The role of surface sulfation in mediating the acidity and oxidation ability of nickel modified ceria catalyst for the catalytic elimination of chlorinated organics

Abstract

Surface sulfation has shown to be an effective way in modifying the acidity and oxygen mobility of metal oxide catalysts. Both of the properties were crucial in the catalytic elimination of chlorinated organics from industrial source of emission. Herein, sulfation of a dry-mixed NiO/CeO2 catalyst was conducted. The catalyst was subsequently utilized for eliminating chlorobenzene (CB) under a simulated realistic condition. A range of analytical techniques, including XRD, XPS, in situ DRIFT and NH3-DRIFT were employed to elucidate the sulfation effect on the physiochemical property and reaction activity of NiO/CeO2. Enhanced Lewis acidity and enriched surface oxygen vacancies originating from the interaction of sulfates and metal ions were observed, which led to improved conversion efficiency and COx (CO + CO2) selectivity in CB oxidation. In particular, qualitative analyses of reaction byproducts in the off-gas indicated that sulfation modification did not cause severe electrophilic chlorination of NiO/CeO2, and resulted in limited production of polychlorinated byproducts and less secondary pollution of the catalyst.