Automotive exhaust catalysi mechanism

CO oxidation, an important step in automotive exhaust catalysis, is relatively simple and has been the subject of numerous fundamental studies. The reaction is catalyzed by noble metals such as platinum, palladium, rhodium, iridium, and even by gold, provided the gold particles are very small. We will assume that the oxidation on such catalysts proceeds through a mechanism in which adsorbed CO, O and CO2 are equilibrated with the gas phase, i.e. that we can use the quasi-equilibrium approximation. 

The dissociation of NO is a crucial elementary step in the mechanism of NO reduction by CO in automotive exhaust catalysis. The overall reaction here is ... 

Most of the bimolecular surface reactions follow the complex LH mechanism, i.e. a scheme consisting of more than one step. A well-known example is the oxidation of CO to produce CO2, i.e. the CO + O —> CO2 on Pt(l 11). The catalytic oxidation of CO on a metal surface is very important from a technological point of view, as it plays a major role in automotive exhaust catalysis. In theory, one may consider three distinct mechanisms for this reaction to occur ... 

The present effort makes no attempt to match in scope the previous review we shall confine ourselves to work concerning chemical poisoning and coking as the primary mechanism of deactivation but retain the classification according to scale — individual kinetics and mechanism, intraparticle problems, and chemical reactor problems. Sintering has been admirably covered in a recent review (2), and the subject of automotive exhaust catalysis (which is almost wholly an exercise in catalyst mortality) will be treated in one forthcoming (3). 

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