화학공학소재연구정보센터
HWAHAK KONGHAK, Vol.41, No.5, 564-571, October, 2003
Co가 첨가된 Cu-Ce/γ-Al2O3 촉매상에서 개질수소가스에 포함된 CO의 선택적 산화반응: (II) CO2와 H2O의 영향
Selective Oxidation of CO in Hydrogen Rich Stream over Cu-Ce/g-Al2O3 Catalysts Doped with Co: (II) CO2 and H2O Effect
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초록
선택적 CO 산화촉매인 Cu-Ce/γ-Al2O3 촉매 및 조촉매로서 Co가 소량(0.2 wt%)첨가된 Cu-Ce-Co/γ-Al2O3 촉매에 대하여 모사개질 가스(1 vol.% CO+1 vol.% O2+60 vol.% H2 in N2 balance) 내에 존재하는 CO2와 H2O가 선택적 CO 산화반응에 미치는 영향을 조사하였다. 이들 CO2와 H2O가 개질가스 내에 존재할 경우 촉매를 피독시켜 저온 산화활성이 크게 감소되어 최고 55 ℃의 반응온도 증가를 가져왔다. 이러한 저온 산화활성 감소가 일어나는 원인이 개질가스 중에 포함되어 있는 CO2와 H2O가 각각 혹은 상호 경쟁적으로 산화 활성점에 강하게 흡착하기 때문이라는 것을 CO2와 H2O의 승온탈착실험(TPD)을 통하여 확인할 수 있었다. Cu-Ce-Co/γ-Al2O3 촉매의 경우는 Cu-Ce/γ-Al2O3에 비하여 CO2와 H2O가 동시에 존재하는 경우에 대한 피독 저항성이 상대적으로 우수하여 이들 피독물이 존재할 경우에도 99.9 %의 CO가 전환되는 T99온도창이 210 - 225 ℃범위에서 존재하였다.
Cu-Ce/γ-Al2O3 and Cu-Ce-Co/γ-Al2O3 promoted with 0.2 wt.% Co were prepared and their catalytic performance was evaluated for the selective oxidation of CO in a H2-rich condition (1 vol.% CO+1 vol.% O2+60 vol.% H2 in N2 balance). When CO2 and H2O were present in the reformed gas feed, both Cu-Ce/γ-Al2O3 and Cu-Ce-Co/γ-Al2O3 showed decrease in oxidation activity of CO at low temperatures especially under 200 ℃. Compared with the Cu-Ce/γ-Al2O3, however, the Cu-Ce-Co/γ-Al2O3 showed higher resistance for the CO2 and H2O and also there existed a temperature window of T99.9 from 210 to 225 ℃ corresponding to the conversion of 99.9% CO. From CO2/H2O-TPD, it can be concluded that the main cause for the decrease in catalytic activity may be attributed to the blockage of the active sites by competitive adsorption of water vapor and CO2 with the reactant at low reaction temperatures.
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