Preparation and application of high stability titanium polyester catalyst TiOC@SiO2
Titanium-based polyester catalysts are ideal substitutes for traditional antimony-based catalysts due to their high catalytic activity and environmental friendliness.In order to prepare titanium polyester catalyst with hydrolysis resistance,good dispersibility and stable catalytic performance,TiOC@SiO2 catalyst was prepared by reverse microemulsion method.A layer of siloxane was coated on the surface of titanium containing organic compound to stabilize the catalytic activity.The morphology,structure and properties of TiOC@SiO2 were characterized by various modern characterization methods,and its catalytic performance in the synthesis of polyethylene terephthalate(PET)was evaluated.The results showed that the TiOC@SiO2 catalyst had a core-shell spherical structure with a particle size of about 200nm,but no Ti—O—Si bond,and a Ti content of 6.95%.The structure and catalytic activity of TiOC@SiO2 catalyst remained unchanged at 90℃for 2h.The composite structure significantly improved the hydrolysis resistance of the titanium organic compounds and dispersibility.In the polyethylene terephthalate synthesis experiment,with only 5μg/g TiOC@SiO2 added and polycondensation at 270℃for 92min,polyester with intrinsic viscosity of 0.677dL/g,terminal carboxyl content of 14.4mol/t and b value of 2.16 was prepared.
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