2.B.2 - Nitric Acid Production

Last updated on 16 Oct 2015 06:19 (cf. Authors)

Short description

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 checkimng 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.


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1. EEA, 2009: EMEP EEA Emission Inventory Guidebook 2009, TFEIP-endorsed draft, May 2009: page 14, table 3.2 Tier 1 emission factor for source category 2.B.2 Nitric acid production - , URL: http://www.eea.europa.eu/publications/emep-eea-emission-inventory-guidebook-2009/part-b-sectoral-guidance-chapters/2-industrial-processes/2-b-chemical-industry/2-b-chemical-industry-tfeip-endorsed-draft.pdf
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