High-Performance Co-MnO _x Composite Oxide Catalyst Structured onto Al-Fiber Felt for High-Throughput O ₃ Decomposition

A highly active and efficient thin-felt Al-fiber-structured Co-MnO _x composite oxide catalyst (named Co-MnO _x -Al) with unique form factor and high permeability is developed for high-throughput catalytic decomposition of gaseous ozone (O ₃ ). Thin-sheet Al-fiber felt (60 μm diameter; 90 vol % voidage) chips underwent a steam-only oxidation and calcination for endogenously growing a 0.7-μm-thick mesoporous layer of γ-Al ₂ O ₃ nanosheets along with the Al-fiber. Cobalt and manganese were placed onto the ns-γ-Al ₂ O ₃ /Al-fiber chips by incipient wetness co-impregnation method. The best catalyst is the one with a Co/Mn molar ratio of 0.36 and Co-Mn loading of 5 wt % after calcining at 500 °C (named Co-MnO _x (0.36)-Al), being able to achieve full O ₃ conversion at 25 °C for a feed gas containing 1000±30 ppm O ₃ , using a high gas hourly space velocity of 48000 mL g _cat. ⁻¹ h ⁻¹ ; full O ₃ conversion is retained in the absence of moisture till the testing end after 720 min; in case with a relative humidity of 50 %, O ₃ conversion slides from 88 % of the initial value to a flat of ∼66 % within 90 min. CoO _x modification is paramount for improved formation of Mn ²⁺ species while leading to the highest fraction of (Mn ²⁺ +Mn ³⁺ ) in total (Mn ²⁺ +Mn ³⁺ +Mn ⁴⁺ ) and more oxygen vacancies on Co-MnO _x (0.36)-Al catalyst surface.