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Preparation Of TiO2-SiO2 Catalysts And Study On Photocatalytic Activity

Posted on:2007-10-14Degree:MasterType:Thesis
Country:ChinaCandidate:L W ZhuFull Text:PDF
GTID:2121360212972257Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
TiO2-SiO2 composite catalysts were prepared by hydrolysis of titanium n-butoxide (Ti(0Bun)4 in microemulsion and Sol-gel process. These composites were charactered by using BET, XRD, FT-IR, DRS and TG-DTA measurements. The photocatalytic activity of the catalysts was investigated by photodegrading the target pollutants of Methyl blue (MB).The TiO2-SiO2 composite catalysts in pure anatase phase with crystallite 9 to 12 nm were produced by microemulsion. The XRD and BET results show that with increasing of the calcination temperature and the TiO2 content, the crystallite size increased, and BET surface area and pore volume decreased. The addition of silica gel could effectively improve the thermal stability of TiO2-SiO2 composite and suppress the formation of rutile phase and the growth of titania crystals during the calcination treatment. The TiO2-SiO2 composite catalysts show much better photocatalytic activity than that of naked TiO2. Among of these catalysts, the 31 wt% TiO2-SiO2 composite catalysts (ME-2) shows best photocatalytic activity, its rate constant attach to 0.0432 min-1 Although the rate constant of P25 is higher than ME-2's, the UV-Vis spectras of Methylene blue (MB) solution which was irradiated by UV light in the presence of catalysts for 90 min showed no absorption by ME-2 and higher absorption by P25 from 200 to 400 nm. In addition to this, the solution with ME-2 is easier to be filtrated than P25. The alkali metals, alkaline earth and transition-metal were doped in ME-2 catalyst by the same method, the results show these metals could not improve the photocatalytic activity of the catalysts.The TiO2-SiO2 composite catalysts were prepared by sol-gel process with different solvent of ethanol and nitric acid respectively. The TiO2-SiO2 composite catalysts with ethanol (ETS) formed the gels by aging, other (NTS) formed the gels by adjusting the pH value. The XRD patterns of ETS show better crystallinity than NTS. The BET surface area of NTS decreased with the calcination temperature increasing, but ETS changed small from 600 to 900 ℃. When the calcination temperature attach to 1000 ℃, the BET surface area rapidly decreased because the...
Keywords/Search Tags:TiO2-SiO2 composites catalyst, Microemusion method, Sol-gel, Nitric acid, Ethanol, Photocatalytic, Methylene blue
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