Question

why are the catalysts used in industrial manufacture of ammonia, sulfur dioxide etc. kept in a finely divided state?​

Answer 1

Catalysts speed up a chemical reaction by lowering the amount of energy you need to get one going. Catalysis is the backbone of many industrial processes, which use chemical reactions to turn raw materials into useful products. Catalysts are integral in making plastics and many other manufactured items.

Answer 2

In a case of manufacturing of ammonia--- The reaction refers to carbon monoxide (CO) that reacts with water (H2O) to form carbon dioxide (CO2) and hydrogen (H2). ... The main purpose of the LTS catalyst is to reduce CO content in the reformate which is especially important in the ammonia production for high yield of H2.

In a case of manufacturing of sulphur dioxide--- Purification of the air and sulfur dioxide (SO2) is necessary to avoid catalyst poisoning (i.e. removing catalytic activities). The gas is then washed with water and dried with sulfuric acid. ... The catalyst only serves to increase the rate of reaction as it does not change the position of the thermodynamic equilibrium.