| Summary: | 碩士 === 國立中興大學 === 環境工程學系所 === 107 === As the global population continues to increase, it not only increases the demand for energy but also produces excessive waste. Currently, Waste to Energy is a widely promoted concept, which is considered to be economically viable and environmentally sustainable. This technology not only to solve waste management but also produce renewable energy to achieve waste recycling.
Plastics are one of the most widely-used and multi-purpose materials. Due to increasing demand, global plastic has continuously grown to 348 million tons in 2017. The treatment of waste plastics is regarded as a serious problem due to its physiochemical stability and non-biodegradation. Waste plastics are composed of hydrocarbons. We can use it as hydrogen production materials. Using heat treatment technology to produce syngas further improve hydrogen production efficiency by catalyst catalysis. However, in the production of hydrogen catalysts from waste plastics have several problems. Metal sintering and carbon deposition are prone to gradual deactivation or severe carbon deposition causing reactor blockage, affecting catalyst life and catalytic efficiency.
In order to solve the problem, we synthesis yolk-shell structure catalyst, which uses nickel as an active phase and redox characteristic ceria-zirconia mixed metal oxide is used as the functional shell layer. The catalyst is applied to produce hydrogen from waste plastics gasification. In the first part, we simulated waste plastic gasification syngas to evaluate catalyst catalytic ability. under core-shell structure, it resolves the problem of metal sintering deactivation caused by nickel core reaction and forms active phase nickel with small particle size and high dispersion. The methane conversion is high as 83%. In the second part, methane cracking reaction simulates high carbon deposition environment. Ni@CeO2-ZrO2 improved Ni@CeO2 deactivation, due to the poor thermal stability of CeO2 causes catalyst sintering and carbon deposition. Further, use CTAB as a porogen to improve catalyst catalytic ability. Ni@CeO2-ZrO2-1-0.5 is the best catalyst parameter, with nearly 60% methane conversion rate and no deactivation for 1 hour. The third part is the two-stage fluidized bed gasification waste PE catalytic hydrogen production experiment. We explore the effects of different catalyst structures on catalysis. Yolk shell structure catalyst is the most advantageous. Because of the hollow space between the core and shell may provide a homogenous for heterogeneous catalysis. The active phase core can sufficiently expose their active sites to enlarge the contact area with the reactants. The optimal hydrogen production is 730.6 mmol/h-g.
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