- 學位論文
金屬負載於二氧化鈦奈米粒子於不同犧牲試劑之產氫應用與產物分析
Comparative study of sacrificial agents in hydrogen evolution reactions by heterogeneous photocatalysis using metal loaded TiO2 catalysts
摘要
在本篇研究中主要目的在探討改質後的二氧化鈦奈米粒子(Anatase)在不同的犧牲試劑條件進行異相催化，以醇類為主使用甲醇、乙醇、甘油、甲酸、葡萄糖和蔗糖等做為犧牲試劑，進行照光5.5 hr光催化且固定濃度為20(v/v%)(醣類0.35M)，並藉由ESI-mass、GC-mass.等儀器偵測氣相和溶液相照光生成的中間產物定性、定量分析，本篇改質條件選用含浸法負載銅金屬於二氧化鈦奈米粒子且進行氫化反應，針對水裂解反應作系統化的討論。 使用含浸法作為負載銅金屬的方法(Cu/TiO2)，並且以810 Torr的氫氣於300oC下氫化3小時(後氫化H:(Cu/TiO2))，最佳優化條件以水裂解測試產氫量作為基準優化樣品進行研究，且使用SEM/EDS、XRD、XPD、UV-Vis、PL、Raman進行樣品物性化性分析。 使用甲醇20(v/v%)作為犧牲試劑，並用300W氙燈將光強度調整至1W進行照光產氫實驗可得，純二氧化鈦的產氫量為0.0021 mmol h-1g-1 ，負載銅Cu/TiO2時產氫量為0.649 mmol h-1g-1，而將負載銅進行後氫化H:(Cu/TiO2)產氫量達到1.05 mmol h-1g-1，純二氧化鈦的520倍、Cu/TiO2的1.6倍，證實負載和氫化能夠提升產氫效率；在溶液相中間產物中分析得到甲醛0.114 mM，甲醛可繼續被氧化成甲酸濃度達到9.59 μM，除了醇醛酸的氧化產物被定量發現外，還發現甲酸甲酯的產生其隨著照光時間濃度先降後升達到26.45 μM；在20(v/v%)乙醇作為犧牲試劑，H:(Cu/TiO2)產氫量為0.36 mmol h-1g-1與相對甲醇減少65%，從溶液相中間產物可以得知乙醇氧化成乙醛濃度達到6.71 mM，但在乙酸則是只能看見特徵峰無法定量，推測在乙醇作為犧牲試劑的其況下反應機制只能到達醛類無法繼續氧化使用故其產氫量低；其他犧牲試劑甲酸0.22 mmol h-1g-1 、甘油0.7 mmol h-1g-1、葡萄糖0.215 mmol h-1g-1、蔗糖0.634 mmol h-1g-1，其中甘油是相對其他犧牲試劑表現次之，倘若可以有效使用甘油作為犧牲試劑，可解決生質柴油反應大量產生副產物甘油的問題，另外蔗糖是極有潛力的犧牲試劑，我們下個目標是積極開發醣類應用並且延伸應用到纖維素。
並列摘要
In this work, systematic studies have been conducted to investigate the heterogeneous catalytic water splitting of modified titanium dioxide (Anatase) nanoparticles (NPs) with different sacrificial agents. Using methanol, ethanol, glycerol, formic acid, glucose, and sucrose as a sacrificial agent, photo-catalytic 5.5 hr photocatalysis was carried out at a fixed concentration of 20 (v/v%) (saccharide 0.35 M), and by ESI-mass, GC-mass. The instrument detects qualitative and quantitative analysis of intermediates generated from gas phase and solution phase. The modification conditions in this study are the impregnation method for depositing copper metal on titanium dioxide nanoparticles and hydrogenation reaction. Hydrogenation at 810 Torr , 300 °C for 3 hr is indicated as H:(Cu/TiO2), and sample physical property analyses was carried out using SEM/EDS, XRD, XPD, UV-Vis, PL, Raman. We used 20v% methanol aqueous solution as sacrificial agent and irradiated with 1W light from a 300W Xe lamp. The hydrogen yield from the photolysis of TiO2 NPs reached 0.0021 mmol h-1g-1, where as Cu/TiO2 reached 0.649 mmol h-1g-1, and H:(Cu/TiO2) was found to be 1.6 times as efficient as Cu/TiO2, reaching [H2] = 1.05 mmol g-1hr-1. These results confirmed a synergetic enhancing effect on H2 evolution between Cu/TiO2 and H:(Cu/TiO2). The solution phase product from CH3OH experiment was analyzed to obtain 0.114 mM formaldehyde. The formaldehyde could continue to be oxidized to a formic acid concentration of 9.59 μM. In addition to the quantitative detection of the oxidation product of aldolonic acid, it was found that the methyl formate produced first decreased with the concentration of illumination time. Rise up to 26.45 μM. In ethanol as a sacrificial agent, the hydrogen production of H:(Cu/TiO2) is 0.36 mmol g-1hr-1 and the relative methanol is reduced by 65%. From the intermediate of the solution phase, we made that the concentration of ethanol to acetaldehyde reaches 6.71 mM, but acetic acid can only founded trace, and the reaction mechanism can only reach the aldehydes and cannot continue to be oxidized, so the hydrogen production is low. Other sacrificial agents such as formic acid 0.22 mmol g-1hr-1, glycerol 0.7 mmol g-1hr-1, glucose 0.215 mmol g-1hr-1, sucrose 0.634 mmol g-1hr-1, Among them, glycerol is second to other sacrificial agents. It can be effectively used as a sacrificial agent. It can solve the problem of a large amount of by-product glycerol produced by biodiesel reaction. In addition, sucrose is a potential sacrificial agent. Our next project is to focus on the development of sugar applications before the final extension to cellulose.