Here's why:

* High Activity: TiO2 is a highly active catalyst, leading to efficient polyester production.

* Selective Catalysis: It promotes the specific esterification reaction without causing side reactions that could degrade the product.

* Versatility: TiO2 can be used in various polyester production processes, including both batch and continuous methods.

* Cost-effectiveness: It's relatively inexpensive compared to other potential catalysts.

While TiO2 is the most common, other catalysts can be used depending on the specific polyester being produced and the desired properties. These include:

* Other metal oxides: Such as zinc oxide (ZnO) or antimony trioxide (Sb2O3)

* Organic catalysts: Like tin(II) 2-ethylhexanoate or dibutyltin dilaurate.

* Solid acid catalysts: For example, sulfonic acid functionalized silica or zeolites.

The choice of catalyst depends on factors like the type of monomers being used, the desired molecular weight of the polyester, and the reaction conditions.