CexTi1-xO2负载锰基催化剂的制备及其低温NH3选择催化还原NO

摘要

The CexTi1-xO2 complex oxides were prepared by co-precipitation method, The XRD and low temperature N2 adsorption-desorption results show that the CexTi1-xO2 exists in amorphous form when x is in the range of 0.2 ≤x≤0.4, and the Ceo.aTi0.6O2 has the largest surface area and pore volume. The activity results of NH3 selective catalytic reduction (SCR) of NO at lower temperature indicate that the activity of Mn-Fe/CexT1-xO2 catalysts increases at the beginning and then decreases with the increase of Ce, and the activity of Mn-Fe/Ce0.4Ti0.6O2 is the best at the spacevelocity of 41 000 h-l, the light-off temperature is at 75 ℃, and the NO conversion exceeds 90％ at 113 ℃. The XRD and XPS results show that the Mn-Fe/Ce0.4Ti0.6O2 mainly exists as amorphous or microcrystalline form, and there is strong interaction between the surface Mn and Fe of Mn-Fe/Ce0.4Ti0.6O2 and its support. The surface of Mn-Fe/Ce0.4Ti0.6O2 has Ce3+/Ce4+ redox couple and more chemisorbed oxygen compared with Mn-Fe/TiO2, which is beneficial to the oxidation of NO to NO2. The Mn-Fe/Ce0.4Ti0.6O2 also exhibits excellent resistance to H2O and SO2.%用共沉淀法制备了CexTi1-xO2复合氧化物载体.XRD和低温N2吸附-脱附结果指出,当0.2≤x≤0.4时,CexTi1-xO2载体主要以无定形态存在,且Ce0.4Ti0.6O2的比表面积和孔容最大.Mn-Fe/CexTi-xO2系列催化剂低温NH3选择性催化还原(SCR)NO活性结果表明,Mn-Fe/CexTi1-xO2的活性随着Ce含量的增加先增大后减小,其中Mn-Fe/Ce0.4Ti0.6O2的活性最佳,在41 000 h-1空速下,催化剂在75℃起燃,NO转化牢在113℃时即超过90%.而XRD和XPS分析结果指出,Mn-Fe/Ce0.4Ti0.6O2催化剂主要以无定形或微晶的形式存在.催化剂表面Mn和Fe与载体间存在强相互作用,且催化剂表面存在Ce3+/Ce4+氧化还原电对和较多的化学吸附氧,有利于NO氧化成NO2,同时催化剂表现出了较好的抗H2O和SO2性能.