What is Catalyst?

Introduction:

In Chemistry, catalysts are defined as those substances which alter the rate is reaction by changing the path of reaction. Most of the time a catalyst is used to speed up or increase the rate of the reaction. However, if we go to a deeper level, catalysts are used to break or rebuild the chemical bonds between the atoms which are present in the molecules of different elements or compounds. In essence, catalysts encourage molecules to react and make the whole reaction process easier and efficient. Some of the important characteristic features of catalysts are,
  • A catalyst does not initiate a chemical reaction.
  • A catalyst does not be consumed in the reaction.
  • Catalysts tend to react with reactants to form intermediates and at the same time facilitate the production of the final reaction product. After the whole process, a catalyst can regenerate.

Brief History

If we look at the general meaning of catalyst it is anything that increases the rate of a process. Catalyst is a term derived from Greek καταλύειν, meaning “to annul,” or “to unite,” or “to pick up.” Meanwhile, the concept of catalysis was first researched by chemist Elizabeth Fulhame and it was described in her book in the year 1794. This book content was based on her work in oxidation-reduction experiments.

The first chemical reaction in organic chemistry that utilized a catalyst was studied in 1811 by Gottlieb Kirchhoff who was a Russian chemist of German origin. The term catalysis was later used by a Swedish chemist named Jöns Jakob Berzelius in 1835 to describe reactions that were sped up by certain substances. The substances further remained unchanged after the reaction.

Types of Catalysts With Examples

There are several types of catalysts that can be used depending on the need or requirement of the chemical reaction. They are as follows;

Positive Catalysts

Catalysts that increase the rate of a chemical reaction are positive catalysts. It increases the rate of reaction by lowering the activation energy barriers such that a large number of reaction molecules are converted into products, thereby the percentage of yield of products increases .Positive catalyst example: In the preparation of NH3 by

Iron oxide acts as a positive catalyst and increases the yield of ammonia in spite of less reaction of Nitrogen.

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