Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Simultaneous Catalytic Reduction of NO and N2O over Pd-Rh Supported Mixed Metal Oxide Honeycomb Catalysts - Use of H2 or CO as a Reductant

혼합금속산화물에 담지된 Pd-Rh의 허니컴 촉매에서 NO와 N2O의 동시 환원 - H2 또는 CO 환원제의 사용

  • Received : 2008.04.10
  • Accepted : 2009.01.18
  • Published : 2009.02.28
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Abstract

In order to lower a reaction temperature with high conversions for simultaneous catalytic reduction of NO and $N_2O$ over Pd-Rh supported mixed metal oxide honeycomb catalysts, $H_2$ or CO was utilized as a reductant. When using the reductants, the effects of reaction conditions were examined in NO and $N_2O$ conversions, where reaction temperatures, concentrations of the reductants and oxygen and the concentration ratio of $N_2O$ to NO were varied. In using $H_2$ reductant, larger than 50% of NO and $N_2O$ conversions was observed at the temperatures below $200^{\circ}C$ in absence of $O_2$. In using CO reductant, NO and $N_2O$ conversions increased from the temperatures higher than $200^{\circ}C$ and $300^{\circ}C$, respectively. However, in use of both reductants, NO and $N_2O$ conversions decreased with increasing oxygen concentration. As a result, $H_2$ reductant could reduce simultaneously NO and $N_2O$ at relatively lower reaction temperature than CO. Also, NO and $N_2O$ conversions were less influenced by using $H_2$ reductant than CO one. Concentration ratio between NO and $N_2O$ did not affect their conversions regardless the type of reductants. Pretreatment of the catalyst in $H_2$ was more effective in simultaneous reduction of NO and $N_2O$ at low reaction temperature than that in $O_2$.

혼합금속산화물에 담지된 Pd-Rh 허니컴 촉매 상에서 NO와 $N_2O$를 동시에 저감하기 위한 반응 온도를 낮추면서 각각의 반응물에 대한 전환율을 높이기 위하여, 환원제로 수소 또는 일산화탄소 사용에 대해 조사하였다. 각각의 환원제 사용 시, NO와 $N_2O$의 전환율에 대한 반응 조건의 영향을 조사하기 위해 반응온도, 각 환원제와 산소의 농도, NO와 $N_2O$ 간의 농도 비율 등을 변화시켰다. 먼저 수소를 환원제로 사용하는 경우, 산소의 부재시 $200^{\circ}C$ 미만의 저온에서 50% 이상의 NO와 $N_2O$ 전환율을 얻을 수 있었다. 한편, 일산화탄소를 환원제로 사용하는 경우에는 NO와 $N_2O$ 전환율이 각각 $200^{\circ}C$와 $300^{\circ}C$ 이상에서 증가하기 시작하였다. 그러나, 두 가지 환원제 모두의 경우에서, 반응 가스내에 산소 농도가 증가함에 따라 $N_2O$와 NO 전환율에 감소하였다. 결과적으로 일산화탄소 환원제에 비해, 수소 환원제가 상대적으로 저온에서 NO와 $N_2O$를 동시에 저감할 수 있으며, 산소 농도에 의한 영향을 덜 받는 것으로 나타났다. 반면, 반응물내 $N_2O$와 NO 농도비에 의한 NO와 $N_2O$ 전환율의 영향은 환원제의 종류에 크게 영향을 받지 않는 것으로 관찰되었다. 저온에서 NO와 $N_2O$를 동시에 저감시키기 위해서는 산소 분위기보다는 수소 분위기에서 촉매를 전처리하는 것이 보다 효과적인 것으로 나타났다.

Keywords

References

  1. Cho, S. S., Choo, S. T., Seo, M. H. and Kim, J. M., 'Simultaneous Removal System for Nitrogen Oxides ($(NOx, N_2O)$) Using Natural Zeolite Honeycomb Catalysts,' Korean Society of Environmental Engineers 2006 Conference, 884-885(2006)
  2. Lee, H.-J., Chang, K.-S., Park, Y.-S. and Woo, J.-W., 'Simultaneous Decomposition of $N_2O$ and N2O over Mixed Metal Oxide catalysts,' Applied Chemistry, 10(1), 244-247(2006)
  3. Coq, B., Mauvezin, M., Delahay, G., Butet, J.-B. and Kieger, S., 'The Simultaneous Catalytic Reduction of NO and $N_2O$ by $NH_3$ Using an Fe-zeolite-beta Catalyst,' Applied Catalysis B: Environmental, 27, 193-198(2000) https://doi.org/10.1016/S0926-3373(00)00148-X
  4. Bosch, H. and Janssen, F., "Formation and Control of Nitrogen Oxides," Catalysis Today, 2, 369-532(1988) https://doi.org/10.1016/0920-5861(88)80002-6
  5. Forzatti, P. and Lietti, L., "Recent Advances in de-NOxing Catalysis for Stationary Applications," Heterogeneous Chemistry Reviews, 3(1), 33-51(1996) https://doi.org/10.1002/(SICI)1234-985X(199603)3:1<33::AID-HCR54>3.0.CO;2-R
  6. Long, R. Q. and Yang, R. T., "Superior Fe-ZSM-5 Catalyst for Selective Catalytic Reduction of Nitric Oxide by Ammonia," Journal of the American Chemical Society, 121(23), 5595-5596(1999) https://doi.org/10.1021/ja9842262
  7. Pieterse, J. A. Z. and Booneveld, S., "Catalytic Reduction of NOx with $H_2/CO/CH_4$ over PdMOR Catalysts," Applied Catalysis B: Environmental, 73, 327-335(2007) https://doi.org/10.1016/j.apcatb.2007.01.005
  8. Qi, G., Yang, R.T. and Rinaldi, F., "Selective Catalytic Reduction of Nitric Oxide with Hydrogen Over Pd-based Catalysts," Journal of Catalysis, 237, 381-392(2006) https://doi.org/10.1016/j.jcat.2005.11.025
  9. Costa, C. N. and Efstathiou, A. M., "Low-temperature $H_2-SCR$ of NO on a Novel Pt/MgO-$CeO_2$ Catalyst," Applied Catalysis B: Environmental, 72, 240-252(2007) https://doi.org/10.1016/j.apcatb.2006.11.010
  10. Nanba, T., Kohno, C., Masukawa, S., Uchisawa, J., Nakayama, N. and Obuchi, A., "Improvements in the $N_2$ Selectivity of Pt Catalysts in the $NO-H_2-O_2$ Reaction at Low Temperatures," Applied Catalysis B: Environmental, 46, 353-364(2003) https://doi.org/10.1016/S0926-3373(03)00227-3
  11. Yokota, K., Fukui, M. and Tanaka, T., "Catalytic Removal of Nitric Oxide with Hydrogen and Carbon Monoxide in the Presence of Excess Oxygen," Applied Surface Science, 121/122, 273-277(1997) https://doi.org/10.1016/S0169-4332(97)00305-X
  12. Kogel, M., Monnig, R., Schwieger, W., Tissler, A. and Turek, T., 'Simultaneous Catalytic Removal of NO and $N_2O$ using Fe-MFI,' Journal of Catalysis, 182(2), 470-478(1999) https://doi.org/10.1006/jcat.1998.2371
  13. Perez-Ramirez, J. and Kapteijn, F., "Effect of NO on the SCR of $N_2O$ with Propane over Fe-zeolites," Applied Catalysis B: Environmental, 47, 177-187(2004) https://doi.org/10.1016/j.apcatb.2003.09.002
  14. Guzman-Vargas, A., Delahay, G. and Coq, B., "Catalytic Decomposition of $N_2O$ and Catalytic Reduction of $N_2O$ and $N_2O$ + NO by $NH_3$ in the Presence of $0_2$ over Fe-zeolite," Applied Catalysis B: Environmental, 42, 369-379(2003) https://doi.org/10.1016/S0926-3373(02)00268-0
  15. Macleod, N. and Lambert, R. M., "Lean NOx Reduction with CO+H2 Mixtures over $Pt/Al_2O_3$ and $Pd/Al_2O_3$ Catalysts," Applied Catalysis B: Environmental, 35, 269-279(2002) https://doi.org/10.1016/S0926-3373(01)00264-8
  16. Holles, J. H., Switzer, M. A. and Davis, R. J., "Influence of Ceria and Lanthana Promoters on the Kinetics of NO and $N_2O$ Reduction by CO over Alumina-Supported Palladium and Rhodium," Journal of Catalysis, 190, 247-260(2000) https://doi.org/10.1006/jcat.1999.2780
  17. Wen, B., "NO Reduction with $H_2$ in the Presence of Excess $O_2$ over Pd/MFI Catalyst," Fuel, 81, 1841-1846(2002) https://doi.org/10.1016/S0016-2361(02)00141-2