Contact process KING OF CHEMICAL

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

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.

How is it done It is separated into 5 steps 1.Combining of sulfur and oxygen 2.Purifying sulfur dioxide 3.adding excess oxygen to sulfur dioxide in presence of vanadium pentoxide (catalyst) with 400˚C and 1~2atm 4.Sulfur trioxide is formed adding sulfuric acid, which gives disulfuric acid 5.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.

Equation Oxidation of SO2 into SO3 by V5+: 2 SO2 + 4V O2- → 2 SO3 + 4V4+ Oxidation of V4+ back into V5+ by oxygen (catalyst regeneration): 4 V4+ + O2 → 4 V 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%.

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.