Abstract: The present invention relates to a catalyst composition for producing polyethylene terephthalate from terephthalic acid and ethylene glycol, comprising: (i) an antimony compound, being present such that the elemental antimony is in a range of about 15 ppm to less than 150 ppm; (ii) a zinc compound, being present such that the elemental zinc is in a range of about 40 to about 160 ppm; as well as a process for the preparation thereof.

Abstract: The present invention relates to a process for the production of polyethylene terephthalate copolyester from terephthalic acid, isophthalic acid and ethylene glycol, comprising the steps of: a) preparing a catalyst composition comprising a zinc compound being present such that the elemental zinc content is in a range of about 50 to about 500 ppm, preferably about 200 to about 500 ppm, most preferably about 180 to about 260 ppm, based on the copolyester, b) placing the catalyst composition, terephthalic acid, isophthalic acid and ethylene glycol in a vessel, and c) reacting the terephthalic acid, isophthalic acid and ethylene glycol in an esterification step and a polycondensation step to obtain polyethylene terephthalate copolyester; to the copolyester obtained thereby and its use, as well as to a catalyst composition suitable in the inventive process.

Abstract: The present invention relates to a catalyst composition for producing polyethylene terephthalate from terephthalic acid and ethylene glycol, comprising: (i) an antimony compound, being present such that the elemental antimony is in a range of about 15 ppm to less than 150 ppm; (ii) a zinc compound, being present such that the elemental zinc is in a range of about 40 to about 160 ppm; as well as a process for the preparation thereof.