sulfur

[5030]

Ralph:

They already do. My new Western Star has 2, one in each exhaust pipe at a replacement cost of 2K each. Just be thankful of all the requirements that your gummit is putting on commercial trucks and that we are passing the cost on directly to you, the consumer. Have you taken notice lately at how your dollar is buying less and less.

On road diesel hasn't been below $2.50 for a long time now. We have been surcharging all shippers and those shippers are backcharging you in the form of higher prices for goods and services. Must be the "trickle down theory"......trickling down to you. /forums/images/graemlins/grin.gif

 

[arthr31]

Many on-road mid-size diesel trucks already have catalytic converters. From mid 1998 the dodge cummins trucks have had them. Same as the ford powerstroke trucks. However we still don't have cats on off-road equipment, by-n-large...

I'm curious about your statement that the cats keep the exhaust warm. From what I've read, heard, know, etc. this is not really the case. The cats don't even work until the egt (exhaust gas temps) get up to at least 140+. So, for the first several minutes of operation, the cat offers no value, when it could potentially offer the most bang... However, once all is up to temp, maybe they help a bit? I thought that the cats burned gases which would have otherwise been released into the air? And, again, after they reached a certain temperature.

And wrt diesels, I think there are as good as alternatives which will not impede performance...

But anyway, RalphVa, i'm interested in your take on catalytic converters...

 

[SkyPup]

The catalytic convertors on gasoline and diesel engines in the US currently are composed of a ceramic platinum-palladium catalyst that only reduces the output of hydrocarbons and carbon monoxide, but they do not have any effect on NOx or SOx emissions, however the newer designed catalytic convertors in European diesels do reduce NOx as well and they will be required here soon after ULSD is commonplace across the US and Canada next year so that the new catalytic convertors don't get poisoned with sulfur contamination.

ULSDiesel and ULSGasoline alone will immediatly reduce the emissons of sulfur by 95% compared to the fuels currently in use now.

 

[HGM]

</font><font color="blue" class="small">( The catalytic convertors on gasoline and diesel engines in the US currently are composed of a ceramic platinum-palladium catalyst that only reduces the output of hydrocarbons and carbon monoxide, but they do not have any effect on NOx or SOx emissions, however the newer designed catalytic convertors in European diesels do reduce NOx as well and they will be required here soon after ULSD is commonplace across the US and Canada next year so that the new catalytic convertors don't get poisoned with sulfur contamination.

ULSDiesel and ULSGasoline alone will immediatly reduce the emissons of sulfur by 95% compared to the fuels currently in use now. )</font>

Thom,
We have been using 3-way cats in the US for several years... I believe they were phased in in '96 or 7.. So we do eliminate Co,Hc, & Nox with most of the cats here..

Arthur,
The catalyst works as a chemical converter (to put it simply) by combining stored O2 whit the harmfull gas' to create H2O and Co2..Most of the Nox is controled by EGR and keeping combustion temps under 2500F(in a perfect world), the rest is modified at the cat..

 

[SkyPup]

How can an "Oxidative" catalytic convertor "Reduce" NOx??

In most gas streams, carbon monoxide (CO) and hydrocarbons (HC) can be removed by combination with oxygen (O2) using an oxidation catalyst (also known as a 2-way catalyst):

CO + ½ O2 -> CO2
[HC] + O2 -> CO2 + H2O

This reaction is suitable for oxygen-rich (“lean”) gas streams, typical of diesel exhaust and many industrial process emissions.

It is chemically impossible to reduce NOx with an oxidative platinum-palladium based catalyst. It takes much more energy to reduce nitrogen oxides.

Corning and Johnson Matthey make 95% of all the internal combustion catalysts here, and very few are reductive, as the new Urea ones are for NOx, they are all oxidative.

BTW, in respone to an earlier question, the catalysts have to warm up to >450*F before they start to even work at all, their normal operational temperature is from 450-850*F, and they have to get up to at least 850*F to burn off concentrated soot.

 

[arthr31]

HGM & SkyPup, Thanks for the information. To follow-up on the temps at which cats work- so, in cold climates, where short drives are made, cats provide minimal value, such as in my case. Most winter days it takes over 15 minutes for my temp guage to go over 140, and by that time, my ride is nearly 1/2 over...

What cats impacting performance on diesel engines? True or false? Thanks!

 

[SkyPup]

Cats have absolutely no effect on the performance of a diesel, they are designed to flow way more exhaust than the engine itself is capable of creating.

 

[HGM]

</font><font color="blue" class="small">( How can an "Oxidative" catalytic convertor "Reduce" NOx??
)</font>

They include a reduction cat, thats what makes them "3"way..
Maybe this will help..

Arthur,
Thom is right about the flow.. The only issue with a cat on a diesel is that when high sulfer fuels are used, it can clogg the cat.. The good part is, that if it gets clogged from the sulfer, running low sulfer fuel will clean it up.. This is of course if it runs.. /forums/images/graemlins/grin.gif

 

[SkyPup]

AH HA - Gottcha! /forums/images/graemlins/wink.gif

 

[dmccarty]

Greg,

So do domestic diesel pickup's have catalytic converters? I have a Ford and it looks like there is a cat on the exhaust but I don't know what it is back there.

Later,
Dan