Catalyst poison

Under catalyst poison , wherein heterogeneous catalysts also contact poison , is meant a substance , the effect of a catalyst permanently reduces or reverses. This slows down a chemical reaction that is usually desired .

Heterogeneous catalysts

Lead is known to the general public as a destroyer of vehicle catalytic converters , which is why leaded motor gasoline - petrol mixed with tetraethyl lead as an anti-knock agent - is no longer available at filling stations. Chemical catalysts can be impaired or destroyed by a number of substances, including heavy metals , halogens , polymers , sulfur and carbon monoxide . Catalyst poisons are removed from the catalystinstead of the substance whose reaction it is supposed to accelerate, bound. As a result, they block the adsorption capacity of the large surface area of ​​the catalyst particles.

Selective catalyst poisoning

Poisoning a catalyst can be desirable in order to reduce the activity of a catalyst in a targeted manner for a specific reaction. Oxidation catalysts are specifically poisoned in order to control the oxidation of primary alcohols to aldehydes and not to oxidize them to carboxylic acids . Targeted poisoning of reduction catalysts with sulfur compounds can, for example, cause alkynes to be hydrogenated to alkenes, but not further to alkanes.

literature

• Charles E. Mortimer, Ulrich Müller: Chemistry - The basic knowledge of chemistry, 8th completely revised and expanded edition, Georg Thieme Verlag, Stuttgart 2003, ISBN 3-13-484308-0

Web links

• Chemistry for engineers , by Guido Kickelbick