A Pt Catalyst with Enhanced Three-Way Catalytic Activity Supported on CeO2 Modified with Al2O3 for Natural Gas Vehicles

Abstract

Pt supported on CeO₂ is a potential three-way catalyst (TWC) used in the aftertreatment of natural gas vehicle (NGV) exhaust emissions. However, the sintering of CeO₂ occurs under harsh operating conditions (>600 °C). Herein, a series of Pt/Al₂O₃-CeO₂ were prepared from the perspective of support modification to enhance the stability in CeO₂ and the catalytic performance of the samples. XRD showed that the addition of 20 wt % Al₂O₃ (20AlCeO) improved the sintering resistance of CeO₂. When the increase in the content of Al₂O₃ was continued, the crystal size of CeO₂ remained nearly unchanged. The differences in CeO₂ particle size and relative cerium content together affect the interaction between Pt and CeO₂. The three-way catalytic performance was estimated under an NGV emission. It was found that Pt/20AlCeO exhibited the best TWC performances. According to H₂-TPR results, the addition of 20 wt % Al₂O₃ enhanced the redox performance of the Pt/20AlCeO sample compared with Pt/CeO₂. However, with further increased Al₂O₃ content (>20 wt %), the interaction between Pt and CeO₂ weakened, resulting in measurable degradation of the catalytic redox performance. XPS further showed that the Pt/20AlCeO sample has the highest oxygen vacancy and Pt⁴⁺ content. Therefore, the improvement in the activity of Pt/20AlCeO can be attributed to its excellent redox properties, abundant oxygen vacancies, and unique electronic properties. These results indicate an avenue to design an advanced Pt-based three-way catalyst with high activity and stability.