catalyst

cat·a·lyst

noun \ˈka-tə-ləst\

Definition of CATALYST

1

: a substance that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible

2

: an agent that provokes or speeds significant change or action

Examples of CATALYST

1. The bombing attack was the catalyst for war.
2. She was proud to be a catalyst for reform in the government.

First Known Use of CATALYST

1902

Other Chemical Engineering Terms

alkali, cation, decant, hygroscopic, isotope, oxidize, slurry, solute, viscous

cat·a·lyst

noun \ˈkat-^əl-əst\   (Medical Dictionary)

Medical Definition of CATALYST

: a substance (as an enzyme) that enables a chemical reaction to proceed under different conditions (as at a lower temperature) than otherwise possible

catalyst

noun    (Concise Encyclopedia)

Any substance of which a small proportion notably affects the reaction rate of a chemical reaction without itself being changed or consumed (see catalysis). One molecule may transform several million reactant molecules a minute. Catalysts may be gaseous, liquid, or solid; they may be inorganic compounds, organic compounds, or complex combinations. They tend to be highly specific, reacting with only one substance or a small set of substances. Substances that reduce the effectiveness of catalysts by altering them or blocking reactants' access to them are called catalyst inhibitors or catalyst poisons. Catalysts are essential to virtually all industrial chemical reactions, especially in petroleum refining and synthetic organic chemical manufacturing. Most solid catalysts are transition elements (metals) or their oxides in finely divided or porous form. In a car's catalytic converter, the platinum catalyst converts unburned hydrocarbons and nitrogen compounds to products less harmful to the environment. Water, especially saltwater, catalyzes oxidation (see oxidation-reduction) and corrosion. Enzymes are among the most active and selective catalysts known.