溶胶-凝胶法制备复合M_xO_(y-)TiO_2光催化剂

Preparation of M_xO_(y-)TiO_2 Photocatalysts by Sol-gel Method

以无机盐 TiCl4为原料制备 TiO_2溶胶 ,并利用溶胶胶粒修饰法制备 SiO_2-TiO_2、 ZrO_2-TiO_2、 WO_3-TiO3、 MoO3-TiO_2及 Pt/TiO_2光催化剂 ,用于光催化氧化甲醛反应 ,考察添加物对催化剂光催化性能的影响 .其中 ,SiO_2-TiO_2催化剂的光催化氧化降解甲醛性能最好 ,而 MoO_3-TiO_2的催化性能最差 .SiO_2-TiO_2催化剂优良的光催化性能可归于 SiO_2-TiO_2催化剂的高比表面积 ,高空隙率 ,小晶粒粒径和强吸光性能等性质的综合影响 .

Titania sols were prepared by acid hydrolysis of a TiCl_4 precursor and mixed oxides SiO_2-TiO_2,ZrO_2-TiO_2,WO_3-TiO_3 and MoO_3-TiO_2 as well as Pt/TiO_2 catalysts for the photocatalytic oxidation of formaldehyde were obtained by using the method of the modification of sol particles.The influence of the additives on the photocatalytic activity was investigated.Comparing with pure TiO_2,the addition of silica or zirconia increased the photocatalytic activity,while the addition of Pt and MoO_3 decreased the activity,and the addition of WO_3 had little effect on the activity.Among these catalysts,the activity of the SiO_2-TiO_2 catalyst was the best while that of the MoO_3-TiO_2 catalyst was the worst.It is of great significance that the conversion of formaldehyde was increased up to 94％ over the SiO_2-TiO_2 catalyst.The increased activity of the SiO_2-TiO_2 catalyst was due to the higher surface area and porosity,the smaller crystallite size and the stronger adsorption of UV light.A comparison of our catalyst compositions with those in the literature suggested that the difference in activity due to the addition of a second metal oxide maybe caused by the surface chemistry of the catalysts,particularly the acidity.