Ultrafine ceo₂ nanodots embedded in porous zro₂ for efficient and sustainable chlorine recycle through hydrochloric acid catalytic oxidation

Ceria (CeO₂) has been regarded as one of the most promising industrial catalysts for hydrochloric acid (HCl) oxidation to replace RuO₂-based catalysts. Thermal sintering and chlorination of CeO₂ limit its large-scale application. In this work, ultrafine CeO₂ nanodots embedded in a porous ZrO₂ matrix (CeO₂@ZrO₂) are successfully prepared by a spontaneous deposition method and evaluated in HCl catalytic oxidation for sustainable Cl₂ recycle. The physicochemical properties of CeO₂@ZrO₂ catalysts are characterized by means of XRD, Raman, SEM, TEM, BET, XPS, H₂-TPR and oxygen storage capacity (OSC). The results reveal that all CeO₂@ZrO₂ catalysts display large specific surface area, pore volume, perfect low-temperature reduction performance and oxygen storage-release capacity. More importantly, the unique structure of the CeO₂ nanodots isolated by amorphous ZrO₂ improves the dispersion and inhibits the sintering of active sites. The optimized 40CeO₂@ZrO₂ catalyst reveals superior activity (1.90g_Cl2 ⋅g_cat-¹ ⋅h^-1) and good durability (100 h under 430 °C). Kinetic studies reveal that the adsorption of O₂ and HCl is competitive at the active sites, and the desorption of surface Cl is the rate-determining step.