| 摘要: | 於石油逐漸告罄之際，蘊藏量尚近百年的天然氣漸受重視，但天然氣儲運極為昂貴，且>50%的天然氣蘊藏於人口稀少的偏遠地區，因此若能直接於產地將天然氣轉化成液態化學品或燃料可大幅降低運輸費用。甲醇用途廣泛，除為許多化學品合成的原料外，近來更被視為優良能量載體，甲醇汽油、直接甲醇燃料電池和甲醇重組產生富氫氣體即為廣為人知的利用例。觸媒催化為現行甲醇合成主流技術，其氣體原料為合成氣，因此若欲利用天然氣合成甲醇必須先將天然氣轉化為合成氣，此步驟所需費用即佔總生成費用的25%。電漿法雖可直接利用甲烷合成甲烷，但其生產成本和甲醇選擇性仍需大幅改善。非熱電漿結合觸媒技術為近年能源和環保領域熱門研究議題之一，除可有效改善非熱電漿能量效率偏低和產物選擇性不佳之技術瓶頸外，對於觸媒催化程序而言，更具降低觸媒工作溫度、減緩觸媒毒化現象等優點，但該技術於甲醇合成之相關研究數量極少，至為可惜。本計畫旨在探討非熱電漿結合觸媒技術將天然氣、合成氣轉化成甲醇之可行性，進流氣體中亦將添加CO2，同時探討溫室氣體資源化之可行性，計畫將比較不同溫度下，填充床反應器、純觸媒和電漿結合觸媒系統各自所得結果，藉此除探討各系統中主要甲醇合成機制外，另一重點則為最佳加乘效應(synergism)之發揮。此外，計畫亦將探討系統比能量密度和轉化率、甲醇選擇性之關係，相關結果除可應用於反應器放大化設計外，更可用來評估技術之經濟可行性。 ; As oil is going to run out, natural gas has gradually been considered as an important energy source for the future. However, the fact that most of the locations of natural gas fields are far from human living areas makes it economically insufficient to use. Conversion of natural gas into liquid hydrocarbon at the natural gas fields, which could significantly reduce the transportation cost, serves as a good alternative for the usage of natural gas. Methanol is a very useful feedstock for synthesizing various chemical materials. Recently, it has been deemed as an excellent energy carrier as well. The most well-known examples include methanol gasoline, direct methanol fuel cell and reforming of methanol to hydrogen. Catalytic process is the mainstream technique used for methanol synthesis, in which the feedstock must be syngas. Hence, in terms of converting natural gas to methanol, two-step catalytic process, including natural gas reforming to syngas and methanol production from syngas, is required. Generally, the cost of the first step is 25% of the total cost. Although it』s possible to directly convert natural gas to methanol by non-thermal plasma, the energy efficiency and methanol selectivity need to be further improved. More recently, a novel technique termed as combined plasma catalysis (CPC) has been demonstrated to be promising both for resolving energy and environmental problems. It could serve as an excellent alternative approach to overcome the major bottlenecks encountered by non-thermal plasma, such as low energy efficiency and poor products』 selectivies. As for catalysis, such combination could reduce the working temperature and retard the poisoning of catalyst. However, it』s a pity that the researches on applying combined plasma catalysis to methanol synthesis are still scarce. The main purpose of this project is to investigate the feasibility of synthesizing methanol from natural or syngas via combined plasma catalysis. Moreover, CO2 would be used as a feedstock as well. The experimental tests using packed-bed plasma reactors, pure catalysis and combined plasma catalysis would be conducted at various temperatures. In addition to discussing the methanol synthesis pathways in those different systems, another purpose is to find out how to reach the best synergetic effect. On the other hand, the relationship between conversion or methanol selectivity and specific energy density would also be carefully examined because it could provide useful information either for scaling law or the economical feasibility of combined plasma catalytic to produce methanol. ; 研究期間 9701 ~ 9712 |
