New catalytic converter could make cars cleaner, more fuel efficient and less expensive
Regular catalytic converters like this one may be on their way to obsolescence (Image: Shutterstock)
By helping to minimize the hydrocarbons and other pollutants that are emitted in a car's exhaust, catalytic converters serve an important purpose. Because they contain precious metals such as platinum, however, they can also be expensive. Now, a British scientist has developed a new type of converter that should be cheaper, longer-lasting and more effective, plus it should boost the vehicle's fuel efficiency.
In a regular catalytic converter, exhaust flows through a honeycomb network of rare-metal-coated microscopic channels, which run throughout a ceramic block. As the emissions contact the metal catalyst, a chemical reaction takes place, eliminating some of the more toxic compounds. As a result, the exhaust that ultimately comes out of the tailpipe is considerably cleaner than it otherwise would be.
Dr. Benjamin Kingsbury, a research associate at Imperial College London, has devised a method of increasing the active surface area of the microscopic channels. Not only does this mean that the catalytic converter can eliminate more pollutants, but because the metal is able to be distributed in a more effective fashion, up to 80 percent less of it is required.
Additionally, laboratory tests indicate that in this new configuration, the metals degrade by approximately four percent after 100,000 km (62,137 miles) of use – by contrast, over the same distance, the metals in a regular converter degrade by about 35 percent.
Finally, the new converter reportedly prevents back pressure, a situation in which exhaust gases build up and cause the engine to work harder. This feature could allow motorists to use up to three percent less fuel.
Kingsbury developed the catalytic converter in collaboration with Imperial's Prof. Kang Li and Dr. Zhentao Wu. He established a company last December, to commercialize the technology.
Source: Imperial College London
About the Author
An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.
All articles by Ben Coxworth
I hope they design them to allow for retrofitting present day cars as the converters break down.
Shucks. Tricked me again. As I started reading this, I was sure this was going to be yet another application of that miraculous material of a thousand uses: graphene. Well, I guess I'll have to wait until next week for another graphene story.
Good stuff, not a perfect solution, but every little helps.
I like how it helps people go green without having to spend a lot of green.
I too hope one can retrofit it to current cars to help be greener and get better MPG.
Since we have to replace converters periodically, this sounds like an excellent advance. No clue on construction costs tho'.
And it will be approved for use in California ........ when ????
I assume it could be a retrofit, but that assumes the form factor hasn't changed much from existing units. Sure would be nice to see a picture, a sketch, a diagram, anything. Even the link offers little.
Bruce H. Anderson
I am not so certain about the 35% degrade after 62,000 miles. My Saturn is but mere inches away from 190,000 miles and passes the exhaust test swimmingly well. By this account, my converter is long ago dead, simply nailed to it's perch.
Another auto hit 278,000 miles, "Last of the v-8 interceptors" --Olds 403 cubic inch engine-- and had just passed exhaust muster for another year. IF driven right, the high 20's per MPG. The '81 Pontiac Bonneville, a true Road Warrior Machine. I took a photo of it at the bottom of the copper mining pit when I was in The Postman. A fitting Warrior tribute.
Now it is a taxi in Belize. Must really really need a retro fit converter now.
I'd rather see them use more of this material, not get the fuel efficiency gain and scrub out more pollutants
Does California's smog patrol still throw a fit if you alter an old car's emissions equipment to be better than new?
"Finally, the new converter reportedly prevents back pressure" - This is unlikely, any flow impedance will cause back pressure and this effect is factored into the valve timing of a conventional engine.
If you simply remove a catalytic converter from your car or fit a 'free flowing' after-market exhaust system the loss in mid-range torque is immediately apparent although it will likely rev more freely and develop more power flat out.
You might in fact find yourself using more throttle in normal driving to make up for the reduced mid-range torque.
@ Sheldon Cooper
Please explain why.
The only thing that makes sense to me is that the reduced back pressure results in higher RPM at a given throttle position so it takes a larger throttle adjustment to reach normal torque levels.
Catalytic converters offer a large back pressure resistance that kills fuel economy.
When all 'Cats' were first introduced (many many moons ago) Rover engineers proved that the same results could be achieved with better fuel mixture & combustion control. Law makers were idiots and ignored it. I guess this new 'Cat' will, also, be ignored.
The combustion gases have inertia and so take a certain time to exit the cylinders – in conventional engines without variable valve timing the exhaust port opens some time before the piston reaches bottom dead centre to give the expanding gases more time to get out at high R.P.M. and so reduce pumping losses as the piston rises. The fixed valve timing is thus a compromise.
At low engine speeds this extra time is not needed and as the gases get out too easily the cylinder pressure is lost too soon and is not available to drive the piston down as much as it could; a little exhaust system back-pressure from the necessary evil of a silencing exhaust maintains the cylinder pressure a little longer and so gets more work out of the fuel burning expanding gases at lower R.P.M.
The inertia that the gas pulses have is useful in tuning the primary exhaust pipes – when the exhaust valve closes the slug of fast moving gas pulls a partial vacuum behind it so we have a train of pressure and rarefaction pulses set up – when a rarefaction is present at an open exhaust valve it helps scavenge the cylinder and reduce the pumping loss of the exhaust expulsion stroke. Tuning the pipe length for higher R.P.M. helps remove the back pressure which is actually useful at lower R.P.M.
This subject is massive; the acoustic wave reflected back at the open end of the tailpipe can also be tuned to help extract the cylinders for example.
My main interest is the renovation and tuning of classic cars such as my E-Type Jaguar and I’ve spent many an hour using a rolling road dynamometer and fiddling with exhaust systems: removing the first stage silencers from the exhaust system and replacing them with straight through pipes resulted in a 15 % loss of torque at 3000 R.P.M. with the same throttle opening; peak power at 5500 R.P.M. was increased by about 10% as I recall.
The situation is much better with modern D.O.H.C. engines with variable cam timing on the inlet and exhaust camshafts – the gas flow is much more positively controlled in terms of timing. Unfortunately I can’t afford such a modern high performance car as engineers and scientists in the UK are not paid that much!
@ Sheldon Cooper
So on antiquated engines add a throttle to the exhaust.
@ Sheldon Cooper
My apologies a fool on a different site left me very snarky.
Thank you for the explanation.
I do think the exhaust throttle might be a good retrofit though.
Yes, but I hope to tackle it a different way - some people have fitted by-pass valves in the exhaust just before the standard silencer so at high revs they can switch to a freer flowing system; I just have to source some suitable high temperature industrial valves...
35% reduction in the metals after about 62,000 miles? My ODB2 car, a '99 Civic I believe will show a Check Engine Light if the Catalytic Converter shows performance of 90% or less. It has 234,000 miles on it and is on the original converter and the exhaust doesn't smell too bad once it's hot, so I'd say that figure is a lie. I'll guess that by 300,000 it'll start complaining.
This discussion about back pressure is enlightening Sheldon. But from the TV show, none of them know anything about cars, or rather how to fix them :) https://www.youtube.com/watch?v=i9en6AcVkBo
Do all modern engines open the exhaust valves a bit early?
According to me catalytic converters are bestdesigned as exhaustive valves for automotive. This catalytic converters also play an important role in pollution control in car's exhaust. This indeed is a very valuable post for any automobile users.
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