What is Nitrous Oxide?

Nitrous oxide is also know as laughing gas. It’s a colorless gas, about 50% percent heavier than air, with slightly sweet smell. It doesn’t burn but will support combustion. It’s widely used as a food additive, a whipping propellant for food grade aerosols. It’s also used in rocket motors, internal combustion engine and as a inhalational anesthetic agent. In the market, nitrous oxide for sale is popular, do you know how to produce it?

4 production methods of nitrous oxide

1, action of zinc on dilute nitric acid.
2, action of hydroxylamine dydrochloride(NH₂OH HCl) on sodium nitrite (NaNO₂).
Above two method are only used in laboratory.

3, separation from adipic acid off gas (tail gas).
4, continuous thermal decomposition of high purity ammonium nitrate (NH₄NO₃)
(NiOx Technical Advisory Panel Report.pdf (usda.gov)
Method 3 and 4 are used for mass production. Here we introduce details about these 2 methods.

Separation from adipic acid off gas

About separation from adipic acid off gas. It’s used because hexanedioic acid process units by-product nitrous oxide, general adipic acid per ton can about produce 0.28 ton of nitrous oxide, Nitrous oxide content has close to 50% (wt) and recycles value well in tail gas.
The method for preparing high-purity nitrous oxide using adipic acid production tail gas, using following steps：
(1) absorption pretreatment process: adipic acid produces tail gas and enters absorption tower, the absorbing liquid of in bottom of the tower will absorb most of the CO₂、NO₂ and H₂O.
(2) cryogenic rectification process：the air-flow that adsorbent equipment comes out enters low-temperature fractionating tower. High purity nitrous oxide is obtained from low-temperature purifying method column.
(https://patents.google.com/patent/CN105110304B/en)

Nitrous oxide produced from this method is usually used in electronic industry. It’s not approved for food grade. Food using nitrous oxide only produced by the last method.

Thermal decomposition of ammonium nitrate (NH4NO3)

Nitrous oxide is produced by careful heating of ammonium nitrate at about 250℃, which decomposes into nitrous oxide and water vapour：
NH₄NO₃ → 2 H₂O + N₂O

Ammonium Nitrate is decomposed in the Melters to give a mixture of Nitrous Oxide & super heated steam. At the same time impurities are produced including Ammonium Nitrate fumes, Nitrogen & other oxides of Nitrogen. The steam & impurities are removed by scrubbing with water, caustic soda and sulphuric acid in sequence. Nitrogen present in traces is removed by bleeding from the top of storage vessels where Nitrous Oxide is stored, after compression by a compressor.

Nitrous oxide from this method is approved by WHO, FDA and GB standard for food additive.
(https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=173.360)

For food grade nitrous oxide for sale, including whip cream chargers, please confirm the nitrous oxide is produced by thermal decomposition of ammonium nitrate.