利用常壓微電漿系統進行二氧化碳之轉化

Abstract

本實驗以高壓交流電源驅動一以銅箔基板(Copper clad laminate, CCL)為基底之常壓微電漿系統，並以低成本之碳粉轉印技術(Toner transfer)於基板上製作微米尺度的圖案，可製作平面上之最小尺寸為200 μm，圖案間的距離為400 μm，並成功地讓低溫微電漿產生於微孔洞中(Micro-cavities)。而圖案的樣式大致分為正方形、圓形及三角形之陣列分佈式，或是長寬比大的線形分佈式電漿(Linear discharges)。 為了瞭解在此元件上產生的電漿性質，第一部分分別對元件進行電性及光學量測。由電性量測中可得知此放電系統為絲狀放電，於氬氣及二氧化碳氣氛下其氣體崩潰電壓分別約為850 Vpp(10 kHz)及2400 Vpp(1 kHz)；以光學觀察其元件壽命，於氬氣電漿中以較溫和的電場條件下，壽命至少一個小時以上，旋轉溫度(Rotational temperature, Tr)約600 K；從外觀影像來看，電漿均勻且穩定地產生於圖案中。 第二個部分為將此系統應用於氣體轉化，以二氧化碳解離反應此一高吸熱可逆反應作為模型，並觀察其產物含量、電漿消耗功率及轉化效率。整體電漿消耗功率均小於2 W，產率約數十 mg/h，能源效率可達到11 %，其中能源效率不遜於文獻。於實驗結果中可發現，一氧化碳濃度皆比平衡轉化濃度高出許多，因此，吾人認為電漿於此反應類型中轉化率不受平衡常數的限制，並證明微電漿系統於氣體轉化方面具有一定的潛力。

In this study, a copper clad laminate (CCL) -based dielectric barrier discharge system was driven by a high voltage alternative current power supply. The device fabrication was proceeded by a low-cost toner transfer technology, 200 μm in the smallest planar size and 400 μm in the closest distance between patterns was obtained successfully. Low-temperature micro-discharge was ignited and sustained in the cavities stably under atmospheric pressure. The arrangement of the patterns can be the array-distributed circle, triangle and square, or the large aspect ratio linear discharges. In order to realize the characteristics of micro-discharges, electrical and optical diagnostics were used to characterize the properties of plasmas in the cavities preliminarily. We investigated that the current is discharged in the filamentary way and the gas breakdown voltage of argon on the devices under atmospheric pressure is about 850 Vpp(10 kHz). Moreover, the micro-discharges can be sustained beyond one hour via the micro-plasmas generation devices and in a uniform way from camera-captured image, the rotational temperature of this system was about 600 K. In second part, the CCL-based DBD system was applied in gas conversion. As the result, the dissociation of carbon dioxide (CO¬2) - the highly endothermic reversible gas reaction is chosen as our reaction model, the concentration of products, discharge power and the efficiency is analyzed primarily through variable experimental parameters. However the discharge was less than 2 watts throughout the experiment, the production of carbon monoxide (CO) was about tens of mg/h, and the efficiency can be reached as high as 11 %. Finally, it’s found that the concentration of CO obtained in the plasma process was larger than the equilibrium concentration of CO counts of order of magnitude, indicating that the plasma process benefit to get over the thermodynamic barrier, and plasmas is proved in an extremely potential way to gas conversion.