The number of automobiles in developing nations has increased dramatically in recent years, which has caused serious air pollution in those countries. In developed nations, tight control on exhaust emission is already being enforced while emission control standards in developing countries are still lax. In the future, emission control standards must become tighter throughout the world.

In general, a three-way catalyst is used for the exhaust of automobiles, where hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx), the harmful compounds in exhaust, are removed with a catalytic converter using Pt (platinum), Rh (rhodium) and Pd (palladium). Since these precious metals exist only in trace amounts in deposits around the world, catalytic converters are collected from discarded automobiles so that the precious metals can be extracted and recycled.

This application note introduces XRF analysis of Pt, Rh and Pd in used automobile catalyst.