| Summary: | 碩士 === 義守大學 === 生物技術與化學工程研究所碩士班 === 97 === Hydrogen gas is the cleanest fuel, and the direct or indirect fuel for all types of fuel cell. However, hydrogen gas does not exist in nature, and mainly comes from the transformation of methane. Nevertheless, the product gas always carries trace amount of carbon monoxide, which in turn will result in the poisoning of the catalyst in the fuel cell and render the fuel cell inactive. Therefore, the elimination of carbon monoxide from the hydrogen rich gas effectively and economically is an important issue. So far, such catalysts are mainly based on novel metals, like Pt or Au. They are effective but expensive.
The current study employed Cu-based CuO/CeO2 catalyst, which is prepared through microemulsion and is of nanoscale. The effects of several catalyst preparation parameters on the performance of the catalyst for selective oxidation of CO in the hydrogen rich gas are investigated, including: varying emulsion mixture composition in preparing the CeO2 support, two different solvents (methanol or D. I. water) for cleaning the CeO2 support, and varying Cu impregnation time. The resulting catalysts are characterized with XRD, BET and TEM for their crystallinity, specific surface area and particle size distribution, and placed in a continuous packed-bed reactor to test their performance in catalyzing the selective oxidation of CO.
The characterization has revealed that nanoscale CuO/CeO2 catalysts can be prepared via microemulsion with an average particle size of about 5 nm. The selective oxidation experiments have shown that CO conversion increases with increasing temperature and is higher with methanol-cleaning or with longer impregnation time, and that the CO selectivity decreases with increasing CO conversion. To achieve 100% conversion and 100% selectivity simultaneously is yet to be accomplished. The CuO/CeO2 catalyst obtained from the best combination of preparation parameters is capable of achieving 100% CO conversion at a temperature as low as 140°C with a CO selectivity of 50%. Its performance is comparable to that of novel metal based catalysts, but its cost is much lower.
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