2.B.2 - Nitric Acid Production

Last updated on 20 Mar 2020 10:50 (cf. Authors)

Short description

Within NFR 2.B.2, NOx emissions from the production of nitric acid are reported.

NFR-Code Name of Category Method AD EF Key Category 1
2.B.2 Nitric Acid Production T2 PS D L/T: NOx

During the production of nitric acid, nitrogen oxide occurs in a secondary reaction. In Germany, there are currently seven nitric acid production plants. HNO3 production occurs in two process stages:

  • Oxidation of NH3 to NO and
  • Conversion of NO to NO2 and absorption in H2O.

Details of the process are outlined below:

Catalytic oxidation of ammonia

A mixture of ammonia and air at a ratio of 1:9 is oxidised, in the presence of a platinum catalyst alloyed with rhodium and/or palladium, at a temperature of between 800 and 950 °C. The related reaction, according to the Oswald process, is as follows:

4 NH3 + 5 O2 —> 4 NO + 6 H2O

Simultaneously, nitrogen, nitrous oxide and water are formed by the following undesired secondary reactions:

4 NH3 + 3 O2 —> 2 N2 + 6 H2O

4 NH3 + 4 O2 —> 2 N2O + 6 H2O


All three oxidation reactions are exothermic. Heat may be recovered to produce steam for the process and for export to other plants and/or to preheat the residual gas. The reaction water is condensed in a cooling condenser, during the cooling of the reaction gases, and is then conveyed into the absorption column.


Activity data:

As this source category is a key category for N2O, plant specific activity data are applied here according to the IPCC guidelines.

These data are made available basically via a co-operation agreement with the nitric acid producers and the IVA (Industrieverband Agrar). As the data provided by the producers has to be treated as confidential, it is anonymised by the IVA before submitting it to the UBA. Here, one producer is delivering its data directly to the UBA. After checking these specific data, they are merged with the IVA.

According to the IVA, catalytic reduction is used as a reduction method in some of the plants.

Emission factor:

For NOx the default emission factor from [1] of 10 kg/t NH3 is used.


With activity data and emission factors remaining unrevised, no recalculations have been carried out compared to last year's submission.

Planned improvements

Germany is in contact with the IVA with the aim to get a Country-specific EF for the NOx emissions. It is expected that the Country-specific EF will be lower than the Default EF.

For more information on recalculated emission estimates for Base Year and 2017, please see the pollutant-specific recalculation tables following chapter 8.1 - Recalculations.

1. EEA, 2013: EMEP EEA Emission Inventory Guidebook 2013, Aug 2013: page 15, table 3.3 Tier 1 emission factor for source category 2.B.2 Nitric acid production
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