AGING-INDUCED CHANGES IN PROPERTIES OF MOTORCYCLE CATALYTIC CONVERTERS

Motorcycle engine exhaust is the major source of air pollutants in Taiwan and some countries with high population densities and low income in Southeast Asia. As a result, catalytic converters are used to reduce motorcycle pollutant emissions, Nevertheless, catalysts’ properties would be affected attributed to deactivation mechanisms during the used periods. According to the results of this study, the presence of thermal deactivation and poisoning was identified. Loss in specific surface area and total pore volume, the growth in pore diameter and the phase transition were observed as the aginginduced changes in catalytic properties. The deactivation phenomena were highly correlated to the age and mileage. A decreasing trend of specific surface area of catalyst with the accumulation of the used time was observed. To determine the effects of age and mileage of converters on specific surface areas, the empirical models were constructed on the basis of physisorption measurements. The constructed exponential model can reflect the actual deactivation conditions according to the high statistical significance of the applicability evaluation.