Multicomponent Reactions catalyzed by Heterogeneous Catalysts Dr. Sandip R. Kale The term 'catalysis' originally coined by Berzelius in 1835 and since then the concept of catalysis has evolved greatly. Catalysis can be defined as 'the change of the rate of chemical reactions under the action of certain substances'. A catalyst is the substance that speeds up the rate of a reaction, by lowering the activation energy, without being consumed in the reaction. They preserve their composition throughout the chemical reaction and are not wasted in the course of the catalysis. Furthermore, catalysts can speed up the reaction in a more selective manner which allows chemical processes to work more efficiently and with less waste. This makes catalysts of great importance in industrial applications.