Polyurethane catalysts are used to accelerate the curing process of polyurethane resins and foams. They are generally divided into two categories: organic catalysts and inorganic catalysts.

Organic catalysts are the most common type of polyurethane catalyst. These are usually amines or organometallic compounds. Amines are basic catalysts whereas organometallic compounds can be acidic or basic. Organic catalysts can effectively promote the reaction between isocyanate and hydroxyl groups. They are also relatively cheap and easy to use.

Inorganic catalysts are less common than organic catalysts, but they offer some advantages. They are generally more stable and less reactive than organic catalysts. They are also less likely to cause yellowing or other discoloration in the final product. Inorganic catalysts are often used in applications where color stability is important.

The type of catalyst used depends on the specific application. For example, amine catalysts are commonly used in the production of polyurethane foams, while organometallic catalysts are commonly used in the production of polyurethane elastomers.

Here are some of the most common types of polyurethane catalysts:

Amine catalysts: Amines are basic catalysts that can effectively promote the reaction between isocyanate and hydroxyl groups. They are commonly used in the production of polyurethane foam.
Organometallic Catalysts: Organometallic catalysts can be either acidic or basic. They are generally more stable and less reactive than organic catalysts. They are also less likely to cause yellowing or other discoloration in the final product. Organometallic catalysts are often used in applications where color stability is important.
Tin catalyst: Tin catalyst is an organometallic catalyst commonly used in the production of polyurethane foam. They effectively promote the reaction between isocyanates and water.
Bismuth catalyst: Bismuth catalyst is an organometallic catalyst commonly used in the production of polyurethane elastomers. They are effective in promoting the reaction between isocyanates and hydroxyl groups.
Zinc Catalyst: Zinc Catalyst is an inorganic catalyst, which is often used in the production of polyurethane coatings. They are effective in promoting the reaction between isocyanates and hydroxyl groups.
The choice of catalyst will depend on the specific application. For example, amine catalysts are commonly used in the production of polyurethane foams, while organometallic catalysts are commonly used in the production of polyurethane elastomers.