Emission standards for vehicles in the United States and Europe have been developed over the past forty years to achieve better than a 99% reduction in regulated pollutants: hydrocarbons (HCs), nitrogen oxides (NOx), CO, and particulate matter (PM). The more stringent standards for engines with both stoichiometric and lean exhaust have required and will need further novel aftertreatment systems. One increasing challenge that comes with improving engine efficiency is cooler exhaust. Hence, catalysts that perform well near 150 C, but still survive the difficult conditions of automotive exhaust are receiving increased attention. Tradeoffs have been made in meeting these pollutant standards and also reducing regulated greenhouse gas emissions (CO2, CH4, N2O). Early work in automotive exhaust catalysis will be discussed that met the targets of that time. In addition, our current goals may be addressed by catalysts using a core@shell architecture where a nanoscale metal particle, such as palladium, is encapsulated by a porous metal oxide shell. Examples of some results and advantages using this architecture will be discussed. Also, examples of the benefits that arise from the rapid cycling of reactants in the exhaust will be presented. The great success in applying technologies to provide successful automotive emissions control over the past forty years has been done largely without sacrificing vehicle performance. We will see that large challenges remain in this century to maintain our personal transportation choices in the future.

Selective review of reactions and catalysts important in automotive emissions control

2019 Spring National Meeting

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