光催化剂的制备与有机物降解机理关系研究

发布时间：2018-01-07 23:15

本文关键词：光催化剂的制备与有机物降解机理关系研究　出处：《沈阳理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：在催化剂制备方面,本课题主要采用溶胶-凝胶法制备出了Ti O2和Sr Ti O3两种粉末光催化剂,对主要的制备条件进行优化后,分别以0.5HZSM-5和0.3HZSM-5作为二者的载体,制备负载型催化剂,考察负载量对光催化剂结构和活性的影响,以获得性能优越的负载型光催化剂,通过XRD、SEM、FT-IR、BET和BJH等表征手段进行深入分析。在有机物降解机理方面,本课题主要研究不同负载量的光催化剂对苯酚和活性艳红X-3B的降解机理,通过UV-Vis、FT-IR和TOC等分析手段进行深入分析。主要实验研究分为以下四部分:(1)以钛酸四丁酯为钛源,0.5 mol/L的H3PO4改性的HZSM-5为载体,采用溶胶凝胶法制备了纯Ti O2以及χTi O2/0.5HZSM-5。结果表明,样品中的Ti O2主要以锐钛矿的形式存在,负载能够降低Ti O2的晶粒尺寸。负载型催化剂具有较大的比表面积,孔径分布范围宽。随着负载量逐渐增加,催化剂比表面积呈现减小的趋势。(2)以钛酸四丁酯为钛源,硝酸锶为锶源,0.3 mol/L的HCl改性的HZSM-5为载体,采用溶胶-凝胶法制备了纯Sr Ti O3以及χSr Ti O3/0.3HZSM-5。结果表明,样品中的Sr Ti O3主要以钙钛矿的形式存在,负载之后Sr Ti O3晶粒尺寸基本没有变化。负载量越大比表面积就越小。负载之后孔径分布范围宽,表现为多级孔道,主要是大孔和介孔结构。(3)采用制备的两类催化剂对活性艳红X-3B进行光催化降解并研究降解历程,光照30 min,50%Ti O2/0.5HZSM-5对活性艳红X-3B的降解率最高,达到40.7%,比纯Ti O2的26.4%提高了14.3%。30%Sr Ti O3/0.3HZSM-5对活性艳红X-3B的降解率最高,达到30.6%,比纯Sr Ti O3的3.5%提高了27.1%。推测羟基自由基首先攻击的是-NH-中的N原子,并且分解开的物质会继续氧化生成醛和酸等小分子物质;萘醌被氧化为邻苯二甲酸,然后被降解为小分子酸或醛。含氯基团被氧化成含氯有机物,但延长反应时间,大部分有机氯能完全转化为Cl-,小分子的酸或醛被进一步氧化为CO2和H2O,最后剩余不可光催化降解的物质。(4)采用制备的两类催化剂对苯酚进行光催化降解并研究降解历程,光照30min,50%Ti O2/0.5HZSM-5对苯酚溶液的降解率最高,达到44.4%,比纯Ti O2的25.5%提高了18.9%。30%Sr Ti O3/0.3HZSM-5对苯酚溶液的降解率最高,达到32.2%,比纯Sr Ti O3的15.7%提高了16.5%。推测羟基自由基首先攻击苯酚中的苯环,并附着在苯环上形成苯二酚,苯二酚被氧化成苯醌,然后苯环被打开降解成小分子的酸或醛,进一步氧化成CO2和H2O,经一定时间可完全降解。
[Abstract]:In the aspect of catalyst preparation, two kinds of powder photocatalysts, TIO _ 2 and Sr _ 2O _ 3, were prepared by sol-gel method, and the main preparation conditions were optimized. The supported catalysts were prepared using 0.5HZSM-5 and 0.3HZSM-5 as the supports, respectively. The effects of loading amount on the structure and activity of photocatalyst were investigated. In order to obtain the supported photocatalyst with superior performance, the mechanism of organic matter degradation was analyzed by means of XRDD-SEMT-IRT-BET and BJH. In this paper, the degradation mechanism of phenol and reactive brilliant red X-3B by different amount of photocatalyst was studied, and the degradation mechanism of phenol and reactive brilliant red X-3B was studied by UV-Vis. The main experimental research is divided into the following four parts: 1) using tetrabutyl titanate as titanium source. The pure TIO _ 2 and 蠂 TIO _ 2 / 0.5 HZSM-5 were prepared by sol-gel method on HZSM-5 modified by 0.5 mol/L H _ 3PO _ 4. The results showed that the pure TIO _ 2 and 蠂 _ 2O _ 2 / 0.5 HZSM-5 were prepared. The TIO _ 2 in the sample mainly exists in the form of anatase, and the loading can reduce the grain size of TIO _ 2, and the supported catalyst has a large specific surface area. The pore size distribution range is wide. With the increase of loading amount, the specific surface area of the catalyst decreases. 2) tetrabutyl titanate is used as titanium source and strontium nitrate as strontium source. The HCl modified HZSM-5 of 0.3 mol/L was used as the carrier. Pure Sr TIO 3 and 蠂 Sr TIO 3 / 0.3 HZSM-5 were prepared by sol-gel method. Sr TIO 3 in the sample mainly exists in the form of perovskite. After loading, the grain size of Sr TIO 3 does not change. The larger the loading amount is, the smaller the specific surface area is. The pore size distribution range is wide after loading, and the pore size distribution is multistage. The photocatalytic degradation of reactive brilliant red X-3B was carried out with macroporous and mesoporous structure. The photocatalytic degradation of reactive brilliant red X-3B was studied under light irradiation for 30 min. The degradation rate of reactive brilliant red X-3B by 50 TIO _ 2 / 0.5 HZSM-5 was the highest, reaching 40.7%. Compared with pure TIO _ 2 26.4%, the degradation rate of active brilliant red X-3B was the highest (30.6%). The degradation rate of 0.3HZSM-5 was higher than that of pure TIO _ 2. 30 Sr TIO _ 3 / 0.3HZSM-5 was higher than that of pure TIO _ 2. Compared with 3.5% of pure Sr TIO 3, it is suggested that the first attack of hydroxyl radical is the N atom in -NH-. And decomposed substances will continue to oxidize to aldehydes and acids and other small molecules; Naphthoquinone was oxidized to phthalic acid and then degraded to small molecular acid or aldehydes. Chlorinated groups were oxidized to chlorinated organic compounds but most of the organic chlorine could be completely converted to Cl- when the reaction time was prolonged. The acids or aldehydes of small molecules were further oxidized to CO2 and H _ 2O. Finally, the remaining non-photocatalytic degradation of phenol was carried out using two kinds of catalysts prepared and the degradation process was studied. The degradation rate of phenol solution was the highest (44.4%) after 30 min irradiation with 50% TIO _ 2 / 0.5 HZSM-5. Compared with pure TIO _ 2 25.5%, the degradation rate of phenol solution by 18.90.30Sr TIO _ 3 / 0.3HZSM-5 was the highest, up to 32.2%. It is suggested that hydroxyl radicals attack the benzene ring in phenol at first and attach to the benzene ring to form dihydroxybenzene, which is oxidized to benzoquinone. Then the benzene ring was opened and degraded to a small molecule of acid or aldehydes, which was further oxidized to CO2 and H _ 2O, and could be completely degraded after a certain time.
【学位授予单位】：沈阳理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ426;X703

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