A CATALYST is indispensable to the production of polyester polymer. More than 90% of all polyester worldwide is currently produced using an antimony catalyst. Other than antimony, titanium and germanium catalysts are used in some specific fields. Each exhibits its own catalytic activity and has both advantages and disadvantages. Although much research has aimed at modifying these catalysts, a solution that thoroughly satisfies market needs has yet to be found. Antimony catalysts lead to the problematic formation of insoluble particles and the gray discoloration in polyester, encouraging businesses to try non-antimony catalysts, a trend of recent. Titanium catalysts, however, cannot meet quality demands such as appearance and thermal stability, and germanium catalysts are expensive to use. Therefore, a new generation of catalyst that solves these problems and allows us to produce polyester of demanded quality and productivity is much wanted.