Haber-Bosch process catalysts

Invented in 1909 by Fritz Haber (1868-1934), the Haber-Bosch process requires very high pressure (250 atmospheres) and a temperature of approximately 932°F (500°C). The reaction also requires a porous iron catalyst. 

Industrially, ammonia has been produced from dinitrogen and dihydrogen by the Haber-Bosch process, which operates at very high temperatures and pressures, and utilizes a promoted iron catalyst. Millions of tons of ammonia are generated annually for incorporation into agricultural fertilizers and other important commercial products. The overall reaction is exergonic, as indicated in equation 6.1 ... 

To appreciate the height of the activation barrier that the biological catalysts are able to overcome one can recall that the Haber-Bosch process ... 

Ammonia is produced from nitrogen and hydrogen at elevated temperature (500 to 550°C) and pressure (200-350 atm) (Haber-Bosch process), using a promoted iron catalyst... 

Most other synthetic processes are modifications of the Haber-Bosch process, using different pressures, temperatures, gas velocities, and catalysts. 

In the Haber-Bosch process, ammonia is formed from the reaction between N2 and H2, using a Fe304 (magnetite) catalyst promoted with A1203, CaO, K20 and a moderately small amount of iron and other elements [25], In this mixture, the catalytically active... 

Biological N2 fixation is catalyzed by Fe/Mo, Fe/V, or FeFe (the Fe-only) nitrogenases (150, 151). The extremely different reaction conditions of the biological and the Haber-Bosch processes of N2 reduction, that is, standard temperature and pressure and biological redox potentials on the one hand, red-hot temperatures and high pressures on the other hand, make the quest for low molecular weight competitive catalysts particularly challenging. 

Over geologic history, most Nr has been formed by BNF. However, in the last half of the twentieth century, the Haber-Bosch process has replaced BNF as the dominant terrestrial process creating Nr. The Haber-Bosch process was invented and developed commercially in the early 1900s. It uses high temperature and pressure with a metallic catalyst to produce NH3 ... 

This reaction is one of the most important industrial processes, with over 120 million tons of ammonia produced in 1990 worldwide. However, in spite of metal oxide catalysts introduced in the Haber-Bosch process in 1913 and improved since then, it is also a reaction that requires temperatures near 400° C and 200 atm pressure and that still results in a yield of only 15% ammonia. Bacteria, however, manage to fix nitrogen (convert it to ammonia and then to nitrite and nitrate) at 0.8 atm at room temperature in... 

In nature, ammonia is produced by the action of nitrogen-fixing bacteria on atmospheric N2 under very mild conditions (room temperature and 0.8 atm N2 pressure). These bacteria contain nitrogenases, iron- and molybdenum-containing enzymes that catalyze the formation of NH3. Industrially, NH3 is synthesized from its elements by the Haber-Bosch process, which typically uses finely divided iron as catalyst ... 

The most important method of synthetic N fixation is by the Haber-Bosch process. Ammonia is synthesized from a 3 1 volume of H2 and N2 at elevated temperature and pressure in the presence of a catalyst ... 

Dobereiner s lighter. In the very important Haber-Bosch process, Os- (and U-) compounds tvere first used by Bosch before World War I (Rompp 1990). Alloys which contain Pt, Rh and Pd in various ratios are used in form of very fine woven wire nets (wire 0 0.06-0.072 mm) as catalysts for the catalytic oxidation of NHj in nitric acid production (Biischel et al. 1999), whereby normal catalyst losses range from 0.05 to 0.35 g Pt per ton HNO3. According to the demand for PGM (see Table 20.3), approximately 40% of Pt, 75% of Pd and 95% of... 

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