[Farhannsm]

Hey I have been doing some research into the sulfur content of diesel fuels and their sulfur content standards around the world, as an example current standards for sulfur content in euro/na are 500 ppm or lower, while in developing countries the standard has been around 5000 ppm. I figured I might as well ask someone or anyone who might know more about chemical reactions than I.

My question is if we were to compare emissions from a 500 ppm sulfur vs. a 5000 ppm sulfur diesel fuel, how would you adjust the emissions of, lets say, NOx (nitrogen oxides) to be comparable between the two types of fuel?

To be more specific, if I were to be getting 0.5 grams/kilometer of NOx from a vehicle using diesel fuel with 5000 ppm sulfur, what would be the best way to compare that to an emission standard of 0.5 gm/Km NOx which uses diesel fuel with 500 ppm sulfur? Can it be assumed that if the vehicle using 5000 ppm sulfur content diesel fuel were to switch to the 500 ppm sulfur fuel instead then its emissions of NOx would be lower than 0.5 gm/Km? or can the change in sulfur content make enough difference to NOx emissions to be noticeable?

I am going with the temporary assumption that all other properties of the fuel are constant except ofcourse any direct changes to the fuel's boiling points, pressure threshholds, etc. caused by the sulfur content. A stoichiometric formula of a diesel fuel with X sulfur content undergoing a process of combustion with air would probably be the key to this, but I can't seem to find one.

any help and answers or information on how to learn more about this would be greatly appreciated, thanks.

(apologies for posting in multiple forum groups, I wasn't sure which level of chemistry this would be most appropriate for)

[Borek]

I am not aware of any reason why sulfur content should be in any way related to the amount of NOx in the exhaust gases.

[Farhannsm]

yeah, I wondered that at first too, but I would like to be sure. I was doing a bit of reading and I noticed that a change of sulfur content may lead to a change in boiling point or in the energy of combustion of the fuel, Is this a possibility? If so then it could be one way to trigger a change in NOx emissions after combustion.

[Borek]

All other things being equal there can be some correlation, but I suppose other things are much more important.

Call it an educated guess.

[BluRay]

As Borek, I'd say the sulfur content is too low (in percent) for such an effect (variation in NOx emission) to happen as a consenquence of different combustion heat. In case, there could be a difference due to a catalythic effect of sulfur, but don't know if in reducing or increasing NOx (and if this really happens).