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A Study on the Influence of the Structural Characteristics of Cu/CeO2 Catalyst on the Low-Temperature Oxidation of Carbon Monoxide

Cu/CeO2 촉매의 구조적 특성이 일산화탄소 저온 산화반응에 미치는 영향 연구

  • Kim, Min Su (Department of Environmental Energy Engineering, Graduate School of Kyonggi University) ;
  • Choi, Gyeong Ryun (Department of Environmental Energy Engineering, Graduate School of Kyonggi University) ;
  • Kim, Se Won (Korea Institute of Industrial Technology, Thermochemical Energy System Group) ;
  • Hong, Sung Chang (Department of Environmental Energy Engineering, Kyonggi University)
  • 김민수 (경기대학교 일반대학원 환경에너지공학과) ;
  • 최경륜 (경기대학교 일반대학원 환경에너지공학과) ;
  • 김세원 (한국생산기술연구원, 고온에너지시스템 그룹) ;
  • 홍성창 (경기대학교 환경에너지공학과)
  • Received : 2020.10.08
  • Accepted : 2020.11.18
  • Published : 2020.12.31

Abstract

This study confirmed the effect of the Cu/CeO2-X catalyst on the CO oxidation activity at low temperature through the catalyst's structure and reaction characteristics. The catalyst was prepared by the wet impregnation method. Cu/CeO2_X catalysts were manufactured by loading Cu (active metal) using CeO2 (support) formed at different calcination temperatures (300-600 ℃). Manufactured Cu/CeO2_X catalysts were evaluated for the low-temperature activity of carbon monoxide. The Cu/CeO2_300 catalyst showed an activity of 90% at 125 ℃, but the activity gradually decreased as the calcination temperature of the CeO2-X and Cu/CeO2_600 catalysts showed an activity of 65% at 125 ℃. Raman, XRD, H2-TPR, and XPS analysis confirmed the physicochemical properties of the catalysts. Based on the XPS analysis, the lower the calcination temperature of the CeO2 was, the higher the unstable Ce3+ species (non-stoichiometric species) ratio became. The increased Ce3+ species formed a solid solution bond between Cu and CeO2-X, and it was confirmed by the change of the CeO2 peak in Raman analysis and the reduction peak of the solid solution structure in H2-TPR analysis. According to the result, the formation of the solid solution bond between Cu and Ce has been enhanced by the redox properties of the catalysts and by CO oxidation activity at low temperatures.

본 연구는 Cu/CeO2-X 촉매의 저온 CO 산화 활성에 미치는 영향을 촉매의 구조적 특성, 반응 특성을 통해 확인하였다. 사용된 촉매는 습윤 함침법으로 제조되었으며, 각기 다른 소성온도(300~600 ℃)에서 형성된 CeO2 (지지체)를 이용하여 Cu (활성금속)를 담지함으로써 Cu/CeO2-X 촉매를 제조하였다. 제조된 Cu/CeO2-X 촉매는 저온 CO 산화 활성을 평가하였다. 125 ℃에서 Cu/CeO2_300 촉매는 90% 이상의 활성을 나타냈으며, CeO2의 소성온도가 증가됨에 따라 활성이 점차 감소하여, Cu/CeO2_600 촉매는 65%를 나타냈다. 다음으로 촉매의 물리/화학적 특성을 Raman, BET, XRD, H2-TPR, XPS 분석으로 확인하였다. XPS 분석 결과, CeO2-X의 소성온도가 낮을 수록 불안정한 Ce3+ 종(비 화학양론 종) 비율이 증가하였다. 증가된 Ce3+종은 Cu와 결합함으로 써 치환결합을 형성하였으며 Raman 분석의 CeO2 peak 변화와 H2-TPR 분석의 치환결합 구조의 환원 peak를 통해 확인하였다. 결과적으로 Cu와 CeO2의 치환 결합 형성은 촉매의 redox 특성 및 저온 CO 산화 활성을 증진시켰다고 판단된다.

Keywords

References

  1. Mock, S. A., Sharp, S. E. Stoner, T. R., Radetic, M. J., Zell, E. T., and Wang, R., "CeO2 Nanorods-supported Transition Metal Catalysts for CO Oxidation," J. Colloid Interface Sci., 466, 261-267 (2016). https://doi.org/10.1016/j.jcis.2015.12.026
  2. Hossain, S. T., Almesned, Y., Zhang, K., Zell, E., Bernard, D. T., Balaz, S., and Wang, R., "Support Structure Effect on CO Oxidation: A Comparative Study on SiO2 Nanospheres and CeO2 Nanorods Supported CuOx Catalysts", Appl. Surf. Sci., 428, 598-608 (2018). https://doi.org/10.1016/j.apsusc.2017.09.199
  3. Hossain, S. T., Azeeva, E., Zhang, K., Zell, E., Bernard, D. T., Balaz, S., and Wang, R., "A Comparative Study of CO Oxidation Over Cu-O-Ce Solid Solutions and CuO/CeO2 Nanorods Catalysts", Appl. Surf. Sci., 455, 132-143 (2018). https://doi.org/10.1016/j.apsusc.2018.05.101
  4. Sun, S., Mao, D., and Yu, J., "Enhanced CO Oxidation Activity of CuO/CeO2 Catalyst Prepared by Surfactant-assisted Impregnation Method", J. Rare Earths, 33(12), 1268-1274 (2015). https://doi.org/10.1016/s1002-0721(14)60556-1
  5. Du, L., Wang, W., Yan, H., Wang, X., Jin, Z., Song, Q., Si, R., and Jia C., "Copper-ceria Sheets Catalysts : Effect of Copper Species on Catalytic Activity in CO Oxidation Reaction", J. Rare Earths, 35(12), 1186-1196 (2017). https://doi.org/10.1016/j.jre.2017.04.005
  6. Lykaki, M., Pachatouridou, E., Carabineiro, S. A. C., Iliopoulou, E, Andriopoulou, C., Kallithrakas-Kontos, N., Boghosian, S., and Konsolakis, M., "Ceria Nanoparticles Shape Effects on the Structural Defects and Surface Chemistry: Implications in CO Oxidation by Cu/CeO2 Catalysts", Appl. Catal. B: Environ., 230, 18-28 (2018). https://doi.org/10.1016/j.apcatb.2018.02.035
  7. Alkhoori, A. A., Polychronopoulou, K., Belabbes, A., Jaoude, M. A., Vega, L. F., Sebastian, V., Hinder, S., Baker, M. A., and Zedan, A. F., "Cu, Sm Co-doping Effect on the CO Oxidation Activity of CeO2. A Combined Experimental and Density Functional Study," Appl. Surf. Sci., 521, 146305 (2020). https://doi.org/10.1016/j.apsusc.2020.146305
  8. Li, R., Yang, Y., Sun, N., and Kuai, L., "Mesoporous Cu-Ce-Ox Solid Solutions from Spray Pyrolysis for Superior Low-Temperature CO Oxidation," Chem. - Eur. J., 25(68), 15586-15593 (2019). https://doi.org/10.1002/chem.201903680
  9. Alketbi, M., Polychronopoulou, K., Jaoude, M. A., Vasiliades, M. A., Sebastian, V., Hinder, S. J., Baker, M. A., Zedan, A. F., and Efstathiou, A. M., "Cu-Ce-La-Ox as Efficient CO Oxidation Catalysts: Effect of Cu Content," Appl. Surf. Sci., 505, 144474 (2020) https://doi.org/10.1016/j.apsusc.2019.144474
  10. Li, Y., Cai, Y., Xing, X., Chen, N., Deng, D., and Wang, Y., "Catalytic Activity for CO Oxidation of Cu-CeO2 Composite Nano Particles Synthesized by a Hydrothermal Method," Anal. Methods, 7, 3238-3245 (2015). https://doi.org/10.1039/C5AY00261C
  11. Jiadong, Z., Yaqiong, S., Jiachun, C., Valery, M., Nikolay, K., and Emiel, J. M. H., "Mechanism and nature of active sites for methanol synthesis from CO/CO2 on Cu/CeO2," ACS catal., 10, 11532-11544 (2020). https://doi.org/10.1021/acscatal.0c02909
  12. Kim, S. B., Kim, M. S., Kim, S. W., and Hong, S. C., "Reaction Characteristics of Cu/CeO2 Catalysts for CO Oxidation," Appl. Chem. Eng., 30(5), 620-626 (2019). https://doi.org/10.14478/ace.2019.1067
  13. Paparazzo, E., "XPS Study of Damage Induced by X-ray Irradiation on CeO2 Surfaces," Sur. Sci., 234(1-2), 253-258 (1990). https://doi.org/10.1016/0039-6028(90)90658-U