Development Of NOx Reduction Process Based On Adsorption-Reduction Decoupling

NH3-SCR NOx reduction technology is widely used as an effective NOx removal method in power plant flue gas NOx reduction.However,in recent years,the traditional NH3-SCR technology has exposed a series of problems,so the search for alternative NH3-SCR reductant has become a research hotspot.As a common reducing agent,CO has a good ability to reduce NOx,but the presence of O2 in the flue gas will preferentially react with CO,resulting in a large consumption of CO,thus affecting the normal progress of denitration reaction.In order to overcome the effect of oxygen on NOx reduction,we have proposed a new type of denitration process through the study of the adsorption and reduction decoupling mechanism of NOx on the catalyst.In order to study the performance of this denitration process,we simulated the NOx adsorption and reduction decoupling process on the catalyst through a fixed-bed reactor.In the previous work,we prepared three different Fe/ZSM-5 catalysts by impregnation,solid-state ion exchange and hydrothermal methods.By testing the CO NO reduction activity of the catalysts,we found that solid-state ion exchange is used among the three catalysts.The Fe/ZSM-5 catalyst prepared by the method has the best NO reduction activity,but the difference with the other two catalysts is not great.Through BET analysis,we also found that the specific surface area of the Fe/ZSM-5 catalyst prepared by the solid-state ion exchange method is the largest.Through analysis of XRD and XPS,we can conclude that for Fe/ZSM-5 catalysts prepared by different methods,some Fe is loaded on the surface of the catalyst in the form of Fe2O3.For the NO reduction characteristics of catalyst adsorption and reduction under constant temperature conditions,the removal performance of NO before 350 ℃ is not much different,but when the temperature exceeds 350 0C,the removal performance of NO significantly decreases,but the NO reduction efficiency As the temperature increases,the NO reduction efficiency increases.When the combined removal efficiency is equal to the reduction efficiency at 350℃.,the NO reduction characteristics of the catalyst for adsorption and reduction decoupling are the best.For the NO reduction characteristics of adsorption and reduction decoupling under variable temperature conditions,the NO reduction performance is affected by two temperatures respectively:adsorption temperature and desorption temperature.The lower the temperature of the adsorption zone in the adsorption process,the better the adsorption performance and the better the adsorption of NO in the flue gas.The higher the desorption zone temperature during desorption,the better the desorption of NO.Therefore,the use of variable temperature decoupling NO reduction,compared to the use of decoupling constant temperature decoupling,efficiency has improved significantly.A series of Fe/ZSM-5 catalysts have been prepared for different processes.The results show that for the adsorption and reduction decoupling process of the catalyst,the removal efficiency of NO obtained by the catalyst prepared by the impregnation method is the best,and at the same time,due to the impregnation method.The preparation process is relatively simple and is more suitable for large-scale preparation.For NOx adsorption and reduction decoupling,although the effect of oxygen on NO removal efficiency is overcome and NO removal efficiency is improved,there is very little NO that is actually reduced,and a large part of NO will follow CO into the reducing atmosphere.Therefore,it is necessary to add a deep desorber to restore this part of NO.In general,the NOx removal technology based on adsorption-reduction decoupling has a high NO reduction efficiency,and due to its wider temperature range,it can be used in more places than coal-fired power plants and coal-fired power plants.The market prospects are very good.