As described in the February 2009 Process Paper of, the large scale manufacture of urea in modern times has been based on synthesis from ammonia and carbon dioxide. This process as originally suggested by Basaroff was first translated into industrial manufacture by German chemists in I. G. Farben in about 1920.
There are two main reactions involved in the synthesis of urea from carbon dioxide and ammonia; the formation of ammonium carbamate from carbon dioxide and ammonia, and the conversion of ammonium carbamate into urea. This paper discusses the thermodynamics of the urea process. The thermodynamic models of Frejacques and Lemkowitz, de Cooker and van de Berg will be presented and in the influence of various process parameters like N/C, H/C, temperature and pressure will be discussed.