Patrick BMW – History of Cats

The History of Catalytic Converters:

Resting silently in the exhaust system beneath most of today’s automobiles is emission-control device called a catalytic converter. These devices have been installed on most cars sold in America since 1975. This device is directly responsible for eliminating thousands of tons of exhaust pollutants that would have been emitted into our atmosphere over the last 40 years.  Here’s the story behind the technology.

What is a Catalytic Converter?

A catalytic converter is an emissions control device that converts specific toxic gases in engine exhaust gas into harmless forms by forming a “redox reaction.” There are two types of catalytic convertors. The early “cats” were two-way convertors that combine carbon monoxide and unburned hydrocarbons to produce harmless carbon dioxide and water. The three-way convertors are similar but also reduce the toxic oxides of nitrogen (NOx).

Who invented them?

In 1952, Eugene Houdry received a patent for the initial catalytic converter design. A mechanical engineer and oil refining expert, Houdry was searching for remedies to the pollution being emitted from smokestacks and other industrial equipment. The converter Eugene Houdry invented was a two-way convertor. Soon after patenting, commercial convertors were built and they performed quite well.

Working for the Engelhard Corporation, Dr. Carl D Keith invented what is known today as the three-way catalytic converter. In addition to turning carbon monoxide into carbon dioxide and hydrocarbons into carbon dioxide and water, the three-way converter converted nitrogen oxides into nitrogen and water.

Automotive applications:

In 1970, Congress passed the United States Clean Air Act which decreed that by 1975 all vehicles sold in the US had to cut down their emissions by 75%.  At the same time, the EPA required that “leaded fuel” be phased out in favor of unleaded fuel. It wasn’t long before the automobile manufacturers were taking a good look at catalytic convertors as a means to meet the 1975 standards. And as a result most 1975 automobiles had the first two-way convertors installed on them.

How they are built:

Earlier models of catalytic converters had a pile of small ceramic beads packed tight and held in place inside the converter. The converter did its job as the exhaust passed through the layer of pellets. Problem was that over time the beads would wear down. The metals that coated the beads would come off thereby reducing or altogether eliminating the productivity of the unit.

Today the most common type of catalytic converter contains what is known as monolithic substrate. The substrate is a honey-comb shaped ceramic and has a coating of three precious metals: Platinum, palladium, and rhodium.

The BMW version:

Cars fitted with catalytic converters emit most of their pollution during the first few minutes of engine operation. Unfortunately, this occurs before the catalytic converter has warmed up to work efficiently. Working with Alpina, BMW came up with an ingenious solution. Their “E-Kat” catalytic convertor has heating coils inside so the catalyst is brought up to speed very quickly. According to Patrick BMW of Schaumburg, a local BMW dealer in Schaumburg, IL, this allows BMW automobiles to qualify for the coveted Low Emission Vehicle (LEV) designation.

Demand for metals:

According to Johnson Matthey Precious Metal Management, catalytic converters are one of the world’s leading uses for precious metals. Over the last decade catalytic converters were responsible for 35-40% of the world’s demand for platinum, 50-70% of the total demand for palladium, and approximately 80% of the demand for rhodium. This, unfortunately, has inflated the price of these precious metals.

The future of the industry:

As long as the majority of the masses commute in fossil fuel-driven vehicles and as long as smokestacks belch their clouds into the sky, catalytic convertors will remain an important part of our society. In time, new types of catalytic convertors will undoubtedly appear but for the present time the standard three-way converter allows automobile manufacturers to meet US Federal Emission Standards.