ABSTRACT
Ammonia is one of the most important chemicals used in the petrochemical industry, with production amounting to more than 120 million tonnes per year. Ammonium salts have been known since earliest times and free ammonia was first made in the late 18th century. The synthesis of ammonia from its elements commenced commercially prior to World War I. The new low-cost ammonia process developed by ICI has revolutionized ammonia production. The reacted gases are cooled to—20°C and most of the ammonia is liquefied. The major outlet for ammonia, accounting for 80% of total demand, is in agriculture either by conversion to fertilizers, of which urea and ammonium nitrate are the most important, or in the form of liquid ammonia for direct soil injection. Ammonia vapour is very irritating to eyes, nose and throat, and at high concentrations can cause coughing, chest pain and pulmonary oedema due to its alkalinity.
