What type of catalysis is shown by following reactions?
\(2C_6H_5CHO + O_2 \longrightarrow 2C_6H_5COOH\) in presence of Diphenyl amine

Negative Catalysis

The answer is 3. negative catalysis.

In negative catalysis, a substance called a negative catalyst slows down a reaction. In the case of the reaction of benzaldehyde with oxygen in the presence of diphenylamine, diphenylamine is the negative catalyst. Diphenylamine reacts with the oxygen to form a compound that is less reactive than oxygen. This slows down the reaction of benzaldehyde with oxygen.

Autocatalysis, induced catalysis, and positive catalysis are all types of catalysis that speed up a reaction.