Synthesis of a heterogeneous catalyst for the acid hydrolysis of PET

Namen diplomskega dela je bil predstaviti delovanje heterogenega katalizatorja za kislinsko katalizirano hidrolizo polietilen tereftalata (PET) s trdnim nosilcem iz aluminijevega (III) oksida in titanovega (IV) oksida. PET je polimerni sintetični material z dobrimi lastnostmi za ogromno različnih vrst uporabe, najbolj se uporablja v proizvodnji plastenk. Zanimanje za alternativne načine recikliranja PET-a je v zadnjih desetih letih naraslo. V sklopu eksperimentalnega dela smo sintetizirali heterogen katalizator na trdnem nosilcu, ki smo ga mokro impregnirali z raztopino nikljevega (II) nitrata heksahidrata, da bi zagotovili kislinska aktivna mesta na površini trdnega nosilca. Nato smo izvajali reakcije razgradnje PET-a v vodi pri konstantni temperaturi in času. Raziskovali smo vpliv različnih koncentracij raztopine za mokro impregniranje na presnovo PET. Za primerjavo smo izvedli reakcijo brez katalizatorja. Produkte, pridobljene pri reakcijah, smo analizirali s tekočinsko kromatografijo visoke ločljivosti. Katalizator smo nato še okarakterizirali z različnimi metodami (infrardeča spektroskopija s Fourierjevo transformacijo, vrstična elektronska mikroskopija, N2 adsorpcija in določanje velikosti por, termogravimetrična analiza, kemisorpcija – temperaturno programirana desorpcija). Končna ugotovitev študije je, da se polietilen tereftalat nasploh dobro presnavlja v vodi pri preiskovanih pogojih, vendar je reakcija s katalizatorjem bolj učinkovita. Sprememba koncentracije raztopine nikljevega (II) nitrata heksahidrata ni imela vpliva na količino kislinskih mest in na presnovo PET-a.The aim of this work is to demonstrate the performance of a heterogeneous catalyst for the acid-catalysed hydrolysis of polyethylene terephthalate with a solid support of aluminium (III) and titanium (IV) oxide. Polyethylene terephthalate is a polymeric synthetic material with good properties for a variety of applications, especially for the production of plastic bottles. Interest in alternative ways to recycle polyethylene terephthalate has increased over the past decade. In the experimental work, a heterogeneous catalyst was synthesised on a solid support which was impregnated with a solution of nickel (II) nitrate hexahydrate to create acid active sites on the surface of the solid support. PET degradation reactions were then carried out in water at constant temperature and time. The effect of different concentrations of the wet impregnation solution on the degradation of PET was investigated. For comparison, a reaction without catalyst was performed. The products obtained from the reactions were analysed by high-performance liquid chromatography. The catalyst was then characterised by various methods (Fourier transform infrared spectroscopy, scanning electron microscopy, N2 adsorption and pore size determination, thermogravimetric analysis, chemisorption - temperature programmed desorption). The final conclusion of the study is that polyethylene terephthalate is generally well metabolised in water under the conditions tested, but that the reaction with the catalyst is more efficient. Changing the concentration of nickel (II) nitrate hexahydrate solution had no effect on the amount of acid sites and on the degradation of PET