Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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Effect of SO2 on the Simultaneous Removal of Mercury and NOx over CuCl2-loaded V2O5-WO3/TiO2 SCR Catalysts

CuCl2가 담지된 V2O5-WO3/TiO2 SCR 촉매에 의한 수은 및 NOx 동시 제거에서 SO2의 영향

  • Ham, Sung-Won (Department of Chemical Engineering, Kyungil University)
  • 함성원 (경일대학교 화학공학과)
  • Received : 2022.01.25
  • Accepted : 2022.02.22
  • Published : 2022.03.31
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Abstract

CuCl2-loaded V2O5-WO3/TiO2 catalyst showed excellent activity in the catalytic oxidation of elemental mercury to oxidized mercury even under SCR condition in the presence of NH3, which is well known to significantly inhibit the oxidation activity of elemental mercury by HCl. Moreover, it was confirmed that, when SO2 was present in the reaction gas together with HCl, excellent elemental mercury oxidation activity was maintained even though CuCl2 supported on the catalyst surface was converted to CuSO4. This is thought to be because not only HCl but also the SO4 component generated on the catalyst surface promotes the oxidation of elemental mercury. However, in the presence of SO2, the total mercury balance before and after the catalytic reaction was not matched, especially as the concentration of SO2 increased. In order to understand the cause of this, further studies are needed to investigate the effect of SO2 in the SnCl2 aqueous solution employed for mercury species analysis and the effect of sulfate ions generated on elemental mercury oxidation. It was confirmed that SO2 also promotes NOx removal activity, which is thought to be because the increase in acid sites by SO4 generated on the catalyst surface by SO2 facilitates NH3 adsorption. The composition change and structure of the components present on the catalyst surface under various reaction conditions were measured by XRD and XRF. These measurement results were presented as a rational explanation for the results that SO2 enhances the oxidation activity of elemental mercury and the NOx removal activity in this catalyst system.

HCl에 의한 원소수은 산화활성을 크게 억제하는 것으로 잘 알려진 NH3가 존재하는 SCR조건에서도 CuCl2가 담지된 V2O5-WO3/TiO2 촉매는 원소수은의 산화에 우수한 활성을 나타내었다. 더구나, HCl과 함께 SO2가 반응가스에 존재할 경우에 촉매표면에 담지된 CuCl2가 CuSO4로 변환되는데도 불구하고 뛰어난 원소수은 산화활성이 유지되는 것이 확인되었다. 이는 HCl 뿐만 아니라 촉매 표면에 생성된 SO4 성분이 원소수은의 산화를 촉진시키기 때문으로 판단된다. 그러나 SO2 존재 하에서는 촉매반응 전후의 전체 수은 수지가 맞지 않는 현상이 나타나는데 특히 SO2 농도가 높을수록 심하게 나타났다. 이의 원인 파악을 위해서는 수은 종 분석 방법으로 적용된 SnCl2 수용액에서 SO2의 영향과 촉매표면에 생성되는 황산이온이 원소수은 산화에 미치는 영향에 대한 추가적인 연구가 필요하다. SO2는 NOx 제거 활성도 촉진시키는 것으로 확인되는데 이는 SO2에 의해 촉매 표면에 생성된 SO4에 의한 산점 증가가 NH3 흡착을 용이하게 하기 때문으로 판단된다. 다양한 반응조건에서 촉매 성분의 조성과 구조 변화는 XRD와 XRF로 측정하였으며 이들 측정 결과는 SO2가 본 촉매시스템에서 원소수은의 산화 활성과 NOx 제거 활성을 증진시키는 현상을 합리적으로 설명하는 근거로 제시되었다.

Keywords

References

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