Study On Aluminum Catalyst For Polyester

The antimony,germanium and titanium compound are three conventional polyester catalysts used in the Polyethylene-terephthalate(PET) industry.With the research going deeply,we find that the three catalysts can not satisfy the demand of production and application anymore.Now the exploitation and making use of novel aluminum catalyst has been received much concern.In this paper,the situation of antimony leaching from the PET bottles was analyzed. According to the migrating theory,the mathematics model had been built and the influence factors of antimony leaching had also been discussed.In order to choose polymerization catalyst,the aluminum coordination properties were analyzed and four aluminum compounds were chosen to use in the reaction.By means of Ubbelohde Viscometer,Differential Scanning Calorimetry and Thermo Gravimetric Analyzer,the PET sample’s intrinsic viscosity,crystallinity and stability etc were tested.In conclusion:1.The antimony average concentration in the dying solvent was up to 0.738ppm, which was 15 times bigger than the limited value 0.005ppm regulations in the《Water Environment Quality Standard》(GB3838-2002).And in the PET-bottled drinking water (carbon acid and alkaline water),the antimony concentration of them were both exceeding the limited value 0.005ppm regulations in the national life drinking water.2.The process of antimony leaching from the PET followed the Fick Diffusion Second Law.According to the model’s boundary and initial conditions,the diffusion coefficient of different temperature and three-dimensional diagram which showed the relation of concentration-time-displacement can be obtained.It turned out that the result of test was close to the theory value of antimony leaching,but a little smaller than that of theory model.Based on the testing and calculated result,the influence factors of temperature,pH and processing techniques were also discussed in this paper.3.Through the method of coordinating strong Lewis alkaline,the Al—N bond, LUMO,orbital populations,bending energy and chemical hardness were calculated. Catalytic activity of Lewis acid was compared and the result was:8-Hydroxyquinolate aluminum＜Aluminate＜Aluminum phosphate＜Aluminum acetylacetonate.4.With the same quantity of catalyst added,the viscosity of PET(catalyzed by Aluminum phosphate) and PET(catalyzed by Aluminum acetylacetonate) were bigger than the PET(catalyzed by Antimony trioxide) and smaller than the PET(catalyzed by tetrabutylorthotitanate).The testing results showed that there was no big difference between the aluminum catalyst and the conventional catalysts.The hue of PET(catalyzed by Aluminum phosphate) and PET(Aluminum acetylacetonate) was good.However,PET samples catalyzed by other aluminum compound got bad result because of the catalyst’s color and instability.5.The thermal stability,the hydrolysis resistance and thermal oxidation stability of PET(catalyzed by Aluminum phosphate or by Aluminum acetylacetonate) were as good as the one catalyzed by Antimony trioxide.Among the samples,the PET(catalyzed by Aluminum phosphate) showed the best result.The Degradation Kinetics study also proved that the PET(catalyzed by Aluminum phosphate) and PET(catalyzed by Aluminum acetylacetonate) owned good stabilities.