The Haber-Bosch Process

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. 

Catalyst preparation involves a reduction stage, using syngas as an in situ reductant before process operation, though, pre-reduced catalysts have become commercially available. Optimal catalyst activity can only be achieved when the catalyst is prepared following a carefully controlled procedure in particular, melt conditions must be well controlled, as this determines the oxygen content of the formed catalyst. Additionally, for optimal activity, the iron present in the catalyst must have an Fe(ii) Fe(iii) ratio in the range of 

1 2 to 1.2 2, similar to the ratio found in magnetite. Catalyst preparation combines magnetite with small amounts of irreducible oxides as promoters before the reduction step, these include aluminium oxide, potassium oxide, calcium oxide, magnesium oxide and silicon dioxide. Various other additives can also be added to fine tune catalyst activity.  

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The synthetic ammonia industry of the latter part of the twentieth century employs only the Haber-Bosch process (12—15), developed in Germany just before World War 1. Development of this process was aided by the concurrent development of a simple catalyzed process for the oxidation of ammonia to nitrate, needed at that time for the explosives industry. N2 and H2 are combined direcdy and equiUbrium is reached under appropriate operating conditions. The resultant gas stream contains ca 20% ammonia. 

Fig. 2. The Haber-Bosch process. Gases in parentheses are minor constituents of the mixture.

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 catalytic synthesis of ammonia from its elements via the Haber-Bosch process is of major industrial importance. The high pressure synthesis is catalyzed by Fe promoted with K20, CaO and A1203. 

Ammonia, another well known cleaner, is also used to manufacture fertilizers, nitric acid, sodium carbonate (washing soda), explosives, nylon, and baking soda. Ammonia is produced by combining nitrogen gas (obtained from the air) and hydrogen gas (obtained from natural gas) in a process called the Haber-Bosch process ... 

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. 

Five years after Haber patented his process, BASF opened its nitrogenfixing ammonia factory in 1913. The Haber-Bosch process, as it is now... 

You want guarantees Our London Charter doesn t say all statements have to be sworn. You want dates Everybody knows how far back this thing goes. Without the Haber-Bosch process, World War I would have ended in 1915 — there s your answer whose side they were on "... 

Let the rest of the world depend on Chile Germany needed her no more. During these first eight months of 1939, by the Haber-Bosch process alone, Farben had doubled the whole Chilean output of nitrates. Nitric-acid production had jumped tenfold since 1933, methanol by six hundred or more. On that first day, diglycol was produced at a rate which would make 50,000 tons of gunpowder every month. 

Frank-Caro Also called the Cyanamide process. An early process for fixing atmospheric nitrogen. Lime and carbon were heated to produce calcium carbide this was reacted with nitrogen to give calcium cyanamide, which was hydrolyzed with steam to yield ammonia and calcium carbonate. Developed by A. Frank and N. Caro from 1895 at Dynamit, Germany, and used in Germany, Norway, and Italy until it was replaced by the Haber-Bosch process after World War I. 

Mont Cenis [Named after a coal mine in the Ruhr] An early ammonia synthesis process, basically similar to the Haber-Bosch process but using coke-oven gas. Operated by The Royal Dutch Group at Ymuiden, The Netherlands, since 1929. 

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 ... 

Reacting dinitrogen with dihydrogen on a catalytic iron surface (the Haber-Bosch process)... 

Production of ammonia (NH ) Anhydrous (dry) ammonia is the fifth most produced industrial compound. The Haber-Bosch process uses steam on hot coke, which is mostly used in South Africa. In the United States, it is mostly produced from partial combustion of natural gas (methane) or by combining several gases using steam. Other methods use coke-oven gas, refinery gas (mostly methane), or even solar energy. Ammonia is toxic if inhaled and has a high pH value when mixed with water (hydration) to form ammonium hydroxide (NH OH), which has many uses, including as a household cleaner. Ammonia forms many compounds, including ammonium nitrate in fertilizer, rocket fuel, and explosives. Ammonia is also explosive when mixed with mercury or silver or when mixed as part of nitrocellulose. 

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

It also is obtained as a by-product in the Haber-Bosch process for the manufacture of ammonia. The method involves passing steam and air over hot coke. 

Carl Bosch developed the industrial stages for the Haber Process. The perfection of the Haber-Bosch process was used by Germany during World War I. Haber also worked on the thermodynamics of gaseous reactions, the electrochemistry and the explosion of gases. 

The nitrogen required is obtained by fractional distillation of liquid air.16 The hydrogen used to be obtained by electrolysis of liquid water if inexpensive surplus electrical capacity becomes available in the future, this method may well be reintroduced. Catalytic photolysis of water using sunlight is another possible future source of H2. The Haber-Bosch process of 1916 used water-gas, which is a mixture of H2, CO, and CO2 made by alternating blasts of steam and air over coke at red heat ... 

Reduction in price of raw material (nitric acid) by the commercialization of the Haber-Bosch process for ammonia synthesis. 

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