POLYESTER, particularly polyethylene terephthalate, is a polymer material widely used everyday in things like textiles and packaging. The market for it continues to grow, estimated at present to grow 5 to 10% annually and likely to exceed 40 million tons per year in 2007. Naturally, this breeds strong interest in improving productivity and reducing costs. One way to meet these demands is to improve the polymerization catalyst used in the production of polyester polymer. Which catalyst is used not only affects productivity but also product quality in terms of appearance, physical properties and so forth.