HWAHAK KONGHAK, Vol.41, No.4, 445-452, August, 2003
Co가 첨가된 Cu-Ce/γ-Al2O3 촉매상에서 개질수소가스에 포함된 CO의 선택적 산화반응: (I) 촉매 반응 및 특성 평가
Selective Oxidation of CO in Hydrogen Rich Stream over Cu-Ce/γ-Al2O3 Catalyst Doped with Co
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초록
γ-Al2O3에 담지된 Cu-Ce 기준촉매에 조촉매로서 Co가 소량 첨가된 촉매를 제조하여 모사개질 가스(1% CO, 1% O2, 60% H2 in N2 balance)의 선택적 CO 산화반응을 수행하였다. 조촉매 함량, 과잉산소율 λ(=2[O2]/[CO])을 변화시켜가면서 반응온도에 따른 활성 및 선택도를 조사하였다. Cu-Ce 촉매의 함량 및 비율에 따른 최적 활성을 실험 조사한 결과, Cu-Ce(4:16 wt%) 촉매가 넓은 온도 범위인 175-220 ℃ 사이에서 99% 이상의 높은 CO 산화 활성을 보였으며, 이때의 CO 선택도는 50-80%로 나타났다. 또한 Co를 조촉매로 첨가한 Cu-Ce-Co(4.0:15.8:0.2 wt%) 촉매는 150-220 ℃의 넓은 온도 범위에서 Cu-Ce 촉매에 비하여 더욱 우수한 반응 활성(>99% CO전환율)과 선택도(50-94%)를 나타내었다. 승온환원(CO-/H2-TPR) 및 승온산화(TPO) 실험 결과, Cu-Ce-Co(4.0:15.8:0.2 wt%) 촉매의 경우 타 촉매에 비해 촉매의 산화/환원 특성이 가장 우수하며, CO에 대한 높은 흡착능을 나타냄을 알 수 있었다.
Cu-Ce/γ-Al2O3 catalysts promoted with Co were prepared and tested for selective oxidation of CO in a H2-rich stream. The effects of promoter content, degree of excess oxygen (λ) were investigated for activity and CO selectivity while changing temperatures. Among the various Cu-Ce catalysts having different metal loadings and composition, Cu-Ce (4:16 wt%) catalyst
showed the highest activity (>T99) and selectivities (80-50%) under wide temperature range of 175-220 ℃. When the Cu-Ce catalyst was further modified with 0.2 wt% Co as a promoter, the highest activity (>T99) and selectivities (94-50%) was obtained over the wide temperature windows of 150-220 ℃. From CO-/H2-TPR and TPO, it was found that by the addition of 0.2 wt% Co on Cu-Ce catalyst, oxidation-reduction activity of catalyst was improved, which resulted in the increase of catalytic activity and selectivity of CO oxidation in excess H2 environment.
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