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코발트와 니켈촉매의 비활성화 및 재생에 관한 연구

Carbon-Deactivation and Regeneration of Supported Cobalt and Nickel Catalysts

HWAHAK KONGHAK, October 1987, 25(5), 468-476(9), NONE
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Abstract

코발트 및 니켈촉매의 표면에 탄소를 누적시키고, 이를 수소처리에 의하여 재생시킬 때에, 촉매의 흡착특성과 반응성이 변화하는 것을 일산화탄소의 승온탈착과 메탄화반응실험으로 관찰하였다. 촉매표면의 탄소는 일산화탄소의 불균일화반응으로 얻었는데, 300 ℃보다는 450 ℃에서 누적시키는 경우에 촉매의 비활성화가 심하게 일어나지만 반면에 수소처리에 의한 촉매재생은 후자의 경우에 잘 이루어지는 것으로 나타났다. 한편 코발트는 니켈보다 탄소누적에 의한 촉매의 비활성화가 크게 일어나며 또한 수소처리에 의하여 비교적 쉽게 재생이 된다. 탄소누적에 의한 촉매의 비활성화는 일산화탄소의 승온탈착곡선에서 200 ℃ 이하의 봉우리가 크게 감소하고 300 ℃ 이상에서 새로운 봉우리가 나타나는 현상으로 추적할 수가 있다. 그러나 수소 처리에 의한 촉매의 재생효과는 재생도와 탈착곡선간에 상관관계를 찾을 수가 없는데, 이것은 비활성화-재생과정에서 촉매의 표면특성이 크게 변화하기 때문으로 보인다.
Adsorption properties and activity of cobalt and nickel catalysts have been studied by temperature programmed desorption (TPD) of carbon monoxide and by methanation test, as the catalysts are contaminated by surface carbon and are regenerated by hydrogen treatment thereafter. Carbon on the catalyst surface has been accumulated by disproportionation of carbon monoxide at elevated temperatures. It has been observed that catalysts with surface carbon deposited at 450 ℃ are deactivated more rapidly than those with carbon deposited at 300 ℃, and also that the former are more easily regenerated by hydrogen treatment than the latter. Cobalt undergoes more severe deactivation than nickel by surface carbon accumulation, but it is readily regenerated by hydrogen treatment. In this study, catalyst deactivation by surface carbon could be monitored by changes in the TPD chromatogram, which showed reduction of peaks below 200 ℃ accompanied by a new peak appearing above 300 ℃. However, the catalyst rege neration process could not be monitored in this manner, which may suggest that the structure of the catalyst has been modified during the deactivation and regeneration processes.

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