Reactions and Thermodynamics of Nitric Acid Production

At about the same time, industrial ammonia production became possible by catalytic conversion of nitrogen and hydrogen (Haber-Bosch process, Section 6.1), at first based on coal and later on natural gas or heavy crude oil fractions. This opened up the modern route to nitric acid by catalytic oxidation of ammonia, which is examined here in detail. 

nitric acid is one of the 15 largest commodity chemicals with an armual world production of about 55 million tonnes (Uhde, 2005). Approximately 80% is used as an intermediate in the production of nitrogeneous fertilizers, primarily ammonium nitrate (NH4NO3). The remainder (20%) goes into the production of various chemicals such as explosives [trinitrotoluene, C6H2(N02)3CH3] or of intermediates for polymers like caprolactam, adipic add (for polyamides), or dinitroto-luene (for polyurethane). 

Many parallel and consecutive reactions are involved, and a simplified representation of the main reactions is the following sequence. 

ammonia is catalytically oxidized with oxygen (air) to nitrogen monoxide  

Subsequently, NO is further oxidized non-catalytically to nitrogen dioxide  

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