The Haber Process and The Contact Process

• • the industrial production of ammonia from hydrogen and nitrogen
  • nitrogen is easily acquired from the air, as it makes up 78% of the air
  • hydrogen is obtained from hydrocarbons from methane
  • the reaction is exothermic meaning it produces heat
  • the reaction is reversible leading to the formation and breakdown of ammonia
• conditions of the haber process

  • temperature: 450 degrees celsius; lower temp favors a higher percentage yield, but a higher temperature is needed for a higher rate of reaction
  • pressure: 200 atm; high pressure is necessary for a high percentage yield and a high rate of reaction. Safety and cost considerations limit the pressure to 200 atm
  • catalyst: iron; the catalyst increases the rate of both the forward and backward reactions by the same amount (by providing an alternative pathway requiring lower activation energy
• Haber process

  1. H2 and N2 obtained from natural gas and air

  2. Gases compressed to 200 atm in compressor

  3. Pressurized gases pumped into tank with catalytic iron beds at 450°C

  4. Hydrogen and nitrogen react to form ammonia

  5. Unreacted H2 and N2, and ammonia product pass to cooling tank

  6. Ammonia liquefied and removed to storage

  7. Unreacted H2 and N2 recycled back into the system
• N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

  Balanced chemical equation for the reaction
• Sulfuric acid is synthesized by the Contact process; it is used in car batteries, making fertilizers, soaps and detergents
• Process of the Contact process

  1. the production of sulfur dioxide either by burning the sulfur to oxidise the sulfur = S + O2 ---> SO2, or roasting sulfide ores.
  2. the main stage in the contact process is the oxidation of sulfur dioxide to sulfur trioxide using a vanadium (V) oxide, V2O5 catalyst

  • 2SO2(g) + O2(g) ⇌ 2SO3(g)
• Main stage of production

  1. Obtain oxygen from air

  2. Temperature of 450°C

  3. Pressure of 2 atm (200 kPa)
• Forward reaction is exothermic

  Increasing temperature shifts the position of equilibrium to the left in the direction of the reactants, therefore the higher the temperature, the lower the yield of sulfur trioxide
• Increasing pressure


  Shifts the position of equilibrium to the right in the direction of a small number of gaseous molecules