The nanosized beta zeolite (BEA) prepared using organic precursors was used to synthesize TiO₂-BEA composite by a simple impregnation of titanium isopropoxide (15 wt% TiO₂) with uncalcined BEA sample. Then, the Ti-BEA composite was modified with different precious metals (0.25 wt% of Ag, Pd and Au) to obtain photocatalysts, which could work under visible light irradiation. The physico-chemical properties of the synthesized composites were analyzed by powder XRD, FTIR, TEM, DRS UV–vis, XPS and N₂-physisorption methods The modification of precious metals reinforced the formation of pure anatase phase. The XRD and TEM results demonstrated that, in combination of BEA and TiO₂ retarded the formation of large size crystals of Pd and Ag with a grain size (∼5 nm), however formation of Au nanoparticles in Au modified Ti-BEA composite was observed. The photocatalytic efficiency of the samples was evaluated using malachite green under visible light irradiation. Au modified Ti-BEA sample was found to exhibit higher photocatalytic activity than Pd and Ag modified samples, bare Ti-BEA and Degussa anatase. The observed high photocatalytic activity under visible light is due to the low band gap energy calculated for Au-Ti-BEA sample (2.27 eV) in comparison with 2.54 eV and 3.46 eV for Pd-Ti-BEA and Ag-Ti-BEA samples respectively. Additionally, the presence of relatively big crystalline Au metal particles on the surface to suppress the electron-hole recombination during the reaction. The synthesized composite catalysts can be easily separable and reused for six cycles without losing any photocatalytic activity.

使用有机前体制备的纳米级β沸石（BEA）用于通过用未煅烧的BEA样品简单浸渍异丙氧基钛（15 wt％TiO ₂）来合成TiO ₂ -BEA复合材料。然后，用不同的贵金属（Ag，Pd和Au的重量百分比为0.25）对Ti-BEA复合材料进行改性，以获得可以在可见光照射下工作的光催化剂。通过粉末XRD，FTIR，TEM，DRS UV-vis，XPS和N _2-物理吸附法分析了合成的复合材料的理化性质。贵金属的改性加强了纯锐钛矿相的形成。XRD和TEM结果表明，BEA和TiO _{2结合使用}阻碍了Pd和Ag晶粒尺寸（〜5 nm）的大尺寸晶体的形成，但是观察到Au修饰的Ti-BEA复合材料中Au纳米颗粒的形成。使用孔雀石绿在可见光照射下评估样品的光催化效率。发现Au修饰的Ti-BEA样品比Pd和Ag修饰的样品，裸露的Ti-BEA和Degussa锐钛矿具有更高的光催化活性。在可见光下观察到的高光催化活性是由于Au-Ti-BEA样品计算出的低带隙能量（2.27 eV），而Pd-Ti-BEA和Ag-Ti-BEA样品分别为2.54 eV和3.46 eV 。另外，在表面上存在较大的结晶Au金属颗粒以抑制反应期间的电子-空穴复合。