| Summary: | 碩士 === 國立交通大學 === 機械工程學系 === 100 === In this study, the preheated ethanol steam flow is reformed using a gliding-arc plasma-assisted catalyst (PAC) system with a power frequency of 20 kHz. Among the PAC reforming, the noble catalyst Rh and non-noble catalyst Ni0.35Mg2.65FeO4.5 respectively is used to compare PAC with catalyst alone reforming by generating the hydrogen selectivity and conversion rate via different experimental parameters. In Rh catalyst alone reforming at the range of air flow rates of 0.5-2.0 SLM, the results show that a 100% conversion rate and a maximum of 115% hydrogen selectivity could be obtained at a C/O ratio of 0.7 with an air flow rate of 1.0 SLM. However, hydrogen selectivity decreases rapidly to 95% and 70% at lower (0.5 SLM) and higher (1.5 SLM) air flow rates, respectively. With the addition of a gliding arc prior to the catalyst, hydrogen selectivity reaches 113% and 111% at air flow rates of 1.0 and 1.5 SLM, respectively, with a plasma absorption power of approximately 200 W. This shows that very high hydrogen selectivity (>110%) can be obtained at air flow rates of both 1.0 and 1.5 SLM under the current experimental setup. However, at a 2.0 SLM air flow rate, the hydrogen selectivity of PAC drops down to 70% and is almost the same as that for reforming with the catalyst alone. The above observations correlate strongly with the residence time of the gas flow in plasma with the catalyst. In the Ni0.35Mg2.65FeO4.5 catalyst reforming at the range of catalyst temperatures of 200-400℃, the highest hydrogen selectivity (~55%) and conversion rate are close the 100% at temperature 400 ℃ and drop down rapidly with decreasing the temperature. However, the PAC with Ni0.35Mg2.65FeO4.5 catalyst can improve the selectivity of catalyst alone reforming to 75% at the temperature 400℃. Even though the selectivity could be raised, the conversion drop down to 73% and hydrogen selectivity is much lower than PAC with Rh catalyst. The reason maybe the plasma generates a lot of H2O but the catalyst is inefficient at water-gas-shift (WGS) chemical reaction equation, as estimated using measurements of the gas composition from gas chromatography.
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