Automobile exhaust nanocatalysts

Abstract

The exhaust emissions from automobiles have been attracted significant attention as a source of air pollution and contribute to global warming. The major concerns of vehicle exhaust contaminants are carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and carbon dioxide (CO2). Therefore, this chapter highlights the various emission control technologies such as two/three/four-way catalysis, selective catalytic reduction of NOx, lean NOx trap, etc., that are used in the internal combustion engines for effective exhaust emissions reduction. A catalytic convertor is the main device of the exhaust system, which converts the poisonous gases into less toxic ones. Usually, the catalytic convertor is composed of nanocatalysts that act as the active catalytic component. Platinum group metals (PGMs) are the most used commercial nanocatalysts because of their superior thermal properties and catalytic activity. Due to the high cost and less availability of PGMs, extensive research for alternative nanocatalysts is continuously going on. Here, we discuss in detail the properties and catalytic performance of various nanostructures such as metal nanoparticles, metal oxides, carbon nanostructures, etc., and their composites that are employed for the reduction of exhaust emissions. The challenges and future prospects of nanocatalysts are also discussed.