The catalytic converter is commonly known in repair shops, auto wrecking yards, and recycling centers simply as a “cat.”
Found between the engine and the muffler, catalytic converters come in a myriad of shapes and sizes, yet their purpose is singular.
How did the catalytic converter industry develop over the years, and what makes this oddly-shaped little auto part so valuable to the automotive industry – and expensive for the consumer?
What is the Catalytic Converter?
Their design allows them to clean the exhaust discharged from the vehicle. As the engine burns fuel, it emits hydrocarbons, carbon monoxide, and nitrogen into the environment. As that exhaust passes through from the engine, through the cat, and eventually into the air we breathe, the catalytic converter silently does its job.
Earlier models of catalytic converters used a layer of small ceramic beads packed tight and held in place on either end of the converter by a steel mesh. The converter did its job as the exhaust passed through the layer of pellets. A problem with the earlier model bead converters was the gradual shifting of the beads.
Over time the beads would wear down. In the process, the metals would come off thereby reducing or altogether eliminating the productivity of the unit. The older style bead-filled catalytic converters have now largely been phased out.
Today the most common type of catalytic converter contains what is known as monolithic substrate. When looking into converter the view through the substrate is akin to looking through honeycomb.
The substrate is ceramic and has a coating of three precious metals. Platinum, palladium, and rhodium are each found in the converters to varying degrees depending on vehicle make and model. Filling the cat with the honeycomb substrate exposes a maximum surface area to the exhaust gasses.
The Houdry Patent
In 1952, Eugene Houdry filed and was eventually awarded a patent for the initial catalytic converter. A mechanical engineer and oil refining expert, Houdry began researching possible remedies to the smog being produced from smokestacks, other industrial equipment, and automobiles.
The converter Eugene Houdry invented worked on two of the three chemicals being jettisoned into the environment. It turned carbon monoxide into carbon dioxide and converted hydrocarbons into carbon dioxide and water.
As designed, the smokestack converters did their work. To a lesser degree the converters designed for industrial equipment performed adequately only when using low-grade non-leaded gasoline. However, there was still a problem with the automobile cats. The leaded gasoline being used in most vehicles would coat the ceramic substrate with lead effectively rendering the cat useless.
The Planets Align
In the early 1970s, two very important steps forward in the catalytic converter industry occurred nearly simultaneously.
In 1970 the United States Clean Air Act decreed that by 1975 vehicles must cut their emissions by an astounding 75%. Part of that transition was to begin transitioning from leaded fuel which contained tetraethyllead, an engine anti-knock agent, to unleaded gasoline.
As the industry eliminated leaded fuel and vehicles began running on unleaded, the converter would be spared from the lead coating, thus extending its lifespan immeasurably.
Working for one of the world’s largest mineral refining companies, 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.
The Only Constant…
The ancient philosopher Heraclitus stated, “All things change.” Such is the way of life and such it has been with catalytic converters for more than 60 years.
Over the years emissions law has become ever more stringent and as the law has changed catalytic converters have changed as well. Along the way catalytic converters designed for diesel engines have improved as well.
Once having been scarcely loaded with any precious metals, they are now some of the most valuable on the market. They use an ammonia product known as urea to aid the process and, because of soot buildup on the substrate base, the engines go through a “hot” cycle to burn away the buildup.
Engineers design engines to run more efficiently and catalytic converters are often loaded with even greater amounts of precious metals. According to Johnson Matthey Precious Metal Management, catalytic converters are one of the world’s leading uses for these particular 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.
A New Industry
When he initially filed for the patent for what in now referred to as an Oxidation Converter, it’s difficult to imagine that Eugene Houdry had any idea the industry he was spawning. Auto catalyst refineries exist in countries all over the globe, many of which are solely dedicated to the refining of that catalytic converter substrate. They patent their refining processes.
They constantly monitor the degree to which each type of converter is loaded and generate extensive catalogs showing value information. In a multiphase process, catalytic converters go from auto repair shops, muffler shops, auto wrecking yards, recycling centers and on to the refineries.
The refineries smelt the precious metals down and in turn those metals end up back on the precious metal market.
The Catalytic Converter Industry
Fueled by a concern for our ecosystem, laws regulating emissions and air quality, and an entire industry revolving around the value of the precious metals, catalytic converters are ever-changing.
However, 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, they will remain an unseen yet important part of our society.