| 摘要: | 本研究以perovskite-type觸媒為基礎發展新穎的double perovskite-type觸媒，並進一步應用於VOCs去除活性測試，其主軸可概分為二，一為double perovskite-type觸媒於催化系統對VOCs之活性評估，另一則是利用觸媒結合非熱電漿技術(含post-plasma catalysis及in-plasma catalysis)進行VOCs之去除測試。研究結果顯示double perovskite-type觸媒對VOCs有高活性，尤其是La2CoMnO6，其在300oC及30,000 h-1對C7H8之轉化效率及礦化率皆可達100%；此外，針對不同的VOCs如異丙醇、乙醛及乙烯，La2CoMnO6亦可分別於150oC、250 oC及350oC達完全去除；本研究亦發現double perovskite-type觸媒對CO2及H2O(g)有極佳的抗性；觸媒的物化特性分析結果顯示double perovskite-type觸媒的BET比表面積較低，但在反應中有良好的氧移動性(由於高比例的晶格氧)，因此觸媒本身有較佳的氧化-還原能力，促進VOCs氧化反應。另一方面，本研究藉由DBD-type plasma-alone系統以不同的參數探討C7H8去除之性能以進一步解析plasma catalysis去除C7H8之機制。本研究發現post-plasma catalysis系統對C7H8的轉化效率與觸媒對於O3之分解效率有顯著相關性，以La2CoMnO6為例，在120oC條件下，O3於12-19 kV皆可完全去除，而C7H8之轉化效率及礦化率最高分別可達100%及66%；另外，於in-plasma catalysis系統，觸媒與電漿存在顯著的加乘效應，在常溫與120oC條件下，C7H8的轉化效率及礦化率皆顯著高於plasma-alone系統， La2CoMnO6之in-plasma catalysis對C7H8的去除效率及礦化率最高分別為100%及98%，且於120oC條件下，perovskite-type觸媒可有效抑制NOx生成。整體而言，本研究結果顯示double perovskite-type觸媒於不僅可單獨應用於催化系統，且在plasma catalysis系統對VOCs之去除亦呈現高效能，證實double perovskite-type觸媒確實有潛力取代或運用於空氣污染物之處理。;In this study, novel double perovskite-type catalysts are developed and tested for VOCs removal. The research could be divided into 2 aspects: (1) catalytic activities of double perovskite-type catalysts for removal of VOCs, and (2) performance of plasma catalysis (including post-plasma catalysis and in-plasma catalysis) for VOCs removal. Experimental results indicate that double perovskite-type catalysts show higher activities for C7H8 removal if compared with traditional perovskite-type catalysts. Especially, C7H8 conversion and mineralization efficiencies achieved with La2CoMnO6 could reach 100% at 300oC and 30,000 h-1. In addition, various VOCs such as isopropanol (C3H8O), acetaldehyde (C2H4O), and ethylene (C2H4) could be converted completely at 150oC, 250oC, and 350oC, respectively, as La2CoMnO6 is applied as catalyst. Additionally, results indicate that double perovskite-type catalysts not only possess tolerance for CO2 and H2O(g), but also present good durability. The analysis of catalyst surface indicates that double perovskite-type catalysts have good mobility of oxygen due to high lattice oxygen ratio, therefore, they are of good oxidation-reduction property to promote VOCs oxdication reaction although they have lower BET specific surface area. On the other hand, DBD-type plasma-alone system is first tested for C7H8 removal at different parameters and is further used to elucidate the mechanism of plasma catalysis in removing C7H8. For post-plasma catalysis system, C7H8 conversion and O3 decomposition efficiency are closely correlated. For example, the highest C7H8 conversion and mineralization efficiency achieved with post-plasma catalysis system with La2CoMnO6 are 100% and 66% at 120oC, while O3 could be removed completely at 12-19 kV.
In addition, in-plasma catalysis system exhibits significant positive effect. Results indicate that C7H8 conversions and mineralization efficiencies achieved with in-plasma systems are higher than that of plasma-alone at room temperature or 120oC. For in-plasma catalysis with La2CoMnO6, the highest C7H8 conversion and mineralization efficiency are 100% and 98% at 120oC, respectively. In addition, formation of NOx could be inhibited in the presence of perovskite-type catalysts at 120oC. Overall, this study demonstrates that double perovskite-type catalysts can be applied for catalysis system for effective removal of VOCs. Further, high performance is achieved as double perovskite-type catalyst is integrated nontherma plasma to form plasma catalysis, demonstrating that double perovskite-type catalysts indeed have good potential to remove VOCs from gas streams. |
