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Contact process

KING OF CHEMICAL. Contact process. What is it. It is the method to produce high concentration of sulfuric acid for industrial needs. Who invented this.

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Contact process

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  1. KING OF CHEMICAL Contact process

  2. What is it • It is the method to produce high concentration of sulfuric acid for industrial needs

  3. Who invented this • This process was created in 1831 by British vinegar merchant Peregrine Phillips.In addition to being a far more economical process for producing concentrated sulfuric acid than the previous lead chamber process, the contact process also produces sulfur trioxide and oleum.

  4. How is it done • It is separated into 5 steps • Combining of sulfur and oxygen • Purifying sulfur dioxide • adding excess oxygen to sulfur dioxide in presence of vanadium pentoxide (catalyst) with 400˚C and 1~2atm • Sulfur trioxide is formed adding sulfuric acid, which gives disulfuric acid • Then its added to water to form high concentrated sulfuric acid To conserve energy, the mixture is heated by exhaust gases from the catalytic converter by heat exchangers.

  5. Equation • Oxidation of SO2 into SO3 by V5+: 2 SO2 + 4V5+ + 2 O2- → 2 SO3 + 4V4+ • Oxidation of V4+ back into V5+ by oxygen (catalyst regeneration): 4 V4+ + O2 → 4 V5+ + 2 O2- • Hot sulfur trioxide passes through the heat exchanger and is dissolved in concentrated H2SO4 in the absorption tower to form oleum: H2SO4(l) + SO3(g) → H2S2O7(l) • Oleum is reacted with water to form concentrated H2SO4: H2S2O7(l) + H2O(l) → 2 H2SO4(l) • The average percentage yield of this reaction is around 30%.

  6. How was it dangerous • Before, people use platinum ad the catalyst, but it is poisonous. So they changed it to vanadium pentoxide • Purification of air and SO2 is necessary to avoid catalyst poisoning (i.e. removing catalytic activities). The gas is then washed with water and dried by sulfuric acid.

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