Synthetic ammonia production thermodynamics

The modem process for manufacturing nitric acid depends on the catalytic oxidation of NH3 over heated Pt to give NO in preference to other thermodynamically more favour products (p. 423). The reaction was first systematically studied in 1901 by W. Ostwald (Nobel Prize 1909) and by 1908 a commercial plant near Bochum. Germany, was producing 3 tonnes/day. However, significant expansion in production depended on the economical availability of synthetic ammonia by the Haber-Bosch process (p. 421). The reactions occurring, and the enthalpy changes per mole of N atoms at 25 C are ... 

The relationship we are about to describe is due to the work of Pierre Duhem (1861-1916) a French physicist who translated Gibbs work into French and was in his own rights a prolific author of thermodynamic studies. So far the applications of thermodynamic (except for the on-stream ammonia synthesis discussed above) have been for what are closed systems where it is possible to enclose the system with a boundary and separate it from the environment. Many of the synthetic applications in chemical engineering are carried out with on-stream processing rather than in a batch reactor, a system in which a continuous flow of reactants is processed and continuous product flows out of some sort of reaction chamber. While most laboratory synthesis is carried out in batch fashion, there are also static phenomena, which depend on adding an arbitrary amount of one... 

---