Question

Which of the following is not an example of heterogeneous catalysis?

• A. Oxidation of sulphur dioxide to sulphur trioxide in the presence of Pt
• B. Combination of dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron in Haber’s process
• C. Hydrogenation of vegetable oils in the presence of finely divided nickel as catalyst
• D. Oxidation of sulphur dioxide to sulphur trioxide with dioxygen in the presence of oxides of nitrogen as catalysts in the lead chamber process

Answer 1

The correct option is D Oxidation of sulphur dioxide to sulphur trioxide with dioxygen in the presence of oxides of nitrogen as catalysts in the lead chamber process

Heterogeneous catalysis refers to the reactants and catalysts being in different phases.
a) Here, the reactants are in the gaseous phase and Pt(catalyst) remains as a solid.
b) In Haber's process, reactants are in the gaseous phase and the catalyst (Fe) is in the solid phase.
c) In the hydrogenation of vegetable oils, hydrogen gas gets adsorbed on the surface of solid nickel which acts as a catalyst. Hence, this is heterogeneous catalysis.
d) The oxidation of sulphur dioxide to sulphur trioxide with oxygen in presence of oxides of nitrogen is an example of homogeneous catalysis because both reactants (sulphur dioxide and oxygen) and catalyst - oxides of nitrogen are in the gaseous phase.
The correct option will be (d)