Ammonia synthesis Haber/Bosch reactor

To demonstrate the accurate approximation approach for parameter estimation, we summarize a case study presented in Vasantharajan and Biegler (1990). Ammonia synthesis performed in a Haber-Bosch reactor is operated at high pressures in an autothermal manner, and produces ammonia from the following catalyzed reaction N2 -t- 3H202NH3. 

During whole development of catalytic ammonia synthesis technology, Haber completed the research foundation of the theory and the technology for ammonia synthesis, and Bosch made it applicable for industrialization. As a result, the process is called Haber-Bosch process. In 1911, first ammonia plant commenced to be built. In 9 September 1913, the plant with reactor of 285mm diameter and 90L of catalyst was switched on at 200 bar (Fig. 1.8). Initially, aimnonia production was about 3-5 tons per day. But the production scale was rapidly expanded. In 1917, the ammonia produced from Haber-Bosch process exceeded 60,000 tons per... 

Haber-Bosch process for synthesis of ammonia 1916 Microcracks in the steel reactor were observed due to the reaction of hydrogen with carbon in the steel to produce methane. Mo and Cr were found to prevent hydrogen embrittlement... 

The Haber-Bosch catalytic process for production of ammonia is perhaps an invention that had the most dramatic impact on the human race (Ritter 2008). The inexpensive iron-based catalyst for ammonia synthesis, which replaced the original, more expensive osmium and uranium catalysts, made it possible to produce ammonia in a substantially effective manner. The objective here was not improvement in selectivity but higher reaction rates for rapid approach to the equilibrium conversion at the specified temperatme and pressme. Higher rates meant lower catalyst volume and smaller high-pressme reactors. The iron catalyst was improved by addition of several promoters such as alkali metals. In contrast to this simple single reaction case of ammonia synthesis, most organic reactions are complex with multiple pathways. 

Catalysts play an important role in overcoming the activation barrier in ammonia synthesis. It is weU known that strong N=N triple bond and the low sticking coefficient of the molecule nitrogen limit the choice of catalyst. However, the mechanism of ammonia formation on an electrocatalyst seems to be different from that of the conventional catalyst. The information about the conventional catalyst in the Haber-Bosch process and the electrocatalyst in the electrocatalytic membrane reactor are described in this section. 

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