| 摘要: | 揮發性有機污染物(VOCs) 對人體健康與環境造成不利的影響，短時間接觸VOCs使人感到不適，產生頭暈、噁心、嘔吐、流淚、刺鼻、咳嗽等症狀，暴露於濃度過高之VOCs時可能導致中毒死亡，長期接觸則導致肝、肺、呼吸道等疾病，而含氯的有機溶劑大部份已證實具有致癌性，其對人體健康及環境造成的影響不容忽視。
本研究分為兩個部份，第一部份為使用檸檬酸凝膠法製備perovskite-type觸媒LaMnO3，以Ce及Ni金屬進行觸媒改質，分別製備LaMnO3、La0.8Ce0.2MnO3及La0.8Ce0.2Mn0.8Ni0.2O3三種觸媒，除比較去除氣流中三氯乙烯之活性外，亦透過XRD、BET、SEM-EDS、XPS儀器分析觸媒之物化特性，藉由操作參數了解最佳之控制技術。研究結果顯示La0.8Ce0.2Mn0.8Ni0.2O3在400oC對三氯乙烯去除效率可達100%且在600oC對三氯乙烯之礦化率已達100%，而La0.8Ce0.2MnO3及LaMnO3則需於450oC及500oC才可達完全去除之效率。從觸媒測試結果顯示改質之La0.8Ce0.2Mn0.8Ni0.2O3對三氯乙烯之去除具有最佳活性，因此以此觸媒進行後續實驗。第二部份為在常溫下進一步利用perovskite-type觸媒結合非熱電漿系統以評估去除三氯乙烯之效能，結果顯示此系統對三氯乙烯之去除效率達100%；與單獨非熱電漿系統相比較，在去除三氯乙烯實驗中電漿催化系統的礦化率可提升至44%，且可大幅降低副產物(O3、NOx)的產生；能量效率方面，單階段電漿結合觸媒系統顯著高於非熱電漿系統。整體而言，本研究所研發之電漿結合觸媒系統是一種創新並且有效的VOCs控制技術，可協助工商業解決VOCs引發之空氣污染問題。
;Volatile organic compounds (VOCs) have been widely used in industrial processes. Among them, trichloroethylene(TCE) is a solvent mainly used for metal degreasing and dry cleaning. However, it is toxic and probably causes cancer for humans. Perovskite-type catalysts such as LaMnO3 have been studied for VOC removal and they can be modified by partial substitution to enhance catalytic activity and mineralization rate. Also, non-thermal plasma (NTP) can effectively eliminate VOCs, because NTP can generate radicals to decompose and oxidize VOC molecules. However, NTP has several drawbacks such as low selectivity and O3 formation. In this study, removal of trichloroethylene (TCE) is investigated using a hybrid system which combines NTP and perovskite-type catalyst. The operating conditions are TCE = 150 ppm, applied voltage = 14 - 17 kV, frequency = 8 kHz, and gas flow rate = 500 mL/min. The removal efficiency of TCE achieved with the DBD plasma increases from 24% to 75% as applied voltage is increased from 14 to 17 kV, while mineralization rate is increased from 4% to 11%. For product analysis, phosgene (PG), dichloro acetyl chloride (DCAC), trichloroacetaldehyde (TCAD), O3, CO, and CO2 were mainly observed in the NTP process. As La0.8Ce0.2Mn0.8Ni0.2O3 is placed into the discharge zone to form the hybrid system, the removal efficiency of TCE achieved increases from 24% to 90% as the applied voltage is increased from 14 to 17 kV, while mineralization rate achieved with plasma catalysis reaches 41% at 17 kV. More importantly, the formation of the hazardous products such as O3, NOx, phosgene, and chlorine is significantly reduced as a perovskite-type catalyst is introduced. Overall, the preliminary results indicate that plasma catalysis can enhance the performance of catalyst for TCE removal. |
