HWAHAK KONGHAK, Vol.30, No.1, 116-124, February, 1992
주기적 조작하에서 Copper Chromite 담지촉매에 의한 일산화탄소의 산화반응
The Oxidation of Carbon Monoxide over Supported Copper Chromite Catalyst under Cyclic Operation
초록
반응물을 주기적으로 공급하면서 γ-Al2O3에 담지된 copper chromite 촉매상에서 CO 산화반응 실험을 수행하여 반응물을 정상적으로 공급할 때의 결과와 비교, 분석하였다. 주기적 조작하에서 CO의 산화반응을 진행시키면 흡착이 더 잘 되는 산소가 촉매표면에 적절히 분해되어 결과적으로 촉매의 활성을 향상시킬 수 있다. 주기적 조작을 통한 반응속도의 향상은 주기를 반응계의 이완(relaxation)시간에 상응하는 크기로 유지할 때 가장 뚜렸하게 나타나는 것으로 관찰되었으며 온도가 상승함에 따라 CO의 탈착속도가 빨라져 주기적 조작의 효과가 감소되었다. 반응물의 조성이 주기적으로 변화도록 공급하면서 온도에 따라 CO의 시간 편균 전환율을 조사하여 정상조작하에서의 CO 전환율과 비교한 결과 360℃ 이하의 온도에서는 주기적 조작의 경우에 CO 전환율이 더 높게 나타났는데 이는 CO의 탈착온도와 직접 연관되는 것이다. 또한 주기적 조작에 있어서의 주요 매개변수인 주기, 조성 및 진폭의 영향을 규명하였다.
An experimental study has been carried out for the oxidation of CO on copper chromite suppor-ted over γ-Al2O3 by using cycled feeds and the results were compared with those obtained by using steady noncycled feeds. When the reaction proceeds under the conditions of cyclic operation, the more strongly adsorbed oxygen is distributed more favorably over the catalytic surface and this gives rise to a substantial enhancement of the catalytic activity. Such an enhancement seems to be more distinct when the period is maintained at the level of the relaxation time of the reaction system. The effect of cyclic operation tends to becrease with the temperature because the rate of CO desorption increases with the temperature. Between the two modes of operation, Cycled and noncycled, with equal time-averaged concentration, the cycled one yields higher conversion of CO when the temperature is below 360℃, which corresponds th the desorption temperature of CO. Examined also are the effects of the period, the composition and the amplitude ratio which are considered as the major parameters in cyclic operation.
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