(509dl) Fundamental Study of the Relationship between Catalytic Performance and Pretreatment for NO Reduction By CO Reaction over CeO2 supported NiOx Catalyst

With the rapid development of automotive industry and technology, toxic gas pollutants (CO, NO_x, HC, PM, VOC_s, etc.) have been increased during the past few decades, which are harmful to humans and threaten the earth’s ecosystem. Among the environmental pollutants, nitrogen oxide (NO_x) is considered as one of the primary atmospheric molecular contaminants, which is emitted from vehicle exhaust, power plants, and the burning of fuel. The NO reduction by CO reaction (Two steps: 2NO + CO → N₂O + CO₂ and N₂O + CO → N₂ + CO₂, Overall: 2NO + 2CO → N₂ + 2CO₂) has gathered more attention due to the simultaneous elimination of two pollutants. Supported platinum group metals (PGMs) catalysts, such as Pt, Pd, Ru and Rh, have been extensively investigated due to their high activity for NO reduction by CO reaction. However, the limitation of supported PGMs catalysts’ application has been becoming more apparent due to the PGMs’ high cost, scarcity, and sintering at high temperatures. Therefore, it has been paid more attention to supported transition metals (e.g., Cu, Fe, Co, and Ni) or metal oxides as alternative materials. In this study, we investigated the relationship between catalytic performance and pretreatment condition for NO reduction by CO reaction over CeO₂ supported NiO_x catalyst. The oxidized NiO_x/CeO₂ sample was reduced under hydrogen reduction treatment at high temperatures (500 and 700 ^oC). The oxidized and reduced catalysts were analyzed by BET, ICP-MS, Raman, XRD, and HR-TEM measurement to characterize the physicochemical properties of the catalysts. The GC and DRIFT techniques were applied to exam the catalytic activity and selectivity in addition to the intermediate species detection.