A catalyst in different to the reactants in a reaction is called heterogeneous catalysis. A heterogeneous catalyst is generally a solide and reactants are usually gases `(` or sometimes liquids `)`. Some important industrial reactions which are hetergeneous catalytic reactions are given below `:`
`a.` Synthesis of ammonia from nitrogen and hydrogen in the presence of iron as catalyst is a heterogeneous catalytic reaction.
`N_(2)(g)+2H_(2)(g)underset(Mo(s))overset(Fe(s))rarr2NH_(3)`
`b.` Manufacture of sulphur trioxide `(SO_(3))` by the oxidation of sulphur dioxide `(SO_(2))` in the presence of vanadium pentoxide `(V_(2)O_(5))` catalystis a heterogeneous catalytic reaction.
`SO_(2)(g)+(1)/(2)O_(2)(g)overset(V_(2)O_(5)(s))rarr underset((Contact Process))(SO_(3)(g))`
`c.` Dehydration of ethanol by alumina `(Al_(2)O_(3))` is a heterogeneous catalytic reaction.
`C_(2)H_(5)OH overset(Al_(2)O_(3)(s))rarr C_(2)H_(4)(g)+H_(2)O(l)`
`d.` Reduction of nitrobenzene in the presence of nickel catalyst.
`underset(Nitrobenzen e)(C_(6)H_(5)NO_(2)(l))+6(H)overset(Ni(s))rarrunderset(Anili n e)(C_(6)H_(5)NH_(2)(l))+2H_(2)O(l)`
