氮氧化物(NOx)排放及其衍生之二次污染已成為全球重要的空氣汙染問題，對人體健康及環境造成深遠的影響，包含酸雨、光化學煙霧、水體品質、能見度降低及人體呼吸系統疾病等。於去除氮氧化物技術中，以SCR技術具有高轉化效率，但典型之SCR觸媒卻只在250~400oC溫度區間有好的轉化效果，於較低溫度下，無法有效轉化NOx，因此仍有改善空間。本研究以錳觸媒為基底，旨在探討於低溫條件對NO之去除效率，並結合非熱電漿進一步使錳基觸媒行fast-SCR反應以提升NO轉化效率。 本研究分為兩主軸，其一為利用含浸法製備錳基觸媒，並以Ce、Ni和Cu金屬改質觸媒活性相，分別製備10 wt.% MnCe/TiO2、10 wt.% MnCeNi/TiO2及10 wt.% MnCeCu/TiO2等三種觸媒，比較三種觸媒之活性與基本物化特性，並藉由操作參數瞭解觸媒的適用性。研究結果顯示10 wt.% MnCeNi/TiO2觸媒可於150oC達100% NO轉化效率，而10% wt. MnCe/TiO2及10% wt. MnCeCu/TiO2則需200oC才可將NO完全轉化，因此以10% wt. MnCeNi/TiO2觸媒進行後續實驗。其二為使用非熱電漿進行氣體組成調整，使氣流中之NO及NO2濃度略等量，以達fast-SCR反應條件，結果顯示於15.5 kV和10kHz之操作條件可使氣流中300 ppm NO有效轉化成165 ppm NO及153 ppm NO2，並於電漿系統下游端串接10 wt.% MnCeNi/TiO2觸媒，於100oC即可有效將NO完全轉化。在同時含有CO、CO2、C2H4、水氣及二氧化硫的氣體組成，可藉由電漿觸媒系統於100oC達90%NO轉化效率，整體而言，非熱電漿結合本研究改質之錳基觸媒具有於低溫下有效還原氮氧化物之效果，具實際應用潛力。 ;Nitrogen oxides (NOx) has been regarded as one of the most serious air pollutants. It not only causes adverse environmental effects such as acid rain, photochemical smog, deterioration of visibility and water quality, but also harms human respiratory system. Among de-NOx technologies, selective catalytic reduction (SCR) is considered as the best control technology for NOx removal. However, SCR typically needs to be operated at a temperature window ranging from 250 to 400oC. If the system is operated at lower temperatures, NOx could not be reduced effectively. The aim of this study is to develop a low-temperature de-NOx technique via plasma catalysis and fast-SCR for effective NO reduction. This study could be divided into 2 aspects: (1) Mn-catalysts modified (including 10 wt.% MnCe/TiO2, 10 wt.% MnCeNi/TiO2 and 10 wt.% MnCeCu/TiO2) for de-NOx, (2) combining plasma catalysis and fest-SCR for de-NOx. Experimental results indicate that NO conversion achieved with 10 wt.% MnCeNi/TiO2 reaches 100% at 150oC, while 10 wt.% MnCe/TiO2 and 10 wt.% MnCeCu/TiO2 need to be operated at ≥200oC for complete conversion. MnCeNi/TiO2 is further applied for plasma catalysis system due to its higher activities. Results indicate that 300 ppm NO could be converted into 165 ppm NO and 153 ppm NO2 with the applied voltage of 15.5 kV and frequency of 10 kHz and 100% NO conversion is achieved at 100oC by fast-SCR. Moreover, NO conversion still maintains 90% at 100oC with plasma catalysis system as CO, CO2, C2H4, SO2 and H2O(g) are introduced into the stream gas simultaneously. Overall, this study demonstrates that combining nonthermal plasma with Mn-based catalyst is effective in reducing NOx emission at a low temperature and has good potential for industrial application.
