Boosting catalytic oxidation of propane over mixed-phase CoO-Co3O4 nanoparticles: Effect of CoO

Article abstract of DOI:10.1016/j.chemphys.2020.110984

A series of pure Co₃O₄ and mixed-phase CoO-Co₃O₄ nanoparticles were synthesized through a facile citric acid complex strategy. Different from pure Co₃O₄, the extra CoO is beneficial to the formation of small crystalline size (11.8 nm), large specific surface area (62.8 m²·g^?1), and high Co²⁺/Co³⁺ and O_ads/O_latt ratios. Moreover, the interaction between CoO and Co₃O₄ diminishes the electron cloud density in the outer layer of O atom, weakens the strength of the Co–O bond, and improves the mobility of active oxygen species. At a GHSV of 30,000 ml·g^?1·h^?1, the mixed-phase CoO-Co₃O₄ converted propane to 90% only at 235 °C. After 40 h of reaction, CoO was oxidized into smaller Co₃O₄ particles and maintained a stable catalytic activity. Further research found that the mixed-phase CoO-Co₃O₄ still has good activity (T₉₀ = 250 °C) even at high GHSV (75,000 ml·g^?1·h^?1). The outstanding performance of nanoparticles makes it possible to achieve deep purification of VOCs under high GHSV.