| 摘要: | 大氣中的NOx是嚴重的污染源，除了會導致光煙霧及酸雨的形成，並會造成臭氧層的破壞與溫室效應的危害。因此，關於含氮化合物的反應機制、動力學常數，將會作一系列的相關研究與探討，期能克服目前嚴重的環境污染窘境。隨著人類社會大量使用煤和石油等化石燃料，CO2氣體排放量急遽攀升，並因此導致了溫室效應以及引發了一系列與人類生活環境問題，迫在眉梢的環境問題對於全球各地的實驗家與理論科學家形成了嚴峻的挑戰。再者，近年來基於很多因素，氫氣成為人類想要獲得的燃料。最重要的原因，是氫氣最不具有污染性，可以利用於內燃機方面，除此之外，亦可用於高效能的氫氣/氧氣之燃料電池以產生電力。然而，在地球上沒辦法找到可直接使用的氫氣，因此它的複雜合成方式成為目前熱門的研究方向。而利用氨氣的分解直接轉化成氫氣，正是目前相當熱門的研究主題。所以，此三年期的研究計畫所要探討的主要目標，是去尋找某個反應物或是金屬催化劑(奈米金屬團簇或是金屬表面)，可以使NOx和CO2等大氣污染物轉變成無污染且相當穩定之氣體–N2或是O2，或是能把NH3氣體分解成乾淨的能源–H2，並且都有著很低的反應能障就可達成。而我們所選用之反應物，為一些含cyanogen的分子，例如: HCCN, HCNC, HNCC, HNCN, 和 HCNN, …等。而選擇具有催化效應的材料，則採用一些特定的奈米金屬團簇或是金屬表面，例如: Fe, W, Cr, Ru, Rh, Ni, Cu, 和Au…等，並探討其對於 NOx和CO2等大氣污染物能否作進一步的分解，或是能把NH3氣體轉換成有用處的H2。故此三年期的計畫，我們將利用理論計算的方式，針對各氣體分子(NOx, CO2與NH3)的反應機制、吸附結構、反應速率常數，以及詳細的電子性質分析，作進一步的探討與研究。至於找出何種反應物、奈米金屬團簇或是金屬表面，可以達到預期的最佳效果，那就是本研究計畫所要探討的重要目標。
Atmospheric nitrogen oxides (NOx) play an important role in the formation of photochemical smog and acid-rain precursors, the destruction of ozone in the stratosphere, and possibly in greenhouse effect. Therefore, the reaction mechanisms and rate parameters for reactions involving nitrogen compounds should be extensively investigated right now in relation to such air pollutants. Moreover, another notorious gas—carbon dioxide (CO2), which was believed to contribute the most well-known “greenhouse effect” to our environment, has been of interest to experimentalists and theoreticians recently. Furthermore, hydrogen is considered to be a desirable fuel for several reasons, among which hydrogen is the least polluting fuel to be used in an internal–combustion engine, and it can also react in a highly efficient hydrogen/oxygen fuel cell to produce electricity. Hence, the hydrogen generated from straightforward decomposition of ammonia (NH3) represents an attractive alternation to hydrocarbons for fuel cells right now. The purposes of this three years project is to find the possible reactants, metal nanoparticles, and metal surfaces that might react with NOx, CO2 and NH3 gases to form a stable products such as N2, O2 gases, which are not harmful to our environment, and to form hydrogen gas, which is an important clean fuel for industrial application. For the possible reactants, we will choose some cyanogen species (such as several cyanogen species: HCCN, HCNC, HNCC, HNCN, HCNN, …etc.). For metal nanoparticles and/or metal surfaces (such as Fe, W, Cr, Ru, Rh, Ni, Cu, and Au…etc.), will be also used herein as model catalysts to study the NO2, CO2 and NH3 decomposition mechanisms. We will investigate the adsorption behavior, reaction mechanisms, rate constants, and detailed electronic analysis of the aforementioned reaction systems. As to which reactants, metal nanoparticles and metal surfaces could do the best work, as well as the understanding of the complicated reaction mechanisms will be the main task that we need to overcome in this project. |
