| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 94 === In this study , two methods, including (1) coprecipritation and (2) hydrothermal processes, were carried out to generate CeO2 nanocrystals with various shapes. On the basis of on the SEM study, the first method only produced polycrystalline CeO2 whereas the second method can generate rod and cube shape of CeO2. According to the TEM images , we found that the predominantly exposed planes are {001} in cerium oxide nanocubes . The predominantly exposed planes are {001} and {110} in cerium oxide nanorods .
The catalytic activity for the conversion of ethanol to hydrogen have been carried out using the 5% wt Rh/CeO2 as the catalysts with as-synthesized CeO2 rods and cubes. The results from H2 selectivity, the effect of C/O ratio and stability test indicate that the cerium oxide which exposed planes under controlled more active than catalyst with irregular shape of CeO2 particles . Under the same condition , hydrogen selectivity of the cerium oxide nanorod catalyst is 10% higher than that of the catalyst prepared by impregnation method whose hydrogen selectivity is about 116% . However , the H2 selectivity for catalyst with rod and cube CeO2 gradually decrease after 24 hours, indicating the {100} and {110} surface are not stable at high temperature .
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