| Polymers have been widely used among the modern life of human beings owing to its excellent performances. However, because of the non-biodegradable property of the polymers, a huge amount of the waste polymers were brought with the extensive use of them, resulting in serious harm to the survival environment of humans. Therefore, how to deal with the ever-increasing waste polymers, especially waste plastics, has become one of the important factors which affects the sustainable development of our country and even the whole world. At the same time, the carbon is the main element of these waste polymers. In this light, it is necessary to investigate the carbonization of polymers to prepare high value-added carbon materials using polymers as carbon feedstock. This is a promising and novel strategy, which can be further developed into a new sustainable method for upcycling the waste polymer to prepare useful carbon production. And in virtue of its unique structure, carbon nanomaterials exhibits wonderful electrical, optical, and mechanical properties as well as the quantum size effect, which are widely applied in the fields of new energy, environment, biology, medicine, information, and national defense and military. In this thesis, we studied the template catalytic carbonation reaction of waste polyethylene terephthalate(PET) beverage bottles and polystyrene(PS) on organically modified montmorillonite(OMMT) and magnesium oxide(MgO), respectively. Details are as follows:1. Porous carbon nanosheet(PCNS) was prepared by template catalytic carbonization of waste poly(ethylene terephthalate)(PET) beverage bottles on organically-modified montmorillonite(OMMT) and the subsequent KOH activation. The morphology, microstructure, phase structure, textural property, surface element composition and thermal stability of CNS and PCNS were studied. It was found that PCNS showed high specific surface area(2236 m~2/g) and large pore volume(3.000 cm~3/g). More importantly, PCNS exhibited high specific capacities of 169 F/g at a current density of 0.2 A/g in aqueous 6 mol/L KOH. It is believed that this work puts forward a novel approach for recycling waste PET to prepare carbon materials.2. Porous carbon sheet and hollow carbon shell were synthesized through the carbonization of polystyrene on magnesium oxide with different morphologies at 700 °C using a one-pot process. The morphology, microstructure, phase structure, surface element composition, thermal stability and textural properties of the obtained nanocarbons were analyzed by SEM, TEM, XRD, TGA and Raman. The yield of nanocarbons increased as the weight ratio of magnesium oxide to polystyrene increased. Magnesium oxide acted as a template for the shape-controlled growth of carbon nanostructures. The surface area of porous carbon sheet and hollow carbon shell reached 854 and 523 m~2/g without any activation, respectively. The porous carbon sheets were used as adsorbents for the removal of methylene blue from water and showed an adsorption capacity of 358.8 mg/g. The pyrolytic product distribution of polystyrene with and without magnesium oxide was analyzed using GC and GC-MS to elucidate the mechanism of the reaction. The yield of styrene in the liquid products reached 50% by the catalysis of polygonal magnesium oxide. This strategy provides a cheap and easily-removed template catalyst for converting polymer into high-value nanocarbons and useful chemicals. |
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