Sciencemadness Discussion Board

How do catalytic converters work?

Yttrium2 - 17-10-2015 at 12:06

How do catalytic converters work?

Do they use them in other types of industry, for example, to remove fumes?

Dumb question, the answer is probably not. To clean what is emitted probably depends upon what the substance is and the catalyst to use.

[Edited on 17-10-2015 by Yttrium2]

aga - 17-10-2015 at 13:12

Catalytic converters work (in cars) by passing the exhaust gasses over a vast surface area of catalyst.

A reaction happens, and the exhaust gasses become other chemicals, hopefully less harmful.

Yes, Catalysts are used in other applications.

Oh. I'll google the links for you as well.

https://en.wikipedia.org/wiki/Catalytic_converter

https://en.wikipedia.org/wiki/Catalysis

Any other extremely simple no-brainer requirements sire ?

zed - 17-10-2015 at 13:47

That being said......In cars, a "hot" catalytic converter, works better than a cooler one.

Here in Oregon, our autos have to pass emission tests periodically. Often, conditions are such at the test stations, that cars are forced to queue up, idling, while waiting to enter the test area. Some drivers may even turn off their engines.

Often, at such test sites, perfectly functional converter systems fail the emission test.

Too cold!

When that catalyst bed is hot, right off of the highway, it performs splendidly.

Fellas in the know, look for a little utilized test station right near a highway exit. Drive in hot, pass the test, and go home.

aga - 17-10-2015 at 13:58

Does that trick work with Breathalyser tests ?

cyanureeves - 17-10-2015 at 14:55

when i lived in houston i had to pay $100.00 every year as well as thousands of others who werent from harris,bexar and dallas counties.it was easier to just pay that once a year and we made it possible for our gas station owner to own a brand new mercedes benz. that same mercedes was hooked up to the "breathalyzer"and all the info from my insurance and vin number was simultaneously sent to austin.this guy had to only hook up 3.5 cars or so a day and be rubbing elbows with the fellas at brown and root in a 1yrs. time.they are most likely rubbing elbows with the guys from enron now though.

Magpie - 17-10-2015 at 15:06

And they might soon be rubbing elbows with the guys at VW.

battoussai114 - 18-10-2015 at 06:45

Every industry is required to control their air emissions. So it's frequent to have some abatement system but the type really depends on what gases are being produced, catalytic oxidation is interesting for removal of VOCs while ashes are abated with electrostatic preciptators and gases like H2S with wet scrubbers.

Dr.Bob - 25-10-2015 at 14:57

Car catalytic converters do a few things, first they help completely burn (oxidize) the fuel, so you get mostly CO2, rather than exhaust with some hydrocarbons, CO, H2, and other gases (VOCs). That was often just a platinum black type material on a sustrate, which helps combust fuels fully, although most newer converters use complex mixes of Pt, Palladium, and many other metals to lower their costs. Most newer cars also have a nitrogen oxide part that then tries to reduce nitric oxides back to O2 and N2. That is the harder part, as the part that burns the extra fuel (from rich engines) generates high temps, which can increase nitric oxides. So it is hard to get both complete combustion and low NOx.

This is part of the issue that VW had, as the EPA rules for cars puts an unreasonably difficult goal of NOx for diesel engines, which is not well based on science and engineering reality, thus it is nearly impossible for diesel engines to meet the rules, even though they often are cleaner per mile of travel, since they are very efficient, but they burn hotter, so they make more NOx per gallon of fuel due to simple chemical reality but less per mile of travel. The EPA does not look at emissions and efficiency in the specs, only emissions.

hamdusf - 26-10-2015 at 12:43



[Edited on 27-10-2015 by hamdusf]