2.B.2 Nitric Acid Production

Last updated on 04 Dec 2014 08:38 (cf. Authors)

Short description

In production of nitric acid, nitrous 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:

The collected activity data for nitric acid production are plant specific, because it's N2O emissions are a key category according to the IPCC guidelines. An cooperation agreement with the nitric acid producers and the IVA - Industrieverband Agrar) is the foundation for this. The activity data of the producers is checked by the IVA and then because of confidentiality reasons aggregated and send to the UBA. According to the IVA catalytic reduction is used as a reduction method in some of the plants. One producer is delivering its data directly to the UBA. After a check of the data, the data is aggregated with the data of the IVA and used for the reporting.

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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