Korean Chemical Engineering Research, Vol.49, No.6, 720-725, December, 2011
일산화탄소 저온 산화에서 금속산화물에 담지된 금촉매의 활성에 미치는 수분첨가의 영향
Effect of Water Addition on Activity of Gold Catalysts Supported on Metal Oxide at Low Temperature CO Oxidation
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초록
금속질산염과 염화금산을 전구체로 사용하여 다양한 금속산화물(Al2O3, ZnO, Fe2O3, Cr2O3, MnO2, CuO, NiO, Co3O4)에 담지된 금촉매를 공침법을 이용하여 제조한 후, 일산화탄소 산화반응에서 수분첨가의 영향을 검토하였다. 이들 중 Co3O4와 ZnO에 담지된 금촉매가 일산화탄소에 대하여 높은 활성을 보여주었다. 반응가스 중에 수분이 첨가될 때 Au/Co3O4 촉매는 활성이 약간 감소하였으나, Au/ZnO 촉매에서는 활성이 크게 증가하여 수분에 의한 일산화탄소산화 활성은 담체의 종류에 크게 의존함을 알 수 있었다. 반응가스 중에 포함된 수분에 관계없이 반응 전과 후의 Au(5 wt%)/ZnO 촉매의 금입자 크기는 거의 변하지 않아 활성이 감소되는 이유는 금입자들의 소결에 의한 영향보다는 카보네이트와 같은 화학종에 의해 불활성화가 일어남을 알 수 있었으며, 이 화학종은 수분의 첨가에 의해 이산화탄소로 분해되어 활성이 증가한 것으로 생각된다.
Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/Co3O4 and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/Co3O4 catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.
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