Deposit, Doping And Photocatalytic Activity Of Fibrous TiO₂

High activity TiO₂ and its composite catalyst were prepared by Atmospheric PressureChemical Vapor Deposition (APCVD) in this paper. Catalysts were characterized usingvarious techniques. The photocatalytic activity of prepared catalysts was determined byphotocatalytic oxidation of phenol in water using UV light (20W, 254nm) and shallow pondreactor. The main research contents and conclusions are as follows:(1) TiO₂ fibers were synthesized by APCVD method, using activated carbon fiber (ACF)as template. Titanium tetrachloride (TiCl₄) was used as precursor in the experiment. Theeffects of the deposition temperature, carrier gas flux and deposition time on the structure,morphology and yield of TiO₂ fibers were studied systematically. The catalysts werecharacterized by SEM, TEM, XRD and physisorption analyser. The optimal preparationcondition was as follows: deposited at 200℃, the carrier gas flux of TiCl₄ and water vaporwere 50mL/min and 200mL/min respectively, the deposition time was 1h. The TiO₂ particlesof the hollow fibers prepared on this condition were in the anatase phase, and the specificsurface area reached 84.34m²/g. There were large amount of micropore, some mesopore andless macropore in the catalyst and the micropore size and mesopore size was 1nm and 6.17nmrespectively. The fibers had better photocatalytic activity when the applied TiO₂ concentrationwas 0.10g/L. The best conversion rate of phenol with primary concentration of 50mg/L underUV reached more than 70% in 2.5h.(2) TiO₂ fibers were prepared by APCVD method using qualitative filter paper astemplate. The catalysts were characterized by XRD and TEM. The effect of depositiontemperature on the photocatalytic activity of TiO₂ fibers was studied. The particle size ofTiO₂ deposited at 100℃was about 30nm. The catalyst was all in anatase phase. The bestconversion rate of phenol with primary concentration of 50mg/L under UV reached 57.29% in2.5h.(3) SnO₂ fibers and SnO₂/TiO₂ fibers were synthesized by APCVD method, using ACFas template. Stannic chloride (SnCl₄) and TiCl₄ were used as precursors in the experiment.The catalysts were characterized by SEM and TEM. The influence of catalysts with differenttheoretic molar ratio of SnCl₄ and TiCl₄ on the photocatalytic activity was studied. When thevalue was 0.05, the phenol conversion rate with primary concentration of 50mg/L under UVreached 76.25% in 2.5h. (4) Ag/TiO₂ and CeO₂/TiO₂ photocatalyst were prepared using a photocatalytic reductionmethod and impregnation respectively. The catalysis activities of Ag/TiO₂ and CeO₂/TiO₂varied with different doping amount and presented an optimum value. The phenol conversionrate reached 77.15% in 2.5h under UV, which was highest with Ag deposition time of 10minute. The best phenol conversion rate was 74.21%, with 1.0% CeO₂ doping amount.(5) Catalysts deposited on ACF were prepared by APCVD method using TiCl₄ asprecursor. The catalysts were characterized by SEM. It was found that the TiO₂ film on thesubstrate was uniform. The catalytic activities of TiO₂/ACF were tested by phenol (50mg/L)degradation under UV in 2.5h, and the best value reached 77.46%.