Haber-Bosch process preparation

Problem 5 In the Haber-Bosch process for the preparation of ammonia, the following reactions occur in a closed system ... 

The Haber-Bosch process has been known and used for over a century, and considerably little has changed over such a long period of time. In early work, Mittasch developed a highly active heterogeneous iron catalyst prepared from magnetite (Fe304) very similar catalyst formulations are still used in modern ammonia synthesis. It was also demonstrated that catalysts prepared from magnetite had superior catalytic activity in comparison to catalysts prepared from other iron oxides. 

A few industrial important heterogeneous catalysts are prepared by melt processes. Examples are the Fe-catalyst for the Haber-Bosch process and the Pt/Rh-net for the ammonia oxidation in the Ostwald process (see also Section 6.4). Melting is also the initial process step for the preparation of Raney-nickel and Raney-copper catalysts. For these catalysts an alloy of Ni/Cu and A1 is prepared by melting. This alloy is later treated with NaOH to dissolve the A1 from the solid to create pores and reactive surface sites. Raney-Ni and Raney-copper are very important hydrogenation catalysts. 

Despite these remarkable model systems, chemists have not yet been able to prepare a catalytic system that can compete with tiie XK century Haber-Bosch process (1895) that is still used in industry to synthesize NH, (see the mechanism in Chap. 20.2.2). 

After development of the ammonia process by Haber and Bosch in 1913, the production of urea from ammonia and C02 (both of which are formed in ammonia synthesis) developed rapidly. In 2001 urea is prepared on an industrial scale exclusively by this method which uses the Basaroff reactions109. 

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