Nitrogen industries Flashcards
Why is nitrogen essential for living organisms?
Nitrogen is a fundamental component of proteins, nucleic acids, and other cellular constituents, crucial for growth and reproduction.
What is nitrogen fixation?
Nitrogen fixation is the process of converting atmospheric nitrogen (N₂) into nitrogen compounds (e.g., ammonia, nitrate, nitrite) usable by organisms.
What are the major types of nitrogen fixation?
- Biological fixation (175 million metric tons/year): Done by microorganisms, primarily in agricultural and forest ecosystems.
- Non-biological fixation (80 million metric tons/year): Includes industrial processes (50), combustion (20), and lightning (10).
What is the Haber-Bosch process?
It is the primary industrial method for producing ammonia from N₂ and H₂ using an iron-based catalyst at high pressures and temperatures.
Use of cyanamide.
Calcium cyanamide (CaNCN) is used as a fertilizer.
What are the primary raw materials for ammonia synthesis?
- Natural gas (via steam reforming).
- Coal or oil (via partial oxidation).
- Refinery hydrogen.
- Electrolytic hydrogen.
What recent innovations improve ammonia synthesis energy efficiency?
Improved heat recovery, low-pressure systems, horizontal converters, and advanced CO₂ removal processes.
What are the steps in ammonia synthesis using natural gas as feedstock?
- Steam reforming: Produces H₂ and CO.
- Secondary reforming: Adds air to introduce N₂.
- Water-gas shift reaction: Converts CO to CO₂.
- CO₂ removal: Purifies synthesis gas.
- Ammonia synthesis loop: Combines H₂ and N₂ to form NH₃.
What are the main processes for hydrogen production?
- Steam reforming of natural gas:
- Partial combustion of hydrocarbons:
- Coal gasification: Conversion of coal to synthesis gas.
- Electrolysis: Splitting water into H₂ and O₂.
Why is feedstock purification important in ammonia production?
To remove sulfur, ash, and other impurities that poison catalysts and reduce efficiency.
What are common methods for removing CO₂ from synthesis gas?
- Water scrubbing.
- Potassium carbonate scrubbing.
- Methanol (Rectisol) process.
- Monoethanolamine (MEA) scrubbing.
What are the challenges of hydrogen production from coal?
- High ash content requires costly handling.
- High sulfur content burdens cleanup systems.
- Slag formation can clog equipment.
What are the main uses of ammonia?
- Fertilizers (e.g., urea, ammonium nitrate).
- Industrial applications (explosives, plastics, textiles).
- Refrigerants and water treatment chemicals.
How is nitric acid produced industrially?
By oxidizing ammonia with air over a Pt-Rh catalyst at 800–950°C
What are the primary uses of nitric acid?
- Fertilizers (65%).
- Explosives (25%).
- Steel refining, dye production, and uranium recovery.
How is urea manufactured?
By reacting ammonia with CO₂ under pressure to form ammonium carbonate, which decomposes into urea and water.
What are the main uses of urea?
- As a nitrogen fertilizer (46% N).
- In resins and plastics.
- As a petroleum refining additive.
- In cosmetics and adhesives.
Why does urea tend to cake, and how is this problem mitigated?
Urea cakes due to its hygroscopic nature. This is reduced by coatings (e.g., formaldehyde), additives (e.g., magnesium carbonate), or thermal treatments.
How does urea benefit agriculture and industry?
- Converts into ammonia/nitrates in soil, supporting crop growth.
- Used in resins, plastics, and chemical synthesis (e.g., melamine, hydrazine).
Why must CO and CO₂ be removed completely in ammonia synthesis?
They poison the ammonia synthesis catalyst and form harmful carbonates that damage equipment.
What safety measures are crucial when handling ammonium nitrate?
Avoid heating, contamination with organic materials, and storing large concentrated solutions at high temperatures.
What are the environmental impacts of nitrogen industries?
- Greenhouse gas emissions from CO₂.
- Potential contamination from ammonium nitrate and urea.
- Air pollution from nitrogen oxides during production.
