Self-Regeneration Effect of Three-Way Catalysts during Thermal Aging Procedure

• Main Authors: Evgeny A. Alikin, Sergey P. Denisov, Konstantin V. Bubnov, Aleksey A. Vedyagin
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Catalysts
• Subjects: three-way catalysts; rhodium; engine bench; high-temperature aging; self-regeneration
• Online Access: https://www.mdpi.com/2073-4344/10/11/1257

One of the most important features of the three-way catalysts is their long-term stability. However, quite often, promising catalytic compositions with excellent activity become deactivated after a relatively short period of exploitation due to various reasons. Therefore, a study on the onboard regeneration of the deactivated three-way catalysts remains its actuality. The present work is mainly focused on the self-regeneration effect of the rhodium-containing component. Aging of the catalysts in the standard and model engine braking regimes revealed the difference in the catalytic performance. Deactivated rhodium species turned to the active state as a result of rapid cooling in air flow from 1200 to 600 °C. The regenerated catalyst shows improved activity towards NO_x reduction and, therefore, widened operation window, which indicates higher accessibility of the rhodium species. X-ray diffraction analysis of the aged catalysts does not reveal any noticeable phase changes. Contrary, significant changes in the Rh oxidation state were registered by X-ray photoelectron spectroscopy. The observed effect opens new horizons for the development of the onboard purification systems with prolonged exploitation lifetime.