If people want to make chemicals with nitrogen in I imagine vaguely that they use the Haber process which fixes the nitrogen in the air into ammonia. And then go from there, making whatever nitrogenous thingies you fancy. This is sheer speculation.
I could swear blind that when I was at school we watched a video about it with John Cleese explaining it all. But maybe I have imagined this totally.
But burning fossil fuel is where most of the no2 pollution comes from innit, I think.
Manufacture...
Nitrous oxide is most commonly prepared by careful heating of ammonium nitrate, which decomposes into nitrous oxide and water vapor.[4] The addition of various phosphates favors formation of a purer gas at slightly lower temperatures. One of the earliest commercial producers was George Poe in Trenton, New Jersey.
NH4NO3(s) → 2 H2O(g) + N2O(g)
This reaction occurs between 170 - 240°C, temperatures where ammonium nitrate is a moderately sensitive explosive and a very powerful oxidizer. Above 240 °C the exothermic reaction may accelerate to the point of detonation, so the mixture must be cooled to avoid such a disaster. Superheated steam is used to reach reaction temperature in some turnkey production plants.[6]
Downstream, the hot, corrosive mixture of gases must be cooled to condense the steam, and filtered to remove higher oxides of nitrogen. Ammonium nitrate smoke, as an extremely persistent colloid, will also have to be removed. The cleanup is often done in a train of 3 gas washes; namely base, acid and base again. Any significant amounts of nitric oxide (NO) may not necessarily be absorbed directly by the base (sodium hydroxide) washes.
The nitric oxide impurity is sometimes chelated out with ferrous sulfate, reduced with iron metal, or oxidised and absorbed in base as a higher oxide. The first base wash may (or may not) react out much of the ammonium nitrate smoke, however this reaction generates ammonia gas, which may have to be absorbed in the acid wash.
[edit] Other routes
The direct oxidation of ammonia may someday rival the ammonium nitrate pyrolysis synthesis of nitrous oxide mentioned above. This capital-intensive process, which originates in Japan, uses a manganese dioxide-bismuth oxide catalyst:[7]
2 NH3 + 2 O2 → N2O + 3 H2O
Higher oxides of nitrogen are formed as impurities. In comparison, uncatalyzed ammonia oxidation (i.e. combustion or explosion) goes primarily to N2 and H2O.
Nitrous oxide can be made by heating a solution of sulfamic acid and nitric acid. A lot of gas was made this way in Bulgaria.[citation needed][8]
HNO3 + NH2SO3H → N2O + H2SO4 + H2O
There is no explosive hazard in this reaction if the mixing rate is controlled. However, as usual, toxic higher oxides of nitrogen form.
Nitrous oxide is produced in large volumes as a by-product in the synthesis of adipic acid; one of the two reactants used in nylon manufacture.[9][10] This might become a major commercial source, but will require the removal of higher oxides of nitrogen and organic impurities. Currently much of the gas is decomposed before release for environmental protection. Greener processes may prevail that substitute hydrogen peroxide for nitric acid oxidation; hence no generation of oxide of nitrogen by-products.
Hydroxylammonium chloride can react with sodium nitrite to produce N2O as well:
NH3OH+Cl− + NaNO2 → N2O + NaCl + H2O
If the nitrite is added to the hydroxylamine solution, the only remaining byproduct is salt water. However, if the hydroxylamine solution is added to the nitrite solution (nitrite is in excess), then toxic higher oxides of nitrogen are also formed.
http://en.wikipedia.org/wiki/Nitrous_oxide
That seemed too easy. I can't believe you didn't look there, so my apologies if this doesn't actually answer your question.
