Selective Catalytic Oxidation of Ammonia in the Presence of Manganese Catalysts

망간촉매하에서 암모니아의 선택적 산화반응

  • Jang, Hyun Tae (Department of Chemical Engineering, Hanseo University) ;
  • Park, YoonKook (Chemical System Engineering Department, Hongik University) ;
  • Ko, Yong Sig (Department of Advanced Material Chemistry, Shinsung College) ;
  • Cha, Wang Seog (School of Civil and Environmental Engineering, Kunsan National University)
  • 장현태 (한서대학교 화학공학과) ;
  • 박윤국 (홍익대학교 화학시스템공학과) ;
  • 고용식 (신성대학 신소재화학과) ;
  • 차왕석 (군산대학교 토목환경공학부)
  • Received : 2008.01.21
  • Accepted : 2008.02.04
  • Published : 2008.06.30

Abstract

The selective catalytic oxidation of ammonia was carried out in the presence of natural manganese ore (NMO) and manganese as catalysts using a homemade 1/4" reactor at $10,000hr^{-1}$ of space velocity. The inlet ammonia concentration was maintained at 2,000 ppm, with an air balance. The manganese catalyst resulted in a substantial ammonia conversion, with adsorption activation energies of oxygen and ammonia of 10.5 and 22.7 kcal/mol, respectively. Both $T_{50}$ and $T_{90}$, defined as the temperatures where 50% and 90% of ammonia, respectively, are converted, decreased significantly when alumina-supported manganese catalyst was applied. Increasing the manganese weight percent by 15 wt% increased the lower temperature activity, but 20 wt% of manganese had an adverse effect on the reaction results. An important finding of the study was that the manganese catalyst benefits from a strong sulfur tolerance in the conversion of ammonia to nitrogen.

천연망간광석과 천연망간광석에 금속산화물을 $Al_2O_3$$TiO_2$에 담지한 촉매을 이용하여 저온 선택적 산화 반응에 대하여 연구하였다. 망간계 금속산화물은 낮은 온도에서 우수한 암모니아 전환율을 나타내었다. NMO 존재하의 저온에서의 $O_2$$NH_3$의 흡착 활성화에너지는 각각 10.5와 22.7 kcal/mol 임을 밝혔다. 망간광석에 미량의 Ag를 함침함으로써 활성온도를 크게 낮출 수 있었다. 티타니아 담체의 경우 저온활성이 우수하게 나타나는 특성을 보였다. 또한 구리와 망간을 사용하면 망간을 단독으로 사용한 경우보다는 저온의 활성이 우수하게 나타난다. 망간이 5 wt.% 이상에서는 동일한 전환율을 나타내고 있으며, 저온 활성이 15 wt.%까지 약간 증가함을 알 수 있으며, 20 wt.%에서는 오히려 감소하는 것으로 나타나 있다. 황산화물의 피독실험 결과 본 연구에서는 최종적으로 망간에 조촉매의 첨가에 의한 내피독성의 향상은 공정의 복잡성과 비용면에서 망간의 단독 사용보다 낮게 나타났다.

Keywords

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