Abstract:
Ozone is a significant indoor air pollutant found in our daily lives. To effectively purify this pollutant at its source, it is essential to develop a high-efficiency ozone decomposition converter, with the catalyst being its pivotal component. This study investigates the catalytic performance of modified zeolites for ozone decomposition by adjusting their topological structure, cation form, modification, and drying methods to enhance their adsorption and catalytic properties. The Mn-USY-DT/WB zeolite catalyst demonstrated effective and stable ozone purification for more than 30 h at −5 ℃ and
720000 h
−1, outperforming commercial MnO
2 catalysts in regeneration. X-ray photoelectron spectroscopy (XPS)characterization revealed that the decrease in the average oxidation state of Mn decreased from 2.95 to 2.81 after regeneration. The X-ray diffraction (XRD) results show that the cationic modification did not alter the crystal structure of the zeolite molecular sieve. The BET results indicate a slight reduction in the specific surface area of the modified samples, with Mn-USY-YX showing a significant drop to 146 m
2·g
−1 owing to the formation of a large number of hydrates during the liquid phase sampling, which was difficult to remove by calcination. The primary pore sizes varied among the samples, with the USY series at approximately 0.74 nm, Mn-Beta-DT zeolite at 0.58 nm, and Mn-ZSM-5-DT at 0.55 nm. The EDS images of the sample show that the content of Mn in Mn-USY-YX was low and that the Mn distribution was distinct. The Mn distribution in the Mn-USY-DT/WB sample was uniform, mostly in a linear arrangement along the crystal structure. The Mn element was obviously aggregated in the Mn-USY-DT/CG sample. Adjusting modification and drying methods helps preserve metal cationic clusters within the zeolite skeleton, preventing aggregation and enhancing catalyst activity. We propose a mechanism for long-term stable catalysis of ozone based on the coordination of ozone molecule adsorption and catalytic decomposition on zeolite, explaining the observed efficiency over time. The optimized zeolite powder was coated on a glass fiber support to obtain a low-gas-resistance monolithic honeycomb catalyst that maintains ≥99.9% efficiency for over
1000 h in practical applications.