Brønsted Acid Sites in Zeolites Activate Ozone to Generate Reactive Oxygen Species for CO Oxidation

Low-temperature catalytic oxidation of carbon monoxide (CO) remains a significant challenge in environmental catalysis, especially under the conditions where H2O and sulfur dioxide (SO2) are present. In this work, we demonstrate that Brønsted acid sites (BAS) in protonated zeolites can effectively activate ozone (O3) to generate reactive oxygen species for efficient CO oxidation at temperatures below 150 °C. Systematic comparison among metal oxides, supported catalysts, and zeolites revealed that H-type beta zeolite (Hβ5, Si/Al = 5) exhibits the highest catalytic CO conversion, achieving complete CO conversion. Hβ5 showed higher resistance to deactivation in the presence of H2O and SO2 than Au/CeO2 and Pt/CeO2 catalysts. Kinetic studies revealed a linear correlation between CO conversion rates and the amount of BASs, suggesting that BAS is active site for this catalytic system. Modulation Excitation Diffuse Reflectance Infrared Fourier Transform Spectroscopy (ME-DRIFTS) and DFT calculations showed that O3 interacts directly with BASs to form reactive oxygen species, which react with CO to give CO2. Our findings provide new insight into non-transition-metal-based oxidation catalysis and offer a promising strategy for designing robust catalysts for industrial CO abatement under harsh flue gas environments.