the harber process

• The Haber Process


  1. Hydrogen and nitrogen gases pumped into compressor

  2. Gases compressed to 200 atmospheres

  3. Pressurised gases pumped into tank with catalytic iron beads at 450°C

  4. Unreacted gases and ammonia product pass into cooling tank

  5. Ammonia liquefied and stored, unreacted gases recycled
• Ammonia is manufactured using the Haber Process which occurs in 5 stages
• Reactants


  Hydrogen and nitrogen extracted from methane and air respectively
• N2(g) + 3H2(g) ⇌ 2NH3(g)


  Reversible reaction that occurs in the Haber Process
• Unreacted H2 and N2 and product ammonia pass into a cooling tank. The ammonia is liquefied and removed to pressurised storage vessels
• The unreacted H2 and N2 gases are recycled back into the system
• The Haber Process


  • Air contains 78% nitrogen, removed by fractional distillation
  • Hydrogen derived from methane (CH4) in steam reforming process
• Dynamic equilibrium


  Applies to a reversible reaction occurring in a closed vessel
• As pressure increases


  Yield of ammonia increases
• As temperature decreases


  Yield of ammonia increases
• Economic considerations


  • Availability and cost of raw materials
  • Production energy costs
• Temperature


  450°C is a compromise between lower yield at lower temperature and higher cost at higher temperature
• Pressure


  200 atm is a compromise between lower yield at lower pressure and higher cost at higher pressure
• Catalyst


  • Increases rate of both forward and backward reactions, does not affect position of equilibrium
  • Allows acceptable yield at lower temperature by lowering activation energy
• The reaction conditions chosen for the Haber process are not ideal in terms of the yield but do provide balance between product yield, reaction rate and production cost
• Essential elements in NPK fertilisers

  • Nitrogen
  • Potassium
  • Phosphorus
• Nitrogen


  Promotes healthy leaves
• Potassium


  Promotes growth, healthy fruit and flowers
• Phosphorus


  Promotes healthy roots
• Fertiliser compounds contain water soluble ions: ammonium ions, nitrate ions, phosphate ions, potassium ions
• Production of ammonium nitrate fertiliser

  1. Ammonia reacts with nitric acid to produce ammonium nitrate

  2. In the lab, ammonia reacts with sulfuric acid to produce ammonium sulfate
• Phosphate rocks contain potassium chloride and potassium sulfate
• Producing water soluble phosphate fertilisers

  1. Phosphate rock reacted with nitric acid to produce phosphoric acid and calcium nitrate

  2. Phosphoric acid neutralised with ammonia to form ammonium phosphate

  3. Phosphate rock reacted with sulfuric acid to produce single superphosphate

  4. Phosphate rock reacted with phosphoric acid to produce triple superphosphate