本研究利用水熱法製備具有氧空缺之管狀CeO2觸媒進行CO2脫氧反應，並以不同金屬前驅物(In、Zr、Gd)修飾的管狀CeO2觸媒進行比較討論。從TPR-TPO-TPR連續反應之實驗結果可得知，所有樣品都含有不可逆和可逆的H2消耗，其中可逆的H2消耗主要發生在600℃以上。另外，由BET的分析結果得知氧化鈰表面積大小為影響不可逆氧空缺之數量。以pulse方式在700℃進行CO2脫氧反應，並探討觸媒結構對CO2脫氧反應持續性。所有觸媒的CO2起始轉化率皆可達到100%，但經過幾次的CO2 pulse脫氧反應後，可以明顯地發現CO2轉化率趨近於零，顯示還原後CeO2的氧空缺確實可以分解CO2生成CO，並且在氧空缺抓滿CO2中的氧後，即無法再繼續進行CO2 pulse脫氧反應。其中，以摻雜5% Zr金屬前驅物修飾的管狀CeO2觸媒，CO2 pulse脫氧反應持續性最佳，可歸因於(1) 高溫下結構穩定佳；(2) Zr金屬與CeO2進行摻雜混合時，由於不同金屬離子之間的配位結構關係，使得在晶格之間產生更多的氧空缺而提升整體觸媒的氧化還原能力。

Cerium oxide exhibits reversible redox with relatively high oxygen storage capacity (OSC). This type of materials contains high concentration of oxygen vacancies, which can make a contribution to catalytic conversion. In this studies, CeO2 nanotubes are synthesized by a hydrothermal method, then impregnated with dopant (In, Zr, or Gd). The H2-TPR results evidenced the improved reducibility compared with CeO2 nanotubes. From TPR-TPO-TPR experiments, all the samples contain irreversible and reversible H2 consumption where reversible H2 consumption occur mainly at above 600℃. Otherwise, the results of BET shows the surface area is the key point that affect the irreversible oxygen vacancy of catalyst. The oxygen stripping reaction of CO2 was tested at 700℃, after catalysts were reduced by hydrogen at high temperature (900℃). The dissociation of CO2 to CO shows an initial steady rate then CO2 conversion decay to zero when the OSC are saturated with increasing pulsing CO2. From the characterization, CeO2 nanotubes with 5% Zr dopant shows the highest OSC. The activity for the oxygen stripping from CO2 has the highest initial CO2 conversion of 100% under the conditions of this study. The implications on the interaction between oxygen vacancies and CO2 are discussed.

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