【作者】 王宽岭；

【导师】 张文杰；

【作者基本信息】 沈阳理工大学 ， 环境工程， 2010， 硕士

【摘要】 在本项研究中,采用溶胶凝胶法成功地制备了TiO₂;以不同浓度盐酸改性NaZSM-5分子筛制得的HZSM-5作为载体,制得负载型TiO₂,并在此基础上研究了掺杂金属离子对负载在HZSM-5分子筛表面的TiO₂光催化性能的影响。测试结果表明:通过分子筛的负载和铁离子掺杂,提高了TiO₂的光催化活性。在乙醇体系中,以钛酸丁酯作钛源、乙醇作溶剂、浓盐酸作催化剂,采用溶胶凝胶法制备出TiO₂。获得性能最佳的TiO₂催化剂的工艺条件为:钛酸丁酯、水、乙醇、浓盐酸的体积比例是1:0.3:3:0.1,500℃煅烧2h。以不同浓度盐酸处理的NaZSM-5得到不同的HZSM-5分子筛,然后再负载TiO₂,考察了盐酸改性对NaZSM-5分子筛作为TiO₂载体的影响,通过光催化实验结果表明:通过盐酸改性,提高了TiO₂/NaZSM-5对甲基橙的吸附和光催化性能,确定了NaZSM-5分子筛的最佳的盐酸处理浓度0.3mol/L,TiO₂最佳负载量为30%;在400℃煅烧2h的催化剂光催化活性最好,回收且重复利用四次,光催化降解的效果基本不受影响,为初次使用效果的82.4%。利用扫描电镜、X射线衍射、红外光谱和X射线光电子能谱对催化剂进行了表征,结果表明:负载TiO₂后HZSM-5分子筛颗粒发生了团聚,TiO₂包覆在分子筛颗粒的外表面;30%TiO₂/HZSM-5中主要是锐钛矿型TiO₂,HZSM-5可提高TiO₂分散性能,降低TiO₂晶粒的尺寸;TiO₂与HZSM-5没有发生明显的化学键合作用;TiO₂和30%TiO₂/HZSM-5中,钛以四价钛的形式存在,氧化物的组成为TiO₂。通过掺杂Fe离子提高了TiO₂和30%TiO₂/HZSM-5的光催化活性,Fe-TiO₂的最佳掺杂比为Fe/Ti的摩尔比为0.05%;30%TiO₂/HZSM-5最佳掺杂比为Fe/Ti的摩尔比为0.07%。通过表征显示:Fe³⁺的引入不足以改变TiO₂的表面形貌;铁离子的掺入并未影响TiO₂的晶型结构,但是可以提高TiO₂的晶型转变温度;掺杂铁离子后TiO₂与HZSM-5也没有发生明显的化学键合作用。更多还原

【Abstract】 In this paper, titanium dioxide was synthesized by acid-catalyzed sol-gel method, and then metal ions doped TiO₂ photocatalyst supported on zeolite was obtained. The experimental results showed that, the photocatalytic activity of TiO₂ was improved through being loaded onto zeolite and doped with Fe³⁺.In the alcohol system, the sol for TiO₂ was prepared with tetrabutyl titanate as precursor, alcohol as solvent, and HCl as catalyst. The optimum photocatalytic activity of the samples was obtained after being calcinated at 500℃for 2h and at the condition that the volume ratio of tetrabutyl titanate: alcohol:H2O:HCl was 1:0.3:3:0.1.TiO₂/HZSM-5 nano-composite photocatalysts were prepared by dispersing TiO₂ onto the external surface of HCl-modified ZSM-5 zeolite using the sol-gel process. Effects of HCl modification on NaZSM-5 zeolite as a carrier of TiO₂ were investigated. Results showed that the adsorption ability and photocatalytic degradation activity of TiO₂/HZSM-5 nano-composites was better than that of bare TiO₂, giving the optimum value of 0.3mol/L. However, HZSM-5 zeolite was not of photocatalytic activity, the optimum photocatalytic activity for the samples with 30% TiO₂ was obtained after being calcinated at 400℃for 2h. The repeatability of photocatalytic activity was also tested and the decolorization rate was 82.4% of initial decolorization rate after four cycles. These materials were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR）, and X-ray photoelectron spectroscopy （XPS） measurements. Results showed that modification of support by HCl did not change the surface morphology and structure of ZSM-5 zeolite. All the samples calcined at 400℃presented anatase structure. Supporting on HZSM-5 improved the dispersion of TiO₂, and restrained the increase of crystalline size. Ti-O-Si bonds were not formed between the HZSM-5 bulk and the supported TiO₂. The titanium was in the oxidation state of Ti⁴⁺, and the oxygen was in the form of O^2- in both TiO₂ and SiO₂.The results showed that doping of Fe³⁺ enhanced the photocatalytic activity of TiO₂ and 30%TiO₂/HZSM-5, and the optimum Fe³⁺ doping of Fe/Ti mole ratios for TiO₂ and 30%TiO₂/HZSM-5 were 0.05% and 0.07%, respectively. Doping Fe³⁺ did not change the surface morphology of TiO₂ and 30%TiO₂/HZSM-5, but inhibited phase transformation of TiO₂ from anatase to rutile, Ti-O-Si bonds were not formed between the HZSM-5 bulk and the supported TiO₂ either.更多还原