One-Pot Synthesis of (CrMnFeCoNi)O<sub><i>x</i></sub> High-Entropy Oxides for Efficient Catalytic Oxidation of Propane: A Promising Substitute for Noble Metal Catalysts
Yang Li, Bowen Han, Feng Bi, Zhongbiao Wu, Xiaole Weng
Abstract
The efficient catalytic oxidation of propane, as a short-chain alkane, remains challenging in environmental catalysis. High-entropy oxides (HEOs) exhibit advantages in abundant and well-dispersed elemental composition, exceptional thermal stability, and enriched lattice defects. Herein, (CrMnFeCoNi)O x HEO catalysts are successfully synthesized by using a continuous hydrothermal flow synthesis (CHFS) route, without any subsequent calcination processes. This route yields HEOs with fine particle sizes, high specific surface areas, and abundant near-surface lattice oxygen compared to the traditional coprecipitation method. Notably, the propane conversion over the CHFS-made (CrMnFeCoNi)O x HEO reaches 90% at 255 °C, with an apparent activation energy of 53.2 kJ/mol, mainly attributed to its enriched lattice oxygen and enhanced oxygen mobility that prevent the accumulation of acetates and the consequent occupation of active sites. In comparison to commercial Pt/Al 2 O 3 and Pd/Al 2 O 3, (CrMnFeCoNi)O x HEO demonstrates exceptional activity and can maintain long-term stability under high-temperature (upon 650 °C) and moisture-rich conditions (at 2–10 vol %). These attributes highlight its potential as a promising substitute for noble metal catalysts in industrial applications.