I guess I should have read a few more articles before posting. From
Wikipedia:
http://en.wikipedia.org/wiki/Nitrous_oxide
--- begin quote ---
Nitrous oxide is most commonly prepared by careful heating of ammonium
nitrate, which decomposes into nitrous oxide and water vapor.[14] 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.[15]
NH4NO3 (s) → 2 H2O (g) + N2O (g)
This reaction occurs between 170 and 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.[16]
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 three 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:[17]
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. Many gases are made this way in Bulgaria.[citation needed][18]
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 are formed.
--- end quote ---
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