利用衝擊波管研究3,1CH2 + O2與CH3CHO的高溫反應動力學

Abstract

我們利用活塞型衝擊波管‐分子共振吸收光譜（MRAS）技術來研究1.溫度2000 K時3,1CH2 + O2反應與2.溫度範圍1391至1547 K下CH3CHO的熱解動力學。使用動力學模擬軟體Chemkin及Senkin適解由實驗測得的CO分子濃度變化，進而得到在該反應條件下的速率常數與反應分支比。 1.3,1CH2 + O2在2000 K其反應途徑的分支比： H原子產生途徑CO + OH + H、CO2 + 2H與HOCO + H佔分支比0.65 O原子產生途徑CH2O + O佔分支比0.29 CO分子產生途徑CO + OH + H與CO + H2O佔分支比0.06 其它途徑：CO2 + H2與HCO + OH佔分支比趨近於0 2.CH3CHO在1391-1547 K其熱解結果： CH3 + CHO途徑分支比為0.72 CH4 + CO途徑分支比為0.28 其它途徑：H2CCO + H2、CH3CO + H與CH2CHO + H佔分支比趨近於0 將所得實驗數據以修正型Arrhenius方程式 [ k = TnAexp(-E/RT) ]適解，配合文獻 [1] [2]已知值共同繪製於圖（5-18）。1391-1547 K的反應速率常數為k(T, 2 atm) = (6.9 ± 4.3) × 1013 exp[(-31300 ± 5500)/T] s-1。

A diaphramless shock tube coupled with molecular resonance absorption spectroscopy (MRAS) was employed to study the kinetics of the reactions of triplet & singlet methylene with oxygen at 2000 K and thermal decomposition of acetaldehyde between 1391 and 1547 K. Kinetics softwares Chemkin & Senkin were used to fit the experiment data to obtain the reaction rate constants and branching ratios. 1.Branching channel of 3,1CH2 + O2 at 2000 K： Hydrogen atom producing channel ratio is 0.65. (Channels CO + OH + H, CO2 + 2H and HOCO + H are included.) Oxygen atom producing channel ratio is 0.29. (Channel CH2O + O is included.) Carbon monoxide producing is a minor channel with a 0.06 ratio. (Channels CO + OH + H and CO + H2O are included.) Others approach to 0 ratios. (Channels CO2 + H2 and HCO + OH are included.)

2.Branching channel of CH3CHO decomposition at 1391-1547 K： CH3 + CHO production channel is the major with a 0.72 branching ratio. CH4 + CO is the minor product with a branching ratio of 0.28. Others approach to 0 ratios. (Channels H2CCO + H2, CH3CO + H and CH2CHO + H are included.)

All the experiment data were fitted to the modified Arrhenius form[ k = TnAexp(-E/RT) ] and plotted in figure (5-18) with literature values. We obtained Arrhenius form between 1391-1547 K k(T, 2 atm) = (6.9 ± 4.3) × 1013 exp[(-31300 ± 5500)/T] s-1.