Question

Give four examples of heterogeneous catalysis.

Answer 1

In this question, heterogeneous catalysts are those catalysts in which the catalyst is present in a different phase than that of the phase of the reactants. That is if reactants are gaseous in nature then the catalyst will be in solid or liquid phase.

Complete step by step answer: By catalyst we mean a substance that can be added to a reaction to increase the reaction rate without getting consumed in the reaction. There are mainly two types of catalysts. These are heterogeneous catalysts and homogeneous catalysts.
In homogeneous catalysis, the catalyst is present in the same phase as that of the reactant phase and in heterogeneous catalysts, the phase of the catalyst is different as that of the phase of the reactants.
The examples of heterogeneous catalysis are given as:
1.) Oxidation of ammonia and oxygen using platinum as a catalyst. Here, platinum is solid and reactants have gaseous phase thus it is called as heterogeneous catalysis. This reaction is called the Ostwald process. This reaction can be given as:
$4N{H_3}(g) + 5{O_2}(g)\xrightarrow{{Pt(s)}}4NO + 6{H_2}O$
2.) Manufacture of ammonia from nitrogen and hydrogen using iron as a catalyst. Here, iron is in solid phase and reactants are in gaseous phase. This process is called as Haber’s process and its reaction can be given as:
${N_2}(g) + 3{H_2}(g)\xrightarrow{{Fe(s)}}2N{H_3}$
3.) Dehydrogenation of ethanol in which nickel is used as a catalyst. This reaction can be given as:
${C_2}{H_5}OH\xrightarrow{{Ni}}C{H_3}CHO + {H_2}$
4.) Oxidation of carbon monoxide using platinum as a catalyst. This reaction can be given as:
$2CO(g) + {O_2}(g)\xrightarrow{{Pt(s)}}2C{O_2}$

Note: Always remember that in heterogeneous catalysis the phase of the product does not matter whether it is different or equal to phase of catalyst but only the phase of reactants matters here.