Experimental Study On Low Temperature H₂O₂-based Oxidized Denitration Catalyzed By TiO₂ Modified Catalyst

Emission reduction of nitrogen oxides(NOx)in boiler flue gas has always been an important issue for air pollutiodn control in our country.At this stage,in commercial boilers with low-temperature flue gas emissions such as chemical,steel,oil,cement,ceramics and large-scale coal-fired utility boilers during start-stop and low-load operation stage,the SCR catalyst can not operate normally due to the low flue gas temperature,so the efficient low temperature flue gas denitration technology need to be developed urgently.Therefore,based on H2O2 catalytic oxidation of flue gas denitration technology was proposed on low-temperature denitration.The key of this technology lies in the choice of oxidant.Based on this,the capability of low temperature oxidation and denitration of H2O2 under non-catalytic conditions was investigated firstly.Then the oxidative denitration performance of H2O2 was studied under the action of nano-TiO2.With the use of nano-TiO2 as the carrier,the catalyst was modified by using the same volume impregnation method to doping CeO2,and the loading of CeO2 was screened.The optimal catalyst for efficient H2O2 decomposition was obtained.In addition,the influence of different flue gas conditions was simulated in flue gas.Combining with the analysis of catalyst characterization,the experimental results were analyzed to provide the data support for the application of modified Ti02 catalyst in the low temperature denitration technology of H2O2 catalytic oxidation.The characterization results show that the loading of CeO2 affects the content of lattice oxygen in the catalyst.The increase of the relative content of lattice oxygen favors the electron transfer in the redox reaction,which is the key to promote the activation and decomposition of H2O2.The experimental results show that the catalytic activity is the highest when the CeO2 loading is 3 wt%,and the NO conversion is highest when the flue gas temperature is 160 0C,the[H2O2]/[NO]molar ratio is 2 and the space velocity is 30000 h-1.Finally,according to the technical requirements of flue gas denitrification for low-temperature boiler,the anti-sulfur modification of low temperature modified TiO2 denitration catalyst was researched.Using anti-sulfur oxide ZrO2 as the active component,ZrO2 was loaded on the nano-TiO2 by the same volume impregnation method.The effect of active ingredient content on the activity of the catalyst was investigated,as well as the anti-SO2 poisoning performance of the ZrO2/TiO2 catalyst.The catalyst was characterized microscopically and the adaptability of the optimal catalyst to different flue gas conditions was studied.The experimental results show that the optimal loading of the anti-sulfur catalyst is 4ZrO2/TiO2.The continuous denitrification efficiency is maintained at about 81%after continuous testing at 160 ? and 30 000 h-1 for 30 h.At the same time,the catalyst has a flue gas condition.Good adaptability.The characterization results show that after ZrO2 doping,Zr atoms will enter into the TiO2 lattice in the form of gaps or homologous substitutions,resulting in changes in the distribution of oxygen ions in the lattice,resulting in defects in the charge compensation and improving the oxygen vacancies in the catalyst.The content has a significant effect on the improvement of catalytic activity.