吳紀聖臺灣大學：化學工程學研究所鄭宇廷Cheng, Yu-TingYu-TingCheng2007-11-262018-06-282007-11-262018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/52200本研究運用傅立葉轉換紅外線光譜儀，研究在紫外線照射下純二氧化鈦以及負載過渡金屬的二氧化鈦對於一氧化氮的光觸媒催化反應。利用改良式溶膠凝膠法水解鈦的醇氧化物製備二氧化鈦以及負載銅、釩、鉻金屬之二氧化鈦。在500°C 通入空氣進行前處理之後，觸媒表面偵測到大量過氧化物以及氫氧基。通入一氧化氮氣體後，發現一氧化氮會移除氫氧基、過氧化物，或過渡金屬與氧分子之間的雙鍵鍵結，並以雙齒亞硝酸基或硝酸基的型式吸附在觸媒表面。此外，一氧化氮也會以亞硝醯基的型式吸附在負載之過渡金屬離子上。觸媒在紫外光照射下受激發形成的電洞將過氧化物氧化成超氧化物；此超氧化物會將雙齒亞硝酸基氧化成硝酸基。當亞硝醯基存在於表面時，會因為亞硝醯基的優選氧化使得亞硝酸基的氧化受到抑制。 在熱穩定性測試中，400°C的高溫仍然無法移除雙齒硝酸基，且吸附在二氧化鈦的氫氧基因為與硝酸產生偶合而不受高溫影響。然而，氫氧基與雙齒亞硝酸基無法進行偶合，故氫氧基的熱穩定性表現與未吸附一氧化氮的二氧化鈦觸媒相同。再者，研究同時發現一氧化氮可再次吸附在存在有雙齒亞硝酸基及硝酸基的二氧化鈦表面。在光穩定性測試中，發現亞硝酸基的氧化是由觸媒照光後產生的中間物觸發進行，而非光觸媒受光反應後的產物對亞硝酸基進行氧化形成硝酸基。X光繞射分析、紫外光–可見光光譜分析證明觸媒的結構，以及對紫外光吸收的能力不會受高溫處理和一氧化氮的光觸媒催化反應影響。 由傅立葉轉換紅外線光譜儀的結果，可推測出一氧化氮在純二氧化鈦和負載過渡金屬的二氧化鈦上，進行光觸媒催化反應的可能機制。Photocatalytic NO oxidation on TiO2 and transition metal-loaded TiO2 (M/TiO2) catalysts under UV irradiation was studied using in situ FT-IR spectroscopy. TiO2 and M/TiO2 catalysts were prepared by sol-gel method via controlled hydrolysis of titanium (IV) butoxide. Copper, vanadium or chromium was loaded onto TiO2 during sol-gel procedure. After treated at 500°C under air flow, a large amount of surface peroxo species and OH groups were detected on the TiO2 and M/TiO2 catalysts. Nitric oxides (NO) can be adsorbed on TiO2 and M/TiO2 in the form of bidentate nitrites, or nitrates via removing OH groups, peroxo species or M=O bonds. In addition, NO can also be adsorbed on Mn+ in the form of nitrosyls. Under UV irradiation, bidentate nitrites were oxidized to monodentate or bidentate nitrates. This transformation was probably triggered by superoxo species which were oxidized from peroxo species via photogenegrated holes. The existence of nitrosyls caused the inhibition of oxidation from nitrites to nitrates because of primary oxidation on nitrosyls. Thermal stability tests showed that even the temperatures were up to 400°C, bidentate nitrates still remained on TiO2 surface. It also showed that OH groups were coupled with nitrates so that the OH groups were not influenced even up to 400°C. However, for bidentate nitrite, it was not coupled with OH groups so the OH groups were influenced at high temperatures. In addition, further NO adsorption and photocatalytic NO oxidation were allowed on nitrite-adsorbed TiO2 and nitrate-adsorbed on TiO2. Photo stability tests evidently showed that it was photogenerated intermediates, not photocatalytic products that involved in the oxidation from nitrites to nitrates. XRD and UV-Visible tests showed that the structures and the abilities of absorbing UV light were not influenced by high temperature treatment and photocatalytic NO oxidation. Based on the FT-IR results, a possible mechanism was proposed for the photocatalytic NO oxidation on TiO2 and M/TiO2.誌謝 I Abstract (English) II Abstract (Traditional Chinese) III Contents IV Contents for Figures VI Contents for Tables X Contents for Schemes XI 1. Introduction 1 1.1 Introduction to TiO2 1 1.2 Motivation 3 2. Paper Review 4 2.1 Photocatalytic Acvity of TiO2 and Its FT-IR Investigation 4 2.2 Photocatalytic Reaction on TiO2 and Its FT-IR Investigation 7 2.3 Reduction of NO on Catalysts and Its FT-IR Investigation 12 3. Experimental Section 18 3.1 Materials 18 3.2 Preparation of Photocatalysts 18 3.3 Characteristic Analyses of Photocatalysts 21 3.3.1 X-ray Diffraction 21 3.3.2 UV-Visible Diffuse Reflectance Spectroscopy 22 3.3.3 Infrared Fourier-Transform (FT-IR) Spectroscopy 23 3.4 In Situ FT-IR Photoreaction System 26 3.4.1 Reaction System 26 3.4.2 Photoreactor 27 3.4.3 In Situ Photocatalytic Reaction of NO Gas 28 4. Results 30 4.1 In situ FT-IR Study of Photocatalytic NO Reaction 30 4.1.1 Pretreatment 30 4.1.2 Photocatalytic NO Reaction 37 4.1.2.1 Photocatalytic NO Reaction on TiO2 37 4.1.2.2 Photocatalytic NO Reaction on Cu/TiO2 44 4.1.2.3 Photocatalytic NO Reaction on V/TiO2 49 4.1.2.4 Photocatalytic NO Reaction on Cr/TiO2 54 4.1.2.5 Photocatalytic NO Reaction on P25 59 4.1.2.6 Summary 63 4.1.3 Thermal and Photo Stability of Surface Peroxo Complexes 66 4.1.4 Thermal Stability of Bidentate Nitrite 72 4.1.5 Thermal Stability of Monodentate and Bidentate Nitrate 75 4.2 X-ray Diffraction 79 4.3 UV-Visible 83 5. Discussion 85 5.1 Photocatalytic NO Reaction on TiO2 85 5.2 Photocatalytic NO Reaction on 2wt%Cu/TiO2 91 5.3 Photocatalytic NO Reaction on 1.9wt%V/TiO2 and 0.65wt%Cr/TiO2 93 5.4 Photocatalytic NO Reaction on P25 96 5.5 Summary 96 6. Conclusion 98 Acknowledgments 99 References 100 Appendices 106 Appendix I. Properties of Useful IR Material 106 Appendix II. Temperature ranges of some commercial thermocouple 110 Appendix III. Structures of Surface Species 111 Appendix IV Photocatalytic NO Reaction on γ-Al2O3 113 個人小傳 1155194559 bytesapplication/pdfen-US二氧化鈦紅外線光催化一氧化氮TiO2FTIRphotocatalyticnitric oxidethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/52200/1/ntu-94-R92524016-1.pdf