Abstract
In present work, the catalytic performance of Cu-SAPO-34 catalysts with or without propylene during the NH3-SCR process was conducted, and it was found that the de-NOx activity decreased during low temperature ranges (<350 °C), but obviously improved within the range of high temperatures (>350 °C) in the presence of propylene. The XRD, BET, TG, NH3-TPD, NOx-TPD, in situ DRIFTS and gas-switch experiments were performed to explore the propylene effect on the structure and performance of Cu-SAPO-34 catalysts. The bulk characterization and TG results revealed that neither coke deposition nor the variation of structure and physical properties of catalysts were observed after C3H6 treatment. Generally speaking, at the low temperatures (<350 °C), active Cu2+ species could be occupied by propylene, which inhibited the adsorption and oxidation of NOx species, confining the SCR reaction rate and causing the deactivation of Cu-SAPO-34 catalysts. However, with the increase of reaction temperatures, the occupied Cu2+ sites would be recovered and sequentially participate into the NH3-SCR reaction. Additionally, C3H6-SCR reaction also showed the synergetic contribution to the improvement of NOx conversion at high temperature (>350 °C).
Highlights
It implied that the CHA structure of Cu-SAPO-34 barely changed after ppm, 6h C3 H6 treatment at 300 ◦ C
Compared to the fresh Cu-SAPO-34, the BET surface area of HCs-Cu-SAPO-34 still remained at 415 m2 /g, which was comparable with the fresh catalyst
HCs-Cu-SAPO-34 still remained atCatalysts m2/g, which was comparable with the fresh catalyst
Summary
Regardless of diesel or lean-burn gasoline engine exhaust, NOx fouling has induced severe environmental problems [1,2,3] and the elimination of NOx is still a big challenge under stringent emission regulations [4]. Selective catalytic reduction of NOx with NH3. (NH3 -SCR) is considered as the most potential de-NOx technology for engine exhaust emission control [5,6]. V2 O5 -WO3 /TiO2 SCR catalyst has been widely used in the commercial de-NOx application [7,8]. The main drawbacks of these catalysts for mobile source domains are their insufficient low temperature SCR activity, poor thermal stability, and latent toxicity [9]. Compared with V2 O5 -WO3 /TiO2 , ZSM-5 and
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