稀土杂多酸改性TiO_2/分子筛纳米光催化剂的制备及性能

Preparation and Photocatalytic Activity of Multicomponent Nano-TiO_2/Zeolite Modified by Rare Earth and Heteropolyacid

采用Sol-Gel法制备了以Y-分子筛为载体,La和H3PW12O40（PW12）改性的TiO2纳米光催化剂（ZLP-TiO2）,通过BET,XRD,XPS,EDX,HRTEM,UV-Vis和Raman光谱对其结构进行表征,催化剂具有Langmuir IV吸附-脱附等温线,平均孔径为3.859 nm,分布在3~8 nm之间,比表面积102.4 m2.g-1。经700℃焙烧后催化剂保持完整的锐钛矿相,La3＋和PW12的改性提高了TiO2的晶相转变温度。EDX和XPS表明,催化剂由Ti,O,La,P,W,Si,Al组成。用亚甲基蓝（MB）溶液的降解评价其光活性。在1 mol TiO2中,当La3＋和PW12的掺杂量分别为0.005和0.001 mol时催化剂的活性较高。当催化剂经600℃焙烧3 h,用量为0.2 g时,在125 W Hg灯照射120 min后,50 ml的MB（40 mg.L-1）脱色率可达98%。随着pH值的增大,MB在催化剂表面的吸附也增大。催化剂重复利用4次后,脱色率仍达95%。

The La and H3PW12O40（PW12） modified TiO2 nanocatalysts（ZLP-TiO2） were prepared by the Sol-Gel method using zeolite-Y as a carrier,and characterized by BET,XRD,XPS,EDX,HRTEM,UV-Vis and Raman.The N2 adsorption-desorption isotherms were characteristic of a type Langmuir IV isotherm.The catalyst had homogenous pore-size distribution（the average pore-size 3.859 nm） and higher specific surface area（102.4 m2·g-1）.The catalyst calcined at 700 ℃ indicated the anatase phase absolutely.The conversion temperature of crystal phase was increased with doping La3＋ and PW12.The EDX and XPS indicated that the sample was made up of Ti,O,La,P,W,Si and Al.The photocatalytic activity of the ZLP-TiO2 was evaluated by the degradation of methylene blue（MB） under UV light irradiation.When La3＋ and PW12 were doped by 0.005 mol and 0.001 mol respectively in 1 mol TiO2,the photocatalyst had the highest activity.The decoloration rate of 50 ml MB（40 mg·L-1） could reach 98% in irradiation time 120 min with 0.2 g catalyst and 125 W Hg lamp.It was of beneficial to degrade for MB due to its more adsorption on the catalyst surface with the pH increase.The decoloration rate could still reach 95% after the catalyst recycled for 4 times.