If there has been an improvement in air quality in our congested town and city centres, or if the sight of a diesel vehicle belching out black smoke is slightly rarer these days, then to a large extent you can thank the efforts of one man.
Dr. Barry Cooper of materials specialist Johnson Matthey led the team that developed the three-way catalytic converter, the device that removes carbon dioxide, unburnt hydrocarbons and nitrogen oxides from car exhausts. A catalyst of this type is fitted to 85 per cent of new cars worldwide.
For his efforts Cooper was presented with the Royal Academy of Engineering’s prestigious MacRobert award in 1980. This would be quite a highlight in anyone’s career. But he then went on to become the co-inventor of the continuously regenerating trap (CRT) for diesel particles – for which he became the only person ever to win a second MacRobert award, in 2000. Last year he was elected a fellow of the RAEng, and travelled to Japan to receive the 2002 Honda Prize, which recognises developments in eco-technology.
The Engineer caught up with him on his return from Japan and found him relaxed, unassuming and full of enthusiasm for his work. Cooper is the first to admit that he never expected to end up working in the automotive catalyst field, which was not an area that anyone paid much attention to before the 1970s.
‘My first six years at Johnson Matthey were spent developing hydrogenation catalysts for various chemical processes in the dyestuffs and pharmaceuticals industry,’ he says. He also embarked on a part-time PhD at Imperial College.
A bill by Senator Ed Muskie in the US put automotive catalysts on the map, which led to the 1970 Clean Air Act. This required car makers to meet emissions standards to be introduced on 1975 models, and was the trigger for a surge of interest in catalysts for automotive applications.
‘I remember the day my boss at the time said, ‘It looks like the Americans may put catalysts on cars – we should start a programme’,’ says Cooper. ‘It wasn’t official for the first month. Four of us started doing experiments and we pretty rapidly filed our first patent.’
The boss in question was Gary Acres, now visiting professor of sustainable development at Birmingham University, who headed JM’s catalyst operations at the time. Such research as had been done by the competition centred on platinum, but Acres, a specialist in modifying the behaviour of catalysts through ‘moderators’, realised that platinum would not do the job by itself but would need to work with a ‘promoter’ such as rhodium. He promised his managing director to demonstrate the merits of this approach within four weeks. Cooper, says Acres, was always ‘a bit of a sceptic – but he came in a few days later saying ‘Look at these results, they’re fantastic.”
It did not take long for the JM board to sanction a substantial investment programme, and Cooper was heading a group of 15 researchers. ‘We made significant progress in six to 12 months. It has been an exciting project from the first day. But there was no indication that it would grow to be the world’s largest catalyst industry. My friends at Imperial College thought I was slightly crazy.’
The project led to a patent for the first three-way catalyst, which oxidises carbon monoxide and hydrocarbons and reduces nitrogen oxides simultaneously. But many technical issues had to be solved along the way. ‘When we put the first auto catalyst on an engine at Ricardo at Shoreham,’ says Cooper, ‘it lasted four hours.’
An early decision was made to adopt a monolith catalyst. In other words the catalyst would be deposited on a ceramic ‘brick’ comprising a multitude of parallel channels, as opposed to a pelleted catalyst more typical of industrial processes. Cooper’s team worked with Corning and 3M to develop a suitable monolith.
‘The monolith was a completely new concept,’ says Cooper. ‘We had to develop that, and solve problems such as how to get the catalyst to adhere to the ceramic substrate, and how to can the substrate effectively.’ Manufacturing processes both for the monolith and catalytic coating had to be developed. But within four years of the project’s inception, production had started and plants had been set up at Royston in the UK, and Devon, Pennsylvania.
Improvements have been made since. But essentially the same design is still the industry standard for petrol vehicles, with JM supplying about a third of the worldwide market.
Cooper transferred to the US in 1979 and during the mid-1980s, turned his attention to the problem of diesel particles – specks of soot, mainly carbon, that can find their way deep into the lungs. It proved a tougher nut to crack.
Early catalysts were prone to clogging and ignition of the soot particles in an uncontrolled way, burning out the support system. ‘Again we formed a small project team. We were determined to solve the problem by a catalytic process. But it was an intractable problem.’
They experimented with various catalysts and the individual gases in diesel exhausts. Oddly, they discovered that a platinum catalyst, which had limited effect under laboratory conditions, had a much greater effect on particles in an engine test cell.Back in the laboratory they found that when nitrogen oxide (NO) and oxygen flowed over a platinum catalyst the particles started to burn faster. It turned out that the catalyst was oxidising nitrogen oxide to nitrogen dioxide, which then reacted with the carbon particles.
‘It was an unusual process,’ says Cooper. ‘The model in our mind was that the carbon particles had to sit on the surface of the catalyst to react. Here we had a process where the catalyst was totally remote from the particulates. What we were doing was making an oxidant in the exhaust gas capable of adsorbing on the particulate and burning it at a low temperature.’ The combustion temperature came down from 500 degrees C in oxygen to 250 degrees C, typical of a diesel exhaust and allowing continuous combustion of particles.
This discovery led to the continuously regenerating trap (CRT). Cooper says it demonstrates the value of what he calls ‘the Skunk Works approach’: a dedicated team of about five focuses on the problem over a limited time. ‘You’ve got to set a timeframe. At the point we were doing the early work on the CRT we had a timeframe of about six months. If we didn’t have a process by the end we’d move on to other projects.’
The CRT’s success was not as dramatic as the three-way catalyst had been earlier. Sulphur in diesel fuel inhibited the oxidation of nitrogen oxide. It was not until fuel suppliers in Sweden began to introduce ultra-low sulphur diesel, driven by the public transport authorities, that the CRT began to find a market. This is mainly as a retrofit for fleet users where operating conditions are well established. For diesels that are never heavily loaded the exhaust temperature drops to the point that the CRT is no longer so effective, although this could be solved through changes to the engine-management system. But Cooper believes that as emissionsregulations tighten the CRT will eventually attain a significance equal to that of the three-way catalyst.
For the future the problem of nitrogen oxide in exhausts remains. So JM is now working on the SCRT – a combination of a CRT and the selective catalyst reduction system (SCR) developed by Bosch in which urea is injected into the exhaust gases to reduce the NO to nitrogen.
Excess of nitrogen dioxide from the CRT speeds up the reaction in the SCR, removing 90 per cent of the nitrogen oxides, says Cooper: ‘It’s a true four-way emission control system, controlling CO, hydrocarbons, particulates and nitrogen oxide.’ JM has been working with Bosch in the US and Europe, and the SCRT is on trial with two automotive manufacturers. Cooper expects it to be introduced in the latter half of this decade to meet stricter emissions regulations.
Acres puts Cooper’s success down to a fundamental understanding of how catalysis works, rather than adopting a ‘recipe’ approach, combined with the ability to talk to customers such as Ford and Honda in their own language as well as scientists. ‘That’s not that common even today,’ he says.
How does Cooper feel as the recipient of all these accolades? ‘It just boggles my mind when I think about it. I’ve been fortunate to be in the right place at the right time.’ That seems altogether too modest.
For the record
Barry Cooper’s academic career followed an unusual path. He didn’t go to grammar school or a red-brick university. Instead, he studied for 10 half-days a week at Luton Technical College, gaining an external London University degree in physics and chemistry.
He joined Johnson Matthey’s central research group in 1964 where he researched carbon molecular sieve catalysts, which was the subject of his PhD thesis to Imperial College in 1976. In 1970 he started the research that led to the three-way catalyst for cars and earned him the RAEng’s MacRobert award in 1980.
After a brief sojourn in the offshore oil industry, in 1979 he returned to JM as principal scientist in its US operation, continuing to work on the development of emission control catalysts. This led to the co-invention, with colleague Jim Thoss, of the continuously regenerating trap for diesel particulates, for which he won a second MacRobert award, in 2000.
Last year he was elected a Fellow of the RAEng, and the Honda Foundation, which honours development in eco-technology, awarded him its 2002 prize in recognition of his work on reducing vehicle emissions.
Cooper is vice-president for diesel emission control systems in JM’s catalytic systems division. He says this means that, after being a technologist for most of his career, he has now been able to invent something, find a market and then sell it.