Fundamentals of Nitric Acid Manufacture

Nitric acid is currently almost exclusively produced by the catalytic oxidation of ammonia using the Ostwald process (1902). The reaction of sodium nitrate (Chile niter, the only nitrate occurring naturally in large quantities) with sulfuric acid, operated at the turn of the century, has not been economic since the emergence of the Haber-Bosch ammonia synthesis process shortly before World War 1. The 

The process for nitric acid manufacture from ammonia consists of three exothermic reaction steps as shown schematically in Fig. 1.4-5  

The three reaction steps are based on very different physical chemical relationships which appreciably influence the operation of the process. The third step is normally followed by tail gas purification, to prevent the emission of nitrous gases. 

The oxidation of ammonia (combustion) with (excess) atmospheric oxygen to nitrogen(II) oxide (NO) is carried out in the presence of a catalyst at 820 to 950 C either at atmospheric pressure or at pressures up to 12 bar  

This reaction is one of the most efficient catalytic processes in industrial chemistry, having an extremely short reaction time (lO s) and a high selectivity. The oxidation of ammonia benefits slightly from pressure reduction, since 

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