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

摘要

A highly active and efficient thin-felt Al-fiber-structured Co-MnOx composite oxide catalyst (named Co-MnOx-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 mu m diameter; 90 vol% voidage) chips underwent a steam-only oxidation and calcination for endogenously growing a 0.7-mu m-thick mesoporous layer of gamma-Al2O3 nanosheets along with the Al-fiber. Cobalt and manganese were placed onto the ns-gamma-Al2O3/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 degrees C (named Co-MnOx(0.36)-Al), being able to achieve full O-3 conversion at 25 degrees C for a feed gas containing 1000 +/- 30 ppm O-3, using a high gas hourly space velocity of 48000 mLg(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 approximate to 66% within 90 min. CoOx modification is paramount for improved formation of Mn2+ species while leading to the highest fraction of (Mn2++Mn3+) in total (Mn2++Mn3++Mn4+) and more oxygen vacancies on Co-MnOx(0.36)-Al catalyst surface.