Catalyst Systems in PET Synthesis
topic
Antimony trioxide (Sb₂O₃) is the dominant polycondensation catalyst (200–300 ppm Sb). Alternatives: titanium alkoxides (TiO₂ precursors, faster but yellowing), germanium dioxide (high purity, used in Japan/Korea), aluminium/titanium co-catalyst systems. Phosphorus stabilisers (H₃PO₄, triphenyl phosphate) suppress thermal degradation and acetaldehyde generation.
Role
Catalyst selection critically affects reaction rate, colour, thermal stability, antimony residue (regulatory concern for food contact and environmental impact), and fibre optical properties.