氣相B, Al, Ga原子分別與 N2O，CO2，NO2分子反應機構的理論計算研究

Theoretical Studies of Recation Mechanisms of Gas B, Al and Ga atoms with N2O, CO2, NO2 molecules

徐淑娘(Shu-Liang Hsu)

指導教授 ： 何嘉仁

國立臺灣師範大學/理學院/化學系在職進修碩士班/碩士(2012年)

摘要

人類的農、工、商活動，貢獻了大量的二氧化碳及一氧化二氮，這些迅速增加的氣體造成溫室效應，導致全球氣候異常；另一個因交通運輸及燃燒過程伴隨生成的污染物二氧化氮，影響生物的健康也不容小覷。本篇研究的目的為找出適當之反應物，並透過能障很低的反應機構，來使N2O、CO2、NO2轉變成穩定且無污染或低污染之氣體；我們也將此三種系統的反應性做比較，並提供可能的解釋。
我們使用Gaussian 03套裝軟體來完成理論計算，先以DFT (Density Functional Theory)使用B3LYP/6-311+G(3df)做結構的最佳化，更進一步做CCSD(T)/aug-cc-PVQZ單點計算。結果顯示氣相B、Al、Ga當起始反應物，分別與N2O 、CO2 、NO2進行反應，三個系統中，皆是以B的反應性最佳，可進行的反應路徑最多(包含Insertion)，且放出的能量也最多，Al次之， Ga的反應性最差。
依據Mulliken DA(donor-acceptor) 的理論，推論電子是從金屬轉移到氣體N2O 、CO2 、NO2分子中，形成金屬原子與這些氣體分子中charge為正電的原子相結合，其中間產物往往也最穩定。
此外，氣相B、Al、Ga當起始反應物，與N2O 、CO2 、NO2進行反應，以NO2 的反應性較多變化，而要將穩定的CO2活化，其反應性最差；只有在N2O系統的反應，才會在不需能障的情形下，將N2O降解生成無害的氣體N2，若在CO2 和NO2系統中要生成無害的氣體O2，皆是能障很高的反應，但仍可達成將CO2 和NO2降解成NO及CO氣體。

關鍵字

DFT計算 ； B ； N2O ； CO2 ； NO2

並列摘要

Human agricultural, industrial and commercial activities, contributed a large amount of carbon dioxide and nitrous oxide, the rapid increase in greenhouse gases, causing global climate anomalies. Another result of transportation and combustion generated pollutants nitrogen dioxide, affect the biological health can not be underestimated. The purpose of this study was to identify the appropriate reactants, and through the low barrier reaction mechanism, to convert N2O, CO2, NO2 into a stable and non-polluting or less polluting gases. We also apply the reactivity of the three systems to compare, and provide possible explanations. We use the Gaussian 03 software package to complete the calculation, First, we using the DFT (Density Functional Theory) at the level B3LYP/6-311 + G (3df) for structural optimization, and then CCSD (T) / aug-cc-PVQZ single-point calculations. The results showed that among gaseous B, Al, Ga atoms , reacting with N2O, CO2, NO2 ,respectively, boron is the most effective in most reaction paths, and aluminum is in the middle and gallium is the least effective toward all these reactants. According to Mulliken DA (donor-acceptor) of the theory, we conclude that electrons are transferred from the metal to the polluting gases N2O, CO2, NO2 molecules.
In addition, the three systems (B, Al, Ga) reacting with N2O, CO2 and NO2 , in which the NO2 is more reactive and has more reaction pathways, while CO2 is less reactive due to its strong stability; N2O may be converted into N2 with barrier-less pathway. Although it is almost impossible to directly convert the CO2 or NO2 into O2, it is possible to convert them into CO and NO.

並列關鍵字

DFT calculation ； B ； N2O ； CO2 ； NO2

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