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標題: 改質觸媒應用於流體化床反應器同時控制一氧化氮及飛灰之研究
Modification of catalysts for simultaneous control of NO and fly ash in a fluidized-bed catalyst reactor
作者: 黃世騰
Huang, Shih-Teng
關鍵字: Fluidized-bed catalyst reactor;流體化觸媒反應器;Pretreatment;NO;Fly ash;Copper catalyst;前處理一氧化氮;飛灰;銅觸媒
出版社: 環境工程學系所
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本研究將改質觸媒應用於流體化床反應器同時去除一氧化氮(NO)及飛灰(Fly ash)。利用活性碳(AC)為擔體,先經不同溶液之前處理動作,並以硝酸銅為前驅溶液使用濕式含浸法製備成觸媒,比較不同溶液前處理對觸媒擔體改質活性之影響,並選擇活性較佳之觸媒搭配流體化床操作參數,於模擬實廠煙道條件下利用流體化觸媒反應器同時對NO 及飛灰之去除進行研究,並利用FESEM、TEM、XRD、BET 儀器對反應前後之觸媒進行特性分析加以佐證。
結果指出,對於不同前處理後之觸媒,經活性測試後以硝酸前處理觸媒具有較高NO 去除效率,依序為CuO/AC-N> CuO/AC-S> CuO/AC-H>CuO/AC-Na,而將選取硝酸前處理之觸媒作為後續實驗之觸媒。
對於不同飛灰濃度下對觸媒同時去除飛灰及NO 之影響,結果顯示,於反應時間為30 分鐘下,隨著飛灰濃度增加,觸媒床質對於飛灰之去除能力仍在負荷範圍內,所以對於飛灰之去除仍維持較高值;而同時,觸媒床質對於NO 之去除效率於飛灰濃度10,737 mg/m3 內,其NO 去除效率並未隨飛灰濃度增加有明顯變化,但當飛灰濃度增加至49,108 mg/m3,NO去除效率才下降,其推測原因為當高濃度飛灰存在煙道氣中,將增加阻塞觸媒表面之飛灰含量,進而堵塞觸媒活性位置而降低NO 還原效率。
對於不同反應時間下對觸媒同時去除飛灰及NO 之影響,由結果顯示,隨著反應時間之增加,觸媒床質對於飛灰之去除能力逐漸超過床質負荷範圍,而導致流體化觸媒床對飛灰之去除效率隨著床質中所累積之飛灰增加而降低;而同時,觸媒對於NO 之去除效率,在反應時間前90 分鐘內,觸媒對於NO 去除效率仍維持穩定值,而隨著反應時間之增加,觸媒對於NO 去除效率則明顯下降,推測為隨著反應時間之增加,將增加飛灰聚集於觸媒表面,進而抑制觸媒活性。此外,由BET 結果可以發現,當操作時間增加,提升飛灰堵塞觸媒的巨孔與中孔體積之行為。

This study investigated the simultaneous removal of nitric oxide (NO) and fly ash by a fluidized-bed catalyst reactor from simulated flue gas. The activated carbon (AC) supports were pretreated by the wet chemical treatment method. After that, the copper catalysts were prepared by wet impregnation method using the modified supports to evaluate the NO reduction efficiency. The effects of different concentrations of fly ash and operation time on the simultaneous removal of NO and fly ash were also considered. Besides, the catalysts were characterized by the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Brunauer Emmett Teller (BET).
The results of activity test showed that the activities of CuO/AC catalysts with different pretreated AC supports were followed the sequence as CuO/AC-N > CuO/AC-S > CuO/AC-H > CuO/AC-Na at temperature was 250 oC. Accordingly, the CuO/AC-N was employed in the experiment of simultaneous removal of NO and fly ash in flue gas.
The results of different concentrations of fly ash showed that the removal efficiency of fly ash was stable in the range of fly ash concentration between 1406 to 49108 mg/m3 within 30 min. High tolerance ability for fly ash was found by using fluidized bed catalyst reactor. On the other hand, the NO conversion presented a slight change when the concentrations of fly ash lower than 10173 mg/m3 within 30 min. But the NO conversion was decreased when the concentration of fly ash was 49108 mg/m3. The results can be explained that decreasing of the catalyst activity was owing to the active sites of the catalysts blocked or occupied by fly ash in high concentration of fly ash environment.
In the experiment of different operating time, the results indicated that removal efficiency of fly ash decreased with increasing of the operating time when the fly ash concentration was 10173 mg/m3. In addition, the NO conversion was maintained about 65 % in the operation time within 90 min, but it significantly decreased after 90 min. It can be considered that the presence of fly ash influenced the activity of CuO/AC-N catalysts. This accumulation behavior of fly ash on the catalyst surfaces reduced the performance of NO conversion when operating time increased. Moreover, the BET results also showed that the decreasing of the volumes of meso- and macro-pore with operating time increased because of fly ash blocked the catalyst surface.
其他識別: U0005-2906201011323800
Appears in Collections:環境工程學系所

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