Synthesis Of Nanoparticle Zeolite ZSM-5 And Cu/ZSM-5 Catalyst Using In SCR

Zeolite is a kind of new materials which has properties of adsorption,ion-exchange,catalysis and acid resistant,so it is widely used as an adsorbent,ion exchanger and catalyst.Also it is always used in gas drying,gas purification and sewage treatment.In present study zeolite is often used as catalyst carrier to carry active substance.However,most of these studies focus on the active substance,such as its sort,loading amount and composite active substance.But few studies has been made on the zeolite carrier.In this paper,hydrothermal is used to synthesize nanoscopic ZSM-5,and then the product is dipping in solution which contains copper ions for ion-exchange to carry the active substance on it.Zeolites of different sizes have been used as carrier and all Cu/ZSM-5 catalysts are tested in SCR.The results obtained are as follows:First ZSM-5 zeolite is synthesized by hydrothermal.The crystal size is adjusted by changing dispersion medium,stiring time,reaction temperature and reaction time.The size and morphology are obtained by SEM and XRD is used to prove that the product is ZSM-5 and to study its degree of crystallinity.Conclusion is made by experiment that prolonging stiring time and reaction time,reducing reaction temperature and adding organic dispersant do good to reducing the crystal size.The most ideal product has a average crystal size of 60nm.Then catalyst product has been made in dipping method.Different amount of copper ions are carried on the 80nm ZSM-5 zeolite as catalyst samples and on the 300nm ZSM-5 zeolite as comparative samples.EDS is used to analyze the loading speculate the existing form of copper in the samples.BET is used to measure the specific surface area and pore size distribution.Results show that when the loading is below 5%,most copper go into the zeolite structure by ion exchange and become new catalytic sites.When the loading is above 5%,part of copper clement deposit on the surface of zeolite in the form of CuO particle.Catalyst samples made with 80nm ZSM-5 have larger specific surface area and bigger pore volume than those made with 300nm ZSM-5.The catalytic properties of samples are tested on the simulation SCR reactor.Experimental data proves that 80nm Cu/ZSM-5 sample always shows better performance than 300nm Cu/ZSM-5 one at the same Cu-loading and reaction temperature.When the removal rate is limited,the 80nm Cu/ZSM-5 sample has wider reaction temperature ranges than 300nm Cu/ZSM-5 one.The best amount of NH3 is 1:1 to the amount of NO.When the SCR temperature is as low as 200℃,it is good for upgrading the removal rate to raise the O2 proportion to 6%but when temperature is 350℃ it affect little.