Control of mercury emissions from coal-combustion flue gases using CuCl2-modified zeolite and evaluating the cobenefit effects on S02 and NO removal

摘要

The effects of CuCI2 impregnation on the physical and chemical properties and the Hg° removal effectiveness of zeolite MCM-41 (MCM) were examined. Multipollutant removal potentials of the resulting samples on simultaneous capture of SO2 and NO were also evaluated. Overall, CuCl2 impregnation within 2-16% reduced the total surface area and pore volume of MCM. The introduced CuCl2 caused the impregnated MCM becoming a micropo-rous adsorbent The Hg° adsorption capacities of CuCl2-impregnated MCMs were greater than those of the untreated sample under both N2 and simulated flue gas conditions. When the CuCl2 impregnation content was >8 wt%, however, the Hg° adsorption capacity decreased because CuCl2 impregnation in excess amounts hindered certain active sites or blocked the pores. Hg° oxidation tests showed that the average oxidation percentages of MCM-4% and MCM-16% were 26.7% and 53.7% respectively in the flue gas condition, compared to..< 26% in the N2 condition. After CuCl2 impregnation, the S02 removal of MCM samples decreased from 42.3% to approximately 38% but NO removal increased from 62.8% to up to 73%, showing that CuCl2-impregnated MCMs may have greater potentials in simultaneous removal of NO than S02. Catalytic oxidation appeared to be important in SO2 and NO removal.