HWAHAK KONGHAK, Vol.40, No.3, 298-303, June, 2002
귀금속 촉매를 이용한 수소혼합가스에 포함된 일산화탄소의 선택적 산화반응
The Selective Oxidation of CO in Hydrogen Mixture on Noble Metal Catalysts
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초록
Alumina, ceria 그리고 ceria가 10 wt% 담지된 alumina를 담체로 한 Pt, Ru, Pt-Ru 이원금속(bimetallic)촉매 상에서 일산화탄소의 선택적 산화반응에 대한 연구를 진행하였다. 실험은 대기압, 50-400 ℃ 온도 영역에서 행하였다. Ceria는 금속표면에 산소를 원활히 공급함으로써 Pt촉매의 활성을 증가시키는 역할을 하였으며, 순수한 ceria에 담지된 Pt촉매가 ceria를 포함한 alumina를 담체로 한 Pt촉매보다 저온 활성이 증가하였다. 금속 전구체로 염화물을 사용하는 경우, 촉매표면에 잔존하는 Cl로 인해 산소의 mobility가 감소하고 활성이 저하되는 것으로 나타났다. Ru 또한 150 ℃ 이하의 저온에서 우수한 활성을 나타내었다. Pt-Ru 이원금속(bimetallic)촉매의 제조과정에서 소성과정 없이 300 ℃에서 환원과정만을 거친 촉매는 소성과정을 거친 촉매보다 더 좋은 활성을 보였는데 이것은 소성과정이 합금형성을 방해하기 때문인 것으로 판단된다.
The selective oxidation of CO in hydrogen mixture was studied over Pt, Ru, and Pt-Ru bimetallic catalysts supported on alumina, ceria, or alumina impregnated with 10wt% ceria. The experiments were conducted at atmospheric pressure and in the temperature range of 50-400 ℃. Ceria was found to significantly promote the catalytic activity of the Pt catalysts by supplying oxygen to the metal interface, particulary at low temperatures where Pt alone was inactive. The Pt supported on pure ceria exhibited better low-temperature activity than the Pt supported on the alumina impregnated with ceria. When using chlorine compound as the metal precursor, the residual chlorine present on the catalyst was found to inhibit the oxygen mobility of the ceria to lower the catalytic activity. Ru also exhibited excellent low-temperature activities at temperatures lower than150 ℃. As to the preparation methods for the Pt-Ru bimetallic catalysts, the catalyst directly reduced under hydrogen at 300 ℃ without prior calcination exhibited better activity than the bimetallic catalysts prepared with a calcination step, indicating that the calcination step may hinder the formation of the alloy phase.
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