以選擇性光催化還原程序處理固定污染源之氮氧化物排放
| 中文摘要 | 本研究之主要目的在製備高度分散性之二氧化鈦溶膠，並探討選擇性二氧化鈦光催化觸媒還原NOx之影響。本研究首先以化學共沈澱-解膠法來製備酸性及中性之二氧化鈦溶膠，並量測所製備光觸媒之表面性質、可見光之光催化活性及塗佈效果。所製備之二氧化鈦溶膠光觸媒及TiO2(P25)將應用在選擇性光催化觸媒還原NOx之處理，探討反應操作條件對NO轉化率以及氮氣生成選擇率之影響，比較不同光觸媒及操作條件對NO去除效率及光量子產率之影響。 結果顯示：中性與酸性的光觸媒溶膠具有銳鈦礦之結晶結構，晶體均呈長條形，兩種溶膠的粒子分佈均十分均勻而狹窄，十分適合用於為塗佈之原料。中性二氧化鈦溶膠具可見光化活性，且由於對基材無腐蝕性，適用於薄膜塗佈；酸性二氧化鈦溶膠則因具備易被覆及擔載量大的特性，因此被廣泛應用於光催化處理污染物。 選擇性光催化觸媒還原程序中NO濃度會隨著反應時間增加而轉換成N2、NO2以及N2O，光觸媒表面NH3在選擇性光觸媒催化程序中受光激發後會與氧氣生成NO，能量過高的紫外光源除了會將NO還原成N2外，亦會在反應過程中氧化NH3生成NO，造成低估NO去除效率的情形。此外NO還原效率亦會隨著氨氣及氧氣濃度上升而提昇，然而當這兩種氣體濃度上升超過某一臨界值時即會使還原速率趨於平緩。實驗結果亦發現，當進料中相對濕度增加時，TiO2表面的活性位置會被水分子佔據，反而會不利於反應之進行。 使用酸性光觸媒溶膠進行選擇性光催化氮氧化物之實驗，結果發現酸性二氧化鈦溶膠在單位觸媒量之NO還原效率遠高於TiO2(P25)之還原效果，足以證明本研究所製備之光觸媒溶膠具有極高的氮氧化物還原活性；然而由於光觸媒溶膠較易吸附NO分子，使得光催化的過程中會產生N2O，因此降低該反應之氮氣選擇率。 | ||
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| 中文關鍵字 | 選擇性光催化還原, 一氧化氮, 二氧化鈦, 氮氣 | ||
基本資訊
| 專案計畫編號 | EPA-98-U1U4-04-003 | 經費年度 | 098 | 計畫經費 | 2828 千元 |
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| 專案開始日期 | 2009/04/02 | 專案結束日期 | 2010/01/30 | 專案主持人 | 顧洋 |
| 主辦單位 | 永續發展室(停用) | 承辦人 | 林燕柔 | 執行單位 | 立曄股份有限公司 |
成果下載
| 類型 | 檔名 | 檔案大小 | 說明 |
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| 期末報告 | 選擇性光催化成果報告.pdf | 12MB | 成果報告 |
Photoassisted Selective Catalytic Reduction of Nitric Oxide with Ammonia over TiO2
| 英文摘要 | In this study, the highly-dispersed TiO2 sol was fabricated by the chemical coprecipitisation–peptisation method for the photocatalytic reduction of NO. The surface properties, visible light responsibility and coating performance of the acidic and neutral TiO2 sols were extenxively examined by XRD, TEM and dynamic light scattering. The photo-assisted selective catalytic reduction (photo-SCR) of NO with ammonia injection was accomplished under various operating conditions to confirm the photocatalytic reactivity of the TiO2 (P25) and prepared TiO2 sol. The reaction products and intermediates were determined and the NO conversion, nitrogen selectivity, and quantum yields for NO reduction were then calculated for the proposition of reaction mechanism and the determination of feasible operating conditions of photo-SCR. Experimental results indicated that the crystal phase of TiO2 sol exhibited anatase phase only. TEM images indicated that the particles of TiO2 sol were in the form of rod. The both of fabricated TiO2 sols were feasible as the coating materials due to the narrow particle size distribution. In addition, the methyl blue could be photocatalytically degraged using the neutral TiO2 sol with visible light illumination. The acidic TiO2 sol was found to be extensively applied for the photocatalytic degradation of pollutants because the acidic TiO2 sol possessed the advantages of high loaging and easy coating. The photocatalytically experimental results showed that most of the reduced NO was converted to N2 as compared to NO2 and N2O. The reactions of NO formation and NO reduction could be simultaneously observed during photo-SCR over TiO2 in the presence of oxygen. More NO molecules may be formed from the oxidation of NH3 during photo-SCR with 254 nm UV illumination; therefore, NO reduction efficiency and quantum yields for NO reduction and N2 formation by photo-SCR with 254 nm UV illumination was fond to be lower than those with 365 nm UV illumination. The reduction of NO was also found to be increased with the increase of initial NH3 and oxygen concentrations until specific concentrations. The competitive adsorption of water and NH3 molecules resulted in the decrease of N¬O reduction rate. The photoassisted selective catalytic reduction of NO with Ammonia over acidic TiO2 sol was also carried out and was compared to the photocatalytically experimental results conducted over TiO2 (P25). The experimental results indicated that the NO reduction rate by photo-SCR over TiO2 sol was much higher than those over TiO¬2 (P25). This fact revealed that TiO2 sol possessed the highly reduction activity of NO. However, the N2 selectivity by photo-SCR over TiO2 sol was decreased with the increase of NO concentration because of the higher adsorption ability of NO molecules on TiO2 surface. | ||
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| 英文關鍵字 | NO;Photo-SCR;TiO2 sol | ||