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

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.