| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 92 === This thesis is related to the study of the catalysts for the preferential oxida- tion of CO in H2-rich stream (PROX). The purpose of this research is to pre- pare PROX catalysts with high CO oxidation activity, selectivity and good sta- bility at ambient temperature (below 100 oC). The results of literature review indicated that Au/TiO2 catalyst is one of the best choices for above-mentioned catalytic performance.
In this research, Au/TiO2 was prepared by deposition-precipitation. The preparation conditions to be investigated were the stirring time and amount of NaOH(aq) addition during pH adjustment. Catalysts were characterized with AA, TEM, EDS, XPS and UV-vis. The reaction tests included CO oxidation and PROX.
The results of reaction tests pointed out that when the gold concentration of gold solution was 1.72 × 10 -3 M (230 mL), the Au/TiO2 catalysts prepared with the proper stirring time (between 6 to 24 h) and amount (between 19 to 22.5 g) of 0.1 M NaOH(aq) addition during pH adjustment possessed best cat- alytic performance for PROX. This was attributed to the small gold particle sizes (characterized with TEM) and very few chloride residual (characterized with EDS and XPS) over catalysts.
Au/TiO2 catalyst prepared with 24 h as stirring time of NaOH(aq) addition possessed high CO oxidation activity (XCO = 100 %), selectivity (S = 0.75) and good stability (t = 23 h) in idealized reformate for PROX test at 25 oC.
The presence of H2O and/or CO2 were found to decrease the CO oxidation activity, but increase the selectivity and not influence the stability of catalysts mentioned above. The effects were also found to be vanished after the remo- val of H2O and/or CO2 in reaction. It was clear that the mechanism of effect was reversible.
Besides, research also revealed that the foregoing reduction of CO oxida- tion activity can be improved by increasing the catalysts amount and reaction temperature.
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