas, thereby greatly simplifying the preparation process. Two Co:P precursors (1:1 and 2:1) were investigated at different temperatures. At 900 °C, the 1:1 Co:P precursor yielded a single Co2P phosphide phase, while the 2:1 Co:P precursor produced a Co2P/Co mixture due to strong phosphorus-support interaction. At 850 °C, the 2:1 Co:P precursor yielded only metallic Co, with no phosphide phase detected, indicating that the temperature was not sufficiently high. XPS analysis further revealed that the presence of metallic Co increased the samples’ susceptibility to oxidation. Notably, the catalyst derived from the 2:1 precursor at 900 °C exhibited higher dry reforming activity than the catalyst obtained from the 1:1 precursor, likely because metallic Co species promoted reversible phase transformations critical to catalytic performance.