Abstract
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 NOx 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.
Highlights
In modern life, automobile transportation represents the main source of air pollution contaminants, facing the most actual environmental problem
three-way catalyst (TWC) accomplishes a function of simultaneous transformation of unburnt hydrocarbons (HC), CO, and NOx into CO2, water, and nitrogen
According to the ecological standards Euro 5+, acting in Russia in the present, TWC for passenger cars should provide efficient neutralization of exhaust gases over a period corresponding to 160,000 km
Summary
Automobile transportation represents the main source of air pollution contaminants, facing the most actual environmental problem. Within the constituents of modern cars, a three-way catalyst (TWC) is irreplaceably applied to diminish the harmful emissions from the gasoline engines [1]. TWC accomplishes a function of simultaneous transformation of unburnt hydrocarbons (HC), CO, and NOx into CO2 , water, and nitrogen. According to the ecological standards Euro 5+, acting in Russia in the present, TWC for passenger cars should provide efficient neutralization of exhaust gases over a period corresponding to 160,000 km. Thereby, a question of the long-term stability of TWCs is of great importance and actuality. The efficiency of the catalyst is most commonly examined by testing the exact automobile on the roll test rig in accordance with the normalized driving cycle
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