Question

Identify the two important classes of catalysts and describe the difference between each.

Answer 1

Two Important class of catalysts:

Many classes of catalysts are there. The two important classes of catalysts are 1) Homogeneous catalyst 2) Heterogeneous catalyst

Homogeneous catalyst	Heterogeneous catalyst
If the catalyst and reactant in same phase (solid-solid, liquid-liquid,gas-gas) called as Homogeneous catalyst Ex; Wilkinson catalyst, (reduction of the alkene double bone)	If the reactant and catalyst in a different phase (solid-liquid, liquid-gas) called a Heterogeneous catalyst. Ex; Pd-C/H2 (reduction of the alkene double bone)

Homogeneous catalyst:

In Homogeneous catalysis, both reactant and catalyst are in same phase.

Advantages:

Homogeneous catalysis has high catalytic activity. It will easily interact with the reactant substrate.

It has both regio & chemoselectivity in the molecules and gives regio & chemoselectivity product.

It has a high turn over number.

Homogeneous catalysis can easily modify, we can easily tune the ligand and metals.

Enantioselective reaction are achieved by this catalyst.

Disadvantages:

Difficult to isolate and reuse the expensive metal catalyst from the product material.

Contamination of metal in the product may be there in a lower concentration level ( ppm or ppb)

In the drug and pharmaceutical industry, It is essential to remove the catalyst(to avoid metal contamination)

Heterogeneous catalyst:

In Heterogeneous catalysis, both reactant and catalyst in a different base.

Advantages:

A heterogeneous catalyst ae very easy to handle.

We can easily separate the heterogeneous catalyst from the product. (because of both reactant and product).

Disadvantages:

It has poor regio, chemoselectivity & it has a low turn over number.

The activity of the catalyst is usually reduced because active sites in heterogeneous catalysts are not as accessible in homogeneous catalysts.