Synergistic removal of NO and soot by Fe-W-Zr-ZSM-5 catalysts in a wide temperature window

Obtaining the synergistic catalytic removal of NO and soot is a highlight topic as both NO and soot are the main pollutants from diesel engine. However, synergistic catalytic removal is still very difficult because the temper-ature window varies with the traditional SCR catalyst of NO at narrow temperature of 300-450 degrees C and the oxidation temperature of soot at high temperature of 500-700 degrees C. Therefore, based on W-Zr-ZSM-5 catalyst, a series of M-W-Zr-ZSM-5 (M = Cu, Fe or Nb) catalysts were prepared by sol-gel method to investigate the syn-ergistic catalytic removal of NO and soot, which emitted from diesel engine at the same time. The results showed that Fe-W-Zr-ZSM-5 catalyst exhibited the best NH3-SCR reaction activity and oxidizing performance of soot among the catalysts, with more than 90 % NO conversion in the temperature range of 320 degrees C to 580 degrees C and completely oxidization of soot in the temperature range of 432 degrees C to 543 degrees C. The results of XRD, BET, XPS and Raman spectrum indicated that there was strong interaction between W and Fe, promoting the formation of W5+ and W = O species, thereby increasing the content of chemisorbed oxygen, the amount of surface acid sites and redox capacity of the catalysts. Meanwhile, the redox capacity of Fe-W-Zr-ZSM-5 was responsible for the improvement of NH3-SCR activity and the oxidation of soot at low temperature. Fe-W-Zr-ZSM-5 catalyst demonstrated to be a promising material to synergistic remove NO and soot.

Automated summary

By studying the Fe-W-Zr-ZSM-5 catalyst, it was found that it exhibited high efficiency in converting NO at temperatures of 300-450℃ and completely oxidizing soot at temperatures of 432-543℃, indicating its great potential in synergistic removal of NO and soot emitted from diesel engines.