Haber’s Process, which is also called the Haber-Bosch process, is used in the synthesis of ammonia from nitrogen and hydrogen. The Haber process to produce ammonia was developed during World War 1 (1914-1918) by a German chemist named Fritz Haber and his assistant in a laboratory. Later, in 1910, Carl Bosch took this idea and created a large-scale industrial machine for ammonia production.
In this article, we will learn What is Haber Process, the Diagram of Haber Process, equations, and thermodynamics involved in Haber’s Process.
What is Haber’s Process?
Haber Process is the industrial process for the manufacturing of Ammonia from hydrogen and nitrogen. Hydrogen is obtained from the reaction of methane and steam, producing carbon monoxide as a by-product. The hydrogen produced from this reaction also reacts with oxygen from air, producing water and leaving nitrogen behind. These gases are then compressed and delivered to the reactor where ammonia is produced. These gases are then cooled down, and ammonia is liquefied, ready to be tapped off. Unused hydrogen and nitrogen are recycled back to the reactor.
Haber Process Definition
Haber Process is a method that combines atmospheric nitrogen with hydrogen primarily sourced from natural gas (methane), to create ammonia. Ammonia is a primary component in the manufacturing of fertilizers that are nitrogen-based. The Haber process requires two essential raw materials – hydrogen and nitrogen.
Haber Process Reaction/Formula
When nitrogen gas reacts with hydrogen in the presence of Fe(iron) catalyst at temperature 450℃ and 200atm pressure, ammonia gas is produced. Haber’s Process Reaction is given as follows:
N2(g) + 3H2(g) ⇌ 2NH3(g) with ΔH = −92.4kJ/mol.
This reaction is a reversible reaction and the forward reaction is exothermic. The Haber process uses Le Chatelier’s Principle (best pressure and temperature conditions) to maximize ammonia production while keeping operating and production costs in mind.
Raw Materials Used in Haber-Process
The Haber-Process utilizes the following raw materials:
- Nitrogen (N2) – Its source is atmosphere.
- Hydrogen (H2) – It is obtained from the reaction of methane and steam, producing carbon monoxide as a by-product.
- Catalyst – Iron catalyst. Osmium and Uranium were used as a catalyst in the first Haber process reaction chambers.
Haber Process Diagram
The Haber-Process diagram involves several stages:
- Nitrogen gas is extracted from the atmosphere, and hydrogen obtained from natural gas. Both gases are combined in a 1:3 volume ratio.
- Through pipes, these gases are pumped into a compressor.
- Within the compressor, the hydrogen and nitrogen blend at a pressure of 200 atm and a temperature of 450 degrees Celsius.
- Then, these compressed gases are pumped into a reaction vessel containing an iron catalyst.
- This process also includes stages such as shift conversion, the extraction of carbon dioxide, steam reforming, and methanation.
- By the reaction with iron catalyst, these gases are cooled in a separate tank, where ammonia goes to liquefy and separate.
- The unused nitrogen and hydrogen are recycled, backed to the reaction vessel to prevent wastage and ensure efficiency.
Haber Process Condition
The Haber Process happens with high pressure, high temperature, and the presence of a catalyst. These conditions are necessary for conducting the reaction and ensuring the efficient production of a sufficient quantity of ammonia.
Temperature During Haber-Process
The Temperature of the Haber-Process is set at 450 degrees Celsius. The forward reaction in this process releases heat (exothermic). Lowering the temperature would increase ammonia yield, but it would slow down the reaction rate. On the other hand, a higher temperature would reduce ammonia yield and the yield of reactants would increase. Therefore, the chosen compromise is a temperature of 450 degrees Celsius to balance both factors efficiently.
Pressure During Haber-Process
Pressure of the Haber-Process is maintained at approximately 200 atmospheres. Higher pressure would increase ammonia yield as is increased then this leads to an increase in the yield of ammonia as there are fewer molecules on the product side of the equation. On the other hand lower pressure would increase the reactant yield, as more molecules are on the left-hand side of the equation. High pressure can be very dangerous and costly. Hence, the chosen pressure of 200 atmospheres ensures a balance, where ammonia production is somewhat lower but produced safely and economically.
Catalyst in Haber-Process
In the Haber-Process, only an iron catalyst is used as a catalyst. Although the catalyst does not change the equilibrium position, but it influences the reaction rate by other pathway and reduce the activation energy. In this process, potassium hydroxide is supplemented to iron as a promoter to enhance its effectiveness. In the place of potassium hydroxide, we can use CaO, K2O, Al2O3, and SiO2 as iron promoters. The initial Haber process used Osmium and Uranium as catalysts in reaction chambers.
The presence of a catalyst not only accelerates the reaction rate but also enables the use of lower temperatures, ensuring a reasonable yield. When we do not use any catalyst, we would require higher temperatures for the reaction which leads to higher costs and lower yield production. Thus, the use of a catalyst is important for optimizing efficiency in the Haber-Process.
Thermodynamics of Haber Process
Whether a catalyst is present or not, the production of ammonia in the Haber-Process is a spontaneous reaction (∆G < 0). There is need to notice that the kinetics and thermodynamics of a reaction are often independent, meaning a thermodynamically favourable reaction might not necessarily be faster. The Haber-Process is an example of this, showing a reaction with favourable thermodynamics but slow kinetics.
Beyond spontaneity, the reaction shows a decrease in entropy (∆S < 0). Now we observe that four moles of reactant gas producing two moles of product gas in the reaction:
N2 + 3H2 → 2NH3
The decrease in gas moles indicates a reduction in microstates, means decreasing entropy. Another way to understand this negative change is through the concept that fewer gas molecules signify greater “disorder.”
The reaction must show a decrease in enthalpy to ensure spontaneity. We know that the Haber Process is exothermic (∆H < 0). According to Gibbs free energy definition, as temperature decreases, spontaneity increases means ∆S, leading to a more negative ∆G:
∆G = ∆H – T∆S
Here, T represents the reaction temperature.
Reaction Rate and Equilibrium of Haber’s Process
The Haber-Process is necessary for synthesizing ammonia through the reaction of nitrogen and hydrogen. This reaction is reversible reaction and that the forward reaction is exothermic involving the release of energy:
N2 (g) + 3H2 (g) → 2NH3 (g)
Nitrogen is obtained by separating it from the atmosphere through liquefaction, while hydrogen is obtained from the reaction of methane and steam:
CH4 (g) + H2O → H2 (g) + CO(g)
As per Le Chatelier’s principle, ammonia production is occurred at high pressure and low temperature. Typically, the Haber process operates within the range of 200 to 400 atmospheres at a temperature of 500°C. In the industrial production of ammonia, the continuous removal of NH3 ensures the continuity of this reaction.
This reversible reaction is influenced by changes in temperature, pressure, and the catalyst applied. It impacts the composition of the equilibrium mixture, the reaction rate, and the overall economic feasibility of the process.
Haber-Process of Ammonia
In Haber Process of Ammonia, methane and water undergo reactions internally to generate hydrogen. Later, oxygen and nitrogen gas are introduced, initiating another process that generates additional hydrogen from methane. In both reactions, carbon monoxide forms as a by-product.
The components of ammonia N2 and H2 combine in a ratio of 1:3.
N2(g) + 3H2(g) ⇌ 2NH3(g) with ΔH = −92.4kJ/mol
After that water vapor is introduced, leading to the oxidation of carbon monoxide to carbon dioxide. The produced carbon dioxide exits the system, leaving behind a gas mixture of nitrogen and hydrogen. This mixture undergoes compression at 200 atmospheres and is heated at approximately 500°C. The heated and pressurized mixture then enters the reaction chamber and then put a metal catalyst (Iron) with small amounts of K2O and Al2O3 to increase the rate of attainment of equilibrium. Ammonia is formed in this stage, and the reaction mixture is distilled by passing a cold water jacket over it. This ammonia gas goes for liquefaction, which is drained from the system.
Initially, only around 15% of the nitrogen and hydrogen undergo reaction. The unreacted gas separates from the liquid ammonia and goes back to the reaction chamber. Through further runs, approximately 98% of the original gas mixture eventually reacts to produce ammonia.
Uses of Ammonia
The applications of ammonia are mentioned below:
- Ammonia is an important component of nitrogen-based fertilizers. Example: ammonium nitrate and urea. These are essential for promoting plant growth and agricultural outputs.
- Ammonia is used in the production of explosives. Examples of nitro-based explosives are TNT (trinitrotoluene) and RDX.
- Ammonia can be used in the pharmaceutical sector in manufacturing of drugs. Example: In the production of sulfonamides, antimalarials, and vitamins like thiamine and nicotinamide, we use ammonia.
- Ammonia can be used as a refrigerant in large-scale industrial refrigeration plants and air-conditioning process.
- Ammonia can be used in the cleaning of household products particularly for glass surfaces.
- Ammonia is used in the textile industry for dyeing and printing of fabrics.
- Ammonia is used in water treatment plant, in the form of ammonium hydroxide to remove impurities.
- Ammonium hydroxide is used in the food industry as a leavening agent in baking foods.
- Ammonia can be an important source of hydrogen for fuel cells in the form of clean energy.
Also, Check
Haber-Process Sample Questions
Q1: What are the factors that influence the Haber-Process?
Answer:
The Haber-Process is a reversible process. It is influenced by the change in temperature and pressure.
Q2: How can ammonia produce through Haber-Process?
Answer:
The production of ammonia is achieved through the Haber-Process, where the hydrogen (H2) and nitrogen (N2) Haber cycles play an important role. In this process, ammonia gas is generated by the synthesis of nitrogen gas from the atmosphere with hydrogen gas.
Q3: How can we get hydrogen in Haber Process?
Answer:
Hydrogen source in Haber-Process primarily is methane gas. The process involves steam reforming, where a nickel catalyst facilitates the separation of carbon and hydrogen atoms in natural gas.
Q4: Write the other catalyst name which can be used instead of iron in Habers Process.
Answer:
In Haber-Process, potassium hydroxide is supplemented to iron as a promoter to enhance its effectiveness. In the place of potassium hydroxide, we can use CaO, K2O, Al2O3, and SiO2 as iron promoters. The initial Haber process used Osmium and Uranium as catalysts in reaction chambers. Practice Questions on Haber-Process
Practice Questions on Haber-Process
Q1. Describe the role of a catalyst in the Haber-Process.
Q2. Write all the sources of raw materials for the Haber-Process.
Q3. What is the primary source of hydrogen?
Q4. How does ammonia impact the environment?
Q5. How does Haber process contribute to increased crop yields?
FAQs on Haber’s Process
1. What is Haber Process?
The Haber-Process, which is also called the Haber-Bosch process, is used in the synthesis of ammonia from nitrogen and hydrogen.
2. What is the Use of Habers Process?
The main use of Haber-Process is nitrogen fixation from atmosphere to produce ammonia for various uses.
3. Which catalyst is Used in Haber’s Process?
Iron is a catalyst used in Haber-Process.
4. Where can we use the Haber Process?
Haber-Process can be used in fertilisers sector, explosive materials production, pharmaceutical sector, water treatment plant for cleaning, textile industry for dying and printing etc.
5. What is the Haber Process Equation?
The Haber Process Equation is,
N2 (g) + 3H2 (g) → 2NH3 (g)
6. Why is Iron catalyst used for Haber Process?
Iron is used as catalyst in Haber Process because iron is a cheap catalyst. It requires less time to reach a reasonable yield.
7. What is Ideal Temperature in Haber-Process?
The temperature of the Haber process is set at 450 degrees Celsius.
8. What is Ideal Pressure in Haber-Process?
The pressure of the Haber process is maintained at approximately 200 atm.
9. How can we Obtain Hydrogen form Haber-Process?
In Haber’s Process Hydrogen can be obtained from the reaction of methane and steam as,
CH4 (g) + H2O → H2 (g) + CO(g)
10. What is Output of Haber Process?
Ammonia is the output of Haber Process with input N2 and H2.
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