- 學位論文
評估不同組成比例的Si-Ti光觸媒於可見光下對一氧化碳之去除反應
Evaluating the CO removal over Si-Ti photocatalyst with different Si/Ti ratios under visible light
摘要
對於CO等氣狀污染物的去除，一般多以氧化鋁擔持過渡金屬觸媒來進行氧化催化作用，雖其催化效果佳，但需在高溫的環境下方能進行，使用條件較受限制。相對於傳統熱處理型觸媒，光觸媒則有簡單、易操作的特點，在一般室溫、室壓下即可操作，不同於傳統觸媒，不需加熱即可進行反應，可減少能源的消耗，提高觸媒的廣用性。 目前研究指出，應用於氣相催化反應之二氧化鈦光觸媒，以往大多將其附載於玻璃基材上以增加光源的穿透性。然而玻璃為緻密性的低孔隙率材料，無法提供高表面積使二氧化鈦達較佳的分散性，因而使光催化反應受到限制。因此，在本研究中以水熱法製備30%Si-70%Ti、70%Si-30%Ti及100%Ti光觸媒，再輔以微波法擔持金屬製備Pt/Si-Ti光觸媒，接著以CO為反應氣體進行光催化反應，探討不同Si-Ti比例、金屬Pt的影響，不同反應光源等因子的影響，而製備所得的觸媒以電子顯微鏡FESEM、TEM觀察觸媒顆粒大小及擔體表面上金屬顆粒分布情形，以XRD分析結晶物種，以供探討其物、化結構性質對光催化活性影響之佐證。 實驗結果顯示，以水熱法改質製備之Si-Ti光觸媒主要結晶物種為rutile，於光催化反應下，金屬Pt之添加有助於大幅提升觸媒反應效率，於可見光與紫外光為光源時，30%Si-70%Ti與100%Ti之Pt/Si-Ti光觸媒對CO皆可達99%的去除效率，本研究最佳反應觸媒與反應條件為: Pt/30%Si-70%Ti，CO 500 ppm，10%O2，空間速度37500 h-1，常溫。
並列摘要
Al2O3 supported catalyst has been used as oxidative catalyst for CO gaseous pollutant removal widely. Although Al2O3 supported catalyst shows the good catalytic activity, the catalytic oxidation is limited with high reaction temperature required. By comparing with a conventional heat-treated catalyst, the photocatalyst may operate at room temperature in the atmospheric pressure without heating. The photocatalytic reaction is a simple and operating easily method, and then the application of photocatalyst is broadly with less energy consuming. Recently, the researches showed that the TiO2 photocatalyst were supported on the silica substrate over gaseous catalytic reaction and the penetration coefficient of light was improved. However, the porosity of silica substrate was low. The low specific surface area contributed to bad dispersion of TiO2, and the photocatlytic activity was decreased. This study prepared three catalysts (30%Si-70%Ti, 70%Si-30%Ti, 100%Ti) by the hydrothermal method, and then Pt/Si-Ti catalyst was prepared by the microwave heating method. CO was chosen as the reactant for photocatalytic reaction, and the different reaction parameters were studied, such as different ratio of Si/Ti, the effect of Pt, and different light sources. Catalyst properties were analyzed by X-ray powder diffractometer (XRD), Field Emission SEM (FESEM), and Trasmission electron microscope (TEM). FESEM and TEM were used to study the particle size and dispersion of catalysts, and the crystal phase was analyzed by the XRD. The experimental results indicated that the main crystal phase of Si-Ti photocatalyst preparted by the hydrothermal method was rutile. For photocatalytic reaction, the catalytic activity was improved by the metal Pt. Under UV light or visible light, 99% CO removal efficiency was carried out over Pt/30%Si-70%Ti or Pt/100%Ti. The optimum reaction conditions for CO removal over Pt/30%Si-70%Ti were O2 concentration 10%, room temperature, CO concentration 500 ppm, and space velocity 375,000 h-1.