【作者】 孙梦君；

【导师】 柳丽芬；

【作者基本信息】 大连理工大学 ， 环境工程， 2007， 硕士

【摘要】 采用TiO₂改性光催化方法对目标污染物甲苯进行降解,针对在日常居住环境内,挥发性有机气体污染物浓度低,分布不均匀的问题,对TiO₂催化剂一方面进行掺杂改性以提高光催化效率,另一方面进行吸附改性以提高催化剂对低浓度污染物的吸附能力;以钛酸四丁酯为主要原料,制备了Ag⁺/TiO₂,电气石/TiO₂,Ce-1%-TiO₂,β-CD修饰的Ce-1%-TiO₂薄膜催化剂;通过X射线衍射（XRD）、透射电镜（TEM）、扫描电镜（SEM）等分析手段对催化剂进行表征,并考察了催化剂光催化脱除空气中甲苯的活性及催化过程中的主要影响因素。（1）采用溶胶-凝胶法制备了负载于不锈钢网上的Ag⁺/TiO₂薄膜光催化剂,通过XRD、TEM对粉末催化剂分析得知,催化剂为锐钛矿型,平均粒径约为8nm。通过使催化剂在紫外杀菌灯照射下光催化流动体系中的甲苯来考察催化活性,分析结果表明:①在流动体系中光催化氧化方法处理甲苯,随着掺杂量的增加,最终获得的去除率将越高,掺杂量为4%,去除率达54.99%;②同一种催化剂在处理初始浓度分别为226mg·m^-3、70mg·m^-3的甲苯时,最终都是在动态反应器中获得较高去除率,分别为54.99%,37.02%。（2）以溶胶-凝胶法和直接混合法制备了两种负载于不锈钢网上的电气石/TiO₂复合催化剂薄膜。经溶胶-凝胶法制得的电气石粉/TiO₂催化剂,在静态反应器中对初始浓度分别为180mg·m^-3、70 mg·m^-3甲苯去除率（反应4小时）都达80%以上,表明电气石复合催化剂由于溶胶制备阶段对催化剂的影响,得到的催化剂晶粒更小;相同条件下,直接混合法制备的电气石/TiO₂催化剂去除率分别为65.1%、65.0%,这是因为电气石在光催化阶段的弱电场作用提高了光催化净化甲苯的效果。（3）以溶胶-凝胶法制备Ce-1%-TiO₂催化剂;进一步吸附β-CD得到表面修饰的以不锈钢网为载体的薄膜负载催化剂。该催化剂膜对初始浓度为70 mg·m^-3的甲苯气体（反应4h～5h）,去除效果达100%,且重复使用第三次后处理效果仍为100%,而对于初始浓度为97 mg·m^-3的中等浓度甲苯气体,处理效果也可达100%,对初始浓度为208 mg·m^-3的高浓度甲苯气体,处理效果也达80%以上。表明环糊精表面修饰改性催化剂比未修饰改性催化剂具有较高的催化活性和更高的甲苯氧化净化效果。更多还原

【Abstract】 Photocatalysis is a new technology extensively studied for the degradation of VOCs in the house recently.The research efforts of this field are focused on improving the efficiency of photocatalytic VOC removal by preparing high activity catalysts or combining adsorbents with photocatalyst.So,this rearch using Ag or Ce modification and tourmaline composite photocatalyst,as well as beta-CD modification to increase adsorption of low concentration toluene,and increase toluene removal efficiency from air.The photocatalysts were prepared, characterized with XRD,TEM,SEM,and the influencing factors for the toluene-removal were investigated.（1） TiO₂-photocatalysts doped with Ag⁺ is prepared with sol-gel method on stainless steel net.The results of XRD and TEM show that the crystal structure of catalysts are of anatase type,and the average size of TiO₂ particles is about 8nm.The oxidation and reduction capability of the thin film have been studied from the removal of toluene in the flowing reactor.Some important factors such as different doping concentration of Ag⁺,different initial concentration of toluene are discussed.The result show that the removal of toluene is 54.99% when the 4%-Ag⁺/TiO₂ is used.To initial concentration of toluene at 226mg·m^-3,70mg·m^-3,the removal of toluene are 54.99%and 37.02%with a better result in the flowing reactor.（2） The tourmaline powders is either mixed to the sol during sol-gel preparation or with P-25 suspension to coat stainless steel net.By using the sol-gel -prepared catalyst,more than 80%toluene removal is obtained when initial concentration either high or low after 4 hours reaction;and the removal of toluene were 60.02%,and 48.06%when the mixed- prepared catalyst is used.Tourmaline addition in the sol gel stage affected crystal size of the prepared composite catalyst,thus increased photocatalytic activity,while the weak electric field effect of the composite catalyst containing tourmaline increased oxidation rate of toluene.（3） Ce-1%-TiO₂ is prepard in sol-gel method;then the immobilized catalyst is dipped in theβ-cyclodextrin（CD） solution to adsorbβ-CD.With the CD modified catalyst,in about 4-5 hours reaction time,100%toluene removal was obtained when the initial toluene concentration was 70mg·m^-3 and the removal rate was still 100%when the catalyst is used repeatedly for a third time.To initial concentration of toluene at 97mg·m^-3,100%toluene removal is obtained and to the high initial concentration of toluene(～208mg·m^-3),80% toluene removal was also obtained usingβ-CD modified Ce-1%-TiO₂.The results indicate CD modified photocatalyst had higher activity in photocatalytic oxidation of toluene,than the un-modified catalyst.更多还原