Catalyst it is a substance that reduces the activation energy of a chemical reaction and increases its reaction speed, without, however, participating in it.
The word catalyst comes from the Greek, katalysis, which means "decomposition", "dissolution". The word catalysis was adopted by the Swedish chemist, Jöns Jacob Berzelius (1779–1848) and appeared in the Portuguese language in the 19th century. The word catalyst appeared in the 20th century.
The catalyst has the ability to accelerate the chemical reactionwithout altering the chemical composition of its reagents and products. The use of catalysts in reactions does not change the amount of substance produced in it.
In reversible reaction, the reverse reaction is also accelerated by the catalyst, as its activation energy will also be lower.
In the human organism there are several catalysts, called enzymes. Pepsin, produced and secreted in the stomach, and ptyalin, secreted by the salivary glands, are examples of catalysts that increase the speed of the digestion reaction.
Catalysts are widely used in the chemical industry, especially in petrochemicals, to speed up reactions and make the process cheaper.
Each chemical reaction requires a different type of catalyst, the most common being:
- Metals: Co, Ni, Pt, Pd;
- Acids: H2SO4;
- Metal oxides: Al2O3, Fe2O3;
- Bases: NaOH;
- Enzymes (produced by living organisms): Ptialin (mouth), pepsin (stomach) and trypsin (pancreas).