The Evolution of Nitric Acid Production Processes

Until the beginning of the 20th century, nitric acid was prepared commercially by reacting sulphuric acid with either potassium nitrate (saltpetre) or with sodium nitrate (Chile saltpetre or nitre). Up to four tonnes of the two ingredients were placed into large retorts and heated over a furnace. The volatile product vapourized and was collected for distillation. An acid of between 93-95%(wt) was produced. 

In 1903 the electric-arc furnace superseded this primitive original technique. In the arc process, nitric acid was produced directly from nitrogen and oxygen by passing air through an electric-arc furnace. 

Although the process benefited from an inexhaustible supply of free feed material (air), the power consumption for the arc furnace soon became cost prohibitive. 

Researchers returned to the oxidation of ammonia in air, (recorded as early as 1798) in an effort to improve production economics. In 1901 Wilhelm Ostwald had first achieved the catalytic oxidation of ammonia over a platinum catalyst. The gaseous nitrogen oxides produced could be easily cooled and dissolved in water to produce a solution of nitric acid. This achievement began the search for an economic process route. By 1908 the first commercial facility for production of nitric acid, using this new catalytic oxidation process, was commissioned near Bochum in Germany. The Haber-Bosch ammonia synthesis process came into operation in 1913, leading to the continued development and assured future of the ammonia oxidation process for the production of nitric acid. 

During World War 1, the intense demand for explosives and synthetic dyestuffs created an expansion of the nitric acid industry. Many new plants were constructed, all of which employed the ammonia oxidation process. This increased demand served as the impetus for several breakthroughs in process technology. These included  

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