Removal of NO and fly ash over a carbon supported catalyst: Effects of fly ash concentration and operating time

This study investigated the removal efficiency of NO and fly ash from flue gas over a Cu catalyst supported on modified activated carbon (AC) in a pilot-scale fluidized-bed catalytic reactor. The fly ash came from a coal-fired power plant was used in our experiment. The AC support was pretreated by either HNO3 (AC–N), H2O2, H2SO4, or NaOH. The acidic concentrations in the four catalysts followed the order CuO/AC–N (0.174 mol g− 1) > CuO/AC–H (0.138 mol g− 1) > CuO/AC–S (0.103 mol g− 1) > CuO/AC–Na (0.009 mol g− 1). Good dispersion of nanoscale CuO particles was observed over the modified supports having a large total number of acidic sites. Moreover, the increase in the number of phenolic and carboxylic groups may increase the NO removal efficiency over modified CuO/AC catalysts. The results was also suggested that the total number of acidic groups decreased in the reduction of NO over the CuO/AC catalysts due to the adsorption of NH3 on NO reduction. Simultaneous removal of NO and fly ash in flue gas under different fly ash concentrations and operating times was studied over the CuO/AC–N catalyst. When fly ash (1406–49,108 mg m− 3) was added in the flue gas, the removal efficiencies of NO and fly ash over Cu/AC–N were 58%–61% and 82%–86%, respectively. At an operating time of 240 min, the removal efficiency of fly ash was 76%, and the NO removal efficiency decreased slightly to 55%. The NO removal efficiency was inhibited slightly under high fly ash concentration and long operating time.

This paper describes our experimental investigation of a pilot-scale reactor that uses a CuO catalyst on a modified active carbon support. The PSD results showed that particles with sizes greater than 67 μm could be produced from catalyst erosion and elutriation, and the NO removal efficiency was inhibited slightly under high fly ash concentration.Figure optionsDownload as PowerPoint slideHighlights
► NO and fly ash were removed over catalysts in a fluidized-bed catalytic reactor.
► AC support was pretreated by HNO3, H2O2, H2SO4, and NaOH, respectively.
► The good dispersion of CuO was observed over AC with a large number of acidic sites.
► High concentration of acidic sites on catalysts may increase the removal of NO.
► The removal efficiency of fine particles decreased with increasing operating time.