What is a catalytic converter?

It is a device that chemically converts harmful engine exhaust emissions into carbon dioxide and water. The converter was developed in the 1960’s to meet stringent new emission legislation, initially in America, followed by the rest of the world. Since 1975 all vehicle manufacturers have used catalytic converters, and other emission control devices, to meet the required reduced emission levels.

catalytic converter

What is the catalyst?

It is a thin coating of precious metals (platinum, palladium and rhodium) applied to the surface of the substrate – the inner lining of the converter; its function is to assist in the chemical reactions that are involved in reducing the emission levels.

scheme Catalytic Converter

What is the difference between “oxidation” and “three-ways'’ converters?

Oxidation converters control two pollutants – carbon monoxide and hydrocarbons. These are reduced to harmless water vapor and carbon dioxide through accelerated oxidization as the gases pass through the converter. Three-ways converters carry out the same function and, in addition, are designed to reduce levels of nitrogen oxides. They may also include an Air Injection tube which assists the chemical reaction in the oxidization catalyst.

oxidation three-way converter

What causes a converter to become red hot?

This will occur if raw fuel is introduced directly into the converter, usually as a result of a problem with the fuel system or the vehicle’s ignition. Improper ignition timing, fouled spark plugs and/or air pump failure are the usual causes.

red converter

What causes a converter to become clogged?

If the converter is operated for a long period at high temperatures, the substrate material may melt down and form a solid mass inside. It is normally a result of a systems fault that allows a too-rich fuel mixture to reach the converter and it will lead to the engine appearing sluggish and lacking power. Early diagnosis and correction will stop further deterioration in the converter.

clogged converter

How much precious metal can you find in a converter?

Content will vary significantly depending on the vehicle model, but on average the ceramic weight is approximately just less than 100 grams, and the precious metal content is 0.2%.

precious metals converter

How pure is the recovered metal – is it, for example, reusable for jewelry manufacture?

99% pure, and once recycled can be put to a variety of uses including jewelry, mobile phones, computer hard disks, satellites and, of course, new catalytic converters.

gold silver bilion bars

Given the rarity and value of the PGM’s used, has anything been done to find a cheaper solution?

Unfortunately no, which makes the recovery of PGM’s even more important.


quarry precious metals

How to recycle my catalytic converter?