Experimental study on the selective catalytic reduction of NO with C₃H₆ over Co/Fe/Al₂O₃/cordierite catalysts

The Co/Fe/Al₂O₃/cordierite catalysts with different Co loadings were prepared by sol-gel and impregnation methods, and their performance in the selective catalytic reduction of NO with C₃H₆ over catalytic were experimentally studied in a ceramic tubular reactor. The results indicated that 1.5Co/Fe/Al₂O₃/cordierite showed the highest C₃H₆-SCR activity with 97% NO reduction in the simulated flue gas at 550 ℃. Cobalt was able to effectively improve the ability of Fe/Al₂O₃/cordierite catalysts to resist SO₂ and H₂O in flue gas. When 0.02% SO₂ and 3% water vapor were added to the simulated flue gas, the NO reduction efficiency of 1.5Co/Fe/Al₂O₃/cordierite was almost unaffected, the NO reduction by 1.5Co/Fe/Al₂O₃/cordierite with C₃H₆ all surpassed 90%. In contrast, the catalytic activity of Fe/Al₂O₃/cordierite without cobalt modification was seriously suppressed by SO₂ and H₂O, the highest NO reduction efficiency of Fe/Al₂O₃/cordierite was less than 50% within the entire reaction temperature range (200-700 ℃).XRD and SEM results showed that the surface of 1.5Co/Fe/Al₂O₃/cordierite after the modification by cobalt became loose, and formed by the cobalt iron and cobalt aluminum metal oxide-based spherical grains.H₂-TPR results showed that 1.5Co/Fe/Al₂O₃/cordierite had better low temperature reduction performance than Fe/Al₂O₃/cordierite. Py-FTIR results confirmed that Co can dramatically increased the Lewis acid and produced Brønsted acid on the catalyst surface. N₂ adsorption/desorption characterization results proved that Co can increase the specific surface area of the catalyst.