Study On Preparation And Catalytic Reduction Of Nitrous Oxide Over Honeycombed Catalyst

Nitrous oxides produced by automobile exhaust emissions which are one of the main sources of air pollutant. Although the reactivity properties of honeycombed catalysts have been reported widely, there are many disadvantages, such as lacking of stability at high temperature and low activity at low temperature. Thus, developing a new type of method for preparing honeycombed catalyst is still an important research work. Cordierite honeycombed ceramics is supposed to be an ideal carrier due to low thermal-expansion coefficient, prominent heat-resistant shock. In this work, cordierite honeycombed ceramics and Fe-Mo/ZSM-5 were selected as carrier and active component, respectively, to prepare monolithic catalyst for removal nitrogen oxides. The effect of different preparation methods on the activity of monolithic catalysts were carried out on a fixed-bed reactor. Meanwhile, in order to illustrate the connection of the activity and construction of catalyst, the catalysts were characterized by XRD, FT-IR, BET and SEM. The main results are summarized as follows:(1) The prepared methods have greatly effect on the properties of catalyst. The catalyst prepared with the cordierite honeycombed ceramics made in the Corning company (USA) as carrier and CMC as surfactant by three times impregnated with assistant of ultrasonic irradiation (30min) which has the largest deposit ration and a lower loss of catalyst after processed at high temperature and vapor.(2) The activity of SCR for NOx of monolithic catalysts is related to the coating amount of Fe-Mo/ZSM-5 catalysts. With the increase of Fe-Mo/ZSM-5 catalysts on the carrier, the activity of SCR for NOx of monolithic catalysts improves. The catalyst, prepared with the cordierite honeycombed ceramics made in the Corning company (USA) as carrier and CMC as surfactant by three times impregnated with assistant of ultrasonic irradiation (30min), which has high reactivity at low temperature (3273-523K) and keeps high conversion efficiency at a long-range temperature.(3) XRD shows that structures of Fe-Mo/ZSM–5 catalyst formed well on cordierite honeycomb ceramics. The peaks of monolithic catalysts did not have any changes after calcined at high temperature for an hour. This proves that the catalyst has high temperature resistant.(4) FT-IR spectra figures that the characterized peaks of Fe-Mo/ZSM-5 appeared and the intensity of cordierite lowered compared with the uncoated cordierite.(5) The BET results indicate that the prepared cordierite honeycomb ceramics is abundant porous catalyst with big surface area and plenty of micropore.(6) The SEM figured that the Fe-Mo/ZSM-5 crystallize closely loaded on the surface of ceramics, while the crystallize of Fe-Mo/ZSM-5 conglomerated and formed clusters after high temperature processed...