| 摘要: | 以傳統方法（熱力學）進行氨的合成時，須要大量的熱能（溫度範圍450-500℃）及壓力（壓力範圍100-300 bar），因此造成大量能源消耗及廢氣產生。本研究嘗試以高週波電漿技術（radio-frequency plasma technology）進行氨合成之研究，探討在低壓、低溫下高週波電漿中，氨合成之反應結果，以尋求低能量消耗進行氨合成之可行性，研究主要探討不同操作條件（輸入必v、反應物混合配比、反應物進流濃度、載流氣體及操作壓力等）對電漿中氨合成轉換率之影響。
研究結果顯示，H2進流濃度（Cin）對氨出流濃度（Cout）及氨產率（YNH3）影響最大，而H2進流濃度（Cin）與氨出流濃度（Cout）成正比，但與氨產率（YNH3）成反比。在能量效率方面則以輸入必v影響最大，但輸入必v越大者其能量效率越低。輸入必v120W，N2:H2混合比例1:3，H2進流濃度50 %，無載流氣體，操作壓力15 Torr時有最佳的氨出流濃度Cout，約為0.14 %。輸入必v150 W，N2:H2混合比例1:0.23，H2進流濃度12.5 %，無載流氣體，操作壓力10 Torr時有最佳的氨產率YNH3，約為0.73 %。輸入必v60W，N2:H2混合比例1:0.6，H2進流濃度25 %，無載流氣體，操作壓力10 Torr時有最佳的能量效率ENH3，約為0.34 mole kW-1h-1。在無載流氣體條件下於低進流濃度時不管在氨產率、氨出流濃度及能量效率方面幾乎為載流氣體選用Ar的二倍。
Application of radio-frequency (RF) plasma for synthesis of ammonia (NH3) was demonstrated. Experiments were conducted to elucidate the effects of operational parameters, input power, feeding ratio, H2 feeding concentration (Cin), carrier gas and operational pressure, on NH3 effluent concentration (Cout), NH3 yield (YNH3) and engry efficiency (ENH3) for synthesis of NH3. Furthermore, the possible reaction pathways of NH3 synthesis and decomposition in the RF plasma system were built-up. The study tried to provide an alternative, more energy-saving, for NH3 synthesis in the RF plasma system.
The results showed that the H2 feeding concentration was the relative important operational parameter for Cout and YNH3. Cout increased with the increasing H2 feeding concentration (Cin), but YNH3 decreased with the increasing H2 feeding concentration (Cin). Additionally, ENH3 increased with the decreasing input power, the relative important operational parameter in the energy efficiency analysis. Cout reached the maximum of 0.14 % at input power of 120 W under the condition: feeding ratio of 1 : 3, H2 feeding concentration (Cin) of 50 %, without carrier gas Ar and operational pressure of 15 Torr. YNH3 reached the maximum of 0.73% at input power of 150 W under the condition: feeding ratio of 1 : 0.23, H2 feeding concentration (Cin) of 12.5%, without carrier gas Ar and operational pressure of 10 Torr. Moreover, ENH3 reached the maximum of 0.34 mole kW-1h-1 at input power of 60 W under the condition: feeding ratio of 1: 0.6, H2 feeding concentration (Cin) of 25 %, without carrier gas Ar and operational pressure of 10 Torr. The results will provide fundamental information for applying the technique for NH3 synthesis in the RF plasma system and a basic guide to improve the future experiments. |
