This section on nitric acid comprises these pages:
Nitric acid – Introduction and uses
Properties and quality, Azeotropic acid
Raw materials and production process chemistry
Production technology and construction materials
Industrial processes, and technology and engineering suppliers
Trends and technology developments
Nitric acid, HNO3, is one of the oldest known chemicals. It is a colourless liquid with an extremely pungent odour and corrosive properties. When stored for a long time and exposed to temperature, it turns yellow due to the spontaneous decomposition into nitrogen oxides and water. It reacts readily with numerous substances and produces heat when dissolved in water. Nitric acid is a strong oxidiser and a significant proportion of reactions involving it are even explosive.
History of nitric acid production
In the past, three primary methods of production of nitric acid have been developed and applied on a large scale:
- Acidulation of natural sodium nitrate with sulfuric acid
- Direct synthesis from nitrogen and oxygen
- Oxidation of ammonia.
The acidulation of sodium nitrate was conducted commercially in Chile for about 30 years, ending in the early 1920s. Sodium nitrate (“Chilean saltpeter”), which had replaced the previously used saltpeter (potassium nitrate), was reacted with sulphuric acid and the resulting nitric acid was distilled off.
Direct oxidation of nitrogen by electric arc was carried out commercially beginning in 1902 in Norway using electrical energy from hydro sources. A commercial plant was also constructed in Poland using the Mościcki process of direct oxidation in an electric arc. That plant operated until the early 1950s.
According to the state of knowledge at around 1900, obtaining nitrogen oxide from the air was only possible with a high temperature of electric discharges and direct binding of oxygen and nitrogen. Nitric oxide was necessary for the formation of nitric acid. The demand for this acid was huge at the time – all because of the dwindling deposits of Chilean nitrate, which was used in its production. Ignacy Mościcki, a former technical manager at Société de l’Acide Nitrique, constructed and patented several types of electric furnaces with a rotating arc.
The solution was unusual at that time (1901), as it meant that nitrogen compounds could be produced cheaper and faster than before. The discovery garnered the interest of the scientific world and industry. Shortly afterwards, however, news came that a method less expensive than Mościcki’s had been developed in Norway. The chemist decided that work on the construction of a nitrogen factory that was to be based on his patent, should be halted. However, he continued his research. Albert Einstein himself praised his efforts. And soon the idea of building a factory returned. It was opened in 1910 in Chippis, Switzerland. Acid production on a massive scale and its sales began. During WWI this proved to be a godsend for countries that had no access to ammonium nitrate and needed explosives.
The first patent on ammonia oxidation was issued to Kuhlman in 1839; in this case platinum was used as a catalyst to oxidise ammonia with air. The ammonia oxidation method using a platinum catalyst on a commercial scale, developed by Oswald and (his son-in-law) Brauer and first operated in Germany about 1908, is at present the principal industrial method of nitric acid production.
In 1908, at Bochum, Germany, Ostwald piloted a 3-t per day nitric acid process based on the catalytic oxidation of ammonia with air. In 1913 the synthesis of ammonia from coal, air, and water was successfully demonstrated using the Haber-Bosch process. With a secure and economical supply of ammonia, ammonia oxidation became firmly established as an industrial route to nitric acid manufacture. Process developments continued and plant scale increased to commercial quantities in both Europe and the United States.
The first full-size plant to be built in the United States was installed in 1917 by Chemical Construction Company (Muscle Shoals, Alabama). The process operated at atmospheric pressure and used multiple ammonia oxidation converters. Since those early days, ammonia oxidation has become the basis of all commercial nitric acid production. There have been many advances in plant design leading to improved process performance and higher production capacities at increased operating pressures.
The ammonia oxidation processes for manufacturing nitric acid are well described in the external resources given below.
Nitric acid and nitrate technologies have also been developed in Russia and various countries in central and eastern Europe. The Commonwealth of Independent States was – and is – a large producer of nitric acid and its downstream products. All technologies in these countries were developed by the Russian state institute of nitrogen industry (GIAP). Several older plants in eastern Europe still use GIAP technologies; these technologies are not applied in western Europe or North-America.
A relevant long-term development in the production of nitric acid through the combustion of ammonia is use of the reaction heat. The combustion is highly exothermic and this energy can be used in the process or be exported and used elsewhere, thus avoiding the need for energy imports. Focus on this has increased and integration of the energy grid with other production plants can be sustainable and advantageous.
Researchers remain attracted to the possibility of manufacturing nitric acid (or even ammonium nitrate) in a one-step-process starting from air/oxygen and nitrogen. Research is often focused on mild conditions, implying low to moderate temperatures and pressure. There is a wealth of articles and patents describing such research, however none of these have yet reached a larger or even industrial scale.
A promising variation is the use of plasma technologies for nitrogen fixation, this is documented in IFS proceedings 771.
Uses of nitric acid
The main use for nitric acid is in fertiliser production, mainly for ammonium nitrate as such or in compound fertilisers, nitrogen solutions, or mixed salts. Some 60 million tonnes are produced annually (2020) and about 80% of total nitric acid production is consumed for nitrate fertilisers, mainly as 50%-65% concentration acid. Smaller fertiliser uses are for calcium and potassium nitrates. A primary use is in acidulation of phosphate rock for production of nitrophosphates. Plant capacities for weak nitric used for fertiliser production vary over a wide range, from as low as 35 to a common value of 1,500 tons per day and up to capacities of well over 2,000 tonnes per day.
Nitric acid also has many industrial uses for production of nitro-aromatics and nitro-alkanes, of which explosives manufacture is the largest. Another application of nitric acid is for adipic acid production (an intermediate product in nylon production). In this case the concentrated acid is used.
Nitric acid is used as an oxidant, rocket propellant, for metal processing, as an analytical agent, for woodworking and as an etchant and cleaning agent.
Links to related IFS Proceedings
50, (1958), An Outline of the Theory and Practice of Nitric Acid Manufacture, D A Spratt
78, (1963), Processes for the Manufacture of Nitric Acid, G Drake
200, (1981), Nitric Acid Technology, J K Bradley, G Drake
217, (1983), Developments in Nitric Acid Plants, W Freitag, R Maurer
246, (1986), Boosting Existing Nitric Acid Production, E Fareid, L Hjørnevik, G Kongshaug
803, (2017), Changes, challenges, and opportunities in fertiliser-manufacturing processes: A personal review and outlook, J G Reuvers
Nitric Acid Collected Proceedings 1958-2014, USB card.
Links to External Resources
On the decomposition of sodium nitrate by sulphuric acid and the distillation of nitric acid, C. W. Volney, J. Am. Chem. Soc., 1891, 13, 9, 246–251.
Fertilizer Manual, edited by the United Nations Industrial Development Organization (UNIDO) and the International Fertilizer Development Center (IFDC), Kluwer Academic Publishers, 1998, pages 209-220.
Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, May 2005; ISBN: 978-0-471-48511-7.
Hager, T. (2008). The Alchemy of Air. Harmony Books, New York, United States of America. ISBN 978-0-307-35178-4. OCLC 191318130.
Nitric acid and fertilizer nitrates, I. Brunborg and P. B. Holmesland, in C. Keleti, Ed., Vol. 4, Marcel Dekker Inc., New York, 1985, pages 1–17.
Nitric acid, Kirk-Othmer Encyclopedia of Chemical Technology, M. C. E. Groves, John Wiley and Sons, June 2020. .
Nitric acid, nitrous acid, and nitrogen oxides, Michael Thiemann, Erich Scheibler, Karl Wilhelm Wiegand, Ullmann’s Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH, Weinheim, Germany. ISBN 978-3527306732.
Integrated Pollution Prevention and Control Reference Document on Best Available Techniques for the Manufacture of Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers, August 2007; pages 95-143.
Nitric acid production, E.-P. Cristescu, 1994, Pollution Control in Fertilizer Production, edited by C. A. Hodge and N. N. Popovici, Chapter 7, pages 81–92.
The competitive performance of the nitrogen plants in the former USSR, British Sulphur, London, 1993.
Peters, B. H. (2015). Chemical production system.
US20140134057, date of patent 15. May 2015. Production of chemical compounds. WO/2013/032540, publication 07. Mar. 2013. Pulse Jet System and Method. US20160045888, publication 18. Feb. 2016, and WO/2013/033039, publication 07. Mar. 2013.
In addition it should be noted that:
The integrated pollution prevention and control reference document on Best Available Techniques for the manufacture of large volume inorganic chemicals – ammonia, acids and fertilisers (BATREF LVIC-AAF) describes in detail the processes, manufacturers, and existing challenges.
Various companies offer technologies and engineering services and the reader is advised to read the information made readily available. Such companies include, but are not limited to, CASALE, KBR-Weatherly, Stamicarbon, and Thyssenkrupp-UHDE.
The presentations made during the yearly conferences on ammonium nitrate and nitric acid (ANNA) are maintained in a library, however, this library is for conference attendees only. To access the downloads, your company must produce either ammonium nitrate or nitric acid and have attended a conference in the last 5 years.
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