Preparation And Performance Of Titanium Silicalite-1 Films On Different Substrates

Film catalytic technology has received increasing attention recently.Titanium silicalite-1 (TS-1)zeolite is an excellent selective oxidation catalyst for reactions using hydrogen peroxide as oxidant.TS-1 films grown on various kinds of substrates have shown potential advantages.This thesis investigates the preparation and properties of TS-1 films supported onα-Al₂O₃ ceramic tubes,SiO₂ pellets and stainless steel circles(SSC),A novel secondary growth method,using silicalite-1(Sil-1)nano-crystals as seed,was introduced to prepare TS-1 films. A systematic study was conducted to understand the influence of synthesis parameters on the formation and performance of the TS-1 films for the first time.The TS-1 films were characterized by SEM,XRD,FT-IR,UV-Vis and their catalytic properties were evaluated by the selective oxidation of styrene using hydrogen peroxide.1.It is demonstrated that the novel secondary method is effective on the formation of the TS-1 film.The Sil-1 nano-crystals can be used as seeds instead of TS-1 seeds to prepare TS-1 films/membranes.TS-1 zeolites prepared from Sil-1 and the TS-1 seeds showed similar morphology,microstructure and catalytic activity.TS-1 film catalysts grown from the two kinds of seeds were structurally and spectroscopically identical and exhibit similar reaction performance.2.TS-1 films were successfully prepared on SiO₂ pellets via the novel secondary growth method.The quality of the seed layer had important effect on the formation of the TS-1 film.The two-step seeded method is better for the SiO₂ pellets with small pore size. While the SiO₂ pellets with a rough surface preferred the dip-coating seeded method.Thus, the as-synthesized TS-1 films were completely coated the SiO₂ pellets and had good adhesion with the substrates.The supported TS-1 fihn catalysts were convenient to recycle and reuse. After the third recycle,the recovery percent of the film catalyst was 95%,and the regeneration activity was 78%of that over the fresh film catalyst.3.The novel secondary growth method is suitable to prepare TS-1 film on the SSC substrate.The crack in the TS-1 film is avoided under the slow temperature programming in the N₂ atmosphere.The defect-free TS-1 film showed good catalytic activity.The conversion of the styrene was 12%. 4.On theα-Al₂O₃ ceramic tubes,the effects of the synthesis parameters,including synthesis solution composition,crystallization time and growth times,on the TS-1 film morphology,thickness and the catalytic performance were investigated.The low TPAOH concentration and high H₂O content faver the formation of thick TS-1 fihn.The thickness of the TS-1 film can be controlled between 2-15μm by changing these synthesis parameters. The TS-1 film prepared from the synthesis solution composition of 1 SiO₂:0.03 TiO₂:0.32 TPAOH:250 H₂O,showed a high content of framework titanium and the best catalytic activity.