駱尚廉臺灣大學:環境工程學研究所歐信宏Ou, Hsin-HungHsin-HungOu2010-05-102018-06-282010-05-102018-06-282008U0001-2902200814200300http://ntur.lib.ntu.edu.tw//handle/246246/181526儘管以TiO2為主之光催化程序多年來已被廣泛地討論與探究，然仍因其高度穩定性與低耗費等優點而不失為一引人入勝之綠色科技。近年來，利用TiO2所衍生出之氧化鈦奈米管(titanate nanotubes, TNTs)由於其高比表面積而持續受到多方關注。但利用傳統水熱法合成TNTs常需20小時以上之合成時間才可以得到完整之管狀結構。因此，本研究旨在利用微波水熱法嘗試增加其合成動力，並探究微波能於其物化特性之影響。而微波型TNTs之光催化潛勢亦以液相氨氮與氣相三氯乙烯作為模擬污染物進而評估其光催化程序之可行性。130℃與90分鐘之水熱合成條件下，傳統水熱法與微波水熱法所得到之比表面積分別為76 與 256 m2g-1。此結果顯示所輸入之微波能可大幅增加TNTs之合成動力。再者，微波型TNTs之結構傾向於NaxH2-xTi3O7，其中之Na/H比則由所輸入之微波能所主導。此現象可經由多種分析技術所證明，諸如XRD晶相圖、氨氣程溫脫附實驗、X射線光電子電譜等。而對於後熱程序對於TNTs之結晶行為而言，結構內具較多氫離子之TNTs會經由[TiO6]之重組堆疊而形成anatase晶相；而當TNTs具有較多之鈉離子時，經700℃燒結後會形成柱狀結構之Na2Ti6O13。Na2Ti6O13內之(Ti6O13)2-為TNTs結構內之(Ti3O7)2-層經由拓樸聯結沿著[110]方向所結合而成。於TNTs之光催化潛勢而言，TNTs晶相對水中氨氮並無強大之光催化能力，然結構內若有rutile晶相存在時，則可提升其光催化效能。而經酸洗後之TNTs則因為其離子交換能力之增強而可提升其光催化效能。此因素為除酸洗可促進TNTs結構內之rutile晶相成長外，藉由離子交換而置入TNTs結構內之氨氮則可避免因過度負載觸媒量所造成之遮蔽效應。而當利用TNTs作為TCE降解之測試觸媒時，TCE之降解速率會隨著TNTs之燒結溫度而提升(100~500℃)。此為因經燒結後之TNTs具有強度明顯之anatase晶相，再者多種晶相的呈現可造就電子傳遞效應而提升光催化效率。而當利用Pt,Pd修飾經TNTs燒結所得TiO2顆粒時，實驗結果說明Pt與Pd之參與皆會造成TCE光降解之效率變低，尤以Pd顆粒之影響為深。此為因Pd顆粒與TiO2之氧原子半徑相似而鍵入TiO2結構內而導致內部氧原子移動率不佳。再者，Pt對TCE光降解之中間產物DCAC與phosgene的生成並無影響，Pd則傾向選擇phosogene之生成與具有較高礦化率之特性。綜言之，微波型TNTs雖無強勢之光催化潛勢與離子交換能力，然其仍可藉由此兩功能並存之特性應用於多種領域中。Despite TiO2-based photocatalysis has been extensively investigated and examined over the past decades, it is still a highly engrossing technology owing to the stability and low cost. Recently, TiO2-induced titanate nanotubes (TNTs) have received much attention as a result of high specific surface area. Traditional method in fabricating TNTs, however, needs at least 20 hr reaction time to achieve a perfect tube structure. Therefore, this research aimed to the rapid formation kinetics of TNTs with the aid of microwave irradiation and attempted to investigate the effect of microwave irradiation on the characterization of titanate nanotubes (microwave-induced TNTs). Photocatalytic behavior of microwave-induced TNTs towards the degradation of gaseous trichloroethylene (TCE) and aqueous ammonia (NH3/NH4+) were also examined to survey the photocatalytic potential of microwave-induced TNTs.ased on the performance of BET surface area (SBET), TNTs synthesized at 130℃ for 1.5 hr with and without 400W irradiation presented the SBET of 256 and 76 m2g-1, respectively. The result indicates that the formation kinetics of TNTs is significantly enhanced via microwave hydrothermal treatment. The microwave-induced TNTs are preferentially assigned for NaxH2-xTi3O7 whose Na/H ratio is dominated by the applied lever of microwave irradiation during fabrication process. This phenomenon can be evidenced by various determinations including powder X-ray diffraction, NH3-temperature programmable desorption, X-ray photoelectron spectroscopic, and ionic coupled plasma-atomic emission spectrometry. Regarding the behavior of TNTs after thermal treatment, TNTs with abounding H atoms presented anatase phase at 500℃ through rearrangement and restacking of [TiO6]. The sintered TNTs synthesized under high irradiation power presented the rod shape at 700℃ which mainly comprise of Na2Ti6O13. The (Ti6O13)2- unit within Na2Ti6O13 is constructed by two (Ti3O7)2- layers within TNTs via the topotactical connection along the [110] direction during thermal process.s for the photocatalytic potential of TNTs, a pure TNTs phase presents no powerful ability towards photocatalytic NH3/NH4+ while the photocatalytic efficiency can be enhanced with the presence of rutile phase within TNTs. Regarding the effect of acid-washing treatment on TNTs, the acid-treated TNTs with enhanced ion exchangeability considerably improve the NH3/NH4+ degradation and NO2-/NO3- yields. This result is likely ascribed to the easy intercalation of NH3/NH4+ into the structure of acid-washing TNTs so that the photocatalytic oxidation of intercalated NH3/NH4+ is not limited to the shielding effect resulting from the overload of TNTs. In the case of photocatalytic TCE over TNTs, the efficiency of TCE degradation enhances with increasing sintering temperature until 700℃。This phenomenon is attributed to the recrystallization of anatase phase and the construction of inter-particle electron transfer effect. Photocatalytic TCE over Pt/Pd doped TNTs-induced TiO2 was also investigated in terms of the effect of Pt and Pd on the TCE degradation and on the yields of dichloroacetyl chloride (DCAC) and phosgene. In the presence of Pt and Pd, the degradation of TCE was retarded; especially Pd had a significantly negative effect on TCE degradation, which was ascribed to the intercalation of Pd into the lattice of TiO2. Moreover, Pt had no influence on the selectivity toward DCAC and phosgene while the selectivity toward phosgene in the presence of Pd was enhanced. As for the behavior of Pt and Pd in TCE degradation, Pt doped TiO2 exhibited the same photocatalytic behavior as P25 TiO2 whereas Pd doped TiO2 led to a different photocatalytic mechanism. Although microwave-induced TNTs have no powerful ability in photocatalysis and ion exchange, they can still be considered as a potential material in some applications owing to the corresponding bi-functions.目錄試委員審定書……………………………………………………………...Ⅰ謝…………………………………………………………………………...Ⅱ文摘要……………………………………………………………………...Ⅲ文摘要……………………………………………………………………...Ⅴ錄…………………………………………………………………………...Ⅷ目錄………………………………………………………………………..ⅩI目錄……………………………………………………………………..…XV一章 緒論…………………………………………………………………..1-1 研究緣起……………………………………………………………1-2 研究目的……………………………………………………………2-3 研究內容……………………………………………………………2二章 文獻回顧……………………………………………………..………5-1 三氯乙烯之基本物化特性………………………………..…………5-2 微波理論………………………………………………………...….12 2-2-1 微波原理……………………………………………………….12 2-2-2 溶液於微波場之反應………………………………………….12 2-2-3 固相樣品於微波場之反應與微波合成……………………….14-3氧化鈦奈米管制程、應用與特性介紹.………………………..…...14 2-3-1 氧化鈦奈米管製成比較……………………………………….14 2-3-2 水熱法合成氧化鈦奈米管………………………………….…15-3-3 水熱法氧化鈦奈米管之形成機制………………………….…20-3-4 水熱法氧化鈦奈米管之修飾與應用性…………………….…23三章 材料與方法…………………………………………………………30-1實驗藥品與設備………………………………..….....……….…….30 3-1-1 藥品…………………………………………………………….30 3-1-2 設備…………………………………………………………….31-2實驗方法……………………………...…………………..…………35 3-2-1 氧化鈦奈米管製備…………………………………………….35 3-2-2 TiO2/Pt與TiO2/Pd之製備……………………………………35 3-2-3 光觸媒覆膜製作…………………………………………….....35 3-2-4 氧化鈦奈米管特性分析……………………………………….36 3-2-5 氣相TCE光催化反應實驗……………………………………38 3-2-6 液相NH3/NH4+光催化反應實驗…………………………...…39-3 分析系統及設備…………………………….………………...……39四章 實驗結果與討論……………………………………………….…..41-1 微波型TNTs之物化性鑑定………………………………...……...41-2 微波型TNTs之形成機制………………………….……………….52-3 微波型TNTs對液相NH3/NH4+之離子交換能力與光催化反應評估…………………………………………………………………...52 4-3-1 TNTs對液相NH3/NH4+之離子交換能力…………….……….52 4-3-2 TNTs對液相NH3/NH4+之光催化反應………………………..54 4-3-3 利用TNTs光催化降解NH3/NH4+之反應機制……………….61-4 微波型TNTs之後熱處理程序………………………….………….62-5 微波型TNTs對TCE之光催化效能……………………………….75-6利用Pd/Pt修飾熱處理TNTs所得到之TiO2奈米顆粒……...……..79-6-1 氧氣水氣之協同效應對DCAC與phosgene之生成影響與CE之光解機制…………………………………………………...79 4-6-2 Pd、Pt顆粒對TCE光降解機制之影響…………………………82-7 合成觸媒之綜合比較與說明………………………….…………...94五章 結論與建議……………………………………………...……….….96-1 實驗結論……………………………………………………………96-2 建議研究方向………………………………………...………… …97考文獻………………………………………….…………….…..………...98錄………………………………………………………………………….108目錄ig. 1-1. Framework of this research………………………...…………………4ig. 2-1. Conceptual diagram of interaction between water molecules and electromagnetic field: a. polarized molecules align in order with the presence of electromagnetic field b. polarized molecules return to disorder state without the presence of electromagnetic field…..…….13ig. 2-2 Structure models of (a) 2 x 2 unit cells of H2Ti3O7 on the [010] projection and (b) a layer of H2Ti3O7 on the (100) plane from which the nanotube is constructed. AA’ and AA’’ indicate the chiral vectors. Schematic diagrams show (c) the introduction of a displacement vector AA’ when wrapping up a sheet to form a scroll-type nanotube and (d) the structure of tritianate nanotubes. The crystal orientations indicated are the orientations according to the H2Ti3O7……………..21ig. 2-3 Schematic diagrams: (a) formation process of Na2Ti2O4(OH)2 and (b) mechanism for breaking of Na2Ti2O4(OH)2………………..……..…22 ig. 2-4. Research scenario of TNTs………….……………...……………….29ig. 3-1. Schematic diagram of Flat-Plate Photocatalytic Reactor (FPPR)…...33ig. 3-2. Schematic diagram of aquatic photocatalytic system……….………34ig. 3-3. Schematic diagram of temperature programmable reduction apparatus …………………………………………..………………...38ig. 3-4. The retention time of TCE, DCAC and phosgene based on the present conditions……...……………………………………………………..40ig. 4-1. The dependence of SBET on the synthesis conditions………...…...…42ig. 4-2. FE-SEM images for TNTs synthesized at (a)110℃, (b)175℃, (c) 130℃ for 3h under 400W, respectively, (d) TEM image of TNTs synthesized at 1300C for 3h under 400W and a cross-sectional view of as-synthesized TNTs in the insert……………………......…………..43ig. 4-3. The dependence of XRD patterns of TNTs on the synthesis conditions………………………………………………………….44ig. 4-4. XRD patterns of P25 and TNTs synthesized at 130℃ for 3hr under different irradiation power of 70W, 200W, 400W, and 700W…….…46 ig. 4-5. HR-TEM of TNTs-70W and TNTs-700W………………...……...…47ig. 4-6. NH3-TPD results for TNTs synthesized at different conditions……..49ig. 4-7. (a) Nitrogen adsorption-desorption isotherms (b) pore size distribution of the TNTs synthesized at 130℃ for 3hr under the irradiation power of 70W, 400W and 700W…………….…………………………………...50ig. 4-8. The normalized concentration of remaining NH3/NH4+ and exchange capacity as a function of the applied irradiation power during the fabrication of TNTs. The experimental conditions were [NH3/NH4+]ini = 25 ± 2.5 ppm; pH = 10 ± 0.2; air saturated. (The ordinate scale refers to the concentrations of NH3/NH4+ after 6 hr reaction normalized with respect to the initial NH3/NH4+ concentration)…………..…………….54ig. 4-9. Detailed view on the XRD patterns of WTNTs-70W, WTNTs-400W, WTNTs-700W, HTNTs-70W, HTNTs-400W, TNTs-700W within the 2θ of 22 ~ 320………………………………………….…………………..55ig. 4-10. Degradation of NH3/NH4+, the yields of NO2- and NO3- as a function of loading amount of (a) WTNTs-70W and (b) HTNTs-70W. The experimental conditions were [NH3/NH4+]ini = 25 ± 2.5 ppm; pH = 10 ± 0.2; air saturated; reaction time = 6 hr……………….…………………56ig. 4-11. X-ray photoelectron spectra (XPS) for (a) N 1s region of HTNTs-70W after reaction, (b) N 1s region of WTNTs-70W after reaction, (c) Ti 2p region of HTNTs-70W before and after reaction, and (d) O 1s region of HTNTs-70W before and after reaction……...…..….58ig. 4-12. Hypothetical scheme related to the photocatalytic oxidation of NH3/NH4+ over TNT structure………………………….………………62ig. 4-13. XRD patterns of (a) TNTs-70W, (b) TNTs-400W, (c) TNTs-700W at the elevated progressively temperatures (100 ~ 700℃) under 20% O2 / 80% N2……………………………………………….…………………64 ig. 4-14. XRD patterns of (a) TNTs-70W, (b) TNTs-400W, (c) TNTs-700W at the elevated progressively temperatures (100 ~ 700℃) under 20% H2 / 80% N2….................................................................................................65ig. 4-15. HR-TEM images and Fourier transform images of TNTs calcined under 20% O2 / 80% N2 atmospheres at 700℃ for 2hr. (a, d) TNTs-70W, (b, e) TNTs-400W, and (c, f) TNTs-700W…………….……………….67ig. 4-16. HR-TEM images and Fourier transform images of TNTs calcined under 20% H2 / 80% N2 atmospheres at 700℃ for 3hr. (a, d) TNTs-70W, (b, e) TNTs-400W, and (c, f) TNTs-700W……………………………..68 ig. 4-17. SEM images of (a) TNTs-70W, (b) TNTs-400W, and (c) TNTs-700W calcined under 20% O2 / 80% N2 atmosphere at 700℃ for 3hr….……70ig. 4-18. SEM images of (a) TNTs-70W, (b) TNTs-400W, and (c) TNTs-700W calcined under 20% H2 / 80% N2 atmosphere at 700℃ for 3h………..71ig. 4-19. Conceptual diagram regarding the transformation of TNTs-70W after thermal treatment……………………………………………..….……..72ig. 4-20. Conceptual diagram regarding the transformation of TNTs-700W after thermal treatment………………………………………….……..73ig. 4-21. HR-TEM images of TNTs-700W and the corresponding SAED pattern (insert)…………………………………..……………………..74ig. 4-22. Possible crystal phases and morphologies of TNTs after thermal treatment……………………………………………………...……….75ig. 4-23. The dependence of TCE observed degradation rate constant over TNTs on the (a) O2 / N2 and (b) H2 / N2 atmospheres at the progressively temperatures (25 ~ 700℃)……………….…………….77ig. 4-24. A suggested photocatalytic mechanism of TCE over P25 TiO2……...…………………………………………………….......…80ig. 4-25. The concentration of TCE、DCAC and phosgene as a function of reaction time…………………………………………………………81ig. 4-26. The dependence of phosgene yield on the concentration of oxygen at the photocatalytic oxidation of DCAC………………………………81ig. 4-27. XRD patterns of P25 TiO2, 10% wt. Pt/TiO2 and 4% wt. Pd/TiO2……………………………………….……………………….82ig. 4-28. TPR spectrum of P25 TiO2, Pt doped TiO2 and Pd doped TiO2………………………..………………………………………….83ig. 4-29. The XPS spectra of (a) 10% wt. Pt/TiO2 for O 1s region (b) 4% wt. Pd/TiO2 for O 1s region (c) P25 TiO2, 10% wt. Pt/TiO2 and 4% wt. Pd/TiO2 for Ti 2P………………………..…………………………….84ig. 4-30. XPS of (a) 10% wt. Pt doped TiO2 for Pt 4f region (b) 4% wt. Pd doped TiO2 for Pd 3d region at reducing temperature of 25, 120, and 400℃, respectively……………………………………………….…...86ig. 4-31. Degradation rate constant of TCE, the yields of DCAC and phosgene as a function of Pt/Pd loading amount in TiO2 (a) Pt/TiO2 (b) Pd/TiO2………………………………..………………………………89ig. 4-32. Degradation rate constant of TCE, the yields of DCAC and phosgene as a function of reduction temperature (a) 10% wt. Pt doped TiO2 (b) 4% wt. Pd doped TiO2…………….…………………………………..90ig. 4-33. Pd/anatase TiO2 surface. Pd species were intercalated into the lattice of TiO2 and aided the cleavage of C-C bond within CHCl2COCl2 radicals……………………………………….………………………..91目錄able 2-1 Physical and chemical properties of TCE………….……..……….…6able 2-2 Results of the parameters in the aforementioned equation…………..8able 2-3 References related to the photocatalytic oxidation of TCE and DCE…..………………………………………………………….…11 able 2-4 The fabrication methods of TNTs…………………………………..17able 2-5 Technical advantages and disadvantages of existing methods in TNTs fabrication…………………………………………………………..18able 2-6 The dependence of synthesis conditions on the chemical structure of TNTs………………………………………………………………..18able 2-7 Recent studies concerning the post treatment of TNTs……….……19able 2-8 Recent techniques used to modify hydrothermal treatment………..25able 2-9 Applications of TNTs on the various fields……………………...…26able 4-1 Comparison of SBET in terms of the duration of hydrothermal treatment…………...……………………………………………….51able 4-2 Effect of irradiation power on the chemical composition, surface acidity, BET specific surface area (SBET), and pore structure of TNTs………………………………………………………………..51able 4-3 Degradation of NH3/NH4+, the yields of NO2- and NO3-, and the mass recoveries as N atom for photocatalytic oxidation of NH3/NH4+ over different catalysts after 6 hr reaction (Uncertainties are 95% confidence intervals)…………………………………………………….….……..59 able 4-4 Phase composition and kobs-TCE of TNTs calcined at 500℃ and 700℃ under O2 / N2 and H2 / N2 atmospheres, respectively…………………78able 4-5 Results of curve-fitting of high resolution XPS spectra for the O 1s region in Pt/TiO2 and Pd/TiO2.…………………………….……….....85able 4-6 Effects of Pt, Pd and their reduction temperature on the mineralization of TCE during photocatalytic reaction.………….……93able 4-7 Comparison of photocatalytic TCE over P25 TiO2, microwave-induced TNTs, and Pt, Pd/TNTs-induced TiO2……...……95application/pdf12910476 bytesapplication/pdfen-US二氧化鈦氧化鈦奈米管微波水熱法光催化水中氨氮氣相三氯乙烯TiO2Titanate nanotubesMicrowave hydrothermalPhotocatalysisAqueous ammoniaTrichloroethylenethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/181526/1/ntu-97-D92541008-1.pdf