Low temperature propane oxidation over Co₃O₄ based nano-array catalysts: Ni dopant effect, reaction mechanism and structural stability

Low temperature propane oxidation has been achieved by Co₃O₄-based nano-array catalysts featuring low catalytic materials loading (15mg under flow rate of 150mL/min). The increased Ni doping into the Co₃O₄ lattice has led to 100% propane conversion at low temperature (<400°C) and has enhanced reaction kinetics by promoting the surface lattice oxygen activity. In situ DRIFTS investigations in tandem with isotopic oxygen exchange reveals that the propane oxidation proceeds via a Mars-van Krevelen mechanism where surface lattice oxygen acts as the active site whereas O₂ in the reaction feed does not directly participate in CO₂ formation. The Ni doping promotes the formation of less stable carbonates on the surface to facilitate the CO₂ desorption. The thermal stability of Ni doped Co₃O₄ decreases with increased Ni concentration despite the increased catalytic activity. A balance between enhanced activity and compromised thermal stability is considered in the Ni doped Co₃O₄ nano-array catalysts for hydrocarbon oxidation. This study provides useful and timely guidance for rational catalyst design toward low temperature catalytic oxidation.