Since the first autocatalyst rolled off the production line at Johnson Matthey’s plant in Royston, UK in 1974, this technology has prevented many millions of tonnes of harmful pollutants from entering our air
Today autocatalysts manufactured by Johnson Matthey are fitted to one in three cars around the world. This technology exemplifies how science and innovation can be applied to tackle some of the planet’s major challenges. But how did the science behind the autocatalyst become commercial reality?
As far back as the 1940s some large cities had begun to experience problems of atmospheric pollution. Mass production of cars powered by the internal combustion engine, as well as giving tremendous personal mobility, was also generating a great deal of man-made urban pollution.
Then in 1970, the Clean Air Amendments Act came into force in the US which required emissions from car exhausts to be reduced by 90% and prompted the need for specific technologies to combat pollution from cars.
Johnson Matthey Targets Research
In the late 1960s scientists at Johnson Matthey were working on the development of catalyst technology to control gaseous pollutants from industrial applications such as chemical manufacturing plants and food processing facilities. These catalysts were based on platinum group metals which offered the right kind of properties for emission control chemistry. Given the opportunity presented by pollution from cars, our research focus switched and in 1972 the company successfully developed and demonstrated the positive benefits of platinum containing catalysts to clean up car exhaust. As a result, catalytic converters (containing an autocatalyst) became the preferred technology for reducing car emissions.
To meet the new legislation, autocatalyst fitment was required for all new models of car from 1975 and so research continued to come up with a commercially viable product.
There were two key developments that underpinned the successful delivery:
Monolithic Catalyst Supports
These provided a single structure for the catalyst with many channels running down their length to allow the gases to pass through. Johnson Matthey concentrated on monolith supported catalysts because the structure was robust, gave only a small drop in exhaust gas pressure and heated up quickly.
Application of Promoted Platinum Based Catalysts
Alumina was chosen as the ‘coating’ for the monolith as it provided a high surface area. It could be formulated into a ‘washcoat’ with other components and the platinum group metal catalyst. The washcoat had to be even, not block the monolith channels and adhere strongly to it. Our scientists came up with both a successful formulation and also a production method to apply the washcoat to the monolith.
Bringing the Science to Life
In late 1973 Johnson Matthey completed construction of its first catalyst line in Royston, UK and by the end of April 1974, the world’s first autocatalyst production pieces were being made for Volkswagen. Construction of a very large plant in Wayne, Pennsylvania followed to supply the US market. The company also invested heavily in testing facilities for evaluating autocatalysts on engines.
In these early days emissions legislation only required catalytic control of two pollutants – hydrocarbons and carbon monoxide, but as regulations tightened, control of nitrogen oxides, or NOx, was also required. Our scientists got to work and developed platinum / rhodium based systems which would simultaneously control all three pollutants. This technology, called the ‘three way catalyst’, was fitted to most American cars by 1982 and was adopted as the standard for gasoline powered cars around the world.
Over the years the importance of our contribution to emission control technology for cars has been recognised with five Queen’s Awards and in 1980, a Royal Academy of Engineering MacRobert Award.
A Major Contribution to Clean Air
Since this pioneering work in the 1960s Johnson Matthey has continued to invest in research, development and manufacturing facilities all around the world. Legislation has continued to tighten globally and the company has constantly worked to develop more efficient, higher performance emission control catalysts and manufacturing processes.
Today Johnson Matthey is a leading global supplier of emission control catalysts and we are proud of the contribution our technology makes to providing cleaner, better quality air.