Removal of Nitrogen Oxides Using Hydrocarbon Selective Catalytic Reduction Coupled with Plasma

플라즈마가 결합된 탄화수소 선택적 촉매환원 공정에서 질소산화물(NOx)의 저감

  • Ihm, Tae Heon (Department of Chemical and Biological Engineering, Jeju National University) ;
  • Jo, Jin Oh (Department of Chemical and Biological Engineering, Jeju National University) ;
  • Hyun, Young Jin (Department of Chemical and Biological Engineering, Jeju National University) ;
  • Mok, Young Sun (Department of Chemical and Biological Engineering, Jeju National University)
  • 임태헌 (제주대학교 생명화학공학과) ;
  • 조진오 (제주대학교 생명화학공학과) ;
  • 현영진 (제주대학교 생명화학공학과) ;
  • 목영선 (제주대학교 생명화학공학과)
  • Received : 2015.12.29
  • Accepted : 2016.01.06
  • Published : 2016.02.10


Low-temperature conversion of nitrogen oxides using plasma-assisted hydrocarbon selective catalytic reduction of (HC-SCR) was investigated. Plasma was created in the catalyst-packed bed so that it could directly interact with the catalyst. The effect of the reaction temperature, the shape of catalyst, the concentration of n-heptane as a reducing agent, the oxygen content, the water vapor content and the energy density on $NO_x$ removal was examined. $NO_x$ conversion efficiencies achieved with the plasma-catalytic hybrid process at a temperature of $250^{\circ}C$ and an specific energy input (SIE) of $42J\;L^{-1}$ were 83% and 69% for one-dimensional Ag catalyst ($Ag\;(nanowire)/{\gamma}-Al_2O_3$) and spherical Ag catalyst ($Ag\;(sphere)/{\gamma}-Al_2O_3$), respectively, whereas that obtained with the catalyst-alone was considerably lower (about 30%) even with $Ag\;(nanowire)/{\gamma}-Al_2O_3$ under the same condition. The enhanced catalytic activity towards $NO_x$ conversion in the presence of plasma can be explained by the formation of more reactive $NO_2$ species and partially oxidized hydrocarbon intermediates from the oxidation of NO and n-heptane under plasma discharge. Increasing the SIE tended to improve $NO_x$ conversion efficiency, and so did the increase in the n-heptane concentration; however, a further increase in the n-heptane concentration beyond $C_1/NO_x$ ratio of 5 did not improve the $NO_x$ conversion efficiency any more. The increase in the humidity affected negatively the $NO_x$ conversion efficiency, resulting in lowering the $NO_x$ conversion efficiency at the higher water vapor content, because water molecules competed with $NO_x$ species for the same active site. The $NO_x$ conversion efficiency increased with increasing the oxygen content from 3 to 15%, in particular at low SIE values, because the formation of $NO_2$ and partially oxidized hydrocarbon intermediates was facilitated.


Supported by : 한국연구재단


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