Catalysts

A catalyst is a substance that increases the rate of a chemical reaction without undergoing a permanent chemical change itself.
Catalysts work by providing an alternative reaction pathway that has a lower activation energy. This makes it easier for reactants to reach the transition state, so the reaction takes place faster.
A catalyst can be a solid, liquid or gas, and can be a single substance or a mixture.
Their efficiency is gauged by how much they can increase the rate of a reaction relative to its mass or volume.

Types of Catalysts

Catalysts can be heterogeneous or homogeneous. Heterogeneous catalysts are in a different phase (solid, liquid, gas) to the reactants, whereas homogeneous catalysts are in the same phase.
Transition metals and their compounds are often used as catalysts due to their ability to donate and receive electrons.

Catalysts play a crucial role in a wide variety of industrial processes, including the Haber process for the synthesis of ammonia, and the Contact process for the production of sulfuric acid.
They help in making these processes more efficient, reducing the energy required and minimizing the formation of waste products.

Catalysts contribute to the principles of green chemistry by reducing the amount of energy required for reactions, minimizing waste and enabling the use of more sustainable reactants.
Biocatalysts, including enzymes and whole cells, are becoming increasingly important in industrial processes as they often work under mild conditions, are highly specific and produce less waste.