Study on the denitrification performance of Fe_xLa_yO_z/activated coke for NH_3-SCR and the effect of CO escaped from activated coke at mid-high temperature on catalytic activity

摘要

Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel Fe_xLa_yO_z/AC catalysts was prepared by the incipient wetness impregnation for NH_3-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe0.3La0.7O1.5/AC exhibited a superior NO_x conversion efficiency of 90.1 % at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH_3-TPD, H_2-TPR, et al., whose results showed that the perovskite-type oxide of LaFe03 and oxygen vacancies were produced on the catalysts' surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NO,,. removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NO_x removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NO_x removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe0.3La0.7O1.5/AC only was 0.0015-.007%/min at 300-400 °C. Hence, 4% Fe0.3La0..7O1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, me mechanisms were proposed on me basis of experiments and characterization result