Journal of Korean Society of Environmental Engineers (대한환경공학회지)

Korean Society of Environmental Engineers (대한환경공학회)
권호 표지

A Study on Hybrid DeNOx Process Using Selective Catalytic Reduction and Adsorption

선택적촉매환원과 흡착을 이용한 복합 탈질공정 연구

  • Moon, Seung-Hyun (Green House Gas Research Center, Korea Institute of Energy Research) ;
  • Jeon, Dong-Hwan (Green House Gas Research Center, Korea Institute of Energy Research) ;
  • Park, Sung-Youl (Green House Gas Research Center, Korea Institute of Energy Research)
  • 문승현 (한국에너지기술연구원 온실가스연구센터) ;
  • 전동환 (한국에너지기술연구원 온실가스연구센터) ;
  • 박성열 (한국에너지기술연구원 온실가스연구센터)
  • Published : 2007.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

This study was carried out to develop an efficient process abating high NO concentration. A hybrid process of selective catalytic reduction(SCR) and activated carbon fiber(ACF) adsorption was newly designed and tested. Used ACF in NO adsorption was regenerated by simultaneously applying heat and vacuum. The result of ACF regeneration was for superior in the desorption condition at $140^{\circ}C$ and vacuum 600 mmHg. A commercial catalyst was used at the conditions of reaction temperature at $300^{\circ}C$, $NH_3/NO$ mole ratio = 1.0 for SCR process. NO evolved from ACF regeneration reactor could be removed by SCR reactor up to 98%. But high concentration of NO was exhausted from SCR reactor for one minute when the flue gas of NO 300 ppm and deserted NO from ACF regeneration were simultaneously treated by the same SCR reactor. Therefore, it is necessary to use additional small sized SCR reactor or to increase $NH_3$ concentration for a short time along with NO concentration rather than to mix flue gas with the gas evolving from ACF regeneration at fixed $NH_3$ inlet concentration. The hybrid process of SCR and ACF showed high NO removal efficiency over 80% at any time courses. Through the repeated cycles, stable DeNOx efficiency was maintained, indicating that the hybrid process would be a good countermeasure to the spotaneously high NO concentration instead of increasing the SCR capacity.

본 연구에서는 간헐적으로 발생되는 고농도의 NO를 효율적으로 제거할 수 있는 혼합 공정으로 선택적촉매환원(Selective Catalytic Reduction, SCR)과 활성탄소섬유(Activated Carbon Fiber, ACF)흡착이 결합된 신 개념의 공정을 설계하고 특성을 고찰하였다. NO를 흡착한 ACF에 열과 진공을 동시에 가하여 재생 실험을 수행한 결과, $140^{\circ}C$에서 600 mmHg의 진공으로 탈착하였을 때 가장 높은 재생효율을 보였다. SCR공정에는 상용촉매를 사용하였으며, 반응온도 $300^{\circ}C$, $NO/NH_3$몰비 1.0인 조건에서 실험을 수행하였다. ACF 재생공정에서 발생한 NO를 SCR공정으로 처리하였을 경우 98%의 매우 우수한 제거효율을 보였다. 그러나 지속적으로 유입되는 300ppm의 NO와 ACF에서 탈착되는 NO를 기존의 SCR공정에서 동시에 처리하였을 때 약 1분간 고농도의 NO가 배출되었다. 따라서 ACF의 재생시 발생하는 고농도의 NO를 기존의 SCR공정에서 병행처리할 때는 탈착속도를 조절하거나 고농도로 배출되는 짧은 시간 동안 $NH_3$농도를 높여서 주입할 필요가 있으며, 소규모의 SCR공정을 추가로 설치하여야 한다. SCR과 ACF를 결합한 공정을 이용하여 NO를 처리하였을 때, 간헐적으로 2배의 농도를 가지는 NO가 유입되어도 80% 이상의 탈질 효율을 가지는 공정의 구현이 가능하였으며, 반복 사용에도 활성이 유지되어 안정적인 운전이 가능함을 입증하였다.

Keywords

References

  1. Drent, P. J. and Woldendrop, J. W., 'Acid rain and eggshells,' Nature, 339, 431 (1989)
  2. Zhu, Z., Liu, Z., Liu, S., and Niu, H., 'Catalytic NO reduction with ammonia at low temperature on $V_2O_5$/AC catalysts: Effect of metal oxide addition and $SO_2$,' Appl. Catal, B: Environ., 30, 267 -276(2001) https://doi.org/10.1016/S0926-3373(00)00239-3
  3. Arai, H. and Mochida, M., 'Removal of NOx through sorption-desorption cycles over metal oxides and zeolites,' Catalysis Today, 20, 97 -109(1994) https://doi.org/10.1016/0920-5861(94)85019-4
  4. Lindholm, A., Currier, N. W., Fridell, E., Yezerets, A., Olsson, L., 'NOx storage and reduction over Pt based catalysts with hydrogen as the reducing agent : Influence of $H_2O$and $CO_2$,' Appl. Catal, B: Environ., 75, 78 - 87(2007) https://doi.org/10.1016/j.apcatb.2007.03.008
  5. Cha, C.Y. and Kong, Y., 'Enhancement of NOx adsorption capacity and rate of char by microwaves,' Carbon, 33(8), 1141 -1146(1995) https://doi.org/10.1016/0008-6223(95)00066-M
  6. Zhu, Z., Liu, Z., Liu, S., and Niu, H., 'Adsorption and reduction of NO over activated coke at low temperature,' Fuel, 79, 651 - 658(2000) https://doi.org/10.1016/S0016-2361(99)00192-1
  7. Mochida, I., Korai, Y., Shirahama, M., Kawano, S., Hada, T., Seo, Y., Yoshikawa, M., and Yasutake, A., 'Removal of SOx and NOx over activated carbon fibers,' Carbon, 38, 227 - 239(2000) https://doi.org/10.1016/S0008-6223(99)00179-7
  8. Mochida, I., Kawano, S., Shirahama, N., Enjoji, T., Moon, S.H., Sakanishi, K., Korai, Y., Yasutake, A., and Yoshikawa, M., 'Catalytic activity of pitch-based activated carbon fiber of large surface area heat-treated at high temperature and its regeneration for NO-$NH_3$ reaction at ambient temperatures,' Fuel, 80, 2227-2233(2001) https://doi.org/10.1016/S0016-2361(01)00096-5
  9. Shirahama, N., Mochida, I., Korai, Y., Choi, K.H., Enjoji, T., Shimohara, T., Yasutake, A., 'Reaction of N02 in air at room temperature with urea supported on pitch based activated carbon fiber,' Appl. Catal, B: Environ., 52, 173 -179(2004) https://doi.org/10.1016/j.apcatb.2004.04.003
  10. Shin, S., lang, L, Yoon, S.H., and Mochida, I., 'A study on the effect of heat treatment on functional groups of pitch based activated carbon fiber using FTIR,' Carbon, 35(12), 1739-1743(1997) https://doi.org/10.1016/S0008-6223(97)00132-2
  11. 문승현, 신대현, 전상구, 권주성, '활성탄소섬유를 이용한 NO의 산화,' 대한환경공학회지, 23(12), 1947-1953(2001)
  12. 문승현, 전상구, 윤형기, 권주성, 성훈제, '반복 흡착-승온탈리법을 이용한 활성탄소섬유의 $NO_2$ 흡착/환원 특성 연구', 대한환경공학회지, 24(7), 1135-1143(2002)
  13. Shirahama, N., Moon, S. H., Choi, K. H., Enjoji, T., Kawano, S., Korai, Y., Tanoura, M., and Mochida, 1., 'Mechanistic study on adsorption and reduction of $NO_2$ over activated carbon fibers,' Carbon, 40, 2605 - 2611 (2002) https://doi.org/10.1016/S0008-6223(02)00190-2
  14. Bjorklund, R. B., Odenbrand, C. U. I., Brandin, J. G. M., Andersson, L. A. H., and Lindberg, B., 'An Infrared and electrical conductance study of $V_2O_5/SiO_2-TiO_2 $catalysts active for the reduction of NO by $NH_3$,' J. Catal., 119, 187(1989)