Sun Xiao,Guo Rui-tang,Li Ming-yuan,Sun Peng,Pan Wei-guo,Liu Shu-ming,Liu Jian,Liu Shuai-wei
Fe was used as the modifier to improve the performance of CeZr 2 O
x
catalyst for the selective catalytic reduction (SCR) reaction with ammonia. Experimental results revealed that proper Fe species (Fe/Ce molar ratio = 2) could effectively improve the SCR activity of CeZr 2 O
x
, along with the elevated resistance to SO 2 and H 2 O. The characterization results including BET, XRD, H 2 -TPR and NH 3 -TPD confirmed that Fe species in Fe 2 CeZr 2 O
x
catalyst could inhibit the formation of ZrO 2 crystals and lead to higher reducibility and surface acidity. In addition, more Ce 3+ and surface active oxygen species could be detected on Fe 2 CeZr 2 O
x
compared with CeZr 2 O
x
. By means of in situ DRIFT technique, it could be deduced that the SCR reaction process over Fe 2 CeZr 2 O
x
was accelerated mainly through theL–H pathway due to the advanced adsorption of NH 3 and NO
x
species, along with the promoted NO conversion to NO 2 . Therefore, the modification of CeZrO
x
catalyst by Fe had a significant stimulation effect on its low-temperature SCR performance.
CeO2–CuO/Al2O3 catalysts were prepared by three different methods and their activities for selective catalytic reduction (SCR) of NO with NH3 were investigated. As can be seen from the experimental results, the catalyst prepared by the single-step sol–gel (SG) method showed the best SCR activity and resistance to SO2 and H2O. In order to investigate the relationship between the preparation method and the performance of SCR catalysts, the catalysts were characterized by using Brunauer–Emmett–Teller, X-ray diffraction, temperature programmed reduction with hydrogen, temperature programmed desorption with ammonia, X-ray photoelectron spectroscopy, Fourier transform infrared and thermo-gravimetric analysis techniques. It was found that the excellent performance of CeO2–CuO/Al2O3 catalyst prepared by the single-step SG method should be resulted from its large surface area, low crystallinity, high oxygen storage capacity, high NH3 adsorption capacity, high concentration of surface chemisorbed oxygen, weak sulphation process and weak water absorption.
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