• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.212-212
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• 2011

In addition to the catalysts' activity and selectivity, the deactivation of catalysts during use is of practical importance. It is crucial to understand the phenomena of the deactivation to predict the loss of activity during catalyst usage so that the high operational costs associated with catalyst replacement can be reduced. In this study, the activity of Ru catalysts, such as nanoparticles (3~6 nm) and polycrystalline thin film (50 nm), have been investigated under CO oxidation and oxidative/reductive reaction conditions at various temperatures with the ambient pressure X-Ray photoelectron spectroscopy (APXPS). With APXPS, the surface oxides on the catalyst are measured and monitored in-situ. It was found that the Ru film exhibited faster oxidation-and-reduction compared to that of nanoparticles showing mild oxidative-and-reductive characteristics. Additionally, the larger Ru nanoparticles showed a higher degree of oxide formation at all temperatures, suggesting a higher stability of the oxide. These observations are in agreement with the catalytic activity of Ru catalysts. The loss of activity of Ru films is correlated with bulk oxide formation, which is inactive in CO oxidation. The Ru nanoparticle, however, does not exhibit deactivation under similar conditions, suggesting that its surface is covered with a highly active ultrathin surface oxide. Since the active oxide is more stable as nanoparticles than as a film, the nanoparticles showed mild oxidative/reductive behavior, as confirmed by APXPS results. We believe these simultaneous observations of both the surface oxide of Ru catalysts and the reactivity in real time enable us to pinpoint the deactivation phenomena more precisely and help in designing more efficient and stable catalytic systems.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.30-32
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• 2012

본 연구에서는 Cu, Mn을 함침 시킨 상용 제올라이트13X 촉매에 CO 산화 전환 반응에 영향을 연구하였다. 촉매 제조는 담지량별로 Cu, Mn을 서로 다른 비율로 물리 혼합하여 상용 제올라이트에 담지하였다. 함침방법은 과잉용액 함침법을 사용하였고, 건조 후 공기분위기에서 소성하여 산화물 형태로 담지하였다. 기본적인 촉매 특성은 X-선 회절분석, 질소흡탈착 등온곡선을 이용하여 기공크기, 기공부피, 비표면적을 구하였으며, FT-IR, 주사현미경, $NH_3$-TPD/TPR, EDX로 특성을 분석하였다. 촉매 산화반응 실험은 고정층 반응기에서 수행하였으며, 외경1/4 inch(내경 4 mm)석영관에 촉매를 중진하고 Gas Chromatograph로 배출가스를 측정하여 Cu-Mn 제올라이트 촉매의 일산화탄소 산화반응을 연구하였다. 일산화탄소 농도, 온도 및 공간속도, Cu-Mn 함량 비율에 따른 산화반응 실험을 수행하여 최적 산화조건과 촉매를 도출하였다.