2. Automotive exhaust gas pollution control

2.1 Context

In the late 1960s, faced with the scale of automobile pollution, the State of California, followed by the US federal government, imposed legislation on exhaust gas emissions: carbon monoxide CO and unburned hydrocarbons HC were targeted. A standard for nitrogen oxides NO + NO ₂ (NO _x ) and then for soot particles completed the regulatory arsenal. The work carried out in record time (just a few years) led to the implementation of catalytic converters. Initially, the catalyst was in the form of beads, then very quickly came the honeycomb monoliths, which substantially reduced the pressure drop in the converter, and hence fuel consumption. Australia and Japan soon followed the American...