Question

Give four examples of heterogeneous catalysis.

Give one example of heterogeneous catalysis.

Give four examples of heterogeneous catalytic reactions.

Illustrate with examples.

Heterogeneous catalysis

Write two examples of heterogeneous catalysis

Answer 1

(i) Oxidation of sulphur dioxide to sulphur trioxide using platinized asbestos or V₂O₅ as a catalyst:

\[\ce{2SO2_{(g)} + O2_{(g)} ->[Pt_{(s)} or V2O5_{(s)}] 2SO3_{(g)}}\]

This reaction forms the basis of the manufacture of sulphuric acid by the contact process.

(ii) Manufacture of ammonia from N₂ and H₂ by Haber’s process using iron as a catalyst:

\[\ce{N2_{(g)} + 3H2_{(g)} ->[Fe_{(s)}] 2NH3_{(g)}}\]

(iii) Synthesis of methyl alcohol from carbon monoxide and hydrogen using a mixture of ZnO and CuO as a catalyst:

\[\ce{CO_{(g)} + 2H2_{(g)} ->[ZnO_{(s)} + CuO_{(s)}] CH3OH}\]

(iv) Polymerisation of ethylene using TiCl₄ and trialkyl aluminium as catalyst:

\[\ce{nCH2 = CH2 ->[TiCl4 + Trialkyl aluminium] \underset{Polyethylene}{-(CH2 - CH2 -)_n}}\]

The reaction forms the basis of the manufacture of polyethylene by the Ziegler method.