Give information about catalysis and explain about promoters.

(N/A) Catalysis is the phenomenon where the rate of a chemical reaction is altered by the presence of a foreign substance that remains chemically and quantitatively unchanged after the reaction. Such substances are called catalysts.
For example,the decomposition of potassium chlorate $(2 KClO_{3} \rightarrow 2 KCl + 3 O_{2})$ occurs slowly at $653-873 \ K$,but in the presence of manganese dioxide $(MnO_{2})$,it occurs at a lower temperature range of $473-633 \ K$ with an accelerated rate.
Promoters are substances that enhance the activity of a catalyst,while poisons decrease the activity of a catalyst.
For example,in Haber's process for the manufacture of ammonia,molybdenum $(Mo)$ acts as a promoter for iron $(Fe)$,which is used as a catalyst:
$N_{2(g)} + 3 H_{2(g)} \xrightarrow{Fe(s), Mo(s)} 2 NH_{3(g)}$