Preparation Of Ce Based Catalysts And Performance Of Catalytic Ozone Oxidation Of NO

Nitrogen oxides（NOx）have always played an important role in flue gas pollution,and the removal of NOx from flue gas has been the focus of many scholars.For NO in NOx,it is difficult to remove because it is not easily soluble in water.NO can be oxidized into water-soluble nitrogen oxides through ozone,although the oxidation effect of high concentration ozone is good,but because high concentration ozone is easy to leak and will cause harm to the human body,the process also has a certain risk.The catalyst has the characteristics of high activity and high selectivity,and the combination with ozone is more conducive to the removal of NO.In the process of reaction,the oxidizing ability of high concentration ozone is too strong,which is easy to produce other side reactions,which is not conducive to observing the reaction path.Using low concentration ozone is more beneficial to reflect the catalytic performance of the catalyst,and it is easy to study the specific reaction path.Therefore,this paper mainly prepared a catalyst to catalyze ozone oxidation of NO.Under the action of low concentration ozone and the catalyst,NO was further removed from the flue gas to achieve a higher NO removal rate,so that NO was converted into NO₂ and other water-soluble nitrogen oxides,and then combined with the absorption liquid to treat the flue gas,so as to achieve efficient NOx removal effect.The main elements are as follows.（1）The catalysts were prepared by impregnation method,and the effects of different conditions of catalyst carrier types on the combined ozone oxidation of NO were investigated.The carrier included Al₂O₃/Ti O₂,activated carbon,Al₂O₃,coconut shell,ZSM-5,and finally concluded that the catalytic effect was best when the carrier was Al₂O₃/Ti O₂;the active components were screened and compared with the one-component loaded catalysts Mn/Al₂O₃/Ti O₂,Ce/Al₂O₃/Ti O₂,Cu/Al₂O₃/Ti O₂ and the two-component loaded catalysts Mn-Ce/Al₂O₃/Ti O₂,Mn-Cu/Al₂O₃/Ti O₂ and Ce-Cu/Al₂O₃/Ti O₂ catalysts for NO oxidation by ozone,and finally selected Mn-Ce and Ce-Cu two-component loaded catalysts,both of which have good catalytic effect and stable performance.The catalysts were compared at different calcination temperatures,and the best conditions were selected at 300℃and 2h.（2）Performance study of Ce-Cu/Al₂O₃/Ti O₂ catalyzed ozone oxidation of NO.T The catalysts with different active group ratios and temperature were analyzed on the performance of catalytic ozone oxidation of NO.At Ce:Cu=2:1,100℃,O₃:NO=1:3,the catalytic ozone oxidation efficiency could reach more than 68%,but the catalysts were poorly resistant to water and sulfur.The Specific surface area aperture analysis（BET）,X-ray diffraction（XRD）and Transmission electron microscopy（TEM）characterization results showed that the catalysts with Ce:Cu=2:1 had mesoporous and The X-ray photoelectron spectroscopy（XPS）and Temperature programmed desorption（TPD）analyses showed that the increase of Ce addition,on the contrary,reduced the loading of Cu,and the redox reaction at Ce:Cu=2:1 was mainly shifted to the right(Cu²⁺+Ce³⁺（?）Cu⁺+Ce⁴⁺),and the number of oxygen species on the surface was the main factor affecting its catalytic performance.（3）Performance study of Mn-Ce/Al₂O₃/Ti O₂ catalyzed ozone oxidation of NO.The catalysts with different active group ratios and temperatures were analyzed for the performance of catalytic ozone oxidation of NO.The average efficiency of catalytic ozone oxidation of NO could reach more than 63%at Mn:Ce=4:1,50-150℃,O₃:NO=1:4.The BET,XRD and TEM characterization results show that the catalyst has the largest specific surface area and pore capacity with a large amount of Mn Ox and Ce Ox distributed on the surface at Mn:Ce=4:1.XPS analysis shows that the redox and oxygen vacancies of Mn（IV）/Mn（III）/Mn（II）and Ce（IV）/Ce（III）have a synergistic effect on the decomposition of O₃ to reactive oxygen species（O*）,thus improving the catalytic ability of the Mn-Ce/Al₂O₃/Ti O₂ catalytic ability of the catalyst for O₃.O₂-TPD analysis showed that the oxygen vacancies and oxygen species in the catalyst can act as active sites for the decomposition of O₃ to O*.The oxygen vacancies and oxygen species in the catalyst can act as active sites for the decomposition of ozone to O*,which enhances the oxidation of NO and reduces the amount of ozone by improving the utilization of ozone.（4）Application of catalyst combined with absorption method for NOx removal,study on the addition of additives to enhance the removal of NOx under 5 wt%Na OH solution,the results show that the additives sodium sulfite and sodium thiosulfate have the ability to synergistically improve the absorption and removal of NOx in solution,the total amount of additives at 0.1 wt%,sodium sulfite and sodium thiosulfate at 2:1 NOx absorption efficiency reached more than 98%,in the Under the condition of SO₂ presence,the above removal ability can still be maintained,and the SO₂ removal rate can also reach more than 95%.Figure[32]Table[7]Reference[118]...