Haber-Bosch.

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Table of Contents

Executive Summary……………………………………………………...…Title  Page

1. Introduction…………….………………………………………………...….....Page 3

2. Haber Bosh Process……………………………..……….………….…….....Page 4

3. Conclusion and analysis………………………….……………………........Page 6

4. References…………………………...………………..……….……………....Page 8

Introduction

The Haber-Bosch process appears in Germany for the first time collaborating with the supply of fertilizers and ammunition in Germany in the First World War after the British naval block cut off the sources of nitrates from Chile. At present it is the industrial process most used for the production of ammonia in bulk is a method that allows the industrial synthesis of ammonia on a large scale, reacting the nitrogen and hydrogen gas. According to Pandemic et al., 2013 the process was developed one hundred years ago, based on the work of Fritz Haber and the process engineering of Carl Bosh. According to Giddey, 2013, ammonia is a colorless alkaline gas, lighter than air with a strong odor. i.e., it preserves a liquid form that maintains a pressure within a range of 9 to 10 bar at room temperature so the storage can be in low-pressure vessels. Nowadays approximately 80% of the ammonia that produced in the world is used for the production of fertilizers that are based on nitrogens; The remaining ammonia is utilized for the manufacture of explosives, pharmaceuticals, cleaning products among others. For the synthesis of ammonia, the source of hydrogen is mostly natural gas and involves desulfuration, reformed with methane vapor followed by the displacement reaction of water gas to convert CO to hydrogen and CO2. The methanation reaction removes residual CO and CO2 is removed by the pressure swing adsorption process, and nitrogen is typically obtained from atmospheric air using cryogenic air separation units. Also, Giddey (2013) states that ammonia is considered an energy storage medium and therefore has been used as fuel for transport vehicles since it can be burned in an internal combustion engine. He says that ammonia has a high potential to play a major role in the future hydrogen economy because ammonia is a significant source of ammonia. The main advantage of using ammonia as a source of hydrogen is that the volumetric density of Hydrogen in liquid anhydrous ammonia is significantly higher than that of liquid hydrogen

Haber-Bosch Process

Anorg (2012), shows the reaction occurred for ammonia synthesis, N2 + 3H2-2NH3, where nitrogen and gaseous hydrogen react in a proportion of 1 molecule of nitrogen to 3 of hydrogen. Moreover, Giddey (2013) points out that nitrogen is an abundant element in the atmosphere, air is mostly composed of it. However, there is some difficulty in reacting with hydrogen because the nitrogen molecule is a very stable molecule. For the reaction to occur with a good performance is necessary to have a high pressure and temperature, in addition to a catalyst of iron. The hydrogen is obtained from methane, which reacts with water vapor, in the presence of the catalysts. The hydrogen obtained is passed through beds of iron oxide, at the same time as the nitrogen comes from the atmosphere. Giddey also adds that to accelerate the reaction the pressure should be at 200 atm and raises the temperature by holding it between 300-500 ° C since the lower temperatures will take longer to make the reaction reach the equilibrium.  

Modak (2002), explains that the formation of ammonia is an exothermic reaction with an abundant release of heat, also adds that it is a reversible reaction meaning that it can proceed both to the synthesis of the ammonia and its decomposition. The reaction is accompanied by a decrease in volume because there is a reduction in the number of moles of gas from 2 to 1. Modak refers to the Chatelier´s principle when he explains that the increase in pressure causes the equilibrium to move to the right resulting in an increase in the yield thanks to the pressure drop accompanying transformation.  Also,  decreasing the temperature will do the same displacement and effect as does the increase in pressure because the reaction is exothermic.

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Hydrogen and nitrogen, are extracted from different sources. Nitrogen is taken from the air. Burning hydrogen in the air removes the oxygen leaving practically pure nitrogen. Hydrogen, however, is made combining methane and steam. Subsequently the production of ammonia starts removing the impurities of the hydrogen and nitrogen, the mixture of hydrogen and nitrogen is compressed until it reaches the pressure of 200 atm, the gases flow to the converter, where beds of iron are kept at 450°C; the iron is used as a catalyst, that force the reaction to move to the right, at this point the ammonia is created, however only the 15% of the total mixture forms the ammonia. The ammonia fired is cooled until it becomes liquid at the bottom of the cooler, the rest of the gases are recycled to form more ammonia. Finally the liquid ammonia is collected.

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