AB Kombine Nomenklatürü · KN kodu · 
Amerika Birleşik Devletleri
Suudi Arabistan
Birleşik Krallık
İsviçre
Japonya
Çin
Hindistan
Norveç
Türkiye
Kanada
Meksika
Brezilya
Arjantin
Peru
Yeni Zelanda
Tayvan
KİK
Kuzey Makedonya
Nijerya3815 90 10 and 3815 90 90 · Other
These subheadings cover mixtures based on compounds, the nature and proportions of which vary according to the chemical reaction to be catalysed. They are frequently used in the manufacture of plastics, often under the name of initiators, transfer agents, terminators or telomers, and reticulating (or cross-linking) agents.
They include the following:
1. ‘radical’ catalysts
These are preparations, based on organic substances, which decompose slowly under reaction conditions and produce fragments that, by colliding with the initial monomers, favour the establishment of a bond and the formation of new free radicals capable of repeating the process and propagating the chain.
Amongst these are:
(a) preparations based on organic peroxides of the type R–O–O–R′ (organic solutions of peroxides such as acetyl and dibenzoyl peroxides). During the reaction, RO· and R′O· radicals are formed and act as activators;
(b) preparations, based on azo-compounds (such as azobisisobutyronitrile), which decompose in the course of the reactions, releasing nitrogen and forming free radicals;
(c) redox preparations (for example, a mixture of potassium peroxide and dodecylmercaptan), in which the formation of activating radicals is due to a redox reaction;
2. ionic catalysts
These are generally organic solutions of compounds which generate ions capable of attaching themselves to the double bond and reproducing active sites in the resulting product.
They include:
(a) ziegler-type catalysts for the production of polyolefins (for example, a mixture of titanium and triethylaluminium);
(b) ziegler-natta-type catalysts (stereocatalysts, orientating catalysts), such as a mixture of titanium trichloride and trialkylaluminium, for the preparation of isotactic polypropylene and ethylene-olefin block copolymers;
(c) catalysts for the preparation of polyurethanes (for example, a mixture of triethylenediamine and tin compounds);
(d) catalysts for the preparation of amino-plastics (for example, phosphoric acid in an organic solvent);
3. catalysts for polycondensation reactions
These are preparations based on various compounds (for example, a mixture of calcium acetate, antimony trioxide, titanium alcoholates, etc.).