Methane is CH4, if you burn in oxygen then you get CO2 (and some CO potentially as you say) and H2O. Where's the NOx come from?
Can you get particulates burning methane? Long chain hydrocarbons, I can see how that works; but methane seems like it would disperse too easily, unless it's liquid/solid methane you're burning or you're doing it in a very low pressure atmosphere. That's my intuition though, any citations showing significant particulate yield with methane combustion?
Any hydrocarbon fuel burning in atmospheric air produces some NOx,and some particulate matter. I should also have mentioned SOx, at least considering that your methane fuel is not going to be chemically pure CH4. Natural gas, in addition to CH4 as the primary component, contains some ethane and propane, plus traces of butane, pentane, hexanes, N2, CO2, and sulfur.
I'm not sure what amounts of pollutants one would consider "significant". Certainly, gas turbines burning methane are comparatively low in pollutants, but even properly functioning automobile engines are extraordinarily low in pollutant emission (just for orientation, I don't consider CO2 "pollution").
Thanks for the reply. I'd guess you're always going to get side combustion of existing products in the air, you could probably say "methane combustion produces heavy metals" too in that case as there's a chance that there'll be an atom of a heavy metal floating around the intake air. But it's needs to be noted and practical effects considered.
>gas turbines burning methane are comparatively low in pollutants //
Do they ever burn just methane or do they burn natural gas [that's been somewhat purified]?
I did have a search before posting and found citations claiming natural gas gave significant particulate reduction, as your second citation mentions, ergo the question of whether burning methane made any - it seems primarily to be a factor of burner efficiency, though there's research showing production of fullerenes and nanotubes that probably feeds in here too.
Looking further I found [1] which gives good info, in particular whilst gas:oil is 7:2704 in production of particulates by weight that citation notes that the PM2.5 [small particulates] as opposed to PM10 particulates may be significantly more damaging due to their penetration further in to the respitory system.
Can you get particulates burning methane? Long chain hydrocarbons, I can see how that works; but methane seems like it would disperse too easily, unless it's liquid/solid methane you're burning or you're doing it in a very low pressure atmosphere. That's my intuition though, any citations showing significant particulate yield with methane combustion?