Effect Of Photocatalytic Properties Of TiO₂/HZSM-5Modified By Zeolite

As an important and promising photocatalyst, TiO₂was brought into publicateention due to its chemically stable, nontoxic, relatively low cost and no secondpollution. Although TiO₂attracts many researchers attention in catalysis field by itsadvantages, many disadvantages of TiO₂appeared at the same time, such as its largeband gap, less productive rate of photogenerated electrons, easy inactivation and hardreuse of the photocatalyst and less surface area. The most effective and fast solution toovercome these shortcomeings is to load TiO₂on the surface of ZSM-5. In this paper,sol-gel method and solvothermal method were used to prepare the photocatalyst in orderto enlarge the surface area and increase photocatalysis activity. The degradation rate oforganic dye could be enhanced simultaneously.First, HZSM-5was prepared by hydrothermal method from NaZSM-5withhydrochloric acid. Next, TiO₂was loaded on the surface of HZSM-5. The TiO₂/HZSM-5was completed. The hydrothermal method （solvothermal method） used to prepare bothHZSM-5and TiO₂/HZSM-5was less reported in the documents. These photocatalystswere characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）,X-ray photoelectron spectroscopy （XPS）, BET surface area analysis and BJH pore sizedistribution analysis to study their surface topography, structure, crystal type, BETsurface area and BJH pore size distribution. The degradation of methyl orange （MO）solution was investigated the activity of photocatalytic by ultraviolet light.The different concentration of hydrochloric acid, different mount of TiO₂loaded onthe surface of HZSM-5and the different mothod to prepare TiO₂/HZSM-5could effectthe photocatalytic performance of TiO₂/HZSM-5. Some conclusions were listed asfollows:1) modification of support by HCl did not change the surface morphology andstructure of ZSM-5zeolite; The best concentration of HCl is0.3mol/L.2)TiO₂in all thesamples existed as anatase, no Rutile appeared.3)The SEM image of TiO₂/HZSM-5showed that TiO₂reunited together because of loading on the surface of HZSM-5;4)Loading TiO₂on the support of HZSM-5improved the dispersion of TiO₂, decreased the crystalline size and enlarged the surface of photocatalyst. These changes couldenhance the degradation rate of MO with the photocatalyst in the ultraviolet light;5)Thebest loading amount of TiO₂on ZSM-5is50%, the activity of50%TiO₂/HZSM-5prepared by sol-gel method was38.7%, and it enhanced13.6%compared with TiO₂prepared with the same method.50%TiO₂/HZSM-5can degrade methyl orange totally in100min;6) The best heat treatment condition was calcined at450℃for2h;We can make some conclusions as follows from the photocatalyst prepared withsolvothermal method:1)TiO₂in all the samples existed as anatase, no type of rutileappeared.2)The SEM image of TiO₂/HZSM-5showed that TiO₂reunited togetherbecause of loading on the surface of HZSM-5;3)Loading TiO₂on the support ofHZSM-5decreased the crystalline size and enlarged the surface of photocatalyst;4) Thephotocatalyst obtained by solvothermal method at loading40%of TiO₂had the bestactivity, the degradation to MO with40%TiO₂/HZSM-5was52.8%, and it enhanced25.3%compared with TiO₂. The organic dye of methyl orange could be degraded in70min with40%TiO₂/HZSM-5we prepared;5)The activity of TiO₂/HZSM-5preparedby solvothermal method was better than TiO₂/HZSM-5prepared by sol-gel method.